Application of Volumetric Absorptive Microsampling (VAMS) for the simultaneous determination of cadmium and lead in blood

Application of Volumetric Absorptive Microsampling (VAMS) for the simultaneous determination of cadmium and lead in blood | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Application of Volumetric Absorptive Microsampling (VAMS) for the simultaneous determination of cadmium and lead in blood Claus Gutknecht, Alexandra Burianova, Stephan Bose-O’Reilly, Stefan Rakete This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7251995/v1 This work is licensed under a CC BY 4.0 License Status: Under Revision Version 1 posted 9 You are reading this latest preprint version Abstract Background Cadmium (Cd) and lead (Pb) are environmental pollutants with toxic effects on humans. This study evaluates the applicability of Volumetric Absorptive Microsampling (VAMS) as an alternative sampling method for the simultaneous biomonitoring of Cd and Pb in blood of humans without occupational exposure. Methods VAMS and blood samples were collected from 87 participants. Of these, 60 VAMS sets were used as supplied by the manufacturer and 27 VAMS sets were washed with 0.5% nitric acid before the sampling to reduce the background contamination. The samples were extracted (VAMS) or diluted (venous blood) with 0.5% nitric acid prior to analysis by ICP-MS. Results Mean recovery rates for Cd and Pb were 104% and 100% using untreated VAMS, and 116% and 110% with prewashed VAMS, respectively. A strong correlation was found for venous blood and unwashed VAMS samples (Cd ρ = 0.85; Pb ρ = 0.94). The correlation was improved when pre-washed material was used (Cd ρ = 0.91; Pb ρ = 0.97). Without washing, the limits of quantification (LOQ) were 0.55 µg/l for Cd and 17.17 µg/l Pb. Washing of VAMS devices lead to a significant reduction of the contamination, especially for Pb. The resulting LOQ were 0.46 µg/l for Cd and 2.19 µg/l for Pb. Conclusion Despite challenges like the background contamination, VAMS is a promising alternative sampling method for human biomonitoring of Cd and Pb in blood. This study also demonstrates the benefits of washing VAMS to reduce background contamination. Cadmium Lead Human Biomonitoring VAMS Volumetric Absorptive Microsampling ICP-MS Figures Figure 1 Figure 2 Figure 3 Introduction Cadmium (Cd) and lead (Pb) are toxic to plants, microorganisms, and animals, including humans. A wide range of effects and diseases are associated with the exposure to these metals (Genchi et al., 2020 ; Tempowski & World Health Organization, 2021; WHO, 2019 ). Both elements are classified as persistent environmental pollutants as they are not metabolized or transformed into less toxic forms and bioaccumulate (UNEP, 2010 ; WHO, 2019 ). Traces of Cd and Pb can be found almost anywhere in the environment. Both metals accumulate in the body, e.g., in tissue and bone. An exposure assessment via blood is suitable to reflect recent exposure from exogenous sources (Adams & Newcomb, 2014 ; Tempowski & World Health Organization, 2021). Venipuncture is the gold standard blood sampling method for the analysis of Cd and Pb in blood (Adams & Newcomb, 2014 ; Breton et al., 2023 ). However, this sampling method bears relatively high logistical costs. It requires medically trained personnel and the samples need a constant cold chain while transported or stored, which exuberates the challenges for human biomonitoring in remote or structurally weak regions (Basu et al., 2017 ; Guerra Valero et al., 2018 ; Jacobson et al., 2022 ; Lehner et al., 2013 ; Schweizer et al., 2021 ). Microsampling methods in contrast offer a less complex and minimally invasive alternative (Williams & McDade, 2009 ). Rather small blood volumes (10 to 50 µl) are taken by finger or heel prick with a lancet. The capillary blood is blotted on filter paper (Dried Blood Spots -DBS) or wicked on special microsampling devices (e.g., Volumetric Absorptive microsampling - VAMS). After drying, samples can be packed for storage at ambient temperatures, thus elimating the need for a cold chain. Microsampling can be performed by non-medically trained personnel and is potentially suitable for the self-collection of samples (Allen et al., 2018 ; Sullivan et al., 2020 ). In addition, other studies show a very high acceptability and willingness of participants to provide microsamples (Andrew et al., 2022 ; Williams & McDade, 2009 ), which is essential for biomonitoring studies or for monitoring purposes in occupational settings. DBS sampling is widely used in numerous applications, including the potential use in biomonitoring for some heavy metals in blood, as Schweizer demonstrated for mercury (Hg) (2021). Studies that used DBS for the quantification of Cd and Pb levels in blood found background levels in the sampling material that exceeded the blood levels of non-exposed participants in the analyte (Chaudhuri et al., 2009 ; Funk et al., 2013 ). Therefore, quantitation of Pb and Cd was not possible. A second drawback of this method is the hematocrit dependency, meaning the hematocrit content, and thus the blood viscosity, affects the blood volume per surface area absorbed by the filter paper and consequently the amount analyzed for quantification (Breton et al., 2023 ; Chaudhuri et al., 2009 ; Demirev, 2013 ; Spooner et al., 2015 ). The VAMS method on the other hand promises an accurate volume sample collection, independent of the hematocrit (Protti et al., 2019 ; Spooner et al., 2015 ). The VAMS method uses hydrophilic polymer tips, attached to a plastic handle, which allows a rather easy and convenient sample collection (Denniff & Spooner, 2014 ; Spooner et al., 2015 ). The tip absorbs a fixed volume of blood by wicking. Until recently, VAMS application has mainly been used in monitoring drug molecules, analyzing peptides and proteins, forensic analysis of drugs, syndrome screening and anti-doping testing, in blood and other specimens (Protti et al., 2019 ; Protti et al., 2021 ; Verstraete & Stove, 2021 ). To our knowledge, VAMS has only been used in a limited number of studies for trace metal analysis in human blood. It has been used to quantify prosthesis-related metals (Al, Ti, V, Co, Cr, Ni, Sr, and Zr) (Bolea-Fernandez et al., 2016 ), Hg (Koutsimpani-Wagner et al., 2022 ), Pb (Breton et al., 2023 ), and recently a wider range of essential and toxic trace elements (Al, As, Cd, Cr, Co, Cu, Hg, Mn, Mo, Pb, Se, U, Zn) (Breton et al., 2024 ). Another study explored its potential using VAMS devices spiked with reference materials (As, Be, Cd, Cs, Cu, Fe, Mg, P, Pb, S, Sb, Se, Tl, V, and U) (Schmidt et al., 2024 ). Although VAMS has been used for the simultaneous biomonitoring of Cd and Pb under field conditions in one study (Breton et al., 2024 ) ours demonstrates significantly lower Limits of Quantification (LOQ). The goal of this study was to develop and validate a simultaneous Cd and Pb biomonitoring method using VAMS in combination with ICP-MS analysis, as well as exploring the potential of pre-washing the materials prior to use. Materials and methods Materials and reagents Nitric acid Optima™ (67–69%) for ultra trace elemental analysis was obtained from Fisher Scientific (Leicastershire, UK). Ultrapure water (resistivity > 18.2 MΩcm) was provided from a Direct-Q® 3 UV Water Purification System from Merk Millipore (Darmstadt, Germany). ICP-MS Stock Tuning Solution (10 µg/l Ce, Co, Li, Tl, Y), Internal Standard Mix (10 µg/l Bi, Ge, In, Li, Sc, Tb, Y) and Environmental Calibration Standard (1000 µg/l Ca, Fe, K, Mg, Na, 10 µg/l Ag, Al, As, Ba, Be, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Sb, Se, Th, Ti, U, V, Zn) from Agilent (Santa Cruz, USA) were used. Certified reference material for whole blood (ClinCheck®, Level I, 1.58 µg/l Cd; 37.6 µg/l Pb) was obtained from RECIPE (Munich, Germany). The VAMS Mitra™ microsampling devices (sample volume 23.6 µl and 24.6 µl, respectively per tip) were obtained from Neoteryx LLC (Torrance, USA) and consisted of 4 VAMS tips per holder (clamshell). Original clamshells were replaced by custom made, 3D printed clamshells made from polylactide (PLA) filaments, obtained from Form Futura (Nijmegen, Netherlands). Venous blood was collected into Li-Heparin-coated S-Monovette® 7.5 ml tubes for trace metal analysis (Sarstedt®) by venipuncture. For fingerpricking, we used disposable lancets (Solofix) from B. Braun (Melsungen, Germany). Clamshells containing the samples were stored in aluminum-coated mylar ziplock bags (12x20 cm). Study design This study was reviewed by the ethics committee of the Ludwig Maximilians University of Munich (#20–091) and conducted according to The Code of Ethics of the Declaration of Helsinki for human experiments. All participants signed an informed consent form prior to sampling and were asked to fill out a questionnaire about possible Cd and Pb exposure. Paired venous and capillary blood samples were collected from consenting, occupationally non-exposed, adult human subjects at the Clinic for Occupational, Social and Environmental Medicine, University Hospital, LMU Munich. Within six weeks (January 11 to February 23, 2023), 60 paired samples were collected using VAMS devices as supplied by the manufacturer. In a subsequent sampling phase (December 18, 2023, to January 24, 2024), an additional 27 paired blood samples were collected under identical conditions, using VAMS devices that had been pretreated to reduce background contamination. Sample collection Approximately 7 mL of blood was collected from each participant by venipuncture. Samples were stored at -20°C until analysis. VAMS sampling devices were prepared in batches of four per clamshell. For each participant, a separate clamshell was used. After finger pricking, three sampling devices were used to collect three separate capillary blood samples per subject. The fourth device was left empty to quantify background Cd and Pb levels. To avoid sample contamination, the capillary blood collection followed a strict protocol. Participants were asked to thoroughly wash their hands and dry them with disposable paper towels. The finger to be pricked was disinfected and kept untouched until airdried. Pricking was done in the fingertip with a disposable lancet. The first drop of blood was wiped away with sterile gauze. If necessary, blood flow was stimulated by gently massaging the finger towards the tip, creating a blood stasis, without applying too much pressure next to the pricked area to avoid sample dilution by tissue fluid. In some cases, a second prick was performed to collect enough blood. To ensure a constant blood volume collected, the polymer tips were just slightly touching the blood drop at the finger without submerging it as recommended by the manufacturer (Neoteryx, 2022 ). Subsequently, the samples were placed upside down within the slightly opened clamshell in a desiccator and dried for at least two hours. Finally, the clamshells were packed in aluminium-coated mylar zip-lock bags, which were additionally thermally sealed at the site of collection. VAMS samples were stored at room temperature until analysis. Pretreatment of VAMS to reduce background contamination A separate batch of VAMS devices was washed in 0.5% nitric acid in an ultrasonic bath for 45 minutes at 60°C and subsequently rinsed in ultrapure water for 15 minutes under the same conditions. VAMS devices were washed upside down, with their tips submerged in the washing solution and subsequently dried in a desiccator overnight. These VAMS devices were then used as described above to collect samples from 27 participants. Potential changes in the blood wicking capability due to the pretreatment were assessed using eight pre-washed and eight unwashed VAMS. This assessment involved weighing the devices individually before and immediately after sampling capillary blood from the same volunteer. Instrumentation For sample analysis, an 8900 Triple Quadrupole ICP-MS with an Integrated Autosampler (I-AS) from Agilent (Santa Cruz, USA) was used. All samples were fed to the ICP-MS in 2 ml polystyrene sample cups obtained from WICOM Germany (Heppenheim, Germany). We tuned the instrument daily to achieve optimum sensitivity, oxide ratio and doubly charged ratio. The ICP-MS/MS operating conditions were as follows: RF power: 1600 W; plasma gas flow: 15 l/min; nebulizer gas flow: 0.82 l/min (venous blood) or 1.05 l/min (VAMS); auxiliary gas flow: 0.9 l/min; dilution gas: 0.15 ml/min (only venous blood), replicates: 3, sweeps/replicate: 30. We ran all analyses in single quadrupole mode and used helium as collision gas (5.5 ml/min) to reduce polyatomic interferences. 111 Cd and 206+207+208 Pb were quantified using an external calibration. As internal standard, we used 159 Tb. Sample Preparation Analysis of venous blood samples were carried out as a simple dilute and shoot process. After thawing the samples on a roller mixer, 50 µl of venous blood were diluted twentyfold with 0.5% nitric acid containing 10 µg/l Tb as internal standard and directly analyzed by ICP-MS. Analysis was carried out in triplicate. For quality assurance, certified reference material was analyzed at the beginning of every sample batch. For VAMS analysis, each polymer tip (three capillary blood samples plus one blank per participant) were placed in a 2 ml Safe-Lock EPPENDORF TUBES ® (Hamburg, Germany), each without any contact to devices or surfaces, by gently pinching the tip with the tube's lid, while removing the handle to avoid contamination or transfer between the samples. Extraction was done in 700 µl 0.5% nitric acid containing 10 µg/l Tb as internal standard in an ultra-sonic bath (Sonorex Super RK 103 H from Bandelin, Berlin, Germany) for 45 minutes at 40°C and subsequently centrifuged at 13,000 rpm for 5 minutes using a Galaxy 16 DH from VWR (Darmstadt, Germany). 650 µl of supernatant were used for ICP-MS analysis. For quality assurance, certified reference material was applied to VAMS and treated like regular VAMS blood samples. Storage stability of Cd and Pb in VAMS VAMS samples were stored inside the 3D-printed clamshells (Fig. 1 ) , which then were thermally sealed in plastic ziplock bags at room temperature. Storage time is randomly distributed between 14 and 42 days for the initial and 14 to 51 days for the subsequent series, which resulted from the availability of participants and time of analysis. Statistical analysis and data processing Data processing was carried out using Microsoft Excel 2023 Version 16.78.3 for Mac. Statistical analysis was performed using R Studio Version 2023.03.1 + 446 for Mac, utilizing R version 4.3.0. For the initial series, using untreated VAMS devices as provided by the manufacturer, employing sampling material from two different batches with distinct LOT numbers (74918 and 76327). Devices from the second batch (LOT:76327) showed high and unevenly distributed Cd levels. Therefore, these samples (six) were excluded from further statistical analysis. Out of the remaining 54 paired samples, two more were excluded from further analysis due to a handling mistake which caused potentially corrupted values. For the sampling using pretreated VAMS devices from a third batch (LOT: 95222) were used. Venous blood levels were calculated as the mean of the three individual values per subject and represent the reference blood Cd and Pb levels (gold standard method). VAMS Cd and Pb levels were calculated the same way, with an additional exclusion criterion, correcting for potentially contaminated samples and a separate adjustment for background contamination. If the relative standard deviation (RSD) of the three individual values exceeded 30%, the highest reading was deleted as potentially contaminated. If the RSD remained above 30% for the remaining two values, the participant was excluded from the study. 51 paired samples from the initial series met these criteria and were used for statistical analysis. In the subsequent series, 25 out of 27 paired samples were used for statistical analysis. The RSD for Cd in one participant exceeded the acceptable limit, leading to the exclusion of this sample. However, an exception to the established RSD threshold of 30% was made in one case where contamination was evident despite the RSD values being marginally below this limit. In this case, two out of three VAMS devices showed unusually high Cd and Pb levels, suggesting an anomaly likely due to contamination. Although the RSD for this sample did not exceed the predefined threshold, the evident disparity between the devices prompted their exclusion to preserve the integrity of the data analysis [1] . In a first step, apparently contaminated blank values, exceeding the maximum venous blood levels, were excluded [2] . In a second step, blank values exceeding 3 times the standard deviation (SD) got excluded from further calculations as potentially contaminated as well, resulting in 49 blank values for Cd and 47 for Pb remaining in the initial series. In the subsequent series, this criterion led to the inclusion of 26 blank values for Cd and 23 for Pb. The resulting mean blank values for each series were then subtracted from each VAMS sample values to adjust for background contamination, resulting in the finally used values. Subtracting the mean blank value from the VAMS reading showed overall better fit then subtracting the individual sample blank value, as the background contamination is randomly distributed and not clamshell specific. Limits of detection (LOD) and limits of quantitation (LOQ) were defined as three- and ten-times the SD of the blank levels. Recovery was used as a measure of accuracy, calculated from the corresponding VAMS and venous blood samples ( \(\:recovery=\frac{{Cd}_{VAMS}}{{Cd}_{VB}}*100\:\%;\:recovery=\frac{{Pb}_{VAMS}}{{Pb}_{VB}}*100\:\%)\) . The relative standard deviation of the three (respectively two) corresponding VAMS values was used as a measure for precision. The correlation is represented by Spearman Rho, Passing-Bablok regression and Cusum test for linearity. Results are graphically displayed by the Passing-Bablok regression graphs. Bland-Altman plots are used to visualize the bias between the methods. Storage stability was tested by a linear model (storage time ~ recovery). Statistical analysis was performed separately for each series by using identical methods and parameters. The wicking capacity of pretreated VAMS was controlled with a two-sided t-test at the 0.05 alpha level. Results and Discussion Venous blood results Cd and Pb levels in the initial series ranged from 0.086–1.14 µg/l and 4.57–43.13 µg/l respectively, with a mean of 0.32 µg/l for Cd (median: 0.24 µg/l) and 11.14 µg/l for Pb (median: 9.76 µg/l). For the subsequent series, Cd and Pb levels ranged from 0.06–1.34 µg/l and 5.28 to 49.77 µg/l respectively, with a mean of 0.40 µg/l for Cd (median: 0.25 µg/l) and 13.01 µg/l for Pb (median: 11.00 µg/l). The 95th percentiles of all participants were 1.16 µg/l for Cd and 21.04 for Pb. The Pb levels observed are consistent with those reported by the Human Biomonitoring Commission of the German Environment Agency among students in Münster between 2010 and 2015, which found a median Pb level of 11.7 µg/l and a mean of 13.2 µg/l in blood (Kommission Human-Biomonitoring des Umweltbundesamtes, 2019 ). The most recent representative study, GerES III from 1998, reported significantly higher levels of Cd and Pb due to the expected reduction in exposure of the last decades (Becker et al., 2002 ; Vogel et al., 2021 ). VAMS background contamination Compared to the DBS material used by Chaudhuri (2009), VAMS provides significantly lower background contamination for Cd and Pb (detailed information in Table 1 ), the tradeoff being an increased standard deviation for Pb. Furthermore, the background contamination varied heavily between manufacturing batches. For the initial series the LOD were 0.16 µg/l for Cd and 5.15 µg/l for Pb in VAMS. The LOQ were 0.55 µg/l for Cd and 17.17 µg/l for Pb. The relatively high LOQ is the main limitation, bottlenecking the method´s potential when used as supplied by the manufacturer. The results of the pre-washed blanks show significantly lower background levels and a lower SD for Cd and especially Pb. This results in LOD and LOQ levels at 0.14 and 0.46 µg/l for Cd and 0.66 and 2.19 µg/l for Pb respectively (detailed results compared to other studies in Table 1 ). Hence, VAMS is a suitable alternative for exposure assessment even at background exposure levels. Results of the t-test show no statistically significant changes in the wicking capacity caused by pre-washing the VAMS devices before use. Table 1 VAMS blank results vs. other studies using VAMS Cd Pb Mean level µg/l SD LOD µg/l LOQ µg/l Mean level µg/l SD LOD µg/l LOQ µg/l unwashed 0.074 0.055 0.16 0.55 3.72 1.72 5.15 17.17 pre-washed 0.054 0.046 0.14 0.46 0.43 0.22 0.66 2.19 Breton et al. ( 2023 ) NR NR NR NR NR NR 1.66 5.59 Schmidt et al. ( 2024 ) < 0.06 NR 0.18 0.60 3.03–6.57 NR 3.06 10.1 Breton et al. ( 2024 ) < 0.0001 NR 0.17 0.56 1.99 NR 4.35 14.50 NR: not reported Correlation between venous blood and VAMS samples The main objective of this study was to evaluate the applicability of VAMS as an alternative method for biomonitoring purposes. Hence, the recovery, as a measure of accuracy, serves as the pivotal quality criterion. Mean recovery rates showed excellent results for both elements in the initial series (Cd: 103.9%; Pb: 100.2%) and good precision (mean RSD, Cd: 12.9%; Pb: 7.6%). For Cd, recovery rates ranged from 28 to 170%, and 68–129% for Pb. Even considering the wide range for Cd, most of the 51 samples for both elements were within the desired range of 70 to 130% (Cd: n = 39, 76.5%; Pb: n = 50, 98.0%), as outlined in Table 2 . Table 2 Summary VAMS performance Mean recovery Mean RSD Spearman- Rho Adjusted R 2 p Passing- Bablok Slope Passing- Bablok Intercept n recovery 70–130% Cd unwashed 103.9% 12.9% 0.846 0.931 < 0.001 1.12 -0.026 39 (76.5%) Pb unwashed 100.2% 7.6% 0.937 0.974 < 0.001 1.06 -0.62 50 (98.0%) Cd pre-washed 116.4% 15.7% 0.905 0.972 < 0.001 1.15 0.001 18 (72.0%) Pb pre-washed 110.1% 6,9% 0.978 0.992 < 0.001 1.00 0.74 24 (96.0%) The pre-washed series showed satisfying results as well, regarding accuracy and precision, with a slightly increased recovery (mean recovery: Cd: 116.4%, Pb: 110.1%; mean RSD: Cd: 15.7%, Pb: 7.0%). A similar proportion were within range of 70 to 130% (Cd: n = 18, 72.0%; Pb: n = 24, 96.0%). The increased recovery rate may be attributed to batch-specific variations in the blood volumes absorbed by the VAMS material. However, this was not tested. The scattering of recovery rates, just like the rather high LOQ in the initial series, can be explained by the presence of randomly distributed background levels within the VAMS devices. Contaminations of the samples while handling and analysis might be attributed to both series. Both elements are ubiquitous in nature e.g., in airborne dust particles. VAMS devices are supplied in non-sealed clamshells within a cardboard box, rendering them susceptible to contamination. This susceptibility extends due to the openly handled, rather small blood volumes of microsamples, which is especially critical for Cd due to the extremely low concentration in blood of occupationally non-exposed participants. As evident from the Bland–Altman plots (Fig. 2 ), both methods are comparable and in good agreement with each other. 48 for Cd and 49 for Pb out of 51 samples from the initial series were within the 95% confidence interval. Overall, Cd and Pb levels in VAMS samples were on average 0.015 µg/l and 0.035 µg/l higher respectively than the corresponding Cd and Pb levels in venous blood. The very low bias accounts for proper background compensation. Notably, no significant trend conditioned by Cd or Pb levels in blood is present, signifying a proper linearity. The results of the subsequent series using pre-washed VAMS are qualitatively comparable, albeit with a slightly increased bias reflecting the enhanced recovery. 24 for Cd and Pb out of 25 samples for Pb fall within the 95% confidence interval. Cd and Pb levels in VAMS samples from this series are on average 0.053 µg/l and 0.88 µg/l higher respectively, than in venous blood. The correlation of Cd and Pb levels in venous blood versus those in VAMS samples for the initial series are in very good agreement. For Cd we identified a strong correlation (ρ = 0.85, p < 0.001 Spearman-Rho) and a very strong one for Pb (ρ = 0.94, p < 0.001 Spearman-Rho), with both elements exhibiting correlations even below the calculated LOD/LOQ. The results for Pb align with those of Breton et al. ( 2023 ). Due to the reduced background contamination, the correlation of the sequential series is significantly higher (Cd ρ = 0.91, p < 0.001; Pb ρ = 0.98, p < 0.001). Passing-Bablok regression analysis further validated these findings for both series. For both elements, the 95% confidence intervals of the intercepts encompass 0, implying the absence of systematic differences. Moreover, no proportional differences between the methods are evident, as the 95% confidence intervals for the slope of both elements encompass 1 (Fig. 3 ). Linearity and model stability are confirmed by the Cusum test at an alpha level of 0.05. Storage stability of VAMS samples Storage stability was assessed by a linear regression model (storage time ~ recovery). No statistically significant correlation for neither series (0.05 alpha significance level) was observed between the time stored and the recovery rate for both elements (storage time between 14 and 42 days for the initial and 14 to 51 days for the subsequent series) suggesting sample stability for at least seven weeks. Strengths and limitations of the study This study confirms the applicability of VAMS in human biomonitoring for the simultaneous analysis of Cd and Pb in blood compared to venipuncture as a gold standard under field conditions. We were also able to improve the sensitivity for Pb and thus detect background levels in low-exposed individuals. Furthermore, our study contributes towards a wider applicability of this novel method, which promises convenient sample collection, higher acceptability, and compliance of probands and lower logistical costs. Additionally, we were able to showcase solutions to circumvent drawbacks of this method by collecting samples in triplicate and removing outliners by RSD, as well as washing the devices prior to use. A major limitation of the study is the high and unstable background contamination in combination with low levels of Cd and Pb due to an unexposed study population. Subsequently, 82% of samples were below the calculated LOQ for Cd and 92% for Pb. 24% of VAMS samples showed a Cd concentration below the LOD and 6% for Pb when the sampling devices were used as provided by the manufacturer. To overcome this, the pre-wash method used in our case reliably eliminates the majority of Pb contamination, but only a fraction of the corresponding Cd levels in the VAMS devices. However, 80% of samples were still below the corresponding LOQ for Cd. For Pb, none of the samples were below the LOQ, demonstrating the efficacy of the washing procedure. Conclusion This study evaluated the applicability of VAMS as an alternative blood sampling method for Cd and Pb biomonitoring of the general population. In conclusion, we were able to demonstrate that this sampling method produces reliable and accurate results and can therefore be used for Cd and Pb exposure assessment, with the limitation of relatively high LOQs when used as provided by the manufacturer. However, this can be compensated by pre-washing the sampling devices prior to use. Declarations Ethics approval The study was carried out in accordance with the Code of Ethics of the Declaration of Helsinki for experiments involving human subjects, as well as reviewed and approved by the ethics committee of the Ludwig Maximilians University of Munich (#20-091). Consent to participate Written informed consent was obtained from all individual participants included in the study. Consent for publication Not applicable. Competing Interests The authors declare that they have no competing interests. Funding This work received no external funding and was carried out using internal institutional resources of the Institute and Clinic for Occupational, Social and Environmental Medicine, LMU University Hospital, LMU Munich. Authors’ contributions Claus Gutknecht: conceptualization,sampling, sample analysis, data analysis, visualization, preparation of the original draft, writing - review and editing. Alexandra Burianova: sampling. Stephan Bose-O’Reilly : conceptualization, writing - review and editing. Stefan Rakete : conceptualization, methodology, funding acquisition, data analysis, writing - review and editing. Availability of data and materials Anonymized Cd and Pb levels in VAMS and venous blood samples as well as in blanks can be found in the supplementary information. Code availability Not applicable. Acknowledgments The authors would like to thank Stefan Gröbmair for performing the ICP-MS analysis. 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Quantification of arsenic, lead, mercury and cadmium in newborn dried blood spots. Biomarkers , 18 (2), 174-177. https://doi.org/10.3109/1354750X.2012.750379 Genchi, G., Sinicropi, M. S., Lauria, G., Carocci, A., & Catalano, A. (2020). The Effects of Cadmium Toxicity. Int J Environ Res Public Health , 17 (11). https://doi.org/10.3390/ijerph17113782 Guerra Valero, Y. C., Wallis, S. C., Lipman, J., Stove, C., Roberts, J. A., & Parker, S. L. (2018). Clinical application of microsampling versus conventional sampling techniques in the quantitative bioanalysis of antibiotics: a systematic review. Bioanalysis , 10 (6), 407-423. https://doi.org/10.4155/bio-2017-0269 Jacobson, T. A., Kler, J. S., Bae, Y., Chen, J., Ladror, D. T., Iyer, R.,…Funk, W. E. (2022). A state-of-the-science review and guide for measuring environmental exposure biomarkers in dried blood spots. J Expo Sci Environ Epidemiol , 1-19. https://doi.org/10.1038/s41370-022-00460-7 Kommission Human-Biomonitoring des Umweltbundesamtes. (2019). Aktualisierung der Referenzwerte für Blei im Blut von Erwachsenen: Stellungnahme der Kommission Human-Biomonitoring des Umweltbundesamtes. Bundesgesundheitsblatt Gesundheitsforschung Gesundheitsschutz , 62 (10), 1280-1284. https://doi.org/10.1007/s00103-019-03002-z Koutsimpani-Wagner, A., Quartucci, C., Rooney, J. P. K., Bose-O'Reilly, S., & Rakete, S. (2022). Mercury biomonitoring in German adults using volumetric absorptive microsampling. Environ Monit Assess , 194 (4), 315. https://doi.org/10.1007/s10661-022-09962-1 Lehner, A. F., Rumbeiha, W., Shlosberg, A., Stuart, K., Johnson, M., Domenech, R., & Langner, H. (2013). Diagnostic analysis of veterinary dried blood spots for toxic heavy metals exposure. J Anal Toxicol , 37 (7), 406-422. https://doi.org/10.1093/jat/bkt048 Neoteryx. (2022). Blood sample collection kit instructions . Retrieved 24th October from https://www.neoteryx.com/hubfs/Mitra%20IFUs%20Dec%202022/IFU-017-0622_071422.pdf?hsCtaTracking=cc7286da-83cf-48d3-9cd7-a24462d039a0%7C45ca505a-4a3c-459b-8ccd-af45e6cd7b36 Protti, M., Mandrioli, R., & Mercolini, L. (2019). Tutorial: Volumetric absorptive microsampling (VAMS). Anal Chim Acta , 1046 , 32-47. https://doi.org/10.1016/j.aca.2018.09.004 Protti, M., Sberna, P. M., Sardella, R., Vovk, T., Mercolini, L., & Mandrioli, R. (2021). VAMS and StAGE as innovative tools for the enantioselective determination of clenbuterol in urine by LC-MS/MS. J Pharm Biomed Anal , 195 , 113873. https://doi.org/10.1016/j.jpba.2020.113873 Schmidt, L., Peterson, K., Nunes, T. S., Knap, M., Petrick, L., & Landero-Figueroa, J. A. (2024). A miniaturized sample preparation method for routine elemental determination in whole blood using volumetric absorptive micro-sampling by ICP-QQQ. Anal Bioanal Chem , 416 (11), 2711-2724. https://doi.org/10.1007/s00216-023-04881-7 Schweizer, A. K., Kabesch, M., Quartucci, C., Bose-O'Reilly, S., & Rakete, S. (2021). Implementation of mercury biomonitoring in German adults using dried blood spot sampling in combination with direct mercury analysis. Environ Monit Assess , 193 (8), 488. https://doi.org/10.1007/s10661-021-09254-0 Spooner, N., Denniff, P., Michielsen, L., De Vries, R., Ji, Q. C., Arnold, M. E.,…Rudge, J. B. (2015). A device for dried blood microsampling in quantitative bioanalysis: overcoming the issues associated blood hematocrit. Bioanalysis , 7 (6), 653-659. https://doi.org/10.4155/bio.14.310 Sullivan, P. S., Sailey, C., Guest, J. L., Guarner, J., Kelley, C., Siegler, A. J.,…Sanchez, T. H. (2020). Detection of SARS-CoV-2 RNA and Antibodies in Diverse Samples: Protocol to Validate the Sufficiency of Provider-Observed, Home-Collected Blood, Saliva, and Oropharyngeal Samples. JMIR Public Health Surveill , 6 (2), e19054. https://doi.org/10.2196/19054 Tempowski, J., & World Health Organization. (2021). WHO guideline for clinical management of exposure to lead. World Health Organization,. Retrieved from http://www.ncbi.nlm.nih.gov/books/NBK575284/ UNEP. (2010). Final review of scientific information on cadmium . https://wedocs.unep.org/bitstream/handle/20.500.11822/27636/Cadmium_Review.pdf?sequence=1&isAllowed=y Verstraete, J., & Stove, C. (2021). Volumetric absorptive microsampling (VAMS) as a reliable tool to assess thiamine status in dried blood microsamples: a comparative study. Am J Clin Nutr , 114 (3), 1200-1207. https://doi.org/10.1093/ajcn/nqab146 Vogel, N., Murawski, A., Schmied-Tobies, M. I. H., Rucic, E., Doyle, U., Kampfe, A.,…Kolossa-Gehring, M. (2021). Lead, cadmium, mercury, and chromium in urine and blood of children and adolescents in Germany - Human biomonitoring results of the German Environmental Survey 2014-2017 (GerES V). Int J Hyg Environ Health , 237 , 113822. https://doi.org/10.1016/j.ijheh.2021.113822 WHO. (2019). Preventing disease through healthy environments: exposure to cadmium: a major public health concern . https://apps.who.int/iris/rest/bitstreams/1257885/retrieve Williams, S. R., & McDade, T. W. (2009). The use of dried blood spot sampling in the national social life, health, and aging project. J Gerontol B Psychol Sci Soc Sci , 64 Suppl 1 (Suppl 1), i131-136. https://doi.org/10.1093/geronb/gbn022 Footnotes This data point, excluded due to contamination concerns, is depicted in red in all graphs to maintain transparency regarding their initial inclusion and subsequent exclusion from further statistical analyses. This only applied for 3 Pb values. The highest individual blank values excluded were at 377 µg/l. Additional Declarations No competing interests reported. Supplementary Files SupplementaryMaterialanonymizeddataset.xlsx Cite Share Download PDF Status: Under Revision Version 1 posted Editorial decision: Revision requested 18 Oct, 2025 Reviews received at journal 16 Oct, 2025 Reviews received at journal 30 Sep, 2025 Reviewers agreed at journal 24 Sep, 2025 Reviewers agreed at journal 24 Sep, 2025 Reviewers invited by journal 22 Sep, 2025 Editor assigned by journal 25 Aug, 2025 Submission checks completed at journal 25 Aug, 2025 First submitted to journal 30 Jul, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7251995","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":523915855,"identity":"b608e753-2a03-4d13-9dc7-e631cf7cfa42","order_by":0,"name":"Claus Gutknecht","email":"","orcid":"","institution":"LMU University Hospital, LMU Munich","correspondingAuthor":false,"prefix":"","firstName":"Claus","middleName":"","lastName":"Gutknecht","suffix":""},{"id":523915856,"identity":"791b99b9-e203-4781-b58b-2d97f8e776a7","order_by":1,"name":"Alexandra Burianova","email":"","orcid":"","institution":"LMU University Hospital, LMU 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11:42:12","extension":"html","order_by":11,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":113557,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7251995/v1/51f66def2302cf91c168f652.html"},{"id":92800982,"identity":"3307f682-a8ed-4ceb-9bbe-21fd71af0636","added_by":"auto","created_at":"2025-10-05 11:34:12","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":470603,"visible":true,"origin":"","legend":"\u003cp\u003eVAMS microsampling devices within the 3D printed clamshell\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7251995/v1/aaa5c24bed2a1e8dc7130787.png"},{"id":92800987,"identity":"ee681a8d-9b41-49fd-aad5-e393156c0c35","added_by":"auto","created_at":"2025-10-05 11:34:12","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":47401,"visible":true,"origin":"","legend":"\u003cp\u003eBland-Altman plot showing the absolute differences between levels in venous blood and VAMS samples vs. levels in both samples. The bias (solid red line) was at Cd: 0.015 μg/l; Pb: 0.035 μg/l; Cd pre-washed: 0.053 μg/l; Pb pre-washed: 0.88 μg/l. The upper and lower statistical limits (± 1.96 the standard deviation of the differences to the mean bias) were at Cd: -0.13 µg/l and 0.16 µg/l; Pb: -2.16 µg/l and 2.23 µg/l; Cd pre-washed: -0.096 µg/l and 0.20 µg/l; Pb pre-washed: -0.74 µg/l and 2.50 µg/l respectively. The sample excluded due to contamination concerns is depicted in red.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7251995/v1/95e67954b0662f5a7d9e6b10.png"},{"id":92802603,"identity":"040ced86-0914-4ffb-8c3e-e557b5546159","added_by":"auto","created_at":"2025-10-05 11:42:12","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":116472,"visible":true,"origin":"","legend":"\u003cp\u003ePassing-Bablok regression plot of concentrations in venous blood vs. concentrations in corresponding VAMS samples. The solid line represents the regression line, the blue area shows 95% CI of the regression line, and the dashed line represents the identity line (x=y). The sample excluded due to contamination concerns is depicted as a red dot.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7251995/v1/4db5dca6e3d59114bc978776.png"},{"id":92803404,"identity":"9b38736a-30d2-4696-a8a3-05caa644f8df","added_by":"auto","created_at":"2025-10-05 11:58:13","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1323531,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7251995/v1/670eb992-5a8d-4aaa-9ea8-46ad62ef8bcb.pdf"},{"id":92802602,"identity":"bd5c704c-6eb8-4cdf-b277-8528683b11dc","added_by":"auto","created_at":"2025-10-05 11:42:12","extension":"xlsx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":22438,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryMaterialanonymizeddataset.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-7251995/v1/5044bcbf3ffbe38b31d7c74d.xlsx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Application of Volumetric Absorptive Microsampling (VAMS) for the simultaneous determination of cadmium and lead in blood","fulltext":[{"header":"Introduction","content":"\u003cp\u003eCadmium (Cd) and lead (Pb) are toxic to plants, microorganisms, and animals, including humans. A wide range of effects and diseases are associated with the exposure to these metals (Genchi et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Tempowski \u0026amp; World Health Organization, 2021; WHO, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Both elements are classified as persistent environmental pollutants as they are not metabolized or transformed into less toxic forms and bioaccumulate (UNEP, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; WHO, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Traces of Cd and Pb can be found almost anywhere in the environment.\u003c/p\u003e\u003cp\u003eBoth metals accumulate in the body, e.g., in tissue and bone. An exposure assessment via blood is suitable to reflect recent exposure from exogenous sources (Adams \u0026amp; Newcomb, \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Tempowski \u0026amp; World Health Organization, 2021). Venipuncture is the gold standard blood sampling method for the analysis of Cd and Pb in blood (Adams \u0026amp; Newcomb, \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Breton et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). However, this sampling method bears relatively high logistical costs. It requires medically trained personnel and the samples need a constant cold chain while transported or stored, which exuberates the challenges for human biomonitoring in remote or structurally weak regions (Basu et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Guerra Valero et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Jacobson et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Lehner et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Schweizer et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eMicrosampling methods in contrast offer a less complex and minimally invasive alternative (Williams \u0026amp; McDade, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). Rather small blood volumes (10 to 50 \u0026micro;l) are taken by finger or heel prick with a lancet. The capillary blood is blotted on filter paper (Dried Blood Spots -DBS) or wicked on special microsampling devices (e.g., Volumetric Absorptive microsampling - VAMS). After drying, samples can be packed for storage at ambient temperatures, thus elimating the need for a cold chain. Microsampling can be performed by non-medically trained personnel and is potentially suitable for the self-collection of samples (Allen et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Sullivan et al., \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). In addition, other studies show a very high acceptability and willingness of participants to provide microsamples (Andrew et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Williams \u0026amp; McDade, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2009\u003c/span\u003e), which is essential for biomonitoring studies or for monitoring purposes in occupational settings.\u003c/p\u003e\u003cp\u003eDBS sampling is widely used in numerous applications, including the potential use in biomonitoring for some heavy metals in blood, as Schweizer demonstrated for mercury (Hg) (2021). Studies that used DBS for the quantification of Cd and Pb levels in blood found background levels in the sampling material that exceeded the blood levels of non-exposed participants in the analyte (Chaudhuri et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Funk et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). Therefore, quantitation of Pb and Cd was not possible. A second drawback of this method is the hematocrit dependency, meaning the hematocrit content, and thus the blood viscosity, affects the blood volume per surface area absorbed by the filter paper and consequently the amount analyzed for quantification (Breton et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Chaudhuri et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Demirev, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Spooner et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2015\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe VAMS method on the other hand promises an accurate volume sample collection, independent of the hematocrit (Protti et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Spooner et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). The VAMS method uses hydrophilic polymer tips, attached to a plastic handle, which allows a rather easy and convenient sample collection (Denniff \u0026amp; Spooner, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Spooner et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). The tip absorbs a fixed volume of blood by wicking. Until recently, VAMS application has mainly been used in monitoring drug molecules, analyzing peptides and proteins, forensic analysis of drugs, syndrome screening and anti-doping testing, in blood and other specimens (Protti et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Protti et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Verstraete \u0026amp; Stove, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eTo our knowledge, VAMS has only been used in a limited number of studies for trace metal analysis in human blood. It has been used to quantify prosthesis-related metals (Al, Ti, V, Co, Cr, Ni, Sr, and Zr) (Bolea-Fernandez et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2016\u003c/span\u003e), Hg (Koutsimpani-Wagner et al., \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2022\u003c/span\u003e), Pb (Breton et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2023\u003c/span\u003e), and recently a wider range of essential and toxic trace elements (Al, As, Cd, Cr, Co, Cu, Hg, Mn, Mo, Pb, Se, U, Zn) (Breton et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Another study explored its potential using VAMS devices spiked with reference materials (As, Be, Cd, Cs, Cu, Fe, Mg, P, Pb, S, Sb, Se, Tl, V, and U) (Schmidt et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Although VAMS has been used for the simultaneous biomonitoring of Cd and Pb under field conditions in one study (Breton et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) ours demonstrates significantly lower Limits of Quantification (LOQ). The goal of this study was to develop and validate a simultaneous Cd and Pb biomonitoring method using VAMS in combination with ICP-MS analysis, as well as exploring the potential of pre-washing the materials prior to use.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cp\u003eMaterials and reagents\u003c/p\u003e\u003cp\u003eNitric acid Optima\u0026trade; (67\u0026ndash;69%) for ultra trace elemental analysis was obtained from Fisher Scientific (Leicastershire, UK). Ultrapure water (resistivity\u0026thinsp;\u0026gt;\u0026thinsp;18.2 MΩcm) was provided from a Direct-Q\u0026reg; 3 UV Water Purification System from Merk Millipore (Darmstadt, Germany). ICP-MS Stock Tuning Solution (10 \u0026micro;g/l Ce, Co, Li, Tl, Y), Internal Standard Mix (10 \u0026micro;g/l Bi, Ge, In, Li, Sc, Tb, Y) and Environmental Calibration Standard (1000 \u0026micro;g/l Ca, Fe, K, Mg, Na, 10 \u0026micro;g/l Ag, Al, As, Ba, Be, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Sb, Se, Th, Ti, U, V, Zn) from Agilent (Santa Cruz, USA) were used.\u003c/p\u003e\u003cp\u003eCertified reference material for whole blood (ClinCheck\u0026reg;, Level I, 1.58 \u0026micro;g/l Cd; 37.6 \u0026micro;g/l Pb) was obtained from RECIPE (Munich, Germany). The VAMS Mitra\u0026trade; microsampling devices (sample volume 23.6 \u0026micro;l and 24.6 \u0026micro;l, respectively per tip) were obtained from Neoteryx LLC (Torrance, USA) and consisted of 4 VAMS tips per holder (clamshell). Original clamshells were replaced by custom made, 3D printed clamshells made from polylactide (PLA) filaments, obtained from Form Futura (Nijmegen, Netherlands).\u003c/p\u003e\u003cp\u003eVenous blood was collected into Li-Heparin-coated S-Monovette\u0026reg; 7.5 ml tubes for trace metal analysis (Sarstedt\u0026reg;) by venipuncture. For fingerpricking, we used disposable lancets (Solofix) from B. Braun (Melsungen, Germany). Clamshells containing the samples were stored in aluminum-coated mylar ziplock bags (12x20 cm).\u003c/p\u003e\u003cp\u003eStudy design\u003c/p\u003e\u003cp\u003e This study was reviewed by the ethics committee of the Ludwig Maximilians University of Munich (#20\u0026ndash;091) and conducted according to The Code of Ethics of the Declaration of Helsinki for human experiments. All participants signed an informed consent form prior to sampling and were asked to fill out a questionnaire about possible Cd and Pb exposure. Paired venous and capillary blood samples were collected from consenting, occupationally non-exposed, adult human subjects at the Clinic for Occupational, Social and Environmental Medicine, University Hospital, LMU Munich. Within six weeks (January 11 to February 23, 2023), 60 paired samples were collected using VAMS devices as supplied by the manufacturer. In a subsequent sampling phase (December 18, 2023, to January 24, 2024), an additional 27 paired blood samples were collected under identical conditions, using VAMS devices that had been pretreated to reduce background contamination.\u003c/p\u003e\u003cp\u003eSample collection\u003c/p\u003e\u003cp\u003eApproximately 7 mL of blood was collected from each participant by venipuncture. Samples were stored at -20\u0026deg;C until analysis. VAMS sampling devices were prepared in batches of four per clamshell. For each participant, a separate clamshell was used. After finger pricking, three sampling devices were used to collect three separate capillary blood samples per subject. The fourth device was left empty to quantify background Cd and Pb levels. To avoid sample contamination, the capillary blood collection followed a strict protocol. Participants were asked to thoroughly wash their hands and dry them with disposable paper towels. The finger to be pricked was disinfected and kept untouched until airdried. Pricking was done in the fingertip with a disposable lancet. The first drop of blood was wiped away with sterile gauze. If necessary, blood flow was stimulated by gently massaging the finger towards the tip, creating a blood stasis, without applying too much pressure next to the pricked area to avoid sample dilution by tissue fluid. In some cases, a second prick was performed to collect enough blood. To ensure a constant blood volume collected, the polymer tips were just slightly touching the blood drop at the finger without submerging it as recommended by the manufacturer (Neoteryx, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Subsequently, the samples were placed upside down within the slightly opened clamshell in a desiccator and dried for at least two hours. Finally, the clamshells were packed in aluminium-coated mylar zip-lock bags, which were additionally thermally sealed at the site of collection. VAMS samples were stored at room temperature until analysis.\u003c/p\u003e\u003cp\u003ePretreatment of VAMS to reduce background contamination\u003c/p\u003e\u003cp\u003eA separate batch of VAMS devices was washed in 0.5% nitric acid in an ultrasonic bath for 45 minutes at 60\u0026deg;C and subsequently rinsed in ultrapure water for 15 minutes under the same conditions. VAMS devices were washed upside down, with their tips submerged in the washing solution and subsequently dried in a desiccator overnight. These VAMS devices were then used as described above to collect samples from 27 participants. Potential changes in the blood wicking capability due to the pretreatment were assessed using eight pre-washed and eight unwashed VAMS. This assessment involved weighing the devices individually before and immediately after sampling capillary blood from the same volunteer.\u003c/p\u003e\u003cp\u003eInstrumentation\u003c/p\u003e\u003cp\u003eFor sample analysis, an 8900 Triple Quadrupole ICP-MS with an Integrated Autosampler (I-AS) from Agilent (Santa Cruz, USA) was used. All samples were fed to the ICP-MS in 2 ml polystyrene sample cups obtained from WICOM Germany (Heppenheim, Germany). We tuned the instrument daily to achieve optimum sensitivity, oxide ratio and doubly charged ratio. The ICP-MS/MS operating conditions were as follows: RF power: 1600 W; plasma gas flow: 15 l/min; nebulizer gas flow: 0.82 l/min (venous blood) or 1.05 l/min (VAMS); auxiliary gas flow: 0.9 l/min; dilution gas: 0.15 ml/min (only venous blood), replicates: 3, sweeps/replicate: 30. We ran all analyses in single quadrupole mode and used helium as collision gas (5.5 ml/min) to reduce polyatomic interferences. \u003csup\u003e111\u003c/sup\u003eCd and \u003csup\u003e206+207+208\u003c/sup\u003ePb were quantified using an external calibration. As internal standard, we used \u003csup\u003e159\u003c/sup\u003eTb.\u003c/p\u003e\u003cp\u003eSample Preparation\u003c/p\u003e\u003cp\u003eAnalysis of venous blood samples were carried out as a simple dilute and shoot process. After thawing the samples on a roller mixer, 50 \u0026micro;l of venous blood were diluted twentyfold with 0.5% nitric acid containing 10 \u0026micro;g/l Tb as internal standard and directly analyzed by ICP-MS. Analysis was carried out in triplicate. For quality assurance, certified reference material was analyzed at the beginning of every sample batch.\u003c/p\u003e\u003cp\u003eFor VAMS analysis, each polymer tip (three capillary blood samples plus one blank per participant) were placed in a 2 ml Safe-Lock EPPENDORF TUBES\u003csup\u003e\u0026reg;\u003c/sup\u003e (Hamburg, Germany), each without any contact to devices or surfaces, by gently pinching the tip with the tube's lid, while removing the handle to avoid contamination or transfer between the samples. Extraction was done in 700 \u0026micro;l 0.5% nitric acid containing 10 \u0026micro;g/l Tb as internal standard in an ultra-sonic bath (Sonorex Super RK 103 H from Bandelin, Berlin, Germany) for 45 minutes at 40\u0026deg;C and subsequently centrifuged at 13,000 rpm for 5 minutes using a Galaxy 16 DH from VWR (Darmstadt, Germany). 650 \u0026micro;l of supernatant were used for ICP-MS analysis. For quality assurance, certified reference material was applied to VAMS and treated like regular VAMS blood samples.\u003c/p\u003e\u003cp\u003eStorage stability of Cd and Pb in VAMS\u003c/p\u003e\u003cp\u003eVAMS samples were stored inside the 3D-printed clamshells (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e,\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003ewhich then were thermally sealed in plastic ziplock bags at room temperature. Storage time is randomly distributed between 14 and 42 days for the initial and 14 to 51 days for the subsequent series, which resulted from the availability of participants and time of analysis.\u003c/p\u003e\u003cp\u003eStatistical analysis and data processing\u003c/p\u003e\u003cp\u003eData processing was carried out using Microsoft Excel 2023 Version 16.78.3 for Mac. Statistical analysis was performed using R Studio Version 2023.03.1\u0026thinsp;+\u0026thinsp;446 for Mac, utilizing R version 4.3.0.\u003c/p\u003e\u003cp\u003eFor the initial series, using untreated VAMS devices as provided by the manufacturer, employing sampling material from two different batches with distinct LOT numbers (74918 and 76327). Devices from the second batch (LOT:76327) showed high and unevenly distributed Cd levels. Therefore, these samples (six) were excluded from further statistical analysis. Out of the remaining 54 paired samples, two more were excluded from further analysis due to a handling mistake which caused potentially corrupted values. For the sampling using pretreated VAMS devices from a third batch (LOT: 95222) were used.\u003c/p\u003e\u003cp\u003eVenous blood levels were calculated as the mean of the three individual values per subject and represent the reference blood Cd and Pb levels (gold standard method). VAMS Cd and Pb levels were calculated the same way, with an additional exclusion criterion, correcting for potentially contaminated samples and a separate adjustment for background contamination. If the relative standard deviation (RSD) of the three individual values exceeded 30%, the highest reading was deleted as potentially contaminated. If the RSD remained above 30% for the remaining two values, the participant was excluded from the study. 51 paired samples from the initial series met these criteria and were used for statistical analysis. In the subsequent series, 25 out of 27 paired samples were used for statistical analysis. The RSD for Cd in one participant exceeded the acceptable limit, leading to the exclusion of this sample. However, an exception to the established RSD threshold of 30% was made in one case where contamination was evident despite the RSD values being marginally below this limit. In this case, two out of three VAMS devices showed unusually high Cd and Pb levels, suggesting an anomaly likely due to contamination. Although the RSD for this sample did not exceed the predefined threshold, the evident disparity between the devices prompted their exclusion to preserve the integrity of the data analysis\u003csup\u003e[1]\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eIn a first step, apparently contaminated blank values, exceeding the maximum venous blood levels, were excluded\u003csup\u003e[2]\u003c/sup\u003e. In a second step, blank values exceeding 3 times the standard deviation (SD) got excluded from further calculations as potentially contaminated as well, resulting in 49 blank values for Cd and 47 for Pb remaining in the initial series. In the subsequent series, this criterion led to the inclusion of 26 blank values for Cd and 23 for Pb. The resulting mean blank values for each series were then subtracted from each VAMS sample values to adjust for background contamination, resulting in the finally used values. Subtracting the mean blank value from the VAMS reading showed overall better fit then subtracting the individual sample blank value, as the background contamination is randomly distributed and not clamshell specific. Limits of detection (LOD) and limits of quantitation (LOQ) were defined as three- and ten-times the SD of the blank levels.\u003c/p\u003e\u003cp\u003eRecovery was used as a measure of accuracy, calculated from the corresponding VAMS and venous blood samples (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:recovery=\\frac{{Cd}_{VAMS}}{{Cd}_{VB}}*100\\:\\%;\\:recovery=\\frac{{Pb}_{VAMS}}{{Pb}_{VB}}*100\\:\\%)\\)\u003c/span\u003e\u003c/span\u003e. The relative standard deviation of the three (respectively two) corresponding VAMS values was used as a measure for precision. The correlation is represented by Spearman Rho, Passing-Bablok regression and Cusum test for linearity. Results are graphically displayed by the Passing-Bablok regression graphs. Bland-Altman plots are used to visualize the bias between the methods. Storage stability was tested by a linear model (storage time\u0026thinsp;~\u0026thinsp;recovery). Statistical analysis was performed separately for each series by using identical methods and parameters. The wicking capacity of pretreated VAMS was controlled with a two-sided t-test at the 0.05 alpha level.\u003c/p\u003e"},{"header":"Results and Discussion","content":"\u003cp\u003eVenous blood results\u003c/p\u003e\u003cp\u003eCd and Pb levels in the initial series ranged from 0.086\u0026ndash;1.14 \u0026micro;g/l and 4.57\u0026ndash;43.13 \u0026micro;g/l respectively, with a mean of 0.32 \u0026micro;g/l for Cd (median: 0.24 \u0026micro;g/l) and 11.14 \u0026micro;g/l for Pb (median: 9.76 \u0026micro;g/l). For the subsequent series, Cd and Pb levels ranged from 0.06\u0026ndash;1.34 \u0026micro;g/l and 5.28 to 49.77 \u0026micro;g/l respectively, with a mean of 0.40 \u0026micro;g/l for Cd (median: 0.25 \u0026micro;g/l) and 13.01 \u0026micro;g/l for Pb (median: 11.00 \u0026micro;g/l). The 95th percentiles of all participants were 1.16 \u0026micro;g/l for Cd and 21.04 for Pb. The Pb levels observed are consistent with those reported by the Human Biomonitoring Commission of the German Environment Agency among students in M\u0026uuml;nster between 2010 and 2015, which found a median Pb level of 11.7 \u0026micro;g/l and a mean of 13.2 \u0026micro;g/l in blood (Kommission Human-Biomonitoring des Umweltbundesamtes, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). The most recent representative study, GerES III from 1998, reported significantly higher levels of Cd and Pb due to the expected reduction in exposure of the last decades (Becker et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2002\u003c/span\u003e; Vogel et al., \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eVAMS background contamination\u003c/p\u003e\u003cp\u003eCompared to the DBS material used by Chaudhuri (2009), VAMS provides significantly lower background contamination for Cd and Pb (detailed information in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), the tradeoff being an increased standard deviation for Pb. Furthermore, the background contamination varied heavily between manufacturing batches. For the initial series the LOD were 0.16 \u0026micro;g/l for Cd and 5.15 \u0026micro;g/l for Pb in VAMS. The LOQ were 0.55 \u0026micro;g/l for Cd and 17.17 \u0026micro;g/l for Pb. The relatively high LOQ is the main limitation, bottlenecking the method\u0026acute;s potential when used as supplied by the manufacturer. The results of the pre-washed blanks show significantly lower background levels and a lower SD for Cd and especially Pb. This results in LOD and LOQ levels at 0.14 and 0.46 \u0026micro;g/l for Cd and 0.66 and 2.19 \u0026micro;g/l for Pb respectively (detailed results compared to other studies in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Hence, VAMS is a suitable alternative for exposure assessment even at background exposure levels. Results of the t-test show no statistically significant changes in the wicking capacity caused by pre-washing the VAMS devices before use.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eVAMS blank results vs. other studies using VAMS\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"9\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"4\" nameend=\"c5\" namest=\"c2\"\u003e\u003cp\u003eCd\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u003cp\u003ePb\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMean level\u003c/p\u003e\u003cp\u003e\u0026micro;g/l\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eSD\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eLOD\u003c/p\u003e\u003cp\u003e\u0026micro;g/l\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eLOQ\u003c/p\u003e\u003cp\u003e\u0026micro;g/l\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eMean level\u003c/p\u003e\u003cp\u003e\u0026micro;g/l\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eSD\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eLOD\u003c/p\u003e\u003cp\u003e\u0026micro;g/l\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eLOQ\u003c/p\u003e\u003cp\u003e\u0026micro;g/l\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eunwashed\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.074\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.055\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.55\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e3.72\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1.72\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e5.15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e17.17\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003epre-washed\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.054\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.046\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.46\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.43\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.66\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e2.19\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBreton et al. (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2023\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eNR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eNR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eNR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eNR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e1.66\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e5.59\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSchmidt et al. (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2024\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.06\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.60\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e3.03\u0026ndash;6.57\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eNR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e3.06\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e10.1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBreton et al. (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2024\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.56\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1.99\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eNR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e4.35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e14.50\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"9\"\u003eNR: not reported\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"9\"\u003eCorrelation between venous blood and VAMS samples\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThe main objective of this study was to evaluate the applicability of VAMS as an alternative method for biomonitoring purposes. Hence, the recovery, as a measure of accuracy, serves as the pivotal quality criterion. Mean recovery rates showed excellent results for both elements in the initial series (Cd: 103.9%; Pb: 100.2%) and good precision (mean RSD, Cd: 12.9%; Pb: 7.6%). For Cd, recovery rates ranged from 28 to 170%, and 68\u0026ndash;129% for Pb. Even considering the wide range for Cd, most of the 51 samples for both elements were within the desired range of 70 to 130% (Cd: \u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;39, 76.5%; Pb: \u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;50, 98.0%), as outlined in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eSummary VAMS performance\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"9\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMean\u003c/p\u003e\u003cp\u003erecovery\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMean\u003c/p\u003e\u003cp\u003eRSD\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eSpearman-\u003c/p\u003e\u003cp\u003eRho\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eAdjusted\u003c/p\u003e\u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003ep\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003ePassing-\u003c/p\u003e\u003cp\u003eBablok\u003c/p\u003e\u003cp\u003eSlope\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003ePassing-\u003c/p\u003e\u003cp\u003eBablok\u003c/p\u003e\u003cp\u003eIntercept\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003e\u003cem\u003en\u003c/em\u003e recovery\u003c/p\u003e\u003cp\u003e70\u0026ndash;130%\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eCd unwashed\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e103.9%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e12.9%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.846\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.931\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e1.12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e-0.026\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e39 (76.5%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003ePb unwashed\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e100.2%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7.6%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.937\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.974\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e1.06\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e-0.62\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e50 (98.0%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eCd pre-washed\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e116.4%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e15.7%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.905\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.972\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e1.15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e18 (72.0%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003ePb pre-washed\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e110.1%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e6,9%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.978\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.992\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e1.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.74\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e24 (96.0%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThe pre-washed series showed satisfying results as well, regarding accuracy and precision, with a slightly increased recovery (mean recovery: Cd: 116.4%, Pb: 110.1%; mean RSD: Cd: 15.7%, Pb: 7.0%). A similar proportion were within range of 70 to 130% (Cd: \u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;18, 72.0%; Pb: \u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;24, 96.0%). The increased recovery rate may be attributed to batch-specific variations in the blood volumes absorbed by the VAMS material. However, this was not tested.\u003c/p\u003e\u003cp\u003eThe scattering of recovery rates, just like the rather high LOQ in the initial series, can be explained by the presence of randomly distributed background levels within the VAMS devices. Contaminations of the samples while handling and analysis might be attributed to both series. Both elements are ubiquitous in nature e.g., in airborne dust particles. VAMS devices are supplied in non-sealed clamshells within a cardboard box, rendering them susceptible to contamination. This susceptibility extends due to the openly handled, rather small blood volumes of microsamples, which is especially critical for Cd due to the extremely low concentration in blood of occupationally non-exposed participants.\u003c/p\u003e\u003cp\u003eAs evident from the Bland\u0026ndash;Altman plots (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e),\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eboth methods are comparable and in good agreement with each other. 48 for Cd and 49 for Pb out of 51 samples from the initial series were within the 95% confidence interval. Overall, Cd and Pb levels in VAMS samples were on average 0.015 \u0026micro;g/l and 0.035 \u0026micro;g/l higher respectively than the corresponding Cd and Pb levels in venous blood. The very low bias accounts for proper background compensation. Notably, no significant trend conditioned by Cd or Pb levels in blood is present, signifying a proper linearity.\u003c/p\u003e\u003cp\u003eThe results of the subsequent series using pre-washed VAMS are qualitatively comparable, albeit with a slightly increased bias reflecting the enhanced recovery. 24 for Cd and Pb out of 25 samples for Pb fall within the 95% confidence interval. Cd and Pb levels in VAMS samples from this series are on average 0.053 \u0026micro;g/l and 0.88 \u0026micro;g/l higher respectively, than in venous blood.\u003c/p\u003e\u003cp\u003eThe correlation of Cd and Pb levels in venous blood versus those in VAMS samples for the initial series are in very good agreement. For Cd we identified a strong correlation (ρ\u0026thinsp;=\u0026thinsp;0.85, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001 Spearman-Rho) and a very strong one for Pb (ρ\u0026thinsp;=\u0026thinsp;0.94, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001 Spearman-Rho), with both elements exhibiting correlations even below the calculated LOD/LOQ. The results for Pb align with those of Breton et al. (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Due to the reduced background contamination, the correlation of the sequential series is significantly higher (Cd ρ\u0026thinsp;=\u0026thinsp;0.91, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001; Pb ρ\u0026thinsp;=\u0026thinsp;0.98, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e\u003cp\u003ePassing-Bablok regression analysis further validated these findings for both series. For both elements, the 95% confidence intervals of the intercepts encompass 0, implying the absence of systematic differences. Moreover, no proportional differences between the methods are evident, as the 95% confidence intervals for the slope of both elements encompass 1 (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eLinearity and model stability are confirmed by the Cusum test at an alpha level of 0.05.\u003c/p\u003e\u003cp\u003eStorage stability of VAMS samples\u003c/p\u003e\u003cp\u003eStorage stability was assessed by a linear regression model (storage time\u0026thinsp;~\u0026thinsp;recovery). No statistically significant correlation for neither series (0.05 alpha significance level) was observed between the time stored and the recovery rate for both elements (storage time between 14 and 42 days for the initial and 14 to 51 days for the subsequent series) suggesting sample stability for at least seven weeks.\u003c/p\u003e\u003cp\u003eStrengths and limitations of the study\u003c/p\u003e\u003cp\u003eThis study confirms the applicability of VAMS in human biomonitoring for the simultaneous analysis of Cd and Pb in blood compared to venipuncture as a gold standard under field conditions. We were also able to improve the sensitivity for Pb and thus detect background levels in low-exposed individuals. Furthermore, our study contributes towards a wider applicability of this novel method, which promises convenient sample collection, higher acceptability, and compliance of probands and lower logistical costs. Additionally, we were able to showcase solutions to circumvent drawbacks of this method by collecting samples in triplicate and removing outliners by RSD, as well as washing the devices prior to use.\u003c/p\u003e\u003cp\u003eA major limitation of the study is the high and unstable background contamination in combination with low levels of Cd and Pb due to an unexposed study population. Subsequently, 82% of samples were below the calculated LOQ for Cd and 92% for Pb. 24% of VAMS samples showed a Cd concentration below the LOD and 6% for Pb when the sampling devices were used as provided by the manufacturer. To overcome this, the pre-wash method used in our case reliably eliminates the majority of Pb contamination, but only a fraction of the corresponding Cd levels in the VAMS devices. However, 80% of samples were still below the corresponding LOQ for Cd. For Pb, none of the samples were below the LOQ, demonstrating the efficacy of the washing procedure.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study evaluated the applicability of VAMS as an alternative blood sampling method for Cd and Pb biomonitoring of the general population. In conclusion, we were able to demonstrate that this sampling method produces reliable and accurate results and can therefore be used for Cd and Pb exposure assessment, with the limitation of relatively high LOQs when used as provided by the manufacturer. However, this can be compensated by pre-washing the sampling devices prior to use.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study was carried out in accordance with the Code of Ethics of the Declaration of Helsinki for experiments involving human subjects, as well as reviewed and approved by the ethics committee of the Ludwig Maximilians University of Munich (#20-091).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWritten informed consent was obtained from all individual participants included in the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work received no external funding and was carried out using internal institutional resources of the Institute and Clinic for Occupational, Social and Environmental Medicine, LMU University Hospital, LMU Munich.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors’ contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClaus Gutknecht:\u0026nbsp;\u003c/strong\u003econceptualization,sampling, sample analysis, data analysis, visualization, preparation of the original draft, writing - review and editing.\u003cstrong\u003e\u0026nbsp;Alexandra Burianova:\u0026nbsp;\u003c/strong\u003esampling.\u003cstrong\u003e\u0026nbsp;Stephan Bose-O’Reilly\u003c/strong\u003e: conceptualization, writing - review and editing. \u003cstrong\u003eStefan Rakete\u003c/strong\u003e: conceptualization, methodology, funding acquisition, data analysis, writing - review and editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAnonymized Cd and Pb levels in VAMS and venous blood samples as well as in blanks can be found in the supplementary information.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCode availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors would like to thank Stefan Gröbmair for performing the ICP-MS analysis.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAdams, S. 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Lead, cadmium, mercury, and chromium in urine and blood of children and adolescents in Germany - Human biomonitoring results of the German Environmental Survey 2014-2017 (GerES V). \u003cem\u003eInt J Hyg Environ Health\u003c/em\u003e,\u003cem\u003e 237\u003c/em\u003e, 113822. https://doi.org/10.1016/j.ijheh.2021.113822 \u003c/li\u003e\n\u003cli\u003eWHO. (2019). \u003cem\u003ePreventing disease through healthy environments: exposure to cadmium: a major public health concern\u003c/em\u003e. https://apps.who.int/iris/rest/bitstreams/1257885/retrieve\u003c/li\u003e\n\u003cli\u003eWilliams, S. R., \u0026amp; McDade, T. W. (2009). The use of dried blood spot sampling in the national social life, health, and aging project. \u003cem\u003eJ Gerontol B Psychol Sci Soc Sci\u003c/em\u003e,\u003cem\u003e 64 Suppl 1\u003c/em\u003e(Suppl 1), i131-136. https://doi.org/10.1093/geronb/gbn022 \u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Footnotes","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003e This data point, excluded due to contamination concerns, is depicted in red in all graphs to maintain transparency regarding their initial inclusion and subsequent exclusion from further statistical analyses.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003e This only applied for 3 Pb values. The highest individual blank values excluded were at 377 \u0026micro;g/l.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"environmental-monitoring-and-assessment","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"emas","sideBox":"Learn more about [Environmental Monitoring and Assessment](http://link.springer.com/journal/10661)","snPcode":"10661","submissionUrl":"https://submission.nature.com/new-submission/10661/3","title":"Environmental Monitoring and Assessment","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Cadmium, Lead, Human Biomonitoring, VAMS, Volumetric Absorptive Microsampling, ICP-MS","lastPublishedDoi":"10.21203/rs.3.rs-7251995/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7251995/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eCadmium (Cd) and lead (Pb) are environmental pollutants with toxic effects on humans. This study evaluates the applicability of Volumetric Absorptive Microsampling (VAMS) as an alternative sampling method for the simultaneous biomonitoring of Cd and Pb in blood of humans without occupational exposure.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eVAMS and blood samples were collected from 87 participants. Of these, 60 VAMS sets were used as supplied by the manufacturer and 27 VAMS sets were washed with 0.5% nitric acid before the sampling to reduce the background contamination. The samples were extracted (VAMS) or diluted (venous blood) with 0.5% nitric acid prior to analysis by ICP-MS.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eMean recovery rates for Cd and Pb were 104% and 100% using untreated VAMS, and 116% and 110% with prewashed VAMS, respectively. A strong correlation was found for venous blood and unwashed VAMS samples (Cd ρ\u0026thinsp;=\u0026thinsp;0.85; Pb ρ\u0026thinsp;=\u0026thinsp;0.94). The correlation was improved when pre-washed material was used (Cd ρ\u0026thinsp;=\u0026thinsp;0.91; Pb ρ\u0026thinsp;=\u0026thinsp;0.97). Without washing, the limits of quantification (LOQ) were 0.55 \u0026micro;g/l for Cd and 17.17 \u0026micro;g/l Pb. Washing of VAMS devices lead to a significant reduction of the contamination, especially for Pb. The resulting LOQ were 0.46 \u0026micro;g/l for Cd and 2.19 \u0026micro;g/l for Pb.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e\u003cp\u003eDespite challenges like the background contamination, VAMS is a promising alternative sampling method for human biomonitoring of Cd and Pb in blood. This study also demonstrates the benefits of washing VAMS to reduce background contamination.\u003c/p\u003e","manuscriptTitle":"Application of Volumetric Absorptive Microsampling (VAMS) for the simultaneous determination of cadmium and lead in blood","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-05 11:34:07","doi":"10.21203/rs.3.rs-7251995/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-10-18T11:32:29+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-10-16T19:35:09+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-30T11:53:16+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"183581025323872192070680002314853894880","date":"2025-09-24T17:46:18+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"76621980960834632068771836361501883417","date":"2025-09-24T17:32:05+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-09-22T17:20:50+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-08-25T07:18:30+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-08-25T07:17:25+00:00","index":"","fulltext":""},{"type":"submitted","content":"Environmental Monitoring and Assessment","date":"2025-07-30T10:42:28+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"environmental-monitoring-and-assessment","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"emas","sideBox":"Learn more about [Environmental Monitoring and Assessment](http://link.springer.com/journal/10661)","snPcode":"10661","submissionUrl":"https://submission.nature.com/new-submission/10661/3","title":"Environmental Monitoring and Assessment","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"81af21c3-cc15-4147-8b84-2f53447feb33","owner":[],"postedDate":"October 5th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"in-revision","subjectAreas":[],"tags":[],"updatedAt":"2026-05-19T09:55:33+00:00","versionOfRecord":[],"versionCreatedAt":"2025-10-05 11:34:07","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7251995","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7251995","identity":"rs-7251995","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}