At least that’s what an NBER working paper states. DiSalvro and Hill (2023). The summary is below:
Previous research in the US has found negative health effects from pollution when it triggers regulatory violations. An important question is whether pollution levels that do not trigger a health-based violation impact health. We studied the impact of drinking water contamination in community water systems on birth outcomes using drinking water sampling results data in Pennsylvania. We created a general water quality index and a specific reproductive health index. We focus on the effects of water pollution on births that are not exposed to regulatory violations. Our most rigorous specification uses maternal fixed effects and finds that moving from the 10th to the 90th percentile of water pollution (among births not exposed to regulatory violations) increases low birth weight by 12% and preterm birth by 17%. .
NBER Health Bulletin It also has a more detailed summary.
