Tap Water Contributes to Plasma Concentrations of Poly- and Perfluoroalkyl Substances

by | Apr 20, 2020 | 2019, Environmental Health, Water

Written by Angeline A. De Leon, Staff Writer. Study suggests that our drinking water, and not just dietary sources, may be a significant contributor to the exposure of the general population to poly- and perfluoroalkyl substances (PFOS).

health hazards - waterPFAS are a group of man-made chemicals used for industrial and commercial applications 1. Exposure to PFAS has been linked to a variety of complications, including metabolic disorders and developmental issues 2. Sources of PFAS are broad and include food, indoor dust, and drinking water 3. In recent years, public drinking water supplies have been linked to concerning concentrations of PFAS 4, with some contaminated sites accounting for up to three-quarters of total PFAS exposure 5. Studies indicate that drinking water with even relatively lower concentrations of PFAS 6 can still result in elevated serum concentrations in tested individuals 7. While other sources of PFAS exposure, like food and consumer products, have been well established as key contributors to overall exposure levels in various human populations 8, the contribution of drinking water to total PFAS exposures in the general American population still warrants further study. Thus, in a study led by researchers at Harvard University (2019), 9 the relative source contribution (RSC) of tap water to overall PFAS exposure was estimated for the general U.S.

A nationwide prospective cohort study was conducted with a total of 225 females (aged 30-55 years) living across geographically diverse areas from 1989-1990. Participants provided whole blood samples, along with 250 mL tap water samples taken from their home kitchen. Water samples were analyzed for relative concentrations of 15 different types of PFAS, and in a subset of 110 participants, plasma PFAS concentrations were measured from blood samples. In order to estimate the RSC of tap water to overall PFAS exposure, mathematical modeling was used to relate external PFAS exposure from tap water to serum PFAS concentrations of select participants.

For participants consuming 8 or more cups of tap water daily, perfluorooctanoic acid (PFOA) and perfluorononanoic acid (PFNA) were found to be significant predictors of plasma concentrations (p < 0.001, p = 0.004, respectively). Mathematical modeling indicated that median relative contribution of tap water consumption to plasma concentrations was 12% for PFOA (Interquartile Range: 7.7%-20%), 13% for PFNA (6.4%-21%), 2.2% for linear perfluorooctanesulfonic acid (PFOS) (nPFOS) (0.9%-0.8%), 3% for branched PFOS (brPFOS) (1.2%-6.5%), and 34% for perfluorohexane sulfonate (PFHxS) (15%-61%). Looking at the U.S. Environmental Protection Agency’s Third Unregulated Contaminant Monitoring Rule (UCMR3) database for 2013-2015, PFOS concentrations in samples measured at the time of the study were significantly and positively correlated with concentration levels (Spearman correlation rho = 0.19, p = 0.008) and detection frequency (rho = 0.20, p = 0.006) in UCMR3 samples in 2013-2015.

Findings indicate that tap water contributed 2.2% to 34% of plasma PFAS concentrations observed in subjects tested in 1989-1990, which corroborates the default RSC value of 20% currently used in PFAS risk assessments for drinking water. For individuals drinking 8 or more cups of tap water daily, the relationships between PFOA and PFNA concentrations in tap water and plasma concentrations were especially strong. Results highlight the importance of identifying different exposure pathways to PFOS, suggesting that drinking water, not just dietary sources, can significantly contribute to total PFOS exposure in the general population. Potential limitations of the present study include the analysis of tap water and plasma samples at only one time point and the failure to account for non-water sources of PFAS exposure (e.g., dietary consumption, consumer product use). As well, because only female subjects were included in the trial, the study sample cannot be considered truly representative of the general U.S. population.

Source: Hu XC, Tokranov AK, Liddie J, et al. Tap water contributions to plasma concentrations of poly- and perfluoroalkyl substances (PFAS) in a nationwide prospective cohort of U.S. women. Enviornmental Health Perspectives. 2019; 127(6): 067006. DOI: 10.1289/EHP4093.

Posted April 20, 2020.

Angeline A. De Leon, MA, graduated from the University of Illinois at Urbana-Champaign in 2010, completing a bachelor’s degree in psychology, with a concentration in neuroscience. She received her master’s degree from The Ohio State University in 2013, where she studied clinical neuroscience within an integrative health program. Her specialized area of research involves the complementary use of neuroimaging and neuropsychology-based methodologies to examine how lifestyle factors, such as physical activity and meditation, can influence brain plasticity and enhance overall connectivity.

References:

  1. Khalil N, Chen A, Lee M, et al. Association of Perfluoroalkyl Substances, Bone Mineral Density, and Osteoporosis in the U.S. Population in NHANES 2009-2010. Environ Health Perspect. 2016;124(1):81-87.
  2. Liu G, Dhana K, Furtado JD, et al. Perfluoroalkyl substances and changes in body weight and resting metabolic rate in response to weight-loss diets: A prospective study. PLoS Med. 2018;15(2):e1002502.
  3. Haug LS, Huber S, Becher G, Thomsen C. Characterisation of human exposure pathways to perfluorinated compounds–comparing exposure estimates with biomarkers of exposure. Environ Int. 2011;37(4):687-693.
  4. Hu XC, Andrews DQ, Lindstrom AB, et al. Detection of Poly- and Perfluoroalkyl Substances (PFASs) in U.S. Drinking Water Linked to Industrial Sites, Military Fire Training Areas, and Wastewater Treatment Plants. Environmental science & technology letters. 2016;3(10):344-350.
  5. Emmett EA, Shofer FS, Zhang H, Freeman D, Desai C, Shaw LM. Community exposure to perfluorooctanoate: relationships between serum concentrations and exposure sources. J Occup Environ Med. 2006;48(8):759-770.
  6. Ericson I, Nadal M, van Bavel B, Lindström G, Domingo JL. Levels of perfluorochemicals in water samples from Catalonia, Spain: is drinking water a significant contribution to human exposure? Environmental science and pollution research international. 2008;15(7):614-619.
  7. Hurley S, Houtz E, Goldberg D, et al. Preliminary associations between the detection of perfluoroalkyl acids (PFAAs) in drinking water and serum concentrations in a sample of California women. Environmental science & technology letters. 2016;3(7):264-269.
  8. Sunderland EM, Hu XC, Dassuncao C, Tokranov AK, Wagner CC, Allen JG. A review of the pathways of human exposure to poly- and perfluoroalkyl substances (PFASs) and present understanding of health effects. J Expo Sci Environ Epidemiol. 2019;29(2):131-147.
  9. Hu XC, Tokranov AK, Liddie J, et al. Tap Water Contributions to Plasma Concentrations of Poly- and Perfluoroalkyl Substances (PFAS) in a Nationwide Prospective Cohort of U.S. Women. Environ Health Perspect. 2019;127(6):67006.