Post GB, Gleason JA, Cooper KR. Key scientific issues in developing drinking water guidelines for perfluoroalkyl acids: Contaminants of emerging concern. PLoS Biol. 2017 Dec 20;15(12):e2002855. doi: 10.1371/journal.pbio.2002855.
Perfluoroalkyl acids (PFAAs), a group of synthetic organic chemicals with industrial and commercial uses, are of current concern because of increasing awareness of their presence in drinking water and their potential to cause adverse health effects. PFAAs are distinctive among persistent, bioaccumulative, and toxic (PBT) contaminants because they are water soluble and do not break down in the environment. This commentary discusses scientific and risk assessment issues that impact the development of drinking water guidelines for PFAAs, including choice of toxicological endpoints, uncertainty factors, and exposure assumptions used as their basis. In experimental animals, PFAAs cause toxicity to the liver, the immune, endocrine, and male reproductive systems, and the developing fetus and neonate. Low-dose effects include persistent delays in mammary gland development (perfluorooctanoic acid; PFOA) and suppression of immune response (perfluorooctane sulfonate; PFOS). In humans, even general population level exposures to some PFAAs are associated with health effects such as increased serum lipids and liver enzymes, decreased vaccine response, and decreased birth weight. Ongoing exposures to even relatively low drinking water concentrations of long-chain PFAAs substantially increase human body burdens, which remain elevated for many years after exposure ends. Notably, infants are a sensitive subpopulation for PFAA’s developmental effects and receive higher exposures than adults from the same drinking water source. This information, as well as emerging data from future studies, should be considered in the development of health-protective and scientifically sound guidelines for PFAAs in drinking water.
Tian Z, Kim SK, Shoeib M, Oh JE, Park JE. Human exposure to per- and polyfluoroalkyl substances (PFASs) via house dust in Korea: Implication to exposure pathway. The Science of the total environment. 2016 Feb 27;553:266-275. doi: 10.1016/j.scitotenv.2016.02.087.
A wide range of per- and polyfluoroalkyl substances (PFASs), including fluorotelomer alcohols (FTOHs), perfluorooctane sulfonamidoethanols (FOSEs), perfluoroalkyl carboxylic acids (PFCAs), and perfluoroalkane sulfonic acids (PFSAs), were measured in fifteen house dust and two nonresidential indoor dust of Korea. Total concentrations of PFASs in house dust ranged from 29.9 to 97.6ngg-1, with a dominance of perfluorooctane sulfonic acid (PFOS), followed by 8:2 FTOH, N-Ethyl perfluorooctane sulfonamidoethanol (EtFOSE), perfluoroctanoic acid (PFOA). In a typical exposure scenario, the estimated daily intakes (EDIs) of total PFASs via house dust ingestion were 2.83ngd-1 for toddlers and 1.13ngd-1 for adults, which were within the range of the mean EDIs reported from several countries. For PFOA and PFOS exposure via house dust ingestion, indirect exposure (via precursors) was a minor contributor, accounting for 5% and 12%, respectively. An aggregated exposure (hereafter, overall-EDIs) of PFOA and PFOS occurring via all pathways, estimated using data compiled from the literature, were 53.6 and 14.8ngd-1 for toddlers, and 20.5 and 40.6ngd-1 for adults, respectively, in a typical scenario. These overall-EDIs corresponded to 82% (PFOA) and 92% (PFOS) of a pharmacokinetic model-based EDIs estimated from adults’ serum data. Direct dietary exposure was a major contributor (>89% of overall-EDI) to PFOS in both toddlers and adults, and PFOA in toddlers. As for PFOA exposure of adults, however direct exposure via tap water drinking (37%) and indirect exposure via inhalation (22%) were as important as direct dietary exposure (41%). House dust-ingested exposure (direct+indirect) was responsible for 5% (PFOS in toddlers) and <1% (PFOS in adults, and PFOA in both toddlers and adults) of the overall-EDIs. In conclusion, house-dust ingestion was a minor contributor in this study, but should not be ignored for toddlers’ PFOS exposure due to its significance in the worst-case scenario.
Flores C, Ventura F, Martin-Alonso J, Caixach J. Occurrence of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in N.E. Spanish surface waters and their removal in a drinking water treatment plant that combines conventional and advanced treatments in parallel lines. Science of The Total Environment. Volumes 461–462, 1 September 2013, Pages 618–626. doi: 10.1016/j.scitotenv.2013.05.026.
Perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) are two emerging contaminants that have been detected in all environmental compartments. However, while most of the studies in the literature deal with their presence or removal in wastewater treatment, few of them are devoted to their detection in treated drinking water and fate during drinking water treatment. In this study, analyses of PFOS and PFOA have been carried out in river water samples and in the different stages of a drinking water treatment plant (DWTP) which has recently improved its conventional treatment process by adding ultrafiltration and reverse osmosis in a parallel treatment line. Conventional and advanced treatments have been studied in several pilot plants and in the DWTP, which offers the opportunity to compare both treatments operating simultaneously. From the results obtained, neither preoxidation, sand filtration, nor ozonation, removed both perfluorinated compounds. As advanced treatments, reverse osmosis has proved more effective than reverse electrodialysis to remove PFOA and PFOS in the different configurations of pilot plants assayed. Granular activated carbon with an average elimination efficiency of 64±11% and 45±19% for PFOS and PFOA, respectively and especially reverse osmosis, which was able to remove ≥99% of both compounds, were the sole effective treatment steps. Trace levels of PFOS (3.0-21ng/L) and PFOA (<4.2-5.5ng/L) detected in treated drinking water were significantly lowered in comparison to those measured in precedent years. These concentrations represent overall removal efficiencies of 89±22% for PFOA and 86±7% for PFOS.
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Xiao, Feng, Matt F., Gulliver, John S. Mechanisms for removal of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) from drinking water by conventional and enhanced coagulation. Water Research, Jan2013, Vol. 47 Issue 1, p49-56
Abstract: Perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) are persistent organic pollutants that have been found to be ubiquitous in the environment. This article, for the first time, delineates removal areas of these polar compounds on a coagulation diagram that associates chemical conditions with different coagulation mechanisms. Variables considered were solution pH, coagulant dosage, coagulants (alum and ferric chloride), natural organic matter (NOM), initial turbidity, and flocculation time. The jar-test results show that conventional coagulation (alum dosage of 10–60 mg/L and final pH of 6.5–8.0) removed ≤20% of PFOS and PFOA. These chemicals tended to be removed better by enhanced coagulation at higher coagulant dosages (>60 mg/L) and (thus) lower final pH (4.5–6.5). A coagulation diagram was developed to define the coagulant dosage and solution pH for PFOS/PFOA removal. The results suggest that the primary PFOS/PFOA removal mechanism is adsorption to fine Al hydroxide flocs freshly formed during the initial stage of coagulation; increasing flocculation time from 2 to 90 min could not further improve PFOS and PFOA removals. Furthermore, the effect of NOM on PFOS/PFOA removal by coagulation was examined, and possible removal mechanisms were discussed.
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Mondal, D., Lopez-Espinosa, M.J., Armstrong, B., Stein, C.R., and Fletcher, T. Relationships of Perfluorooctanoate and Perfluorooctane Sulfonate Serum Concentrations Between Child-Mother Pairs in a Population with Perfluorooctanoate Exposure from Drinking Water. Environ Health Perspect. 2012 Jan 23.
Background: There are limited data on the associations between maternal, newborn and child exposure to perfluoroalkyl acids (PFAAs), including perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS). This study provides an opportunity to assess the association between PFAA concentrations in mother-child pairs in a population exposed to PFOA via drinking water.
Objectives: To determine the relationship between child-mother PFAA serum concentrations, and examine how the child:mother ratio varies with child’s age, child’s gender, drinking water PFOA concentration, reported bottle water usage and mother’s breastfeeding intention.
Methods: We studied 4,943 child-mother pairs (child age: 1-19 years). The child:mother PFAA ratio was stratified by possible determinants. Results are summarized as geometric mean ratios and correlation coefficients between child-mother pairs, overall and within strata.
Results: Child and mother PFOA and PFOS concentrations were correlated (r=0.82 and 0.26, respectively). Children had higher serum PFOA concentrations than their mothers up to about age 12 years. The highest child:mother PFOA ratio was found among children ≤5 years (44% higher than their mothers) which we attribute to in utero exposure and to exposure via breast milk and drinking water. Higher PFOS concentrations in children persisted until at least 19 years of age (42% higher than their mothers). Boys aged >5 years had significantly higher PFOA and PFOS child:mother ratios than girls.
Conclusion: Concentrations of both PFOA and PFOS tended to be higher in children than their mothers. This difference persists until they are about 12 years for PFOA and at least until 19 years of age for PFOS.
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Loccisano, A.E., J.L. Campbell, Jr., M.E. Anderson, and H.J. Clewell, 3rd. Evaluation and prediction of pharmacokinetics of PFOA and PFOS in the monkey and human using a PBPK model. Regul Toxicol Pharmacol. 2011 Feb;59(1):157-75.
Perfluoroalkyl acid carboxylates and sulfonates (PFAAs) have many consumer and industrial applications. The persistence and widespread distribution of these compounds in humans have brought them under intense scrutiny. Limited pharmacokinetic data is available in humans; however, human data exists for two communities with drinking water contaminated by PFAAs. Also, there is toxicological and pharmacokinetic data for monkeys, which can be quite useful for cross-species extrapolation to humans. The goal of this research was to develop a physiologically-based pharmacokinetic (PBPK) model for PFOA and PFOS for monkeys and then scale this model to humans in order to describe available human drinking water data. The monkey model simulations were consistent with available PK data for monkeys. The monkey model was then extrapolated to the human and then used to successfully simulate the data collected from residents of two communities exposed to PFOA in drinking water. Human PFOS data is minimal; however, using the half-life estimated from occupational exposure, our model exhibits reasonable agreement with the available human serum PFOS data. It is envisioned that our PBPK model will be useful in supporting human health risk assessments for PFOA and PFOS by aiding in understanding of human pharmacokinetics.
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C. Cornelis, W. D’Hollander, L. Roosen, A. Covaci, R. Smolders, R. Van Den Heuvel, E. Govarts, K. Van Campenhout, H. Reynders, and L. Bervoets. First assessment of population exposure to perfluorinated compounds in Flanders, Belgium. Chemosphere 2011 Nov. 18.
With the objective to evaluate exposure of the population in Flanders (Belgium) to perfluorinated compounds (PFCs), we measured perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in settled dust in homes and offices, in a selection of food items from local origin, in drinking-water and in human serum. We complemented the data with results from a literature survey. Based on this dataset we calculated intake by children and adults from food, drinking-water, settled dust and soil, and air. Dietary exposure dominated overall intake. For adults, average dietary intake equalled 24.2 (P95 40.9) ng PFOS kg(-1)d(-1) and 6.1 (P95 9.6) ng PFOA kg(-1)d(-1), whereas for children the dietary intake was about 3 times higher. Predicted intake is high when compared to assessments in other countries, and to serum levels from Flanders, but comparable to the intakes published by The European Food Safety Authority (EFSA) in 2008. Intake of PFOS and PFOA remained below the Tolerable Daily Intake.
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