Toxicity of pesticides in mixtures with the same mode of action.

Abstract Pesticides probably co-occur in the environment as mixtures, posing a risk to human beings and all other organisms present in the environment. Their number in the environment is too large to allow for all of them to be studied. However, single pesticides are assessed for their risk to the environment, ignoring the existence of their mixtures. This chapter describes some approaches used for predicting and assessing mixture toxicity, including the toxic unit model, concentration addition model, median effect/combination index model and toxic equivalence approach. It also discusses the interactions in pesticide mixtures; interactive effects of pesticide mixtures; toxicokinetic interactions between pesticides; risk of pesticides mixtures to the environment; and the independent joint action of pesticides in mixtures.