Final answer:
Atrazine at concentrations as low as 0.1 ppb can harm amphibians by causing reproductive issues, feminization, and increased disease susceptibility. The EPA sets a maximum limit of 3 ppb for atrazine in drinking water to protect human health.
Step-by-step explanation:
The harmful level of atrazine to amphibians can vary depending on the exposure and species. However, studies have shown that atrazine at concentrations as low as 0.1 parts per billion (ppb) can cause adverse effects on amphibians. These effects include reduced reproductive success, feminization of males, and increased susceptibility to disease.
The U.S. Environmental Protection Agency (EPA) sets standards for atrazine based on human health. The EPA has established a maximum contaminant level (MCL) of 3 ppb for atrazine in drinking water. This limit is set to protect human health and considers potential risks associated with long-term exposure to atrazine.