The Effect of Long-run PFAS Exposure on Mortality

From the mid-80s roughly 140,000 people in Veneto, Italy, were exposed to PFAS-contaminated water through the public supply. Exposure stopped in 2013, when the contamination accident — the largest in Europe — was discovered. Municipalities across the Red zone, the contaminated supplier’s catchment area, consist of neighborhoods of around 5,000 people, shown in balance tests to be similar to each other before 2013. Exploiting the sharp exposure discontinuity at the Red Zone’s border reveals that, compared to the control group, age-standardized mortality was 4% higher in exposed municipalities in 1982–2012. While these differences were insignificant until the 90s, mortality in the Red Zone was 5% higher from the 2000s onward and did not decrease after pollution discovery, suggesting a role for long-run exposure consistent with PFAS bioaccumulation. Difference-in-differences analysis shows that mortality in municipalities exclusively contaminated via public water supply tracked the control group until 2009, before rising to match the high levels already present in more polluted municipalities. These findings provide the first causal evidence that long- run exposure to relatively low levels of PFAS results in economically significant increases in mortality, and suggest that current EU safe exposure limits may not be sufficiently protective.