Report from the Sub-comittee on the environment and health

Better monitoring of <strong>the</strong>
groundwater
Early warning of <strong>the</strong> risk
of leaching to <strong>the</strong>
groundwater
Clarification of
fundamental problems
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addition, all <strong>the</strong> substances could be run through MACRO after it has
been decided what data and scenarios are relevant.
The examination of <strong>the</strong> ranking methods also showed:
• that, in <strong>the</strong> case of 9 pesticides, <strong>the</strong>re was not complete laboratory
data for <strong>the</strong>ir adsorption to soil or degradation in soil
• that leachable metabolites are not included as part of <strong>the</strong> basis for
ranking in <strong>the</strong> methods studied, except for <strong>the</strong> expert assessment
• that, with a view to reviewing pesticides’ leaching, <strong>the</strong> gross list can
be included in recommendations on substitution with less dangerous
substances in <strong>the</strong> treatment situation.
To clarify <strong>the</strong> extent to which <strong>the</strong> use of pesticides threatens our
groundwater resources, a number of activities have been initiated in <strong>the</strong>
last few years, partly to determine <strong>the</strong> extent to which our groundwater is
affected by <strong>the</strong> pesticides authorised for use today and partly to clarify
<strong>the</strong> more fundamental problems relating to <strong>the</strong> risk assessment. In order
to learn more about <strong>the</strong> leaching of pesticides to <strong>the</strong> groundwater, <strong>the</strong>
countrywide monitoring programmes for groundwater (LOOP and
GRUMO) have been considerably expanded. The results of this will
begin to emerge in <strong>the</strong> middle of 2000.
The groundwater analysed is mainly more than five years old and often
more than 25 years old. Feedback cannot occur before substantial parts of
<strong>the</strong> groundwater resources must be presumed to be affected if <strong>the</strong>
authorised pesticides or <strong>the</strong>ir metabolites leach to <strong>the</strong> groundwater.
GEUS, DIAS, DEPA and DMU must toge<strong>the</strong>r plan and establish a
warning system that monitors young groundwater for pesticides that are
used under <strong>the</strong> current rules. The warning system must make it possible
to assess quickly and possibly remove authorised pesticides if, with
lawful use under Danish conditions, <strong>the</strong>y prove able to leach to <strong>the</strong>
groundwater in concentrations that exceed <strong>the</strong> limit value. The first
results are expected to become available in <strong>the</strong> second half of 2000.
Do we understand properly <strong>the</strong> transport of pesticides <strong>from</strong> <strong>the</strong> ploughing
layer down to <strong>the</strong> groundwater and on to <strong>the</strong> extraction wells? As <strong>the</strong>
results <strong>from</strong> <strong>the</strong> monitoring programmes have emerged over <strong>the</strong> last 10
years, showing that <strong>the</strong> groundwater is polluted with pesticides, several
different hypo<strong>the</strong>ses have been advanced on <strong>the</strong> reasons for this: <strong>the</strong>y
include preferential flow, colloidal transport or <strong>the</strong> right description of
<strong>the</strong> degradation process of <strong>the</strong> individual substances. To achieve greater
understanding of <strong>the</strong>se problems, a number of research activities have
been initiated, including The Danish Environmental Research
Programme (SMP96): “Pesticides and Groundwater”, which runs <strong>from</strong>
1996 to 2000, and <strong>the</strong> Interministerial Pesticide Research Programme,
1995-1998. Activities under SMP96 will shed light on <strong>the</strong> importance of
preferential flow for <strong>the</strong> transport of pesticides in structured soil <strong>from</strong> <strong>the</strong>
ploughing layer down to <strong>the</strong> groundwater, <strong>the</strong> transport and metabolism
of pesticides in <strong>the</strong> groundwater itself, and <strong>the</strong> possibilities of describing
<strong>the</strong> transport of pesticides on a regional scale by means of ma<strong>the</strong>matical