An assessment of maternal concentrations of per- and polyfluoroalkyl substances (PFAS) and trace elements during the second trimester of pregnancy in western Pennsylvania.

The Magee Obstetric and Maternal Infant (MOMI) Database and Biobank collects blood, urine, and placenta from participating women who give birth at Magee-Women’s Hospital in Pittsburgh or University of Pittsburgh Medical Center (UPMC) Hamot in Erie. The database and biobank include over 100,000 biospecimens and data from over 220,000 pregnancies since 1995. In this pilot study, 46 pregnant women were selected from the biobank population ( n  = 4622) based on smoking status and preterm birth status (defined as < 37 weeks gestation). This included women with a self-reported smoking status of current ( n  = 15), former ( n  = 6), and never ( n  = 25), as well as women with preterm birth ( n  = 21) or term birth ( n  = 25). Urinary cotinine, a biomarker of recent tobacco smoke exposure, was measured in addition to self-reported smoking status. All pilot study samples were collected from the 4622 births between 2017 and 2021. The study was approved by the University of Pittsburgh Institutional Review Board (IRB #: STUDY21050159). Anonymized samples were used in this analysis so additional consent for participation was not required. For population-based comparisons with this pilot study, we analyzed publicly available data from the US NHANES 2015–2016 (for urinary strontium and uranium concentrations) and 2017–2018 respondent populations (for all other urine trace elements and serum PFAS). NHANES uses a complex, multistage probability sampling design to ensure that the data collected is nationally representative. Participants are selected through stratified, clustered sampling, with oversampling of certain subgroups, such as racial/ethnic minorities and older adults. Sampling weights can then be applied to the data to account for the unequal probability of selection. Additionally, using these weights, researchers can generalize findings from the survey respondent population to the US population. We used a subset of women of reproductive age (defined in NHANES as women aged 20–44 years). With the sampling weights applied, the survey sample who had serum PFAS measured represented 50,343,314 women of reproductive age, while the sample with all but two urine trace elements represented 49,693,391 women and the sample with urinary strontium and uranium concentrations measured represented 49,660,243 women. Maternal urine and whole blood samples were collected during the second trimester of pregnancy and stored at − 70 °C until analysis. Serum was separated by centrifugation prior to storage at − 70 °C until subsequent analyses. Urine trace elements and serum PFAS were analyzed at the New York State Department of Health’s (NYSDOH) Wadsworth Center, a CLIA-certified laboratory and NIH-designated lab hub for targeted analysis of biospecimens for environmental contaminants. In all, 38 trace elements were quantified: barium (Ba), cobalt (Co), cadmium (Cd), cesium (Cs), molybdenum (Mo), nickel (Ni), rubidium (Rb), selenium (Se), strontium (Sr), thallium (Tl), zinc (Zn), arsenic (As), lead (Pb), uranium (U), manganese (Mn), chromium (Cr), tin (Sn), tellurium (Te), antimony (Sb), vanadium (V), cerium (Ce), lanthanum (La), gadolinium (Gd), tungsten (W), neodymium (Nd), praseodymium (Pr), yttrium (Y), beryllium (Be), erbium (Er), europium (Eu), dysprosium (Dy), holmium (Ho), lutetium (Lu), scandium (Sc), samarium (Sm), terbium (Tb), thulium (Tm), and ytterbium (Yb). The methods for quantification were developed and validated specifically for use in the NIH CHEAR/HHEAR programs, and quality assurance protocols for HHEAR were followed for this study (Galusha et al., 2021 ). Samples were thawed to room temperature and mixed on a laboratory rocker, and a 0.3-mL aliquot was removed for trace element analysis on an Agilent Model 8900 Inductively Coupled Plasma Tandem Mass Spectrometer (ICP-MS/MS), equipped with an Octopole Reaction System (ORS) and axial acceleration technology. The ICP-MS/MS was configured with an SPS 4 autosampler (Agilent Technologies, Santa Clara, CA USA) and an ultra-low particulate arrester air filter (Elemental Scientific, Omaha, NE USA) to minimize airborne contamination. Typical operating conditions and key analytical details for each isotope monitored are provided in Table S1 . Urine samples were diluted to 5 mL with a reagent solution containing 2% (v/v) double-distilled HNO 3 , 0.5% double-distilled HCl, 1000 µg L −1 Au (Inorganic Ventures, Christiansburg, VA USA), and 0.005% (v/v) Triton X-100 ™ (Sigma Aldrich Co., St. Louis, MO USA). Samples were analyzed alongside NIST SRM 2668 (NIST, Gaithersburg, MD) and CHEAR Reference Materials (RMs) (23). Accuracy was typically within ± 20% of the assigned values. Sample analyses were bracketed with 3 levels of internal urine QC materials that were previously verified using available reference materials and sample spikes. Duplicate analyses were performed on 14 samples; repeatability was typically within the allowable discrepancy established by the laboratory based on their CLIA-approved standard operating procedures. Eleven long and short chain PFAS included in the analysis were perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexanesulfonic acid (PFHxS), perfluorodecanoic acid (PFDA), perfluorobutanesulfonic acid (PFBS), perfluoroheptanoic acid (PFHpA), n-methyl perfluorooctanesulfonamide (N-MeFOSAA), perfluoroundecanoic acid (PFUnDA), perfluorododecanoic acid (PFDoDA), perfluorooctanesulfonamide (PFOSA), and perfluorononanoic acid (PFNA). Ultra-performance liquid chromatography (UPLC) separation coupled with electrospray triple quadrupole tandem mass spectrometry (ESI–MS/MS) was used for the analysis as previously described (Honda et al., 2018 ). Briefly, 50 µL of serum are added into a Phree™ 96-well plate containing isotopically labeled PFAS internal standards in acetonitrile. Sample matrix protein precipitation occurs, followed by simultaneous extract filtration and phospholipid removal performed by a Perkin-Elmer Janus Liquid Handling System. After extraction, the sealed sample plates are placed in the UPLC autosampler, and 10-µL portions of each extract are analyzed using an Agilent UPLC-MS/MS (1290 UPLC with 6460 C Triple Quadrupole Mass Spectrometer). PFAS compounds are separated on a Waters Acquity™ UPLC BEH C18 column. For MS/MS, electrospray ionization in the negative-ion mode is used, and selected reaction monitoring with specific precursor-ion and product-ion pairs for each analyte is used for the detection of 11 PFAS targets. Quantitation is achieved using the stable-isotope dilution technique with a series of 13C/18O/2H-labeled internal standards. A matrix-matched calibration curve is prepared in newborn calf serum over the range of 0.5 to 100 μg/L. The method limits of quantification (LOQ) are 0.5 μg/L. The method has excellent repeatability (inter-day CV: < 7.3%), accuracy (bias: < 5%), and precision (intra-day CV: < 5.7). Total urine cotinine was analyzed using a liquid chromatography-tandem mass spectrometry (LC–MS/MS) method as previously described (Kotandeniya et al., 2015 ; Nikam et al., 2021 ). Briefly, urine was mixed with [D3]cotinine internal standards, treated with β-glucuronidase, and purified by supported liquid extraction plates and Oasis MCX 96-well plates. The purified samples were analyzed by LC–MS/MS using m /z 178.08 →  m / z 98.14 for cotinine, and corresponding fragments for the isotope labeled internal standards. Values below the limit of detection (LOD) were imputed as LOD/sqrt(2). Urine cotinine concentrations were used to confirm self-reported smoking status. A urine cotinine threshold of 1.8 µg/L was used to recategorize pilot study participants who had recently smoked or had been exposed to secondhand smoke despite their self-reported smoking status (Kim, 2016 ). Two never smokers and two former smokers were recategorized as smokers due to urine concentrations of cotinine above the threshold of 1.8 µg/L. A urinary cotinine threshold of 1.8 µg/L was selected based on a study conducted in a New Hampshire birth cohort, which demonstrated that this value optimized the sensitivity and specificity for distinguishing between non-smoking and smoking status (Peacock et al., 2022 ). T -tests for continuous variables and chi-square or Fisher’s exact test were used to determine statistical differences between the MOMI pilot study sample ( n  = 46) and the full MOMI biobank sample from the same period of 2017–2021 ( n  = 4622). We calculated the geometric mean, minimum, median, 95th percentile and maximum for trace elements and PFAS. Because smoking is a known source of cadmium exposure and may be a source of exposure to other trace elements as well, we calculated the geometric means and 95th percentiles of trace elements and PFAS for those with cotinine both above and below the urinary cotinine threshold to identify smoking and non-smoking participants. Spearman’s correlation coefficients were calculated for trace elements and PFAS for smoking and non-smoking participants separately. We used the Mann–Whitney U test to compare the distributions of metal concentrations between MOMI pilot smoking and non-smoking participants. We calculated geometric means and 95th percentiles using data from the 2015–2016 and 2017–2018 NHANES survey samples with sampling weights applied to generate nationally representative estimates. These descriptive estimates were compared to corresponding values from the MOMI pilot study population. NHANES trace element and PFAS measurement protocols have been previously described (CDC, 2020 ). Serum cotinine (as opposed to urine cotinine) was measured for a higher percentage of NHANES participants who also had trace elements and PFAS measured, so a serum cotinine threshold of 10 μg/L was used to distinguish non-smoking and smoking participants, as established by the EPA’s Report on the Environment (E P A, 2024 ). Both the urine and serum cotinine thresholds have been previously established in studies and can be considered comparable in determining smoking status (E P A, 2024 ; Kim, 2016 ). As a sensitivity analysis, urine metal concentrations were adjusted for urine creatinine concentrations and expressed as metal-to-creatinine ratios (µg/g creatinine) to account for urine dilution, which can affect the urinary concentration of some metals. Creatinine-adjusted and unadjusted metal concentrations were compared to determine if hydration status affected results. We calculated a summed serum concentration of 7 PFAS, including imputed values for any samples below the limit of detection, per the National Academies of Sciences, Engineering and Medicine (NASEM) recommendation to determine the risk of health effects for participants. Guidelines for PFAS exposure and clinical follow-up by the NASEM recommended testing for at-risk populations and established concentration thresholds for clinical care (NASEM, 2022 ). The NASEM report highlighted 7 PFAS of interest, including PFOA, PFOS, PFHxS, PFNA, N-MeFOSAA, PFDA, and PFUnDA. These compounds were selected by the NASEM because they are collected routinely as part of NHANES.

The median age of participants was 32 (IQR: 29–34) years, and the median pre-pregnancy BMI was 26 (IQR: 22–33) (Table  1 ). Of the participants, 76% of the women identified as White, and 39% were enrolled in Medicaid. Most participants resided in Allegheny County (72%), while the remainder resided in less densely populated counties in western Pennsylvania. Participant characteristics between the pilot study sample and the full MOMI biobank database sample did not differ except for the distributions of smoking and preterm birth. The overrepresentation of smokers and those with preterm birth was expected due to participants with those characteristics being oversampled in this pilot study. Table 1 Participant characteristics Characteristic MOMI pilot study ( n  = 46) MOMI Total Biobank Database ( n  = 4622) p -value Age, mean (SD) 31.3 (5.2) 30.6 (5.1) 0.35 Pre-pregnancy BMI, mean (SD) 1 28.5 (8.5) 27.8 (7.5) 0.53 Self-reported history of smoking, n (%)  < 0.01   Never 25 (54.3) 3350 (72.5)   Former 6 (13.0) 647 (14.0)   Current 15 (32.6) 422 (9.1)   Unknown 0 (0.0) 203 (4.4) Preterm birth, n (%) 2  < 0.01   Yes 21 (45.7) 675 (14.6)   No 25 (54.3) 3944 (85.4) Race, n (%) 0.73   White 35 (76.1) 3611 (78.1)   Black 9 (19.6) 725 (15.7)   Other 2 (4.3) 221 (4.8)   Unknown/declined 0 (0.0) 65 (1.4) County of residence, n (%)  > 0.99   Allegheny 33 (71.7) 3310 (71.6)   Other 13 (28.3) 1312 (28.4) Insurance status, n (%) 0.43   Medicare/Medicaid 18 (39.1) 1410 (30.5)   Private 28 (60.9) 3140 (67.9)   Self-pay 0 (0.0) 69 (1.5)   Unknown 0 (0.0) 3 (0.1) 1 BMI MOMI Total Biobank Database, n  = 4334 2 Preterm birth MOMI Total Biobank Database, n  = 4619 n , number of participants; SD , standard deviation Participant characteristics 1 BMI MOMI Total Biobank Database, n  = 4334 2 Preterm birth MOMI Total Biobank Database, n  = 4619 n , number of participants; SD , standard deviation Out of the 38 trace elements and 11 PFAS measured, 16 trace elements and 2 PFAS (PFOA and PFOS) were highly detected (> 60% of samples were above the LOD) (Table  2 ). Urinary concentrations for Ba, Cd, Co, Cs, Mo, Rb, Se, Sr, Tl, Zn, and serum PFOS were above detectable levels in all participants. Over 80% of samples had detectable levels of 14 trace elements, including As (geometric mean (GM): 4.6 μg/L; 95th percentile (pct): 61.2 μg/L), Cd (GM: 0.2 μg/L; 95th pct: 1.1 μg/L), and Pb (GM: 0.3 μg/L; 95th pct: 1.3 μg/L), as well as PFOS (GM: 1.6 μg/L; 95th pct: 4.2 μg/L). Smoking pilot study participants had distributions of Cd, Cs, Pb, Mo, Ni, Rb, Se, Tl, Sn, and U concentrations that tended to be significantly higher compared to non-smoking participants (Table  3 ). PFOS and PFOA did not have significantly different distributions between smoking and non-smoking pilot study participants. Table 2 Detection rates and concentrations of urinary trace elements and serum PFAS (μg/L) for MOMI participants ( n  = 46) Analyte LOD % Det GM GSD Min Median 95th Pct Max Highly detected (> 60%) Ba 0.100 100 2.34 2.32 0.300 2.50 7.08 24.8 Cd 0.010 100 0.203 2.88 0.020 0.208 1.11 1.32 Co 0.008 100 0.403 2.66 0.050 0.412 1.60 4.21 Cs 0.200 100 3.93 2.36 0.500 4.20 10.7 20.7 Mo 1.00 100 34.9 2.65 4.00 38.0 136 412 PFOS 0.500 100 1.57 1.80 0.530 1.48 4.25 5.32 Rb 13.0 100 958 2.22 133 999 2690 4040 Se 0.900 100 28.5 2.70 3.10 33.7 98.4 141 Sr 1.00 100 117 2.38 20.0 118 460 592 Tl 0.006 100 0.157 2.37 0.020 0.176 0.418 0.501 Zn 5.000 100 227 3.12 24.0 267 1000 3470 Ni 0.500 97.8 2.21 1.66  < LOD 2.30 4.25 6.80 As 0.600 89.1 4.57 3.99  < LOD 4.05 61.2 82.9 Pb 0.090 87.0 0.281 2.40  < LOD 0.270 1.25 1.43 U 0.001 87.0 0.004 2.44  < LOD 0.004 0.012 0.018 PFOA 0.500 78.3 0.729 1.75  < LOD 0.679 1.90 2.34 Mn 0.190 71.7 0.267 1.78  < LOD 0.300 0.728 1.33 Cr 0.400 69.6 0.647 1.96  < LOD 0.650 1.58 3.70 Te 0.007 67.4 0.011 1.88  < LOD 0.011 0.028 0.051 Sn 0.190 63.0 0.498 3.93  < LOD 0.390 5.76 10.6 Not highly detected (≤ 60%) Sb 0.060 57.8 NC NC  < LOD 0.070 0.170 0.350 PFHxS 0.500 52.2 NC NC  < LOD 0.525 1.63 4.02 V 0.030 43.5 NC NC  < LOD  < LOD 0.135 0.320 Ce 0.006 37.8 NC NC  < LOD  < LOD 0.113 0.451 La 0.004 37.8 NC NC  < LOD  < LOD 0.061 0.283 Gd 0.004 21.7 NC NC  < LOD  < LOD 0.113 0.200 PFNA 0.500 19.6 NC NC  < LOD  < LOD 0.715 1.55 W 0.290 10.9 NC NC  < LOD  < LOD 0.353 0.740 Nd 0.006 8.90 NC NC  < LOD  < LOD 0.009 0.010 Y 0.004 8.90 NC NC  < LOD  < LOD 0.005 0.006 Pr 0.002 4.30 NC NC  < LOD  < LOD  < LOD 0.003 PFDA 0.500 2.20 NC NC  < LOD  < LOD  < LOD 0.506 LOD limit of detection; % Det , percent detected; GM , geometric mean; GSD , geometric standard deviation; 95th Pct , 95th percentile; NC , not calculated Be, Dy, Er, Eu, Ho, Lu, N-MeFOSAA, PFBS, PFDoDA, PFHpA, PFOSA, PFUnDA, Sc, Sm, Tb, Tm, and Yb were not detected in any participants Table 3 Geometric mean concentrations of urinary trace elements and serum PFAS comparing MOMI pilot participants and NHANES women of reproductive age Non-smoking participants Smoking participants p -values comparing MOMI smoking and non-smoking participants Analyte (μg/L) MOMI ( n  = 27) NHANES ( n  = 38,631,117) 2 MOMI ( n  = 19) NHANES ( n  = 11,162,633) 3 As 3.51 6.14 6.64 6.12 0.191 Ba 2.05 0.99 2.82 1.37 0.343 Cd 0.14 0.13 0.36 0.22 0.002 Co 0.32 0.48 0.57 0.74 0.153 Cr 0.67 0.18 0.62 0.21 0.610 Cs 2.96 4.25 5.90 4.27 0.001 Mn 0.24 0.12 0.32 0.16 0.206 Mo 24.8 32.1 56.8 38.5 0.003 Ni 1.91 0.95 2.72 1.49 0.025 Pb 0.20 0.18 0.47 0.33 0.001 Rb 742 1380 0.004 Se 20.1 46.8 0.002 Sn 0.31 0.48 0.97 0.54 0.005 Sr 1 101 75.6 143 90.6 0.260 Te 0.01 0.01 0.937 Tl 0.12 0.18 0.22 0.2 0.008 U 1 0.003 0.004 0.006 0.006 0.003 Zn 176 324 0.103 PFOA 0.79 0.91 0.65 0.74 0.267 PFOS 1.75 1.8 1.34 1.78 0.099 1 Urinary Sr and U concentrations are from NHANES 2015–2016 2 n  = 37,639,910 for Sr and U only, n  = 38,819,191 for PFAS only 3 n  = 11,327,811 for Sr and U only, n  = 11,524,123 for PFAS only n , number of participants; MOMI: 46; NHANES 2017–2018 Trace elements: 52,624,659; NHANES 2017–2018 PFAS: 52,224,082; NHANES 2015–2016 Sr & U: 51,540,810 Detection rates and concentrations of urinary trace elements and serum PFAS (μg/L) for MOMI participants ( n  = 46) LOD limit of detection; % Det , percent detected; GM , geometric mean; GSD , geometric standard deviation; 95th Pct , 95th percentile; NC , not calculated Be, Dy, Er, Eu, Ho, Lu, N-MeFOSAA, PFBS, PFDoDA, PFHpA, PFOSA, PFUnDA, Sc, Sm, Tb, Tm, and Yb were not detected in any participants Geometric mean concentrations of urinary trace elements and serum PFAS comparing MOMI pilot participants and NHANES women of reproductive age 1 Urinary Sr and U concentrations are from NHANES 2015–2016 2 n  = 37,639,910 for Sr and U only, n  = 38,819,191 for PFAS only 3 n  = 11,327,811 for Sr and U only, n  = 11,524,123 for PFAS only n , number of participants; MOMI: 46; NHANES 2017–2018 Trace elements: 52,624,659; NHANES 2017–2018 PFAS: 52,224,082; NHANES 2015–2016 Sr & U: 51,540,810 Smoking and non-smoking participants had different correlation patterns between all highly detected trace elements and PFAS (Figs. S1 and S2). Non-smoking participants had stronger correlations between trace elements generally compared with smoking participants. PFOA and PFOS were strongly correlated with each other for smoking participants ( ρ  = 0.7), but not strongly correlated with any trace elements for either group. After summing the 7 PFAS compounds included in the NASEM guidelines, all pilot study participants had a total PFAS concentration above 2 μg/L, suggesting that these women should be screened for dyslipidemia, hypertensive disorders of pregnancy, and breast cancer, while also receiving counseling to reduce PFAS exposure (31). No pilot study participants had total PFAS concentrations above the NASEM threshold of 20 μg/L, where additional screening tests are recommended. PFOA and PFOS together contributed 22–62% of total serum PFAS concentrations. PFOS was the highest PFAS for all but three pilot study participants, with PFOA being highest in two of these cases, and PFHxS in one. The geometric mean urinary concentrations of Ba, Cd, Cr, Mn, Ni, Pb, and Sr were higher in both the non-smoking and smoking pilot study participants compared to their respective NHANES non-smoking and smoking counterparts (Table  3 ). As, Cs, Mo, Sn, and Tl were also higher in smoking pilot study participants compared to NHANES smoking participants. PFOA and PFOS were lower in pilot study participants compared to their respective NHANES non-smoking and smoking counterparts. For non-smoking participants, the 95th percentile concentration of Sr was higher in both pilot study non-smoking and smoking participants compared to their respective NHANES non-smoking and smoking counterparts (Table  4 ). Ba, Mn, and Sn were also higher in non-smoking pilot study participants compared with NHANES non-smoking participants, while Cd, Co, Cr, Mo, and Ni were also higher in smoking pilot study participants compared to NHANES smoking participants. Over 40% of pilot study non-smoking participants had a concentration of urine Mn higher than the 95th percentile of NHANES non-smoking participants. For smoking participants, the 95th percentile concentrations of urine Cd and Cr for pilot study participants were higher compared to NHANES smoking participants. Over 53% of pilot study smoking participants had a urine Cr concentration higher than the 95th percentile of NHANES smoking women, while over 21% had a Cd concentration higher than the NHANES 95th percentile. No pilot study participants had PFOA or PFOS concentrations higher than the 95th percentile of the NHANES participants. The differences in the geometric means and 95th percentiles were compared descriptively. Table 4 95 th percentile concentrations of urinary trace elements and serum PFAS comparing MOMI pilot participants and NHANES women of reproductive age Non-smoking participants Smoking participants Analyte (μg/L) MOMI ( n  = 27) NHANES ( n  = 38,631,117) 2 MOMI ( n  = 19) NHANES ( n  = 11,162,633) 3 As 23.2 150.48 64.8 196 Ba 6.34 4.92 9.05 25.5 Cd 0.54 0.66 1.15 1.03 Co 1.18 1.98 2.9 1.94 Cr 1.57 2.73 1.72 0.53 Cs 7.95 14.12 10.8 11.2 Mn 0.41 0.31 1.28 1.33 Mo 106 128 186 165 Ni 3.86 5.6 6.08 5.68 Pb 0.49 0.66 1.37 2.27 Rb 2000 2870 Se 81.5 103 Sn 4.71 3.25 4.89 5.24 Sr 1 409 278 482 398 Te 0.03 0.03 Tl 0.32 0.57 0.43 1 U 1 0.01 0.03 0.02 0.05 Zn 798 1430 PFOA 1.89 2.8 1.81 2 PFOS 5.01 6.1 2.61 4.5 1 Urinary Sr and U concentrations are from NHANES 2015–2016 2 n  = 37,639,910 for Sr and U only, n  = 38,819,191 for PFAS only 3 n  = 11,327,811 for Sr and U only, n  = 11,524,123 for PFAS only n , number of participants; MOMI: 46; NHANES 2017–2018 Trace elements: 52,624,659; NHANES 2017–2018 PFAS: 52,224,082; NHANES 2015–2016 Sr & U: 51,540,810 95 th percentile concentrations of urinary trace elements and serum PFAS comparing MOMI pilot participants and NHANES women of reproductive age 1 Urinary Sr and U concentrations are from NHANES 2015–2016 2 n  = 37,639,910 for Sr and U only, n  = 38,819,191 for PFAS only 3 n  = 11,327,811 for Sr and U only, n  = 11,524,123 for PFAS only n , number of participants; MOMI: 46; NHANES 2017–2018 Trace elements: 52,624,659; NHANES 2017–2018 PFAS: 52,224,082; NHANES 2015–2016 Sr & U: 51,540,810 The geometric mean of urine creatinine for smoking pilot study participants was higher compared to non-smoking participants (118.2 ± 2.1 mg/dL and 54.0 ± 2.5 mg/dL, respectively). Similarly, the geometric mean of urine creatinine for NHANES smoking respondents was also higher compared to non-smoking respondents (110.2 ± 1.8 mg/dL and 91.3 ± 2.2 mg/dL, respectively). The geometric means of creatinine-adjusted metal concentrations were generally higher in non-smoking pilot study participants, compared to smoking pilot study participants as well as smoking and non-smoking NHANES respondents (Table S2).

To our knowledge, this is the first study to examine urinary concentrations of trace elements and/or serum PFAS in smoking and non-smoking pregnant women in western Pennsylvania. We found that women in western Pennsylvania were exposed to essential and non-essential trace elements and PFAS. Fourteen trace elements were measured at concentrations above detectable levels for 80% of this pilot study sample, including As, Cd, and Pb. PFOS was detected in 100% of the study population. We observed significantly different distributions in urinary concentrations for 10 trace elements among individuals who smoked compared with non-smoking individuals. Exposure to tobacco smoke, via smoking or second-hand, can be a significant source of as Cd, Pb, as well as As, depending on the soil conditions where the tobacco is grown (Angelova et al., 2004 ; Caruso et al., 2013 ; Pinto et al., 2017 ). Our results confirmed these findings for Cd and Pb, but not for As, which is less readily taken up into the leafy green portions of plants. While smoking may be associated with the observed higher trace element concentrations in smoking pilot study participants compared with non-smoking participants, identifying the source of non-essential trace elements was beyond the scope of this preliminary study. Additional research is needed to determine the source of these trace elements in western Pennsylvania pregnant women. The geologic makeup of western Pennsylvania, in particular the Marcellus shale formation, in conjunction with the region’s industrial activities may contribute as possible sources of environmental trace elements (Burgos et al., 2017 ; Capo et al., 2014 ; Hill et al., 2023 ; Maxim et al., 2022 ; Niu et al., 2018 ; Rimmer, 1991 ; Rossi et al., 2017 ; Schatzel & Stewart, 2003 ). The concentrations of highly detected PFAS, namely, PFOA and PFOS, were comparable between smoking and non-smoking participants. A few studies have highlighted that smokers may have higher levels of certain PFAS compared to non-smokers, due to the potential contamination of tobacco products during processing or the use of PFAS-containing materials (Cho et al., 2015 ; Shu et al., 2018 ; Tseng, 2009 ). Overall, studies examining smoking as a predictor of PFAS in mothers and infants have reported mixed findings (McAdam & Bell, 2023 ). Predictors of PFAS in a study of 235 people in eastern Pennsylvania included age, education, military base employment as well as water source and quantity of daily water consumption (Nair et al., 2021 ). Many urine trace element concentrations were higher in pilot study participants compared to a nationally representative population of US women of reproductive age. Yet, the trace element concentrations in the pilot study were comparable to, or lower than, pregnant women in other populations around the world. When comparing geometric means and medians from multiple studies of adults across North America, Europe, Africa, and Asia, the median of these reported values served as a reference (Adams et al., 2016 ; Aprea et al., 2018 ; Asante et al., 2012 ; Basu et al., 2011 ; Caron‑Beaudoin et al., 2019 ; Health Canada, 2010 ; Hoet et al., 2013 ; Li et al., 2022 ; Mizuno et al., 2021 ; Morton et al., 2014 ; Nisse et al., 2017 ; Rango et al., 2015 ; Snoj Tratnik et al., 2019 ; Soleimani et al., 2024 ). Non-smoking MOMI participants had geometric means at or below the median for all trace elements except Ba, second only to a study population in Ghana (Asante et al., 2012 ). In contrast, smoking MOMI participants had a geometric mean concentration above the median for several trace elements, including Ba, Cs, Mo, Se, Sr, Tl, and Zn. None of the geometric means for smoking MOMI participants, however, were the highest when comparing to these other study populations. Additionally, none of the metal concentrations met the criteria for requiring medical follow-up for participants. Having comparatively higher concentrations of trace elements does not necessarily indicate higher risks of adverse health outcomes. However, the differences in concentrations between populations can highlight unique patterns of exposure, which may reflect differences in cultural- and lifestyle-related factors and regionally specific factors like industrial or agricultural activities. These unique patterns of exposure can inform research into exposure sources and potential adverse health outcomes. Urine metal concentrations are typically adjusted for creatinine to account for urine dilution, although recent studies have advocated for the discontinuation of these procedures due to the possibility of introducing biases (Bulka et al., 2017 ; O’Brien et al., 2016 ; Weaver et al., 2016 ). Smoking is associated with increased muscle metabolism which both produces creatinine to be cleared in the urine and also affects kidney function (Degens et al., 2015 ; 2014, Rom et al., 2012 , 20132012, 2013 , 2014 ). Our results showed that smoking participants had higher urine creatinine concentrations compared to non-smoking participants which is consistent with prior studies (53). Since urine creatinine concentrations may be higher in smokers for reasons unrelated to metal exposures, adjusting for creatinine could lead to an underestimation of metal exposure in smokers. Additionally, pregnancy causes physiological changes further complicating the relationships between environmental contaminant metabolism and kidney function (G. Lee et al., 2021 ). As a result, alternative measures of hydration status should be considered when assessing urinary toxicant exposure among smoking or pregnant populations. Other measures of urine dilution will be considered in future studies. All 46 pilot study participants had combined PFAS values over 2 μg/L, but none exceeded 20 μg/L. The 2022 NASEM guidance for population-based PFAS assessment concluded that clinicians should (1) provide the usual standard of care at < 2 μg/L of total PFAS, (2) between 2 and 20 μg/L, encourage exposure reduction, and screen for dyslipidemia, hypertensive disorders of pregnancy, and breast cancer, and (3) for concentrations over 20 μg/L add testing for thyroid function, and screening for kidney cancer, testicular cancer and ulcerative colitis (31). Concentrations of PFOA and PFOS in the pilot study participants were lower or comparable to several other studies in the US states of Pennsylvania, Wisconsin, Georgia, New York, and Massachusetts (Boronow et al., 2019 ; Chang et al., 2021 ; H.‑W. Liang et al., 2024 ; Nair et al., 2021 ; Schultz et al., 2023 ), as well as Japan, New Zealand, South Korea, and several European countries (Pirard et al., 2020 ; Tsai et al., 2018 ). Additionally, geometric mean concentrations of PFOA (0.729 μg/L) and PFOS (1.567 μg/L) in this pilot study were lower than the German Human Biomonitoring Commission’s guidance values for women at reproductive age which are set at 5 μg/L and 10 μg/L for PFOA and PFOS, respectively (German Human Biomonitoring Commission, 2020 ). Despite PFAS’ persistence in the environment and the human body, levels of PFOA and PFOS have been declining due to restrictions on their use in many countries; however, no international standard exists and PFAS exposures remain a global concern. Despite reduced production in some countries, production has increased in others (Land et al., 2018 ). Biomonitoring of environmental chemicals during pregnancy is vital as both trace elements and PFAS can cross the placenta and mother and fetus are vulnerable to associated health effects, such as adverse pregnancy outcomes as well as developmental issues (Stone et al., 2021 ). However, only a few US states or cities have developed longstanding biomonitoring programs for pregnant women (Association of Public Health Laboratories, n.d. ). The most comprehensive biomonitoring program in the USA is the NHANES program which collects samples to measure a number of environmental contaminants routinely over time. While NHANES collects samples from pregnant women from varying locations around the USA, the survey is not designed to have a representative sample of pregnant women nor any one geographic location within the country. It is vital to have biomonitoring programs locally that are better able to capture how environmental exposures vary by lifestyle, culture, socioeconomic disparities, natural characteristics, and the historical or ongoing industrial activities of a region, especially among pregnant people. There were some limitations to this study. While the differences in trace element and PFAS concentrations compared to other cohorts may represent true differences in exposure patterns for pregnant women in this region, the small sample size limits our ability to generalize to the population of pregnant individuals in western Pennsylvania. However, after examining the differences between the pilot study sample compared to the MOMI biobank population, there were only differences in smoking status and preterm birth as those were oversampled intentionally as part of this and other related studies. Additionally, because Magee-Women’s Hospital is a large referral hospital, there is likely an overrepresentation of women with pregnancy and birth complications in the MOMI database population, which may also limit the generalizability of these results. While smoking is a known source of exposure to trace elements, the differences in metal and PFAS concentrations between smoking and non-smoking may be due to unmeasured toxicokinetic factors related to smoking status or other source(s) of toxicant exposure. Future work will aim to include a robust study sample and employ inverse probability weighting to correct for the overrepresentation of some characteristics in the biobank (Narduzzi et al., 2014 ). We analyzed spot urine samples collected at a single time point during pregnancy (second trimester) and were not able to examine samples collected at other time points. Urine metal concentrations reflect excretion but not necessarily circulating levels within the body. For some metals, bone or blood concentrations are more reliable biomarkers compared to urine concentrations. However, urine is an established biomarker for many of the measured metals with the exceptions of metals like Cu, Cr, Mn, and Pb (Agency for Toxic Substances and Disease Registry (ATSDR), 2012 ; Martinez‑Morata et al., 2023 ). Regardless, urinary measurements of these metals can still provide valuable insights, such as indicating disruptions in essential metal homeostasis (e.g., excessive urinary excretion of copper or manganese) or reflecting physiological changes, such as the mobilization of lead from bone stores during pregnancy, which may result in elevated urinary concentrations (Agency for Toxic Substances & Disease Registry, 2024 ; Collin et al., 2022 ). The strengths of this study included that we were able to measure 49 analytes from simultaneously collected biobanked samples from pregnant women. The MOMI database is well characterized and phenotyped for future epidemiologic analyses with specific adverse maternal and child health outcomes. The labs that performed trace element and PFAS quantification performed stringent QA/QC and are NIH HHEAR-designated lab hubs for these analyses.

This study provided for the first time an important characterization of trace elements and PFAS in a pilot study of western Pennsylvanian pregnant women. We observed differences in trace element concentrations between both smoking and non-smoking pilot study participants as well as compared to a nationally-representative sample of US women of reproductive age. PFAS and trace element concentrations of pilot study participants were comparable to larger studies from the USA and other countries in Europe and Asia. Biomonitoring studies among pregnant women and children are successful in identifying individuals with elevated exposures to toxic chemicals. Understanding environmental exposures among pregnant women at a regional level can support strategies for intervention to reduce and mitigate potentially harmful exposures.

Exposure to non-essential trace elements (including metals and metalloids) and per- and polyfluoroalkyl substances (PFAS) during pregnancy poses potential adverse health implications for both pregnant women and the developing fetus. The US National Health and Nutrition Examination Survey (NHANES) biomonitoring studies reported detectable urinary concentrations of arsenic, cadmium, and lead in 83–99% of women of reproductive age over the 2015–2016 and 2017–2018 cycles (Watson et al., 2020 ). Moreover, concentrations for a majority of the 13 trace elements measured in NHANES were higher among pregnant women compared to non-pregnant women. Due to their consistent use for decades and their persistence in the environment and the human body, PFAS are ubiquitous and detected in most human biospecimens sampled in NHANES within the last 10 years (Schultz et al., 2023 ). Exposure to trace elements or PFAS is associated with adverse pregnancy and birth outcomes including an increased risk of spontaneous abortion, preeclampsia and preterm birth (Nian et al., 2022 ; Preston et al., 2022 ; Stone et al., 2021 ). Additionally, women of reproductive age who are exposed to trace elements and PFAS are at higher risk of reproductive conditions including infertility, dysregulated menstrual cycles, endometriosis, and polycystic ovary syndrome (PCOS) (Campbell et al., 2016 ; S. Lee et al., 2020 ; C. Liang et al., 2022 ; Lin et al., 2023 ; Rickard et al., 2022 ). As such, environmental chemical exposure for pregnant women and women of reproductive age carries risks for long-term health. Prenatal exposures pose risks to the developing fetus as well, since some metals, metalloids, and PFAS can cross the placental barrier (Stone et al., 2021 ). As a result, neonates are more likely to experience adverse events including abnormal organ development, infant mortality, preterm birth, and low birth weight, which can have long-term health effects (Issah et al., 2024 ; Zhang et al., 2023 ). Women’s exposure to trace elements arises predominantly through inhalation of air-borne particles and ingestion of contaminated water and food (Red et al., 2011 ). Exposure to PFAS predominantly arises through consumption of foods as well as contact with other consumer products, such as cosmetics and stain-resistant or waterproof fabrics (Boronow et al., 2019 ; Wu & Kannan, 2019 ). The ubiquity of trace elements and PFAS in the environment is directly reflected in concentrations of these toxicants measured in urine or blood from US women (1). Smoke from tobacco products is also a major source of arsenic, cadmium and lead for those exposed to it either actively or passively (Caruso et al., 2013 ; Pinto et al., 2017 ). Exposure to trace elements or PFAS rarely occurs in isolation, and assessment of co-exposures is a critical public health need. Western Pennsylvania’s recent land use changes, including an increase in both agricultural land and urban areas, as well as the steel, fossil fuel, and other manufacturing industries, may result in unique trace element and PFAS exposure profiles for pregnant women in the region (Breitmeyer et al., 2023 ; Maxim et al., 2022 ; Schatzel & Stewart, 2003 ; Wilkin et al., 2015 ). Additionally, Pennsylvania has higher rates of smoking during pregnancy compared to the US as a whole with some counties in western Pennsylvania exceeding 20% (Kipling et al., 2024 ; PA Department of Health, 2023 ). Yet, no prior studies have assessed concentrations of non-essential trace elements and PFAS among pregnant populations in this region. In this study, we characterized prenatal urinary trace elements and serum PFAS in a pilot study of 46 pregnant women living in western Pennsylvania and compared these concentrations with a nationally representative US population, as well as studies from other countries.

Below is the link to the electronic supplementary material. Supplementary file1 (DOCX 185 KB) Supplementary file1 (DOCX 185 KB)