Childhood Vaccination Response
Some of the most compelling evidence for PFAS immune system effects comes from studies of childhood vaccination responses. Research in the Faroe Islands — where background PFAS exposure is elevated through marine food consumption — found that children with higher PFAS blood levels showed diminished antibody responses to standard childhood vaccines. This finding suggests that PFAS exposure may reduce immune system effectiveness in responding to infections and vaccines at concentrations within the range found in US populations.
Adult Immune Markers
Studies of adults in PFAS-contaminated communities and occupationally exposed workers have found associations between PFAS exposure and altered immune cell populations, including reduced natural killer cell activity and changes in T-cell subsets. The immunotoxicology literature is growing rapidly as PFAS-related immune endpoints receive increased research attention following earlier focus on cancer and reproductive outcomes.
Regulatory Recognition of Immunotoxicity
The EPA’s reference dose methodology for PFOA and PFOS — the health-protective exposure level used to derive drinking water standards — was ultimately based on immunotoxicity endpoints rather than cancer or reproductive toxicity. Specifically, studies showing reduced vaccine antibody responses in children drove the most health-protective effect level that informed the 2024 PFAS maximum contaminant levels. This represents a significant development in risk assessment methodology, using immune endpoints to set environmental standards.
COVID-19 and PFAS Interaction Hypothesis
Several researchers have investigated whether PFAS immunotoxicity might have contributed to variation in COVID-19 outcomes, given PFAS’s demonstrated effects on innate and adaptive immune responses. While this hypothesis remains under investigation, it illustrates the broad potential consequences of immune system disruption from chronic PFAS exposure. Protecting drinking water from PFAS contamination is an intervention that may benefit immune resilience across multiple infectious disease contexts.