These practical problems probably are the reason
why only one out of the six methods reviewed (Reus
and Pak, 1993) uses a simulation model to assess
pesticide environmental impact. The other authors
have opted for simpler, semi-quantitative approaches.
They have identified a number of parameters of pesticide exposure and toxicity, which are
aggregated into one or several indicators. Contrary to
the approach using a simulation model which tries to
quantitatively assess pesticide environmental impact,
these simpler approaches are rather attempts to summarise
a range of parameters related to pesticide
environmental impact. As these approaches can not
pretend to assess environmental impact, their validation
(i.e. compare its 'environmental impact score' to
the 'real' environmental impact) does not make sense.
The appeal of these indicator-type approaches lies in
their simplicity and their implicit lack of pretentiousness.