Report from the Sub-comittee on the environment and health

measuring programmes have not been going on long enough to enable
a description of <strong>the</strong> trends.
2. In <strong>the</strong> expanded analyses in <strong>the</strong> groundwater monitoring programme,
pesticides or degradation products were detected in 34% of <strong>the</strong>
screens examined in <strong>the</strong> interval 0 to 10 metres below soil surface.
The limit value was exceeded in 23% of <strong>the</strong> screens. The detection
frequency decreases with <strong>the</strong> depth, which may indicate that remnants
of <strong>the</strong> last 50 years’ increasing use of pesticides are moving towards
<strong>the</strong> deeper aquifers, with increasing future groundwater pollution as a
consequence. Ano<strong>the</strong>r possible explanation might be that degradation
is taking place during <strong>the</strong> onward movement because <strong>the</strong>
concentrations in <strong>the</strong> deeper soil strata have been exposed to
biological and chemical degradation for a longer period of time than
concentrations in <strong>the</strong> uppermost strata. Only when sufficiently long
time series <strong>from</strong> <strong>the</strong> monitoring programmes are available – which
means in 5 to 10 years time – will it be possible to test <strong>the</strong>se
hypo<strong>the</strong>ses. The latest research indicates that <strong>the</strong> degradation of
certain pesticides in <strong>the</strong> aquifers is very slow, while o<strong>the</strong>rs show
degradation.
3. In <strong>the</strong> expanded analyses in <strong>the</strong> groundwater monitoring programme,
pesticides or degradation products were found in 21% of <strong>the</strong> screens
examined. The limit value was exceeded in 13% of <strong>the</strong> screens. The
degradation product BAM <strong>from</strong> <strong>the</strong> now banned herbicide dichlobenil
was detected in about 30% of <strong>the</strong> wells analysed in connection with
<strong>the</strong> water companies’ raw water monitoring system. However, a wide
range of substances that are used in agriculture for treating crops are
also present in relatively many wells analysed in connection with <strong>the</strong>
water companies’ raw water monitoring system. Larger amounts of
pesticides were detected in drain water and soil water than in
groundwater, and this may reflect concentrations that may similarly
later move towards <strong>the</strong> groundwater, during which <strong>the</strong>y may undergo
degradation and possible formation of metabolites. In both
watercourses and ponds, a number of pesticides have been detected in
higher concentrations than <strong>the</strong> concentrations that have effected
aquatic organisms in <strong>the</strong> laboratory.
4. It is a condition of authorisation of pesticides that <strong>the</strong>y degrade in <strong>the</strong>
environment and are metabolised into water, carbon dioxide and salts
or into harmless organic substances. However, <strong>the</strong> sub-committee has
noted that, in <strong>the</strong> case of pesticides detected in <strong>the</strong> different
compartments, it is often only a fraction of <strong>the</strong> quantities used that can
be accounted for, apart <strong>from</strong> degradation. There is thus a lack of
information concerning <strong>the</strong> total mass flows and <strong>the</strong> largest flows,
including volatilisation and drift, and a lack of actual systematic
measurements in <strong>the</strong> environment of degradation and metabolism as
an element of <strong>the</strong> integrated mass flow analysis. It is thus not possible
to make a real and complete description of <strong>the</strong> fate of <strong>the</strong> pesticides in
relation to <strong>the</strong> environmental and health loads.
5. The detection of authorised pesticides above <strong>the</strong> limit value in both
groundwater near <strong>the</strong> surface and in aquifers at greater depths
indicates that <strong>the</strong> present authorisation scheme does not ensure
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