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Lindborg A, Bradley A, Durda J. An analysis of the use of the relative source contribution term in derivation of drinking water standards using perfluorooctanoic acid as an example. Integr Environ Assess Manag 2023; 19:605-612. [PMID: 35838061 DOI: 10.1002/ieam.4659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 07/01/2022] [Accepted: 07/07/2022] [Indexed: 06/15/2023]
Abstract
The relative source contribution (RSC) term has long been used by the US Environmental Protection Agency (USEPA) and state regulatory agencies in setting criteria in water. The RSC reflects the proportion of the total daily intake of a chemical that can be derived from water when all other sources of exposure (e.g., food, air) are considered. This term is applied by the USEPA and state regulatory agencies when deriving ambient water quality criteria, maximum contaminant level goals, and drinking water health advisories for noncarcinogenic and threshold carcinogenic compounds. The value assigned to the RSC term affects the calculated criteria directly, with the allowable concentration in water decreasing with a decreasing RSC. A default RSC value of 20%-applied by regulatory entities in the USA for more than 40 years-assumes that 80% of an individual's exposure to a chemical's reference dose is from nonwater sources. Although the RSC is a chemical-specific parameter, there are few instances where a value other than the default of 20% has been approved and used. In 2000, USEPA outlined the process for developing chemical-specific RSC values, yet primary use of the default RSC value has continued since then. This article reviews USEPA's methodology for deriving chemical-specific RSC values and provides a case example using perfluorooctanoic acid (PFOA) to explore how the USEPA and state regulatory agencies are applying USEPA's guidance. The case study highlights inconsistent derivation of the RSC term, rooted in limitations in the current methodology. We suggest additional clarification of and more thoughtful use of the available data that may not meet USEPA's current adequacy requirements. We also recommend that the USEPA discuss recommendations for using biomonitoring data to set RSCs. Integr Environ Assess Manag 2023;19:605-612. © 2022 SETAC.
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Affiliation(s)
| | - Ann Bradley
- Integral Consulting Inc., New York, New York, USA
| | - Judi Durda
- Integral Consulting Inc., Annapolis, Maryland, USA
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Zhang S, Kang Q, Peng H, Ding M, Zhao F, Zhou Y, Dong Z, Zhang H, Yang M, Tao S, Hu J. Relationship between perfluorooctanoate and perfluorooctane sulfonate blood concentrations in the general population and routine drinking water exposure. Environ Int 2019; 126:54-60. [PMID: 30776750 DOI: 10.1016/j.envint.2019.02.009] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2018] [Revised: 02/01/2019] [Accepted: 02/02/2019] [Indexed: 06/09/2023]
Abstract
In regions with heavily contaminated drinking water, a significant contribution of drinking water to overall human perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) exposure has been well documented. However, the relationship of PFOA/PFOS blood concentrations in the general population to routine drinking water exposure is not well characterized. This study determined the PFOA and PFOS concentrations in 166 drinking water samples across 28 cities in China. For 13 of the studied cities, PFOA and PFOS concentrations were analyzed in 847 human blood samples which were collected in parallel with the drinking water samples. The geometric mean PFOA and PFOS concentrations in drinking water were 2.5 ± 6.2 ng/L and 0.7 ± 11.7 ng/L, and population-weighted geometric mean blood concentrations were 2.1 ± 1.2 ng/mL and 2.6 ± 1.3 ng/mL, respectively. We found a significant correlation between the PFOA concentration in drinking water and blood (r = 0.87, n = 13, p < 0.001). The total daily intake of PFOA (0.24-2.13 ng/kg/day) and PFOS (0.19-1.87 ng/kg/day) were back-calculated from the blood concentrations with a one-compartment toxicokinetic model. We estimated relative source contributions (RSCs) of drinking water to total daily intake in China of 23 ± 3% for PFOA and 12.7 ± 5.8% for PFOS. Using the mean RSCs, we derived the health advisory values of 85 ng/L for PFOA and 47 ng/L for PFOS in China.
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Affiliation(s)
- Shiyi Zhang
- MOE Laboratory for Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
| | - Qiyue Kang
- MOE Laboratory for Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
| | - Hui Peng
- Department of Chemistry, University of Toronto, Toronto, Canada
| | - Mengyu Ding
- MOE Laboratory for Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
| | - Fanrong Zhao
- MOE Laboratory for Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
| | - Yuyin Zhou
- MOE Laboratory for Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
| | - Zhaomin Dong
- School of Space and Environment, Beihang University, Beijing 100191, China
| | - Haifeng Zhang
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Min Yang
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Shu Tao
- MOE Laboratory for Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
| | - Jianying Hu
- MOE Laboratory for Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
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Melnyk LJ, Donohue MJ, Pham M, Donohue J. Absorption of strontium by foods prepared in drinking water. J Trace Elem Med Biol 2019; 53:22-26. [PMID: 30910202 PMCID: PMC6436642 DOI: 10.1016/j.jtemb.2019.01.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 12/20/2018] [Accepted: 01/03/2019] [Indexed: 10/27/2022]
Abstract
Strontium (Sr) is a natural element, ubiquitous in the environment and known to occur in water, food, air, and soils. Strontium is present in media as a salt or an ionized divalent cation. The Sr ion (dissociated) is toxicokinetically important because it is easily absorbed into systemic circulation when inhaled with particulates or ingested with water or foods. Dietary exposure can be influenced by using tap water containing dissolved Sr in food preparation. Research was conducted to determine the amount of Sr transferred from water to individual foods during preparation. Strontium transferred to broccoli, lentils, and spaghetti at all levels tested (1.5, 10, and 50 mg/L) as evidenced by the residual Sr in the pour-off water following food preparation (33-64%). The data from the cooking study support the hypothesis that cooking of foods with water containing Sr adds to total dietary exposure. This information can inform the determination of the relative source contribution (RSC) that is typically used in developing drinking water advisory guidelines. These cooking study results indicate that food prepared in water containing Sr should be considered as part of the food in a dietary exposure assessment.
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Affiliation(s)
- Lisa Jo Melnyk
- National Exposure Research Laboratory, Office of Research and Development, U.S., Environmental Protection Agency, 26 West Martin Luther King Drive, Cincinnati, OH, 45268, USA.
| | - Maura J Donohue
- National Exposure Research Laboratory, Office of Research and Development, U.S., Environmental Protection Agency, 26 West Martin Luther King Drive, Cincinnati, OH, 45268, USA.
| | - Maily Pham
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 26 West Martin Luther King Drive, Cincinnati, OH, 45268, USA.
| | - Joyce Donohue
- Office of Science and Technology, Office of Water, U.S. Environmental Protection Agency, 1200 Pennsylvania Avenue, Mail Code 4304T, Washington, DC, 20460, USA.
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Nachman KE, Ginsberg GL, Miller MD, Murray CJ, Nigra AE, Pendergrast CB. Mitigating dietary arsenic exposure: Current status in the United States and recommendations for an improved path forward. Sci Total Environ 2017; 581-582:221-236. [PMID: 28065543 PMCID: PMC5303536 DOI: 10.1016/j.scitotenv.2016.12.112] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 12/08/2016] [Accepted: 12/16/2016] [Indexed: 05/19/2023]
Abstract
Inorganic arsenic (iAs) is a well-characterized carcinogen, and recent epidemiologic studies have linked chronic exposures to non-cancer health outcomes, including cardiovascular disease, diabetes, skin lesions and respiratory disorders. Greater vulnerability has been demonstrated with early life exposure for health effects including lung and bladder cancer, immunotoxicity and neurodevelopment. Despite its well-known toxicity, there are important gaps in the regulatory oversight of iAs in food and in risk communication. This paper focuses on the US regulatory framework in relation to iAs in food and beverages. The state of existing regulatory agency toxicological assessments, monitoring efforts, standard setting, intervention policies and risk communication are explored. Regarding the approach for standard setting, risk-based evaluations of iAs in particular foods can be informative but are insufficient to create a numeric criterion, given current uncertainties in iAs toxicology and the degree to which traditional risk targets can be exceeded by dietary exposures. We describe a process for prioritizing dietary exposures for different lifestages and recommend a relative source contribution-based approach to setting criteria for arsenic in prioritized foods. Intervention strategies begin with an appropriately set criterion and a monitoring program that documents the degree to which this target is met for a particular food. This approach will promote improvements in food production to lower iAs contamination for those foods which initially do not meet the criterion. Risk communication improvements are recommended to ensure that the public has reliable information regarding sources and alternative dietary choices. A key recommendation is the consideration of meal frequency advice similar to what is currently done for contaminants in fish. Recent action level determinations by FDA for apple juice and infant rice cereal are evaluated and used as illustrations of how our recommended approach can further the goal of exposure mitigation from key sources of dietary iAs in the US.
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Affiliation(s)
- Keeve E Nachman
- Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA; Johns Hopkins Center for a Livable Future, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA; Department of Health Policy and Management, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA; Johns Hopkins Risk Sciences and Public Policy Institute, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.
| | | | - Mark D Miller
- Western States Pediatric Environmental Health Specialty Unit, University of California, San Francisco, CA, USA
| | - Carolyn J Murray
- Dartmouth Children's Environmental Health and Disease Prevention Research Center, Hanover, NH, USA; Geisel School of Medicine at Dartmouth, Hanover, NH, USA
| | - Anne E Nigra
- Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
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