Toxicity of Chlorpyrifos, Endrin, or Fenvalerate to Fathead Minnows Following Episodic or Continuous Exposure

摘要

Fathead minnow larvae (Pimephales promelas) were exposed to three individual pesticides during brief or continuous exposure in 96-hr and 28- to 30-day toxicity tests. Brief exposure chronic test results indicated that fathead minnow exposure to chlorpyrifos, for as few as 5 hr at a concentration similar to a continuous exposure 96-hr LC(sub 50) value resulted in increased deformities and a reduction in growth, whereas a 48-hr exposure at a concentration similar to a continuous exposure 96-hr LC(sub 50) value was required to cause a reduction in growth for endrin and a reduction in survival and growth for fenvalerate. It is suggested that although constant exposure laboratory tests are essential for hazard assessment, the relationships of exposure duration and toxicant intensity to ecotoxic effects are necessary for reliable risk assessments and implementation of water quality standards.