Evidence shows that APIs in aquatic environments can have negative effects on organisms. Long term, multi-generational exposure to low levels of APIs may disrupt endocrine systems and cause alterations to sexual differentiation, as seen in studies on Boulder Creek and Potomac River. While APIs have been detected in most US streams sampled, questions remain about their potential low-dose, interactive, and chronic effects. More research is needed to understand risks to both environmental and human health from exposure to multiple APIs at low concentrations over long time periods.