Report from the Sub-comittee on the environment and health

20
system. However, <strong>the</strong> analysed pesticides occur in 26% of <strong>the</strong> water
samples taken <strong>from</strong> wells with “top screen” in <strong>the</strong> interval <strong>from</strong> 10 to 20
metres below ground level, compared with 13% in <strong>the</strong> groundwater
monitoring programme. This may be because <strong>the</strong> water companies in
some areas extract groundwater <strong>from</strong> high-lying, fractured limestone,
where <strong>the</strong> groundwater is presumably younger and more affected by <strong>the</strong>
use of pesticides on <strong>the</strong> surface of <strong>the</strong> earth.
As a consequence of <strong>the</strong> many detections of <strong>the</strong> degradation product
BAM (2.6-dichlorobenzamide) in <strong>the</strong> last few years, some water
companies have analysed for this substance in <strong>the</strong>ir routine monitoring.
The water companies have carried out 2,310 BAM analyses of water
samples <strong>from</strong> 1,656 wells and have detected BAM in 448 of <strong>the</strong>m,
corresponding to around 30%. The limit value for drinking water was
exceeded in 187 wells, corresponding to about 11% of <strong>the</strong> analysed
wells. Most of <strong>the</strong> detections of BAM in waterworks wells were made
<strong>from</strong> ground level to a depth of 0-30 metres, where <strong>the</strong> highest
concentrations were also measured. BAM’s parent compound is a
herbicide, dichlobenil, which has primarily been used in urban areas.
Because of <strong>the</strong> earlier widespread use of <strong>the</strong> now prohibited parent
compound dichlobenil, BAM can thus be expected to occur both under
built-up areas and under farmyards, gravel roads and o<strong>the</strong>r areas kept free
of vegetation.
In recent years, <strong>the</strong> county authorities, <strong>the</strong> water companies and DMU
have carried out a number of expanded analytical programmes for
groundwater and waterworks water. Results covering 108 pesticides and
metabolites are available. Of <strong>the</strong>se 108 substances, around 40 have been
detected in Danish groundwater, 29 of <strong>the</strong>m in concentrations above <strong>the</strong>
limit value for drinking water, see table 4.4. DMU's expanded analytical
programmes comprise mainly analyses of groundwater <strong>from</strong> <strong>the</strong> LOOP
regions. The data in <strong>the</strong> table are <strong>from</strong> analyses carried out in 1997, <strong>from</strong>
older analyses that were not reported to <strong>the</strong> groundwater database at
GEUS, and <strong>from</strong> analyses that were partly or totally reported to <strong>the</strong>
groundwater database at GEUS, e.g. analytical programmes carried out in
LOOP and a few groundwater monitoring areas. The table does not
include data <strong>from</strong> <strong>the</strong> general monitoring of <strong>the</strong> groundwater monitoring
areas. Twenty of <strong>the</strong> pesticides detected in groundwater were in use in
Denmark in 1996, but some of <strong>the</strong>m have since had restrictions imposed
on <strong>the</strong>ir use or have been banned. However, a few substances, e.g. <strong>the</strong>
degradation product ETU, was found in both soil water and groundwater
in a research project by Fladerne Bæk (river) and in an analysis carried
out by Copenhagen County Council in 1997, in which ETU was detected
in piezometric wells close to a landfill site.
Table 4.3 Detections of pesticides analysed in connection with <strong>the</strong> water companies’ raw water monitoring system
(Brüsch et al. 1998). Ranked by falling number of analyses. Consumption data <strong>from</strong> Bekæmpelsesmiddelstatistik
(Pesticide Statistics) 1997 (Danish Environmental Protection Agency 1998a).
Pesticide/metabolite Analyses Analysed Wells with Wells with finds Consumption in
wells finds ≥0.1 µg/L 1997
number number number number in kg a.i.
Atrazine 5759 4015 148 31 B
Desethylatrazine M
1335 1169 50 6 MB
Hydroxyatrazine M
594 562 3 MB
Desisopropylatrazine M
Expanded analytical
programmes
1290 1133 33 3 MB
5714 3998 88 19 4560
Dichlorprop a