Precipitation now contains pesticides

Rainwater is not what it used to be. A new study reveals that much of the precipitation in Europe contains such high levels of dissolved pesticides, that it would be illegal to supply it as drinking water.
Studies in Switzerland have found that rain is laced with toxic levels of atrazine, alachlor and other commonly used crop sprays.

"Drinking water standards are regularly exceeded in rain," says Stephan Muller, a chemist at the Swiss Federal Institute for Environmental Science and Technology in Dubendarf.
The chemicals appear to have evaporated from fields and become part of the clouds. Both the European Union and Switzerland have set a limit of 100 nanograms for any particular pesticide in a litre of drinking water. But, especially in the first minutes of a heavy storm, rain can contain much more than that. In a study to be published by Muller and his colleague Thomas Bucheli in Analytical Chemistry this summer, one sample of rainwater contained almost 4,000 nanograms per litre of 2,4-dinitro- phenol, a widely used pesticide.

Previously, the authors had shown that in rain samples taken from 41 storms, nine contained more than 100 nanograms of atrazine per litre, one of them around 900 nanograms. In the latest study, the highest concentra-tions of pesticides turned up in the first rain after a long dry-spell, particularly when local fields had recently been sprayed. Until now, scientists had assumed that the pesticides only infiltrated groundwater directly from fields.

Muller warns that the growing practice of using rainwater that falls onto roofs to recharge underground water may be adding to the danger. This water often contains dissolved herbicides that have been added to roofing materials such as bitumen sheets, to prevent vegetation growing. He suggests that the first flush of rains should be diverted into sewers to minimise the pollution of drinking water, which is not usually treated to remove these herbi-cides and pesticides.

Meanwhile, Swedish researchers have linked pesticides to one of the most rapidly increasing cancers in the Western world. Non-Hodgkin's lymphoma, which has risen by 73 per cent in the US since 1973, is probably caused by several commonly used crop sprays, say the scientists. Lennart Hardell of Orebro Medical Centre and Mikael Eriksson of Lund University Hospital found Swedish sufferers of the disease were 2.7 times more likely to have been exposed to MCPA, a widely used weedkiller, than healthy peo-ple (Cancer 85:1353). (MCPA, which is used on grain crops, is sold as Target by the Swiss firm Novartis.) In addition, patients were 3.7 times more likely to have been exposed to a range of fungicides-an association not previously reported. The patients were also 2.3 times more likely to have had contact with glyphosate, the most commonly used herbicide in Sweden. Use of this chemical, sold as Round-Up by the US firm Monsanto, is expected to rocket with the introduction of crops such as Roundup-Ready soya beans that are genetically modified to resist glyphosate. The researchers suggest that the chemi-cals have suppressed the patients' immuni-ty, allowing viruses such as Epstein-Barr to trigger cancer.