The environmental impact of a pesticide depends
on its dispersion and the resulting concentration in
the environment and on its toxicity. Distribution in
the environment is affected by a large number of
factors (Section 2) and toxicity involves several phenomena
and very many species (Section 3). It is not
surprising therefore that the methods which have
been proposed to evaluate the environmental impact
of pesticides (Section 4) are diverse. In this section
the methods will be compared regarding choice,
transformation and aggregation of parameters. The
use of simulation models to assess environmental
impact will be discussed.