Acute and chronic toxicity of atrazine to estuarine fauna

Acute and chronic estuarine invertebrate and fish toxicity testes were conducted to evaluate possible consequences of measured concentrations of atrazine in estuarine areas. The 96-h LC50 values ranged from 0.094 mg per 1 for copepods to >30 mg per 1 for larvae of eastern oysters. Maximum acceptable toxicant concentrations of >0.08<0.19 mg per 1 and >1.9<3.4 mg per 1 were determined for mysid shrimp and sheepshead minnows, respectively in life cycle and early life cycle testes. The approximate application factor limits in both tests were 0.1–0.2. Use of an application factor of 0.1 with the most sensitive species tested acutely provides a no effect, concentration of approximately 0.009 mg per 1 for estuarine fauna. Therefore, the maximum reported measured concentration of approximately 0.002 mg per 1 atrazine in estuarine areas would not be suspected to adversely impact estuarine fauna.