Chronic toxicity to fathead minnow Pimephales promelas of wastewater from a conventional wastewater treatment system receiving organic priority pollutants

Abstract

Chronic toxicity tests were made with unchlorinated and dechlorinated effluent from a conventional wastewater treatment system receiving 22 organic priority pollutants. The early-life-stage (ELS) tests began with fathead minnow embryos less than 1-day old and exposure continued for 30 days post hatch. There was no significant difference in hatchability between any effluent concentration (5·0–0·16%) and control. Survival and growth of larvae-juveniles in all unchlorinated concentrations were similar to controls. The chronic value for this exposure was 5% and the acute-chronic ratio was <6·6. Survival and growth of fish in 5% dechlorinated effluent were significantly less than survival and growth of control fish. Survival of fish in the 2·5% effluent was similar to survival of control fish. However, growth of these fish was only 75% of control fish and was significantly less than growth of control fish. Survival and growth of fish in the 1·3% effluent were not different from controls. The chronic value of the dechlorinated effluent was 1·8% and the acute-chronic ratio, ∼ 19.