§ Mr. Cartwright
asked the Secretary of State for the Environment what is the lowest known concentration in parts per million of any particular health risk arising from traces of atrazine, simazine, lindane or dieldrin pesticides in water.
§ Mr. Macfarlane
In 1984 WHO set drinking water guidelines values of 0.0003 parts per million for dieldrin and 0.03 parts per million for lindane. No guideline values have been set for triazine herbicides, which include atrazine and simazine, but it has been calculated from available data that concentrations found in drinking water have a safety factor of the order of several thousand.
§ Dr. David Clark
asked the Secretary of State for the Environment what is his estimate of the aerial transport of organo-chlorine pesticides in the context of inputs of these and other substances into the North sea following the report commissioned by his Department from the Institute of Offshore Engineering at Heriot-Watt university; and what further research is planned on this matter.
§ Mr. Waldegrave
The Institute of Offshore Engineering examined the available information on this subject as part of a wider review for the Department of the literature on inputs of contaminants to the North sea. The review is available, at cost, from the university. It quotes estimates made by the Netherlands Organisation for Applied Scientific Research (TNO) of 10–100 tonnes annually of HCH (alpha and gamma), 10–160 tonnes of PCBs and 2–25 tonnes each of DDT (and its metabolites), and of the "drins" (aldrin, dieldrin, endrin). These estimates are tentative, being based on very few measurements, but are probably the best available. The United Kingdom therefore referred to them in preparing for the North sea conference in Bremen last year and similar estimates for HCH and for PCBs were quoted in the paper on the "Quality Status of the North Sea" which synthesised the scientific contributions made by the participating states. A working group has been set up by the Paris commission to examine the whole question of atmospheric inputs to the sea and is considering research into the methodology and accuracy of the estimated inputs. The United Kingdom is participating actively in this group.