Tue, Apr 14, 2015 - Page 9 News List

Pesticides likely more harmful than previously thought

European scientists say chemicals known as neonicotinoids, which are linked to honeybee deaths, pose great risks

By David Jolly  /  NY Times News Service, PARIS

Illustration: Yusha

An influential European scientific body on April 8 said that a group of pesticides believed to contribute to mass deaths of honeybees is probably more damaging to ecosystems than previously thought and questioned whether the substances had a place in sustainable agriculture.

The finding could have repercussions on both sides of the Atlantic for the companies that produce the chemicals, which are known as neonicotinoids because of their chemical similarity to nicotine. Global sales of the chemicals reach into the billions of dollars.

The European Commission in 2013 banned the use of three neonicotinoids — clothianidin, imidacloprid and thiamethoxam — on flowering plants after a separate body, the European Food Safety Authority, found that exposure to the chemicals created “high acute risks” to bees.

However, the chemicals continue to be employed on an industrial scale in the US. The US Environmental Protection Agency (EPA) is reviewing their use after US President Barack Obama last year established a national Pollinator Health Task Force amid concerns about so-called colony collapse disorder, a phenomenon still under study that has devastated commercial apiaries.

Pesticides are thought to be only one part of the widespread deaths of bees, however. Other factors are believed to include Varroa destructor mites, viruses, fungi and poor nutrition.

Two of the main producers of neonicotinoids — Syngenta AG, a Swiss biochemical company, and the German company Bayer CropScience AG — have sued the European Commission in an effort to overturn the ban, saying it is not supported by the science. That legal case is still pending.

Research has been directed largely at the effects of neonicotinoids on honeybees, but that focus “has distorted the debate,” according to the report released on April 8 by the European Academies Science Advisory Council.

The council is an independent body composed of representatives from the national science academies of EU member states. The European ban is up for review this year, and the council’s report, based on the examination of more than 100 peer-reviewed papers that were published since the food safety agency’s finding, was prepared to provide officials with state-of-the-science recommendations on how to proceed.

A growing body of evidence shows that the widespread use of the pesticides “has severe effects on a range of organisms that provide ecosystem services like pollination and natural pest control, as well as on biodiversity,” the report’s authors said.

Predatory insects like parasitic wasps and ladybugs provide billions of dollars worth of insect control, they said, and organisms like earthworms contribute billions more through improved soil productivity. All are harmed by the pesticides.

The report found that many farmers have adopted a preventive approach to insect control, soaking their seeds in the pesticides, a method that releases most of the chemicals directly into the environment. They said a farming approach known as integrated pest management, which takes a more natural approach to insect control, would allow for a dramatic decrease in their use.

The authors were critical of studies of neonicotinoids on bee health that tested the insects’ ability to survive a single exposure to a given quantity of pesticide dust; they said that the effect of the chemicals is cumulative and irreversible, meaning that repeated sublethal doses will eventually be deadly if a certain threshold is passed.

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