Abstract |
LC50 values for 30-day old fathead minnows (Pimephales promelas) exposed to bromacil were 185, 183, 182, and 167 mg/l at 24, 48, 96, and 168 hr, respectively; and for exposure to diuron were 23.3, 19.9, 14.2, and 7.7 mg/l at 24, 48, 96, and 192 hr, respectively. In early life-stage exposures, it was not possible to determine a 'no effect' concentration for bromacil, as growth was reduced at the lowest exposure of 1.0 mg/l. The 'no effect' concentration for diuron was 33.4 micrograms/L following a 64-day exposure, while a concentration of 78.0 micrograms/l adversely affected fry in their appearance and survival. It also affected the survival of juvenile fish. Neither herbicide accumulated significantly in fish tissue. Rainbow trout (Salmo gairdneri) injected with radiolabeled bromacil or diuron eliminated over 90% of the radioactivity within 24 hr. Metabolites of diuron included 3,4-dichloroaniline and several demethylated products. (Copyright (c) 1987 Springer-Verlag New York Inc.) |