What are the health effects of PFAS?
Statement on Potential Intersection between PFAS Exposure and COVID-19:
CDC/ATSDR understands that many of the communities we are engaged with are concerned about how PFAS exposure may affect their risk of COVID-19 infection. We agree that this is an important question.
CDC/ATSDR recognizes that exposure to high levels of PFAS may impact the immune system. A National Toxicology Program review found that exposure to perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) is an immune hazard to humans based on a high level of evidence that PFOA and PFOS suppressed the antibody response from animals and a moderate level of evidence from studies in humans (NTP, 2016). More research is needed to understand how PFAS exposure may affect illness from COVID-19.
NTP (National Toxicology Program). 2016. Monograph on Immunotoxicity Associated with Exposure to Perfluorooctanoic acid (PFOA) and Perfluorooctane Sulfonate (PFOS).
Research is ongoing to understand the mechanisms of PFAS toxicity. The epidemiological evidence suggests associations between increases in exposure to (specific) PFAS and certain health effects
Increases in cholesterol levels (PFOA, PFOS, PFNA, PFDA)
Lower antibody response to some vaccines (PFOA, PFOS, PFHxS, PFDA)
Changes in liver enzymes (PFOA, PFOS, PFHxS)
Pregnancy-induced hypertension and preeclampsia (PFOA, PFOS)
Small decreases in birth weight (PFOA, PFOS)
Kidney and testicular cancer (PFOA)
The risk of health effects associated with PFAS depends on
- Exposure factors (e.g., dose, frequency, route, and duration)
- Individual factors (e.g., sensitivity and disease burden)
- Other determinants of health (e.g., access to safe water and quality healthcare)
Some animal and human studies find positive associations between PFAS exposure and a much wider range of health effects. However, results of animal studies do not always correlate with human health effects because of physiologic differences between species. Inconsistent findings among human studies and study design limitations are some reasons why other potential health effects are not identified as associated with PFAS.
At this time, scientists are still learning about the health effects of exposures to mixtures of different PFAS. Additional research may change our understanding of the relationship between exposure to PFAS and human health effects.
One way to learn about whether PFAS will harm people is to do studies on lab animals.
- Most animal studies have tested doses of PFAS that are higher than the doses people experience from environmental exposure.
- These animal studies have found that PFAS can cause damage to the liver and the immune system.
- PFAS have also caused low birth weight, birth defects, delayed development, and newborn deaths in lab animals.
Humans and animals react differently to PFAS, and not all effects observed in animals may occur in humans. Scientists have ways to estimate how the exposure and effects in animals compare to what they would be in humans.