Report from the Sub-comittee on the environment and health

Potential sources of
pesticides in groundwater
54
indications that point sources with pesticides do pollute. For example,
pesticides are sometimes detected in groundwater or watercourses in
such high concentrations that it is unlikely that <strong>the</strong> source is application
on fields. Point-source pollution can thus explain some local instances
found today of limit values having been exceeded in groundwater and
wells.
In one of <strong>the</strong> few studies carried out, Jørgensen and Spliid (1993)
examined a washing and filling site in an orchard and found a very large
content of phenoxy acids in <strong>the</strong> analysed soil samples.
O<strong>the</strong>r studies have shown that farmers’ wells and boreholes can be
seriously contaminated with pesticides (Anon 1995; Spliid 1998b)
caused ei<strong>the</strong>r by point sources or by use of herbicides on farmyard areas.
Areas surfaced with gravel and stone present a special risk of leaching of
pesticides compared with ordinary agricultural land. Areas of this type
are found in farmyards (Jacobsen et al. 1998).
A German study by Fischer et al. (1996) showed that 98% of <strong>the</strong>
considerable pollution of a watercourse was caused by discharge of
isoproturon directly <strong>from</strong> yard areas via sewerage systems or drains.
Where pesticides are used and handled outside normal field spraying,
<strong>the</strong>re is a risk of pollution of <strong>the</strong> surrounding environment – of <strong>the</strong>
groundwater, <strong>the</strong> farmer’s own well or borehole and watercourses – via
drainage systems <strong>from</strong> <strong>the</strong> farm yard. Table 4.21 shows <strong>the</strong> potential
water pollution <strong>from</strong> filling and washing sites.
There are no data showing whe<strong>the</strong>r washing water or pesticide spills
cause serious groundwater pollution, nor is it known whe<strong>the</strong>r buried
packaging is a serious problem. Before 1980. <strong>the</strong> authorities
recommended burying empty packaging.
In directions <strong>from</strong> <strong>the</strong> Pesticide Board of <strong>the</strong> former Ministry of
Agriculture <strong>from</strong> 1966 it was stated in a section entitled “Disposal of
residual stocks of pesticides” that small remnants of pesticides and up to
approx. 1 kg should be emptied into an 0.5 metre deep hole and that <strong>the</strong>
packaging should be destroyed. The hole had to be at least 50 m <strong>from</strong> any
well, watercourse, lake or drainage pipes. In <strong>the</strong> case of larger quantities,
it was stated that <strong>the</strong>se should be buried at a tip after permission for this
had been obtained <strong>from</strong> <strong>the</strong> local health inspector.
Table 4.21
Potential sources of water pollution <strong>from</strong> filling and washing sites
(Jensen et al. 1998).
Risk areas
• Spilling of concentrated pesticide
during filling, e.g. 100 ml IPU
• Overflow <strong>from</strong> <strong>the</strong> sprayer tank
during filling, e.g. 10 l Express spray
liquid
• Washing <strong>the</strong> outside of spraying
equipment
• Can pollute 500,000 m 3 water
above <strong>the</strong> limit value
• Can pollute 5,000 m 3 water
above <strong>the</strong> limit value
• The IPU UK Task Force has
estimated that washing <strong>the</strong>
outside of a sprayer can pollute