A study was made of the differences in the accumulation of IBP, parathion and EPN by killifish
(Ouyz&s latipes) between experiments with individual and mixed pesticides. The bioconcentration
factors (BCF) of IBP, parathion and EPN reached plateau levels after 6 hr, 24 hr and 48 hr,
respectively, in both experiments. There was little difference in the BCF of the pesticides between the
experiments. It was revealed that the accumulation of pesticides present in mixtures can be evaluated
by data for the individual pesticides.