Radiological investigation of radon in groundwater around the active Taal Volcano (Philippines) and dose evaluation

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Radon-222 is one of the naturally occurring radionuclides that can accumulate in groundwater which poses potential health risks through ingestion and inhalation. This study investigates the groundwater radon concentrations around the active Taal Volcano, Philippines. A total of 86 groundwater samples were collected and analysed using Liquid Scintillation Counter (LSC). Radon concentrations ranged from 4 to 51 Bq/L, with an average of 16.84 Bq/L. About 63% of the samples exceeded the US-EPA and PNSDW limit of 11.1 Bq/L, while none surpassed the WHO limit of 100 Bq/L. The estimated inhalation dose ranged from 16.38 to 61.32 µSv/y, while the ingestion dose surpassed the 100 µSv/y limit for most infants and children. While most groundwater radon levels remain within international safety limits, certain municipalities may require mitigation strategies. Public awareness initiatives and continuous monitoring are recommended to minimize the long-term health risks from radon exposure in groundwater. Radon groundwater ingestion dose inhalation dose radiological risk Taal volcano Figures Figure 1 Figure 2 Figure 3 Figure 4 INTRODUCTION Radon-222 is a radioactive gas formed naturally via the decay of uranium in the Earth’s crust. It is an odourless, colourless, and tasteless gas that has a half-life of about 3.8 days. It is considered a health risk due to its carcinogenic potential, particularly lung cancer. Radon can be accumulated in the groundwater as a decay product of uranium from the surrounding rocks and soils (Ajiboye et al., 2022 ; Idriss et al., 2011 ; Samuel et al., 2022 ). Human exposure to radon and its progenies from water is mostly from inhalation or ingestion, with inhalation serving as the main route and is responsible for most of the received dose which makes ingestion substantially low and can be ignored (Rahimi et al., 2022 ). Radon has a relatively short half-life however, exposure to radon can induce damage to vulnerable human cells. Moreover, radon decays to form other radioactive progenies that can further damage the cells (WHO, 2007 ). Various international organizations suggested a maximum allowable limit (MAL) for the concentration of Radon in water to protect the public from Radon exposure equivalent to 100 Bq/L as suggested by the World Health Organization (WHO) and 11.1 Bq/L from drinking water as suggested by the United States – Environmental Protection Agency (US-EPA) and European Atomic Energy Agency (EAEC). In the Philippine setting, the Philippine National Standards for Drinking Water (PNSDW) of 2017 suggested a threshold of 11 Bq/L. The US-EPA radon threshold was used as the basis of PNSDW radon threshold. There are several analytical methods to carry out the quantification of radon in water samples and among them, Liquid Scintillation Counting (LSC) is the most sensitive and widely used analytical method (Mamun & Alazmi, 2022 ). The advantage of the technique relies on several factors including excellent accuracy and precision of the method, low limit of detection, relative ease of sample preparation, and short analysis/counting time. The concentration of radon in groundwater relatively varies on the surrounding rock and soil material. However, natural environmental events such as volcanic eruption can abruptly affect the amount of radon in the water as radon is a part of the volcanic plumes spewed from different volcanic activities (Idriss et al., 2011 ). Recently, Taal Volcano, one of the most active volcanoes in the Philippines, had a series of volcanic activities with the most recent eruption to be in 2020 and still displaying minor activities in 2021 and 2022. Despite this, people still opted to live within the vicinity resisting the volcanic activities of Taal, and still use the groundwater in the area for various domestic activities. With this, the present work measured the radon in groundwater from the areas surrounding the Taal volcano and estimated its annual effective dose when accumulated by humans either by inhalation or ingestion. The results are compared with the international safety standard set by various organizations. MATERIALS AND METHOD Study Area The study area is Batangas province, located from 120° 51’ to 121° 8’ East and 13° 50’ to 14° 8’ North, in the Southwest Luzon of the Philippines with a total land area of 3,119.75 km 2 . A total population of 2,908,494 and 934 persons / km 2 has been reported for the whole province as of 2020 (Philippine Statistics Authority, 2021 ). Batangas province’s geology is predominantly Tertiary to Quaternary and consists largely of igneous and sedimentary rocks. These rocks that formed during late Miocene to early Pliocene periods, are widespread in the province. Moreover, there are faults that can be found within and around Batangas with Laiya fault and Marikina fault being the most notable faults. Batangas is home for the small but one of the most destructive volcanoes in the Philippines, the Taal Volcano. Taal Volcano is one of the most active volcanoes in the country that has erupted around 40 times in the past 400 years. Batangas experiences two main climate types: Type I and II which are both characterized having a dry season from November to April and a wet season from the rest of the year with sometimes a longer wet season. Eleven municipalities of Batangas province consisting of Taal, Sta. Teresita, Lemery, Laurel, Alitagtag, San Nicolas, Agoncillo, Tanauan, Talisay, Balete, and Mataas na Kahoy are only covered in this study. Sample Collection Groundwater samples were collected from springs, wells, and boreholes across selected municipalities, as these sources represent the primary water supply types used by local community for drinking and domestic purpose. Inclusion of these varied source types ensures that the result would be directly relevant to public health assessments and potential mitigation strategies. A more representative analysis of radon behaviour is possible when varied groundwater source types are allowed. Boreholes and deep wells often access confined aquifers with longer water-rock interaction, which leads to higher radon concentrations. In contrast, springs and shallow wells are typically influenced by surface conditions and may exhibit lower radon levels due to natural degassing. Sampling across these different systems provides a broader and more comparative profile of groundwater radon across the region. A total of 86 water samples around the Batangas Province were collected. One-liter plastic polyethylene terephthalate (PET) bottles were filled to the brim to prevent the formation of air pockets. For borehole sources, the water sample is collected about 10 minutes after turning on the tap or when the conductivity of water becomes constant. Water from water tanks was not collected. After sample collection, they are marked and carefully labelled. Samples are transported almost immediately to the laboratory to reduce the decay coefficient for the analysis. Sample Analysis The 222 Rn analysis was performed based on an in-house method developed at Nuclear Analytical Techniques Application Section–Philippine Nuclear Research Institute (Sucgang et al., 2012 ). A 10 mL aliquot of groundwater sample was pipetted to a 20 mL plastic vial and mixed with a 10 mL OptiPhase HiSafe scintillation cocktail. The solution was homogenized and then allowed to equilibrate for one hour. A blank sample was prepared with the same method but using sonicated ultrapure water to ensure the absence of radon. The set of samples was analysed with Tri-Carb 5110 TR Liquid Scintillation Counter for two cycles. Annual effective doses of drinking water samples due to ingestion and inhalation As suggested by the (UNSCEAR, 2000 ) Report, the value of the annual intake of drinking water is 730 L/y for adults. The annual effective dose due to the ingestion of radon from drinking water is calculated by the equation: AED ing = R W x L W x EDC ing where AED ing is the annual effective dose caused by the consumption of water with radon, R W is the calculated radon concentration in water, L W is the estimated annual consumption of water = 730 L/y, and the effective dose coefficient for ingestion is EDC ing = 3.5 nSv/Bq (Kolo et al., 2023 ; Qadir et al., 2021 ; UNSCEAR, 2000 ). According to (Bem et al., 2014 ; Isinkaye et al., 2023 ), a more realistic ingestion dose coefficient values can be used in calculating the ingestion dose. The values of the coefficient used were 1 x 10 − 8 Sv/Bq, 2 x 10 − 8 Sv/Bq, 7 x 10 − 8 Sv/Bq for adults, children, and infants, respectively. The annual effective dose due to inhalation of radon can be computed by using the equation: AED inh = R W x R AW x OF x EF x EDC inh where R AW is the air-water ratio of radon (10 − 4 ), OF as the average global indoor occupancy factor = 7000 h/year, EF is the equilibrium factor = 0.4, and EDC inh is the effective dose coefficient for inhalation with a value of 9 nSv/h (Bq/m 3 ) −1 (UNSCEAR, 2000 ). RESULTS AND DISCUSSION A total of 86 groundwater samples were collected from 11 municipalities of Batangas province surrounding the Taal volcano. Radon-222 concentration varied from a minimum of 4 Bq/L to a maximum of 51 Bq/L with an average of 16.84 Bq/L and a standard deviation of 9.57 Bq/L. A summary of the activity concentrations from different municipalities of Batangas province in shown in Table 1 . The weighted results mirrored the trend observed in the unweighted model, confirming that locations with higher average radon concentrations such as Taal and Tanauan, remained consistently associated with increased probability of elevated radon levels. This reinforces the robustness of the findings and assures that observed patterns are not simply artifacts of sample size variability across sites. The radon distribution map is presented in Fig. 1 along with its corresponding activity. Based on the map, the southwestern and northeastern parts have a high groundwater radon activity compared to other parts of the sampling sites. The high radon activity pattern could be attributed to the fractures and fault in the area as reported (Austria et al., 2023 ). The spatial distribution of radon reveals a clear relationship between elevated radon concentrations and the presence of geological faults and fractures as shown in Fig. 2 . A significant clustering of moderate to high radon concentrations is observed along the southwestern, southern, and northeastern peripheries of Taal Lake. These areas coincide with dense networks of mapped fractures and faults, suggesting that these structural features serve as conduits for radon migration from subsurface sources to the surface. Radon, being a noble gas and a decay product of uranium, typically migrates through permeable zones such as fractures and fault lines, and its elevated concentrations often signal zones of high subsurface permeability or tectonic activity. Recommended limits of radon activity in water varies per regulatory agency. The maximum contaminant level (MCL) of radon is shown in Table 2 . It is shown that the MCL of WHO, UNSCEAR, and US-EPA are 100 Bq/L, 40 Bq/L, and 11.1 Bq/L respectively. It is clear that only 2 out of 86 water samples (2.33%) has exceeded the UNSCEAR MCL of 40 Bq/L. About 63% of the samples (54 out of 86) have exceeded the US-EPA prescribed MCL of 11.1 Bq/L. None of the groundwater samples exceeded the WHO (2004) limit of 100 Bq/L. Only 37% of the total samples (32 out of 86) passed the MCL of the regulatory bodies. This significant gap in regulatory thresholds can lead to divergent public health responses, potentially underestimating or overestimating risk depending on the adopted standard. The US-EPA's more conservative limit reflects a precautionary approach, aiming to minimize long-term exposure risk by addressing even low-level chronic intake, particularly for vulnerable populations. In contrast, the UNSCEAR reference level may be more applicable in contexts where exposure is dominated by inhalation rather than ingestion. For regions like the study area, where groundwater is a primary drinking water source, adherence to stricter guidelines may be warranted to safeguard public health. The findings underscore the need for national policy frameworks to clearly define risk thresholds and mitigation strategies, ideally informed by both local exposure patterns and international best practices. Table 3 summarizes the measured radon concentration in water for this study and other parts of the world. It highlights the significant variability in radon levels worldwide. The average radon concentration reported in this study (Batangas province, Philippines) is 16.84 Bq/L with a concentration range of 4–51 Bq/L. As reported by the findings, the average radon concentration in this study is higher than what is reported at New South Wales, Australia and Hunan province, China (Atkins et al., 2016 ; Tan et al., 2019 ). The relatively lower values could be influenced by different hydrogeological conditions and rock types with minimal uranium content. The results of this study is notably lower than some regions with elevated radon levels such as Bauchi State, Nigeria with an average of 38.3 Bq/L (Shu’aibu et al., 2021 ) and Karoo Basin, South Africa (Botha et al., 2019 ). While this study offers valuable insight into radon levels in water across different communities, there are a few limitations worth noting. Since the sampling was done at a single point in time, it does not capture how radon levels might change with the seasons or over longer periods. it would be helpful to carry out long-term and seasonal monitoring, and to explore additional factors that could affect radon levels. This would give us a clearer picture of the risks and help support more informed public health decisions. The variation in groundwater radon concentration across different municipalities is shown in Fig. 3 which highlights significant heterogeneity in radon levels. Taal exhibits the highest variability and highest median radon concentration which suggests localized geological factor such as rock composition and fault structures resulting to an enhanced radon emanation. The presence of outliers in Taal and Lemery indicates occasional extreme values that may be influenced by specific hydrogeological conditions or well depth variations. Figure 4 and Table 4 shows the ingestion dose statistics for different age groups across the municipalities. Infants consistently receive the highest ingestion dose across all locations, followed by children and adults. This is primarily due to higher water consumption per body weight in infants and higher ingestion dose coefficient used (Bem et al., 2014 ) which results to them being more susceptible to radon-related radiation exposure. Municipalities of Taal, Tanauan, and San Nicolas exhibit the highest ingestion dose values, which aligns with their relatively high groundwater radon concentrations. The observed interquartile ranges and whiskers suggest variability in ingestion doses which emphasizes the influence of individual water sources on exposure levels. In terms of inhalation dose, the value ranges from 16.38 µSv/y to 61.32 µSv/y across municipalities with an average of 42.43 µSv/y. Regardless of the average annual ingestion and inhalation dose values, it is still below the maximum contamination level of 100 µSv/y (World Health Organization, 2004 ). Two samples have exceeded the permissible limit for the inhalation dose. All samples have exceeded the limit for ingestion dose of infant while for adult and children, only 46 and 78 samples respectively (53.5% and 90.7%) exceed the 100 µSv/y limit. Table 1 Radon concentration in groundwater of the eleven municipalities surrounding Taal volcano Municipality N Average Rn concentration (Bq/L) Standard deviation (Bq/L) Rn concentration range (Bq/L) Taal 12 24.33 13.11 6–51 Sta. Teresita 4 16.75 4.86 12–23 Lemery 13 16.54 8.97 5–39 Laurel 9 12.56 7.23 5–24 Alitagtag 9 19.22 9.82 6–36 San Nicolas 7 13.43 6.18 6–22 Agoncillo 7 14.00 6.38 7–26 Tanauan 8 23.88 10.16 9–37 Talisay 4 6.50 1.73 4–8 Balete 7 13.71 5.91 8–25 Mataas na Kahoy 6 13.83 7.36 4–24 Overall 86 16.84 9.57 4–51 Table 2 Recommended radon concentration limits in drinking water Regulatory body Maximum Contamination Level (MCL) (Bq/L) References PNSDW (Philippine National Standards for Drinking Water) 11.0 (DOH-Philippines, 2017) US-EPA 11.1 (USEPA, 1999 ) UNSCEAR 40 (UNSCEAR, 2000 ) WHO 100 (WHO, 2004) Table 3 Similar groundwater radon studies from various locations Location Average radon concentration (Bq/L) Radon concentration range (Bq/L) References Batangas, Philippines 16.84 4–51 This study New South Wales, Australia 4.90 0.14–20.33 (Atkins et al., 2016 ) Bauchi State, Nigeria 38.3 4.92–82.89 (Shu’aibu et al., 2021 ) Hunan Province, China 10.47 1.29–31.31 (Tan et al., 2019 ) Karoo Basin, South Africa 41 <LLD-183 (Botha et al., 2019 ) Budgam, Jammu and Kashmir 32.5 15.2–54.5 (Nazir, Sahoo, et al., 2021 ) Punjab, India 3.37 0.17–9.84 (Rani et al., 2021 ) Jammu and Kashmir, Himalayan Region 26.4 14–189 (Chakan et al., 2024 ) Akoko area, Nigeria 26.09 2.81-132.94 (Isinkaye et al., 2023 ) Srinagar, Kashmir 8.94 0.2–38.5 (Nazir, Simnani, et al., 2021 ) Table 4 Annual effective dose due to ingestion (AED ing ) and inhalation (AED inh ) of radon in groundwater Municipality Average AED ing (µSv/y) Range AED ing (µSv/y) AED inh (µSv/y) Adult Child Infant Adult Child Infant Average Range Taal 177.63 355.27 621.72 43.80-372.30 87.60-744.60 153.30-1303.05 61.32 15.12-128.52 Sta. Teresita 122.28 244.55 427.96 87.60-167.90 175.20-335.80 306.60-587.65 42.21 30.24–57.96 Lemery 120.73 241.46 422.56 36.50-284.70 73.00-569.40 127.75-996.45 41.68 12.60-98.28 Laurel 91.66 183.31 320.79 36.50-175.20 73.00-350.40 127.75–613.20 31.64 12.60-60.48 Alitagtag 140.32 280.64 491.13 43.80-262.80 87.60-525.60 153.30-919.80 48.44 15.12–90.72 San Nicolas 98.03 196.06 343.10 43.80-160.60 87.60-321.20 153.30-562.10 33.84 15.12–55.44 Agoncillo 102.20 204.40 357.70 51.10-189.80 102.20-379.60 178.85–664.30 35.28 17.64–65.52 Tanauan 174.29 348.58 610.01 65.70-270.10 131.40-540.20 229.95-945.35 60.17 22.68–93.24 Talisay 47.45 94.90 166.08 29.20–58.40 58.40-116.80 102.20-204.40 16.38 10.08–20.16 Balete 100.11 200.23 350.40 58.40-182.50 116.80–365.00 204.40-638.75 34.56 20.16-63.00 Mataas na Kahoy 100.98 201.97 353.44 29.20-175.20 58.40-350.40 102.20-613.20 34.86 10.08–60.48 Overall 122.91 245.82 430.19 29.20-372.30 58.40-744.60 102.20-1303.05 42.43 10.08-128.52 CONCLUSION In this study, a groundwater radon baseline database around the Taal volcano, Philippines, has been developed. The average radon value exceeds the recommended limit of 11.1 Bq/L by US-EPA and 11 Bq/L by PNSDW. The concentration distributions have been well delineated on a map using ArcGIS software. The map will serve as a valuable instrument for planning and regulation purposes in the future. It was found out that 63% of the samples exceeded the US-EPA and PNSDW limit while 2.33% of them exceeded the UNSCEAR limit. None of the samples have exceeded the recommended limit of 100 Bq/L set by the WHO. The average annual effective dose for inhalation did not exceed the 100 µSv/y limit set by the WHO aside from two samples. The average annual effective ingestion of radon and its progenies surpass the limit for adult, children, and infant. Only 46.5% of adults and 9.3% of children have not exceeded the safe limits for annual effective ingestion dose. As a result, pertinent agencies should conduct proactive measure, mitigation efforts, and awareness programs to safeguard the residents against the potential health risks of ingestion and inhalation of radon. Additional studies are warranted to explore seasonal variations, potential correlations with water quality parameters and geological conditions. Declarations Author Contribution D.G.C. and J.D.V. wrote the main manuscript textD.G.C. and J.M.R. and J.D.V. analyzed samplesC.D.R. prepared figures 1-3, revised manuscript textJ.M.R. and N.M. and C.D.R. data analysisR.S. prepared figure 4 and all tablesAll authors performed water samplingAll authors reviewed the manuscript Acknowledgement We extend our sincere gratitude to Dr. Rhodora Reyes of the Batangas Medical Center for her invaluable support and hospitality during our research. Her assistance in securing the coordination between our team and the local government units was indispensable to the successful completion of this study. 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Indoor Radon a Public Health Perspective . 110. World Health Organization. (2004). Guidelines for drinking-water quality (Vol. 1). World Health Organization. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 27 Jun, 2025 Read the published version in Environmental Geochemistry and Health → Version 1 posted Editorial decision: Accepted 13 Jun, 2025 Submission checks completed at journal 11 Jun, 2025 First submitted to journal 09 Jun, 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-6013689","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":470779118,"identity":"2af19437-75fb-4426-9780-007f3261b943","order_by":0,"name":"Dave Gabriel Cadungog","email":"data:image/png;base64,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","orcid":"","institution":"Department of Science and Technology (Philippines) - Philippine Nuclear Research Institute","correspondingAuthor":true,"prefix":"","firstName":"Dave","middleName":"Gabriel","lastName":"Cadungog","suffix":""},{"id":470779119,"identity":"1d759405-f831-4799-a1f1-ffd7974476d4","order_by":1,"name":"Charles Darwin Racadio","email":"","orcid":"","institution":"Department of Science and Technology (Philippines) - Philippine Nuclear Research Institute","correspondingAuthor":false,"prefix":"","firstName":"Charles","middleName":"Darwin","lastName":"Racadio","suffix":""},{"id":470779121,"identity":"4463d1e4-8625-4d39-9da4-09e300888efe","order_by":2,"name":"Jeff Darren Valdez","email":"","orcid":"","institution":"Department of Science and Technology (Philippines) - Philippine Nuclear Research Institute","correspondingAuthor":false,"prefix":"","firstName":"Jeff","middleName":"Darren","lastName":"Valdez","suffix":""},{"id":470779123,"identity":"97c62ab8-2a3c-4aac-9870-0a3a8ca4dad0","order_by":3,"name":"Norman Mendoza","email":"","orcid":"","institution":"Department of Science and Technology (Philippines) - Philippine Nuclear Research Institute","correspondingAuthor":false,"prefix":"","firstName":"Norman","middleName":"","lastName":"Mendoza","suffix":""},{"id":470779125,"identity":"c27305b8-d580-490f-8797-44106364b1fe","order_by":4,"name":"Joseph Michael Racho","email":"","orcid":"","institution":"Department of Science and Technology (Philippines) - Philippine Nuclear Research Institute","correspondingAuthor":false,"prefix":"","firstName":"Joseph","middleName":"Michael","lastName":"Racho","suffix":""},{"id":470779128,"identity":"7bd15dce-69ff-46da-94d6-53c1b70ab011","order_by":5,"name":"Raymond Sucgang","email":"","orcid":"","institution":"Department of Science and Technology (Philippines) - Philippine Nuclear Research Institute","correspondingAuthor":false,"prefix":"","firstName":"Raymond","middleName":"","lastName":"Sucgang","suffix":""}],"badges":[],"createdAt":"2025-02-12 09:23:16","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6013689/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6013689/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10653-025-02610-w","type":"published","date":"2025-06-27T15:57:43+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":85367151,"identity":"21d82824-dc76-4711-b86f-3ee6ffdb2fc9","added_by":"auto","created_at":"2025-06-25 06:56:33","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":732081,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution map of sampling points with the corresponding \u003csup\u003e222\u003c/sup\u003eRn activity in groundwater\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6013689/v1/87721bbe53357cddfba2cde2.png"},{"id":85367161,"identity":"d28d4855-967d-4ca8-b99b-cc4f922fcb26","added_by":"auto","created_at":"2025-06-25 06:56:33","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":518937,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution map of sampling points with the reported fractures and faults\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6013689/v1/9e5f95b6bdeb93d00937d4c9.png"},{"id":85367155,"identity":"e8356951-8116-447b-93ef-14cadcb5b78c","added_by":"auto","created_at":"2025-06-25 06:56:33","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":48510,"visible":true,"origin":"","legend":"\u003cp\u003eSee image above for figure legend\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6013689/v1/a53ae50fe4ccca8cadf93296.png"},{"id":85367711,"identity":"ea766f6c-0500-4990-8f9e-4941ebcc6dcf","added_by":"auto","created_at":"2025-06-25 07:04:33","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":62897,"visible":true,"origin":"","legend":"\u003cp\u003eSee image above for figure legend\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-6013689/v1/39f8e72c545b31e39af45831.png"},{"id":85686216,"identity":"38f02e92-80f5-4fb0-8079-7fd23bda764b","added_by":"auto","created_at":"2025-06-30 16:05:07","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2106572,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6013689/v1/019a7fac-7783-4ae2-8fdc-0926d24348e4.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Radiological investigation of radon in groundwater around the active Taal Volcano (Philippines) and dose evaluation","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eRadon-222 is a radioactive gas formed naturally \u003cem\u003evia\u003c/em\u003e the decay of uranium in the Earth\u0026rsquo;s crust. It is an odourless, colourless, and tasteless gas that has a half-life of about 3.8 days. It is considered a health risk due to its carcinogenic potential, particularly lung cancer. Radon can be accumulated in the groundwater as a decay product of uranium from the surrounding rocks and soils (Ajiboye et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Idriss et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Samuel et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Human exposure to radon and its progenies from water is mostly from inhalation or ingestion, with inhalation serving as the main route and is responsible for most of the received dose which makes ingestion substantially low and can be ignored (Rahimi et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Radon has a relatively short half-life however, exposure to radon can induce damage to vulnerable human cells. Moreover, radon decays to form other radioactive progenies that can further damage the cells (WHO, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2007\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eVarious international organizations suggested a maximum allowable limit (MAL) for the concentration of Radon in water to protect the public from Radon exposure equivalent to 100 Bq/L as suggested by the World Health Organization (WHO) and 11.1 Bq/L from drinking water as suggested by the United States \u0026ndash; Environmental Protection Agency (US-EPA) and European Atomic Energy Agency (EAEC). In the Philippine setting, the Philippine National Standards for Drinking Water (PNSDW) of 2017 suggested a threshold of 11 Bq/L. The US-EPA radon threshold was used as the basis of PNSDW radon threshold. There are several analytical methods to carry out the quantification of radon in water samples and among them, Liquid Scintillation Counting (LSC) is the most sensitive and widely used analytical method (Mamun \u0026amp; Alazmi, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). The advantage of the technique relies on several factors including excellent accuracy and precision of the method, low limit of detection, relative ease of sample preparation, and short analysis/counting time.\u003c/p\u003e \u003cp\u003eThe concentration of radon in groundwater relatively varies on the surrounding rock and soil material. However, natural environmental events such as volcanic eruption can abruptly affect the amount of radon in the water as radon is a part of the volcanic plumes spewed from different volcanic activities (Idriss et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). Recently, Taal Volcano, one of the most active volcanoes in the Philippines, had a series of volcanic activities with the most recent eruption to be in 2020 and still displaying minor activities in 2021 and 2022. Despite this, people still opted to live within the vicinity resisting the volcanic activities of Taal, and still use the groundwater in the area for various domestic activities. With this, the present work measured the radon in groundwater from the areas surrounding the Taal volcano and estimated its annual effective dose when accumulated by humans either by inhalation or ingestion. The results are compared with the international safety standard set by various organizations.\u003c/p\u003e"},{"header":"MATERIALS AND METHOD","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy Area\u003c/h2\u003e \u003cp\u003eThe study area is Batangas province, located from 120\u0026deg; 51\u0026rsquo; to 121\u0026deg; 8\u0026rsquo; East and 13\u0026deg; 50\u0026rsquo; to 14\u0026deg; 8\u0026rsquo; North, in the Southwest Luzon of the Philippines with a total land area of 3,119.75 km\u003csup\u003e2\u003c/sup\u003e. A total population of 2,908,494 and 934 persons / km\u003csup\u003e2\u003c/sup\u003e has been reported for the whole province as of 2020 (Philippine Statistics Authority, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Batangas province\u0026rsquo;s geology is predominantly Tertiary to Quaternary and consists largely of igneous and sedimentary rocks. These rocks that formed during late Miocene to early Pliocene periods, are widespread in the province. Moreover, there are faults that can be found within and around Batangas with Laiya fault and Marikina fault being the most notable faults. Batangas is home for the small but one of the most destructive volcanoes in the Philippines, the Taal Volcano. Taal Volcano is one of the most active volcanoes in the country that has erupted around 40 times in the past 400 years. Batangas experiences two main climate types: Type I and II which are both characterized having a dry season from November to April and a wet season from the rest of the year with sometimes a longer wet season.\u003c/p\u003e \u003cp\u003eEleven municipalities of Batangas province consisting of Taal, Sta. Teresita, Lemery, Laurel, Alitagtag, San Nicolas, Agoncillo, Tanauan, Talisay, Balete, and Mataas na Kahoy are only covered in this study.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eSample Collection\u003c/h3\u003e\n\u003cp\u003eGroundwater samples were collected from springs, wells, and boreholes across selected municipalities, as these sources represent the primary water supply types used by local community for drinking and domestic purpose. Inclusion of these varied source types ensures that the result would be directly relevant to public health assessments and potential mitigation strategies. A more representative analysis of radon behaviour is possible when varied groundwater source types are allowed. Boreholes and deep wells often access confined aquifers with longer water-rock interaction, which leads to higher radon concentrations. In contrast, springs and shallow wells are typically influenced by surface conditions and may exhibit lower radon levels due to natural degassing. Sampling across these different systems provides a broader and more comparative profile of groundwater radon across the region.\u003c/p\u003e \u003cp\u003eA total of 86 water samples around the Batangas Province were collected. One-liter plastic polyethylene terephthalate (PET) bottles were filled to the brim to prevent the formation of air pockets. For borehole sources, the water sample is collected about 10 minutes after turning on the tap or when the conductivity of water becomes constant. Water from water tanks was not collected. After sample collection, they are marked and carefully labelled. Samples are transported almost immediately to the laboratory to reduce the decay coefficient for the analysis.\u003c/p\u003e\n\u003ch3\u003eSample Analysis\u003c/h3\u003e\n\u003cp\u003eThe \u003csup\u003e222\u003c/sup\u003eRn analysis was performed based on an in-house method developed at Nuclear Analytical Techniques Application Section\u0026ndash;Philippine Nuclear Research Institute (Sucgang et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2012\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eA 10 mL aliquot of groundwater sample was pipetted to a 20 mL plastic vial and mixed with a 10 mL OptiPhase HiSafe scintillation cocktail. The solution was homogenized and then allowed to equilibrate for one hour. A blank sample was prepared with the same method but using sonicated ultrapure water to ensure the absence of radon. The set of samples was analysed with Tri-Carb 5110 TR Liquid Scintillation Counter for two cycles.\u003c/p\u003e\n\u003ch3\u003eAnnual effective doses of drinking water samples due to ingestion and inhalation\u003c/h3\u003e\n\u003cp\u003eAs suggested by the (UNSCEAR, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2000\u003c/span\u003e) Report, the value of the annual intake of drinking water is 730 L/y for adults. The annual effective dose due to the ingestion of radon from drinking water is calculated by the equation:\u003c/p\u003e \u003cp\u003eAED\u003csub\u003eing\u003c/sub\u003e= R\u003csub\u003eW\u003c/sub\u003e x L\u003csub\u003eW\u003c/sub\u003e x EDC\u003csub\u003eing\u003c/sub\u003e\u003c/p\u003e \u003cp\u003ewhere AED\u003csub\u003eing\u003c/sub\u003e is the annual effective dose caused by the consumption of water with radon, R\u003csub\u003eW\u003c/sub\u003e is the calculated radon concentration in water, L\u003csub\u003eW\u003c/sub\u003e is the estimated annual consumption of water\u0026thinsp;=\u0026thinsp;730 L/y, and the effective dose coefficient for ingestion is EDC\u003csub\u003eing\u003c/sub\u003e = 3.5 nSv/Bq (Kolo et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Qadir et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; UNSCEAR, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). According to (Bem et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Isinkaye et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2023\u003c/span\u003e), a more realistic ingestion dose coefficient values can be used in calculating the ingestion dose. The values of the coefficient used were 1 x 10\u003csup\u003e\u0026minus;\u0026thinsp;8\u003c/sup\u003e Sv/Bq, 2 x 10\u003csup\u003e\u0026minus;\u0026thinsp;8\u003c/sup\u003e Sv/Bq, 7 x 10\u003csup\u003e\u0026minus;\u0026thinsp;8\u003c/sup\u003e Sv/Bq for adults, children, and infants, respectively.\u003c/p\u003e \u003cp\u003eThe annual effective dose due to inhalation of radon can be computed by using the equation:\u003c/p\u003e \u003cp\u003eAED\u003csub\u003einh\u003c/sub\u003e= R\u003csub\u003eW\u003c/sub\u003e x R\u003csub\u003eAW\u003c/sub\u003e x OF x EF x EDC\u003csub\u003einh\u003c/sub\u003e\u003c/p\u003e \u003cp\u003ewhere R\u003csub\u003eAW\u003c/sub\u003e is the air-water ratio of radon (10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e), OF as the average global indoor occupancy factor\u0026thinsp;=\u0026thinsp;7000 h/year, EF is the equilibrium factor\u0026thinsp;=\u0026thinsp;0.4, and EDC\u003csub\u003einh\u003c/sub\u003e is the effective dose coefficient for inhalation with a value of 9 nSv/h (Bq/m\u003csup\u003e3\u003c/sup\u003e)\u003csup\u003e\u0026minus;1\u003c/sup\u003e (UNSCEAR, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2000\u003c/span\u003e).\u003c/p\u003e"},{"header":"RESULTS AND DISCUSSION","content":"\u003cp\u003eA total of 86 groundwater samples were collected from 11 municipalities of Batangas province surrounding the Taal volcano. Radon-222 concentration varied from a minimum of 4 Bq/L to a maximum of 51 Bq/L with an average of 16.84 Bq/L and a standard deviation of 9.57 Bq/L. A summary of the activity concentrations from different municipalities of Batangas province in shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The weighted results mirrored the trend observed in the unweighted model, confirming that locations with higher average radon concentrations such as Taal and Tanauan, remained consistently associated with increased probability of elevated radon levels. This reinforces the robustness of the findings and assures that observed patterns are not simply artifacts of sample size variability across sites.\u003c/p\u003e \u003cp\u003eThe radon distribution map is presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e along with its corresponding activity. Based on the map, the southwestern and northeastern parts have a high groundwater radon activity compared to other parts of the sampling sites. The high radon activity pattern could be attributed to the fractures and fault in the area as reported (Austria et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). The spatial distribution of radon reveals a clear relationship between elevated radon concentrations and the presence of geological faults and fractures as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. A significant clustering of moderate to high radon concentrations is observed along the southwestern, southern, and northeastern peripheries of Taal Lake. These areas coincide with dense networks of mapped fractures and faults, suggesting that these structural features serve as conduits for radon migration from subsurface sources to the surface. Radon, being a noble gas and a decay product of uranium, typically migrates through permeable zones such as fractures and fault lines, and its elevated concentrations often signal zones of high subsurface permeability or tectonic activity.\u003c/p\u003e \u003cp\u003eRecommended limits of radon activity in water varies per regulatory agency. The maximum contaminant level (MCL) of radon is shown in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. It is shown that the MCL of WHO, UNSCEAR, and US-EPA are 100 Bq/L, 40 Bq/L, and 11.1 Bq/L respectively. It is clear that only 2 out of 86 water samples (2.33%) has exceeded the UNSCEAR MCL of 40 Bq/L. About 63% of the samples (54 out of 86) have exceeded the US-EPA prescribed MCL of 11.1 Bq/L. None of the groundwater samples exceeded the WHO (2004) limit of 100 Bq/L. Only 37% of the total samples (32 out of 86) passed the MCL of the regulatory bodies. This significant gap in regulatory thresholds can lead to divergent public health responses, potentially underestimating or overestimating risk depending on the adopted standard. The US-EPA's more conservative limit reflects a precautionary approach, aiming to minimize long-term exposure risk by addressing even low-level chronic intake, particularly for vulnerable populations. In contrast, the UNSCEAR reference level may be more applicable in contexts where exposure is dominated by inhalation rather than ingestion. For regions like the study area, where groundwater is a primary drinking water source, adherence to stricter guidelines may be warranted to safeguard public health. The findings underscore the need for national policy frameworks to clearly define risk thresholds and mitigation strategies, ideally informed by both local exposure patterns and international best practices.\u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e summarizes the measured radon concentration in water for this study and other parts of the world. It highlights the significant variability in radon levels worldwide. The average radon concentration reported in this study (Batangas province, Philippines) is 16.84 Bq/L with a concentration range of 4\u0026ndash;51 Bq/L. As reported by the findings, the average radon concentration in this study is higher than what is reported at New South Wales, Australia and Hunan province, China (Atkins et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Tan et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). The relatively lower values could be influenced by different hydrogeological conditions and rock types with minimal uranium content. The results of this study is notably lower than some regions with elevated radon levels such as Bauchi State, Nigeria with an average of 38.3 Bq/L (Shu\u0026rsquo;aibu et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) and Karoo Basin, South Africa (Botha et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). While this study offers valuable insight into radon levels in water across different communities, there are a few limitations worth noting. Since the sampling was done at a single point in time, it does not capture how radon levels might change with the seasons or over longer periods. it would be helpful to carry out long-term and seasonal monitoring, and to explore additional factors that could affect radon levels. This would give us a clearer picture of the risks and help support more informed public health decisions.\u003c/p\u003e \u003cp\u003eThe variation in groundwater radon concentration across different municipalities is shown in Fig.\u0026nbsp;3 which highlights significant heterogeneity in radon levels. Taal exhibits the highest variability and highest median radon concentration which suggests localized geological factor such as rock composition and fault structures resulting to an enhanced radon emanation. The presence of outliers in Taal and Lemery indicates occasional extreme values that may be influenced by specific hydrogeological conditions or well depth variations.\u003c/p\u003e \u003cp\u003eFigure 4 and Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e shows the ingestion dose statistics for different age groups across the municipalities. Infants consistently receive the highest ingestion dose across all locations, followed by children and adults. This is primarily due to higher water consumption per body weight in infants and higher ingestion dose coefficient used (Bem et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2014\u003c/span\u003e) which results to them being more susceptible to radon-related radiation exposure. Municipalities of Taal, Tanauan, and San Nicolas exhibit the highest ingestion dose values, which aligns with their relatively high groundwater radon concentrations. The observed interquartile ranges and whiskers suggest variability in ingestion doses which emphasizes the influence of individual water sources on exposure levels. In terms of inhalation dose, the value ranges from 16.38 \u0026micro;Sv/y to 61.32 \u0026micro;Sv/y across municipalities with an average of 42.43 \u0026micro;Sv/y. Regardless of the average annual ingestion and inhalation dose values, it is still below the maximum contamination level of 100 \u0026micro;Sv/y (World Health Organization, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2004\u003c/span\u003e). Two samples have exceeded the permissible limit for the inhalation dose. All samples have exceeded the limit for ingestion dose of infant while for adult and children, only 46 and 78 samples respectively (53.5% and 90.7%) exceed the 100 \u0026micro;Sv/y limit.\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\u003eRadon concentration in groundwater of the eleven municipalities surrounding Taal volcano\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\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=\"char\" char=\".\" 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=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMunicipality\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eN\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAverage Rn concentration (Bq/L)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eStandard deviation (Bq/L)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRn concentration range (Bq/L)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTaal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e24.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e13.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e6\u0026ndash;51\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSta. Teresita\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e16.75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e12\u0026ndash;23\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLemery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e16.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e8.97\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5\u0026ndash;39\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLaurel\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e12.56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e7.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5\u0026ndash;24\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAlitagtag\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e19.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e9.82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e6\u0026ndash;36\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSan Nicolas\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e13.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e6.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e6\u0026ndash;22\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAgoncillo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e14.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e6.38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e7\u0026ndash;26\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTanauan\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e23.88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e10.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e9\u0026ndash;37\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTalisay\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4\u0026ndash;8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBalete\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e13.71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e5.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8\u0026ndash;25\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMataas na Kahoy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e13.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e7.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4\u0026ndash;24\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOverall\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e16.84\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e9.57\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4\u0026ndash;51\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\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\u003eRecommended radon concentration limits in drinking water\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRegulatory body\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMaximum Contamination Level (MCL) (Bq/L)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eReferences\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePNSDW (Philippine National Standards for Drinking Water)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e(DOH-Philippines, 2017)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUS-EPA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e(USEPA, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e1999\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUNSCEAR\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e(UNSCEAR, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2000\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWHO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e(WHO, 2004)\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\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSimilar groundwater radon studies from various locations\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLocation\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAverage radon concentration (Bq/L)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRadon concentration range (Bq/L)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eReferences\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBatangas, Philippines\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e16.84\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4\u0026ndash;51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eThis study\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNew South Wales, Australia\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.14\u0026ndash;20.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Atkins et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2016\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBauchi State, Nigeria\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e38.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.92\u0026ndash;82.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Shu\u0026rsquo;aibu et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2021\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHunan Province, China\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.29\u0026ndash;31.31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Tan et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2019\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKaroo Basin, South Africa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026lt;LLD-183\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Botha et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2019\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBudgam, Jammu and Kashmir\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e32.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15.2\u0026ndash;54.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Nazir, Sahoo, et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2021\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePunjab, India\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.17\u0026ndash;9.84\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Rani et al., \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2021\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eJammu and Kashmir, Himalayan Region\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e26.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e14\u0026ndash;189\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Chakan et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2024\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAkoko area, Nigeria\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e26.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.81-132.94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Isinkaye et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2023\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSrinagar, Kashmir\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8.94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.2\u0026ndash;38.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Nazir, Simnani, et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2021\u003c/span\u003e)\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\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eAnnual effective dose due to ingestion (AED\u003csub\u003eing\u003c/sub\u003e) and inhalation (AED\u003csub\u003einh\u003c/sub\u003e) of radon in groundwater\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=\"char\" char=\".\" 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=\"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=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eMunicipality\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003eAverage AED\u003csub\u003eing\u003c/sub\u003e (\u0026micro;Sv/y)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003eRange AED\u003csub\u003eing\u003c/sub\u003e (\u0026micro;Sv/y)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e \u003cp\u003eAED\u003csub\u003einh\u003c/sub\u003e (\u0026micro;Sv/y)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eAdult\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eChild\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003eInfant\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003eAdult\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003eChild\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003eInfant\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003eAverage\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u003cb\u003eRange\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTaal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e177.63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e355.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e621.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e43.80-372.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e87.60-744.60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e153.30-1303.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e61.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e15.12-128.52\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSta. Teresita\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e122.28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e244.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e427.96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e87.60-167.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e175.20-335.80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e306.60-587.65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e42.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e30.24\u0026ndash;57.96\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLemery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e120.73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e241.46\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e422.56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e36.50-284.70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e73.00-569.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e127.75-996.45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e41.68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e12.60-98.28\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLaurel\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e91.66\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e183.31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e320.79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e36.50-175.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e73.00-350.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e127.75\u0026ndash;613.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e31.64\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e12.60-60.48\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAlitagtag\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e140.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e280.64\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e491.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e43.80-262.80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e87.60-525.60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e153.30-919.80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e48.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e15.12\u0026ndash;90.72\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSan Nicolas\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e98.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e196.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e343.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e43.80-160.60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e87.60-321.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e153.30-562.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e33.84\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e15.12\u0026ndash;55.44\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAgoncillo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e102.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e204.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e357.70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e51.10-189.80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e102.20-379.60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e178.85\u0026ndash;664.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e35.28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e17.64\u0026ndash;65.52\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTanauan\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e174.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e348.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e610.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e65.70-270.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e131.40-540.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e229.95-945.35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e60.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e22.68\u0026ndash;93.24\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTalisay\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e47.45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e94.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e166.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e29.20\u0026ndash;58.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e58.40-116.80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e102.20-204.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e16.38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e10.08\u0026ndash;20.16\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBalete\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e200.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e350.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e58.40-182.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e116.80\u0026ndash;365.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e204.40-638.75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e34.56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e20.16-63.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMataas na Kahoy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e201.97\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e353.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e29.20-175.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e58.40-350.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e102.20-613.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e34.86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e10.08\u0026ndash;60.48\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOverall\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e122.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e245.82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e430.19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e29.20-372.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e58.40-744.60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e102.20-1303.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e42.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e10.08-128.52\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eIn this study, a groundwater radon baseline database around the Taal volcano, Philippines, has been developed. The average radon value exceeds the recommended limit of 11.1 Bq/L by US-EPA and 11 Bq/L by PNSDW. The concentration distributions have been well delineated on a map using ArcGIS software. The map will serve as a valuable instrument for planning and regulation purposes in the future.\u003c/p\u003e \u003cp\u003eIt was found out that 63% of the samples exceeded the US-EPA and PNSDW limit while 2.33% of them exceeded the UNSCEAR limit. None of the samples have exceeded the recommended limit of 100 Bq/L set by the WHO.\u003c/p\u003e \u003cp\u003eThe average annual effective dose for inhalation did not exceed the 100 \u0026micro;Sv/y limit set by the WHO aside from two samples. The average annual effective ingestion of radon and its progenies surpass the limit for adult, children, and infant. Only 46.5% of adults and 9.3% of children have not exceeded the safe limits for annual effective ingestion dose.\u003c/p\u003e \u003cp\u003eAs a result, pertinent agencies should conduct proactive measure, mitigation efforts, and awareness programs to safeguard the residents against the potential health risks of ingestion and inhalation of radon. Additional studies are warranted to explore seasonal variations, potential correlations with water quality parameters and geological conditions.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eD.G.C. and J.D.V. wrote the main manuscript textD.G.C. and J.M.R. and J.D.V. analyzed samplesC.D.R. prepared figures 1-3, revised manuscript textJ.M.R. and N.M. and C.D.R. data analysisR.S. prepared figure 4 and all tablesAll authors performed water samplingAll authors reviewed the manuscript\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eWe extend our sincere gratitude to Dr. Rhodora Reyes of the Batangas Medical Center for her invaluable support and hospitality during our research. Her assistance in securing the coordination between our team and the local government units was indispensable to the successful completion of this study.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAjiboye, Y., Isinkaye, M. O., Badmus, G. O., Faloye, O. T., \u0026amp; Atoiki, V. (2022). Pilot groundwater radon mapping and the assessment of health risk from heavy metals in drinking water of southwest, Nigeria. \u003cem\u003eHeliyon\u003c/em\u003e, \u003cem\u003e8\u003c/em\u003e(2), e08840. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.heliyon.2022.e08840\u003c/span\u003e\u003cspan address=\"10.1016/j.heliyon.2022.e08840\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAtkins, M. L., Santos, I. R., Perkins, A., \u0026amp; Maher, D. T. (2016). 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EPA Federal Register 64 (USEPA, Office of Radiation Programs) Washington, DC (1999)\u003c/em\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWHO. (2007). \u003cem\u003eIndoor Radon a Public Health Perspective\u003c/em\u003e. 110.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWorld Health Organization. (2004). \u003cem\u003eGuidelines for drinking-water quality\u003c/em\u003e (Vol. 1). World Health Organization.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"environmental-geochemistry-and-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"egah","sideBox":"Learn more about [Environmental Geochemistry and Health](https://www.springer.com/journal/10653)","snPcode":"10653","submissionUrl":"https://submission.nature.com/new-submission/10653/3","title":"Environmental Geochemistry and Health","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Radon, groundwater, ingestion dose, inhalation dose, radiological risk, Taal volcano","lastPublishedDoi":"10.21203/rs.3.rs-6013689/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6013689/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003ePollutants such as naturally occurring radioactive materials (NORM) are ubiquitous in the environment. Radon-222 is one of the naturally occurring radionuclides that can accumulate in groundwater which poses potential health risks through ingestion and inhalation. This study investigates the groundwater radon concentrations around the active Taal Volcano, Philippines. A total of 86 groundwater samples were collected and analysed using Liquid Scintillation Counter (LSC). Radon concentrations ranged from 4 to 51 Bq/L, with an average of 16.84 Bq/L. About 63% of the samples exceeded the US-EPA and PNSDW limit of 11.1 Bq/L, while none surpassed the WHO limit of 100 Bq/L. The estimated inhalation dose ranged from 16.38 to 61.32 \u0026micro;Sv/y, while the ingestion dose surpassed the 100 \u0026micro;Sv/y limit for most infants and children. While most groundwater radon levels remain within international safety limits, certain municipalities may require mitigation strategies. Public awareness initiatives and continuous monitoring are recommended to minimize the long-term health risks from radon exposure in groundwater.\u003c/p\u003e","manuscriptTitle":"Radiological investigation of radon in groundwater around the active Taal Volcano (Philippines) and dose evaluation","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-06-25 06:56:28","doi":"10.21203/rs.3.rs-6013689/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Accepted","date":"2025-06-13T07:58:30+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-06-11T17:01:31+00:00","index":"","fulltext":""},{"type":"submitted","content":"Environmental Geochemistry and Health","date":"2025-06-09T15:45:07+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"environmental-geochemistry-and-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"egah","sideBox":"Learn more about [Environmental Geochemistry and Health](https://www.springer.com/journal/10653)","snPcode":"10653","submissionUrl":"https://submission.nature.com/new-submission/10653/3","title":"Environmental Geochemistry and Health","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"b13c0580-5530-4234-8835-d8ea9e7464a2","owner":[],"postedDate":"June 25th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-06-30T16:03:27+00:00","versionOfRecord":{"articleIdentity":"rs-6013689","link":"https://doi.org/10.1007/s10653-025-02610-w","journal":{"identity":"environmental-geochemistry-and-health","isVorOnly":false,"title":"Environmental Geochemistry and Health"},"publishedOn":"2025-06-27 15:57:43","publishedOnDateReadable":"June 27th, 2025"},"versionCreatedAt":"2025-06-25 06:56:28","video":"","vorDoi":"10.1007/s10653-025-02610-w","vorDoiUrl":"https://doi.org/10.1007/s10653-025-02610-w","workflowStages":[]},"version":"v1","identity":"rs-6013689","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6013689","identity":"rs-6013689","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}