Abstract
Various chemical substances are used in our industrial, agricultural, and daily activities, and are continuenly discharged into the environment. Several toxic chemical substances have been detected from wastewater and surface water, and their additive or synergistic effects have become growing concerns. Thus, there is an apparent limitation in the risk assessment and management based on the individual chemical assays. In the present study, 28 samples were collected at first class rivers in Japan between October 2011 and April 2012. We conducted the short term chronic toxicity test using fish, daphnia and algae of the USEPA's whole effluent toxicity (WET) method to evaluated the toxic effects of the river water samples, and investigated distribution and trend of the toxicity all over Japan. As results, the significant growth inhibition for green algae (Pseudokirchnerella subcapitata) was found from three samples. The significant mortality and reproductive effects were found for Ceriodaphnia dubia from eight samples. The significant inhibition of hatching and survival was found for zebra fish (Danio rerio) from four samples.
