A 2025 study by UC Davis analyzed 201 toddlers (ages 2–4) from four U.S. states and found 96 different chemicals in their urine—48 found in over half of the kids, 34 in more than 90%—many not even tracked by national surveys.

A 2023 U.S. Geological Survey study found that at least 45% of the nation’s tap water is estimated to have one or more types of per- and polyfluoroalkyl substances (PFAS). PFAS are used in various products like non-stick cookware and firefighting foams and are known for their persistence in the environment.