Report from the Sub-comittee on the environment and health

The sub-committee’s
recommendations
concerning <strong>the</strong> impacts of
pesticides in <strong>the</strong>
environment
86
aquatic ecosystems. In <strong>the</strong> case of <strong>the</strong> aquatic environment, any effect
<strong>from</strong> pesticides is undesirable, including changes of flora and fauna in
coastal waters, lakes, ponds and watercourses. Among <strong>the</strong> aquatic
ecosystems, it is particularly ponds, watercourses and lakes near fields
that could potentially be affected.
The freshwater environment is in all probability 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> magnitude of <strong>the</strong> impact nationally. On <strong>the</strong> basis of
information <strong>from</strong> <strong>the</strong> county authorities, it is provisionally estimated that
around 2% of <strong>the</strong> unfulfilled targets of about 11,000 km watercourses can
be due to toxic substances, including pesticides. In particular, <strong>the</strong>
concentration levels measured indicate that it is insecticides – and
especially pyrethroids – that can have an adverse effect. Owing to <strong>the</strong>ir
persistence, pyrethroids can also occur in <strong>the</strong> freshwater ecosystems for a
long period of time. There are also documented cases of effects of
herbicides on algae and o<strong>the</strong>r primary producers. Several measurements
indicate concentrations of pyrethroids and certain thiophosphate
insecticides that are close to <strong>the</strong> level that has effects according to <strong>the</strong>
existing literature. For some pesticides, this level is lower than <strong>the</strong> limit
value of 0.1 microgramme per litre for drinking water.
In both cultivated areas and <strong>the</strong> adjacent biotopes, <strong>the</strong> use of pesticides
involves a risk of reduced populations of flora and fauna, changed
biodiversity, changes in <strong>the</strong> cultivation medium and natural pest
regulation, and of food-chain effects and o<strong>the</strong>r indirect effects. Seen
overall, it is not <strong>the</strong> individual field and its possible loss of wild flora that
are <strong>the</strong> problem, but ra<strong>the</strong>r <strong>the</strong> total, countrywide effects on characteristic
farmland flora and <strong>the</strong> associated fauna.
In forestry, very little use is made of pesticides, whereas, in Christmas
tree and ornamental greenery cultures, <strong>the</strong> same quantities are used as in
farming. The treatment frequency index in nurseries and market gardens
is high. There is a lack of specific studies of <strong>the</strong> effect of herbicides on
forest-floor plant species, but <strong>the</strong>re is no doubt that even <strong>the</strong> limited use
made of pesticides in forestry has adverse effects. Many woodland plant
species have a very slow recolonisation rate of less than 1 metre per year,
which makes <strong>the</strong>m particularly sensitive to herbicides, even though <strong>the</strong>se
are only applied in connection with clear cutting and afforestation.
For <strong>the</strong> scenarios in which pesticides are used, <strong>the</strong>re are no systematic
studies of how pesticides in large, connected areas affect wild flora and
<strong>the</strong> associated fauna in hedgerows, waysides and o<strong>the</strong>r small biotopes
and in neighbouring nature areas. The effects on <strong>the</strong> flora caused by
precipitation of long-distance transported herbicides in Denmark is not
known. Foreign studies show that effects probably exist, but fur<strong>the</strong>r
investigations of both <strong>the</strong> atmospheric transport and <strong>the</strong> effects are
needed for any closer determination. There is also a need to assess <strong>the</strong>
effect of pesticides on aquatic organisms in relation to <strong>the</strong> actual finds in
watercourses and surface water. The sub-committee recommends that <strong>the</strong>
necessary knowledge be built up and that time series be established to
document any effects on <strong>the</strong> terrestrial and aquatic ecosystems seen in
relation to <strong>the</strong> proven occurrence of pesticides in <strong>the</strong> environment.