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<\/a><\/p>\nStudy: Associations between PFAS in public water system drinking water and serum among Southern California adults<\/a>. Image Credit: Megane Ad \/ Shutterstock<\/p>\n In a recent article in the\u00a0Journal of Exposure Science & Environmental Epidemiology<\/a>, researchers examined blood chemical levels in adults exposed to per- and polyfluoroalkyl substances (PFAS) through public drinking water systems.<\/p>\n Their findings suggest that even in areas without industrial PFAS manufacturing, people can be significantly exposed to these \u201cforever chemicals\u201d through contaminated drinking water, requiring ongoing monitoring.<\/p>\n PFAS Persistence and Environmental Impact<\/p>\n PFAS are man-made chemicals used for resistance to heat, stains, and water. They persist in the environment and human body, accumulating in water and living organisms due to their long half-lives.<\/p>\n Major Human Exposure Pathways<\/p>\n Humans are mainly exposed through contaminated water and food. There is also exposure via skin contact, dust, or consumer products. Certain PFAS have been linked to health problems such as cancer, hormone disruption, reduced birth weight, and immune system effects.<\/p>\n Nationwide Contamination and EPA Findings<\/p>\n High PFAS contamination is often found near chemical manufacturing plants or sites using firefighting foams, but low-level contamination is now widespread. The U.S. Environmental Protection Agency (EPA) estimates that thousands of water systems serving millions of Americans exceed newly established limits for at least one PFAS.<\/p>\n California\u2019s PFAS Monitoring Efforts<\/p>\n Although California lacks PFAS manufacturing facilities, it has contamination sources such as airports, military bases, and landfills. To address this, California\u2019s State Water Resources Control Board began monitoring PFAS in public water systems in 2019.<\/p>\n Gaps in Research on General Populations<\/p>\n Most previous studies focused on areas with severe contamination, leaving uncertainty about PFAS exposure in general populations.<\/p>\n Study Linking Water Quality and Blood PFAS<\/p>\n In this study, researchers linked biomonitoring data from Southern California adults to public water system data to assess whether PFAS in drinking water corresponded with higher PFAS levels in blood. They used data from the California Regional Exposure (CARE) study, a biomonitoring program assessing environmental chemical exposure across Eastern and Southern California.<\/p>\n Participant Selection and Laboratory Analysis<\/p>\n Adults aged 18 and older who had lived in their region for at least a year provided blood and urine samples and completed questionnaires during 2018\u20132020. Blood samples were analyzed for 12 PFAS using advanced chromatography and mass-spectrometry methods with rigorous quality controls.<\/p>\n Drinking Water Data and Geographic Mapping<\/p>\n Drinking-water data were obtained from the California State Water Resources Control Board\u2019s monitoring program (2019\u20132022), which tested public water systems, primarily untreated source wells with some post-treatment samples, for 18 PFAS compounds. Participant addresses were geocoded and matched to specific public water system boundaries to determine whether their water supply had detectable PFAS levels at State Consumer Confidence Report Detection Limits of 2\u20134 ng\/L (for the modeled analytes, 4 ng\/L).<\/p>\n Sample Size and Statistical Adjustments<\/p>\n After excluding participants with private wells or missing data, 563 individuals were included in the final sample. Serum PFAS concentrations were compared across participants with and without PFAS detections in their local water systems, adjusting for race\/ethnicity, sex, education, age, income, parity, and nativity. Additional sensitivity analyses considered the type of drinking water and water purchasing practices between systems.<\/p>\n Demographic Profile of Participants<\/p>\n Among 563 adults from Southern California, the majority of participants were middle-aged women, with nearly 40% identifying as Hispanic and 54% primarily drinking tap water.<\/p>\n Prevalence of PFAS in Blood Samples<\/p>\n PFAS were detected in almost all blood samples, with PFOS, PFOA, and PFHxS being the most prevalent. Serum PFAS levels were generally lower than national averages but still indicated a potential for health effects in 86% of participants, according to National Academies of Sciences, Engineering, and Medicine (NASEM) guidance.<\/p>\n PFAS Detections Across Public Water Systems<\/p>\n Seventy public water systems serving the study area had PFAS testing data, and 56% of participants were connected to systems in which at least one PFAS was detected. PFBS, PFHxS, PFOA, PFOS, and PFHxA were the most frequently detected chemicals, particularly in urban Southern California.<\/p>\n Blood PFHxS Levels and Water Exposure Correlation<\/p>\n Participants whose water systems had PFHxS detections exhibited 31.9% higher serum PFHxS concentrations, with even stronger associations when detections were frequent (\u226550% of sampling locations, 64% higher).<\/p>\n Post-Treatment Water Findings and Drinking Habits<\/p>\n When analysis was limited to post-treatment water samples, participants exposed to detected PFAS had significantly higher serum levels for PFHxS (~80% higher), PFOA (~30% higher), PFOS (~31% higher), and total PFAS (~42% higher). The association between drinking water and blood PFHxS was strongest among tap-water drinkers, while overall serum PFAS were lower among bottled-water drinkers, although some effect estimates for PFOS and \u22115 PFAS were approximately 20% higher but not statistically significant.<\/p>\n Low-Level PFAS Still Influence Blood Levels<\/p>\n These results indicate that even relatively low PFAS levels in drinking water contribute to measurable increases in blood PFAS concentrations.<\/p>\n Health Implications of PFAS Exposure<\/p>\n This study demonstrated that even at low environmental levels, PFAS in drinking water contribute to elevated blood concentrations, particularly for PFHxS, a compound with a long biological half-life.<\/p>\n Regional Context and Firefighting Foam Legacy<\/p>\n Compared with national and highly contaminated regions, PFAS levels in Southern California were lower but still of health concern. The strong link between PFHxS in drinking water and serum supports previous findings and highlights the legacy of aqueous film-forming foam (AFFF) contamination.<\/p>\n Study Strengths and Key Limitations<\/p>\n Strengths include robust linkage of biomonitoring data with statewide water-quality records and adjustment for key demographic variables. However, notable limitations included potential exposure misclassification from raw (pre-treatment) water data, the selection of larger or higher-risk systems that may bias associations upward, a temporal mismatch between some water sampling and serum collection, and a lack of information on other exposure routes (such as dust or diet).<\/p>\n Policy Implications and Need for Regulation<\/p>\n Despite these limitations, the findings emphasize that\u00a0PFAS-contaminated drinking water remains a significant exposure pathway, even in non-industrial areas, reinforcing the need for stricter PFAS regulations, expanded monitoring, and improved water treatment across California.<\/p>\n Journal reference:<\/p>\n Fillman, T., Coffin, S., Ta, B., Beglarian, E., Linck, W., Baek, H., Gao, S., Smith, S., Park, J., Wu, N., & Attfield, K. (2025). Associations between PFAS in public water system drinking water and serum among Southern California adults. Journal of Exposure Science & Environmental Epidemiology. DOI: 10.1038\/s41370-025-00817-8, https:\/\/www.nature.com\/articles\/s41370-025-00817-8<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"A new California study reveals that \u201csafe\u201d levels of PFAS in tap water may still lead to elevated…\n","protected":false},"author":2,"featured_media":35358,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[25110,25111,9133,7,9,8,4900,25112,25113,25114,413,3896,25115,25116,1289,25117],"class_list":{"0":"post-35357","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-california","8":"tag-biomonitoring","9":"tag-birth-weight","10":"tag-blood","11":"tag-california","12":"tag-california-headlines","13":"tag-california-news","14":"tag-cancer","15":"tag-chemicals","16":"tag-contamination","17":"tag-epidemiology","18":"tag-food","19":"tag-heat","20":"tag-hormone","21":"tag-immune-system","22":"tag-manufacturing","23":"tag-skin"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/posts\/35357","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/comments?post=35357"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/posts\/35357\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/media\/35358"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/media?parent=35357"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/categories?post=35357"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/tags?post=35357"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}