Report from the Sub-comittee on the environment and health

The groundwater
monitoring programme,
GRUMO
“mixed sample” of different types of water of different age and
containing different substances. Since a number of water companies have
extraction wells near towns, pesticides detected in <strong>the</strong> raw water
monitoring system often bear signs of non-agricultural use.
In its yearly reporting of <strong>the</strong> results <strong>from</strong> <strong>the</strong> groundwater monitoring
programme, GEUS gives <strong>the</strong> results <strong>from</strong> GRUMO, LOOP and <strong>the</strong> water
companies’ raw water monitoring system separately because <strong>the</strong>y
concern different types of water sample.
Detection of a pesticide, or a metabolite, is defined as detection of <strong>the</strong>
substance in question above <strong>the</strong> current detection limit. The laboratories
use different detection limits. For example, DMU specifies a detection
limit of 0.005 microgramme per litre for some substances, while o<strong>the</strong>r
laboratories specify a detection limit of 0.01 microgramme per litre for
<strong>the</strong> same substances. The detected substances are <strong>the</strong>n divided into two
groups: one over <strong>the</strong> detection limit and one over or equal to <strong>the</strong> limit
value (i.e. <strong>the</strong> latter is a subset of <strong>the</strong> first group).
Pesticides have been found in groundwater all over <strong>the</strong> country with <strong>the</strong>
exception of some areas north of <strong>the</strong> Limfjord and in North Zealand.
Table 4.3 shows <strong>the</strong> pesticides detected in <strong>the</strong> raw water monitoring
system.
The national groundwater monitoring programme gives a complete
picture of <strong>the</strong> state of <strong>the</strong> groundwater, including <strong>the</strong> situation with
respect to pesticides (GEUS 1998). Under <strong>the</strong> groundwater monitoring
programme, analyses were carried out for eight pesticides in 1,014 well
screens in <strong>the</strong> period 1990-1997. The programme covers two triazines
(atrazine, simazine), four phenoxyacetic acids (dichlorprop,
mechlorprop, MCPA, 2,4-D) and two nitrophenols (dinoseb, DNOC). Of
<strong>the</strong> eight GRUMO pesticides, three (atrazine, dinoseb and DNOC) are
now banned, while five of <strong>the</strong> o<strong>the</strong>rs are subject to restrictions with
respect to dosage, crops, etc. In all, 4,230 analyses of water samples have
been carried out for <strong>the</strong>se eight substances. As a consequence of <strong>the</strong>
county authorities’ expanded analytical programmes, data were reported
in 1998 <strong>from</strong> 594 well screens in <strong>the</strong> monitoring system <strong>from</strong> which
water samples were analysed for more pesticides and <strong>the</strong>ir degradation
products.
One or more of <strong>the</strong> eight GRUMO pesticides were detected one or more
times in 121 well screens. The screens came <strong>from</strong> 101 wells, in 16 of
which pesticides were found in two or three screens. The 121 screens
correspond to just over 12% of <strong>the</strong> screens analysed, while <strong>the</strong> limit
value for drinking water (0.1 microgramme per litre) was exceeded in 35
screens, corresponding to just under 3.5%, see table 4.2. There is often an
interval of three years between sampling, and as pesticides normally
occur in pulses, <strong>the</strong>y are often not detected again in subsequent samples.
In <strong>the</strong> 594 screens in which some of <strong>the</strong> county authorities have carried
out expanded analytical programmes, pesticides or degradation products
have been detected in 21% and <strong>the</strong> limit value has been exceeded in
13%, see table 4.2. However, data have usually only been reported on
one set of water samples <strong>from</strong> <strong>the</strong> 594 screens.
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