Research shows that there are health disparities in PFAS levels linked to drinking water, access to food and industrial pollution

Evidence is mounting of the health problems associated with per- and polyfluoroalkyl substances (PFAS), a group of manufactured chemicals used in consumer products that build up in the body and take a very long time to break down. These substances increase the risk of a number of medical problems, including cancer, liver damage and fertility problems.

In a new study, researchers from USC’s Keck School of Medicine examined whether drinking water, food access and industrial pollution were associated with differences in blood levels of PFAS among 446 Southern California residents. It is one of the first studies to analyze PFAS in relation to certain neighborhood factors, including access to food and proximity to Superfund sites – areas designated by the U.S. Environmental Protection Agency (EPA) as contaminated with toxic substances.

“Rather than placing the burden on individuals to avoid PFAS, we look at neighborhood factors outside their control. How can we improve our neighborhood environment to reduce PFAS and associated disease risk?” said first author Shiwen (Sherlock) Li, Ph.D., a postdoctoral fellow in the Department of Population and Public Health Sciences at the Keck School of Medicine.

Several factors were associated with higher levels of PFAS in the blood. These include living in a neighborhood with little access to food, living in a water district with PFAS contamination, and living within three miles of a PFAS-contaminating facility or Superfund site. The results are published in the news Environmental research.

Because the study participants were primarily Latino, the findings provide evidence for the power of addressing neighborhood-level factors in reducing racial and ethnic disparities in environmental health.

“We add a different perspective to solving the PFAS problem, because the risk of PFAS exposure at the neighborhood level is not evenly distributed,” Li said.

Mapping PFAS contamination

Li and his colleagues started with a simple question: What neighborhood factors predict differences in blood levels of PFAS? After obtaining blood samples and home addresses from two predominantly Hispanic participant groups, the Metabolic and Asthma Incidence Research Study and the Study of Latino Adolescents at Risk, they conducted a series of analyzes to dig deeper.

Using drinking water pollution data from both the EPA and the state of California, researchers found that people who lived in areas where perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), or perfluorohexane sulfonic acid (PFHxS) were found in drinking water had higher levels of that substance in their blood: an average increase of 1.54 nanograms per milliliter for PFOS; 0.47 ng/ml for PFOA; and 1.16 ng/ml for PFHxS, compared to people living in areas without PFAS-contaminated water. The national averages for these PFAS range from about 1 to 6 ng/ml, so the increases are significant, Li said.

Because PFAS are common in food packaging, the researchers also examined whether low access to fresh food was associated with PFAS exposure. They used data from the U.S. Department of Agriculture, which defines low food access as a census tract where more than 500 people, or a third of the population, live more than a half mile from the nearest supermarket.

They found that people living in neighborhoods with little access to food had higher levels of PFOS, PFOA and perfluoroheptane sulfonic acid (PFHpS) in their blood (2.51 ng/ml, 0.6 ng/ml and 0.06 ng/ml respectively ), probably because they are more likely to consume packaged foods, Li said.

Finally, researchers examined whether living near a designated Superfund site or an industrial site known to handle PFAS was associated with higher PFAS levels in the blood. They found that for every industrial site within a three-mile radius where PFAS was processed, blood levels of PFOS increased. Living near a Superfund site predicted higher levels of PFOS, PFHxS, PFHpS, and perfluoropentane sulfonic acid (PFPeS) in the blood.

Increase awareness of PFAS risks

New EPA rules change the way PFAS are regulated. Beginning in 2024, these chemicals will be included on the list of hazardous substances that could lead to a Superfund site designation, making additional funding available for toxic waste cleanup. Another new rule, set to take effect in 2029, will regulate the levels of six PFAS in public drinking water.

“But in the meantime, those water systems are still contaminated with PFAS, and many people don’t know they live in a neighborhood with water contamination. So the first step is to raise awareness,” Li said. The Keck School’s Department of Population and Public Health Sciences has launched several community engagement efforts to share their research findings with people living in at-risk areas.

Next, Li and his team will investigate PFAS exposure near chrome plating facilities, which use high levels of PFAS in their manufacturing processes.

Provided by Keck School of Medicine of USC