Toxic “forever chemicals” are increasingly appearing in U.S. pesticides — contaminating waterways and posing a possible threat to human health, a new study has found.

Pesticides containing these compounds, called per- and polyfluoroalkyl substances (PFAS), are used widely nationwide on staple foods, such as corn, wheat, kale, spinach, apples and strawberries, according to the study, published Wednesday in Environmental Health Perspectives.