Abstract
The United States Environmental Protection Agency has recently proposed water quality criteria for pesticides which are much stricter than any that have been applied before. For example, the U.S. EPA has proposed that the recommended maximum limit in whole (unfiltered) water for DDT be 0.002 ug/l. The recommendation for parathion and toxaphene are 0.004 ug/1 and 0.01 ug/l, respectively. They have also recommended that general standard of 0.001 × 96 hr LC50, where 0.01 is the application factor which relates acute to chronic toxicity.