Report from the Sub-comittee on the environment and health

Conclusions concerning
model analyses of <strong>the</strong>
impacts on ponds
Conclusions concerning
spray drift and impacts on
<strong>the</strong> terrestrial environment
Conclusions concerning
spray drift and impacts on
<strong>the</strong> aquatic environment
218
years because mechanical weed control with spraying against couch grass
every ten years is more effective than conventional spraying. However,
<strong>the</strong>se analyses must be treated with caution because <strong>the</strong> model has not
been verified in practice.
From <strong>the</strong> model analyses carried out, <strong>the</strong> sub-committee concludes that
<strong>the</strong>re would probably be effects on both flora and fauna as a consequence
of run-off in scenarios corresponding to present production, <strong>the</strong>
++scenario and <strong>the</strong> +scenario. The probability of effect falls with <strong>the</strong>
quantity of pesticides used in <strong>the</strong> scenarios. The models show that, all
else being equal, <strong>the</strong> use of pesticides in <strong>the</strong> crops winter cereal,
potatoes, beets and peas constitutes a serious risk to <strong>the</strong> flora and fauna
in ponds. Less burdensome crops are spring cereal, spring rape, maize
and, to some extent, winter rape. The model predicts that <strong>the</strong> critical
pesticides for algae and aquatic plants (macrophytes) in ponds are
isoproturon, glyphosate, fenpropimorph, ethofumesate, metamitron,
pendimethalin, metribuzin, prosulfocarb, mancozeb, maneb and
clopyralid. Crustaceans and insects are largely equally sensitive, and <strong>the</strong>
simulated effects on crustaceans can in principle be considered to apply
to insects as well. The critical pesticides with respect to effects on
crustaceans and insects are esfenvalerate, propiconazol, pendimethalin,
metribuzin, prosulfocarb, mancozeb and maneb. If <strong>the</strong>re are no run-off
events within a growth season, <strong>the</strong> only source of load on <strong>the</strong> pond is
spray drift. The analyses show that this supply is only of importance in
<strong>the</strong> case of esfenvalerate, with a 6-9% reduction in daphnia biomass.
During spraying, spray drift carries pesticides to <strong>the</strong> surrounding areas.
However, hedgerows, dikes, dry stone walls and o<strong>the</strong>r small biotopes are
so narrow that <strong>the</strong>y should in practice be included in <strong>the</strong> area that is
affected by spray agents. Spray drift can affect both terrestrial and
aquatic ecosystems. Several studies have demonstrated effects <strong>from</strong>
spray-agent drift up to 50 metres <strong>from</strong> <strong>the</strong> sprayed area. However, most
of <strong>the</strong> flora were only affected in an area between 0 and 5 m <strong>from</strong> <strong>the</strong>
field. However, <strong>the</strong>re is a lack of experimental data on effects of
herbicides in low doses on wild plant species, and <strong>the</strong> extent of spray
drift and its effect on wild flora have not been systematically studied in
Denmark. In both <strong>the</strong> 0-scenario and <strong>the</strong> 0+ and +scenarios, <strong>the</strong>
consumption of herbicides would be reduced and thus <strong>the</strong> risk of spray
drift to areas near <strong>the</strong> sprayed field. This would considerably reduce <strong>the</strong>
load, whe<strong>the</strong>r spraying was discontinued altoge<strong>the</strong>r or was only carried
out occasionally. However, owing to <strong>the</strong> lack of data, it is not possible to
quantify <strong>the</strong> beneficial effect on <strong>the</strong> vegetation. The areas affected would
be reduced in step with <strong>the</strong> herbicide consumption. In <strong>the</strong> 0+scenario, <strong>the</strong>
load would be reduced to <strong>the</strong> few localities in which pesticides were
used. In <strong>the</strong> 0-scenario, <strong>the</strong>re would no longer be any impact on <strong>the</strong>
neighbouring areas.
For <strong>the</strong> aquatic environment, any form of impact <strong>from</strong> pesticides,
including changes in <strong>the</strong> flora and fauna in coastal waters, lakes, ponds
and watercourses, is undesirable. Of <strong>the</strong> aquatic ecosystems it is
particularly ponds, watercourses and lakes near fields that could
potentially be affected. It is likely that <strong>the</strong> freshwater environment is
already affected by <strong>the</strong> present use of pesticides, but it is not possible on
<strong>the</strong> basis of <strong>the</strong> existing data to quantify <strong>the</strong> impact at national level. On