A new report on pesticides in water from the UK Department of the Environment shows that more than 21,000 drinking water samples contained pesticides at concentrations above the legally acceptable limit of 0.1µg/l. Some 89 pesticides were detected in surface waters in England and Wales, and 37 pesticides were found in ground water. (See also p. 26, 'UK water report'.) But many pesticides in widespread use do not have adequate analytical methods and are therefore not looked for in water samples; other pesticides are not sought because of the expense involved. Neither are all water bodies and sources adequately monitored for pesticides because of the expense involved.
Pesticides in water are monitored by the Environment Agency, River Purification Authorities, Department of the Environment (Northern Ireland) and water companies. Their objectives and standards differ and as a result the pesticides they seek differ as does the way in which their findings are reported.
The Working Party on the Incidence of Pesticides in Water which produced the report recommended that:
All the monitoring programmes should look for all pesticides which have the potential to contaminate water, and that findings should be reported consistently.
More information should be gathered and published about the usage of non-agricultural pesticides and veterinary pesticides. More detailed information about localised pesticide use particularly in relation to catchments, and about application timing should also be gathered.
Satisfactory analytical methods are not available for all pesticides which pose a potential threat to water. Manufacturers should provide appropriate methods with their applications for approval of products. These should be capable of detecting the pesticide at the drinking water standard of 0.1µg/l or at Environmental Quality Standards if these are lower.
More information about the environmental fate and behaviour of pesticides, including veterinary medicines, needs to be generated in order to manage them better and to allow responsible authorities such as water companies and river purification boards to prevent their use from lowering water quality.
Pesticides which are regularly found to contaminate water at above the legal or officially determined standards should be referred to the government's Advisory Committee on Pesticides for review. Pesticides which have been restricted because of their water contamination potential should continue to be monitored to ensure that controls are working.
This report is valuable in bringing together diverse sources of information about pesticides in water. Its main contribution is in highlighting the gaps in data and in knowledge about pesticides which currently exist.
Pesticides in Water: Report of-The Working Party on the Incidence of Pesticides in Water, Department of the Environment, HMSO, May 1996, £25, 106pp.
[This
article first appeared in Pesticides News No. 33, September 1996,
page 27]