RAIN 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 Müller, a chemist at the Swiss Federal
Institute for Environmental Science and Technology in
Dübendorf. 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 Müller and his
colleague Thomas Bucheli in Analytical Chemistry this summer,
one sample of rainwater contained almost 4000 nanograms per litre of
2,4-dinitrophenol, 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
concentrations 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.
Müller
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 had 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 herbicides 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 people (Cancer, vol 85 p 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 chemicals have
suppressed the patients' immunity, allowing viruses such as
Epstein-Barr to trigger cancer.
From New Scientist, 3 April
1999 |