Over the concerns of its own scientists, the Environmental Protection Agency continues to approve a controversial pesticide introduced to U.S. markets shortly before the honeybee collapse, according to documents leaked to a Colorado beekeeper.

The pesticide, called clothianidin, is manufactured by German agrochemical company Bayer, though it's actually banned in Germany. It's also banned in France, Italy and Slovenia. Those countries fear that clothianidin, which is designed to be absorbed by plant tissue and released in pollen and nectar to kill pests, is also dangerous to pollen- and nectar-eating bees that are critical to some plants' reproductive success.

In 2003, the EPA approved clothianidin for use in the United States. Since then, it's become widely used, with farmers purchasing $262 million worth of clothianidin last year. It's used on used on sugar beets, canola, soy, sunflowers, wheat and corn, the last a pollen-rich crop planted more widely than any other in the United States, and a dietary favorite of honeybees.

During this time, after several decades of gradual decline, honeybee colonies in the United States underwent widespread, massive collapses.

Up to one-third have now vanished, troubling farmers who rely on bees to fertilize $15 billion worth of U.S. crops and citizens who simply like bees. Though colony collapse disorder likely has many causes – from mites to bacteria to fungus to the physiological stresses and epidemiological risks of industrial beekeeping – pesticides are prime suspects, and the EPA's leaked documents (.pdf) are troubling.

The memo, obtained by Colorado beekeeper Tom Theobald and publicized by the Pesticide Action Network, was written in November by scientists from the EPA's Environmental Fate and Effects Division, who are considering Bayer's request to use clothianidin in cotton and mustard. They describe how a key Bayer safety study used by the EPA to justify its original clothianidin approvals, which were granted before the study was actually conducted, was sloppily designed and poorly run, making it a "supplemental" resource at best.

"Clothianidin's major risk concern is to non-target insects (that is, honey bees)," write the EFED researchers (.pdf). "Exposure through contaminated pollen and nectar and potential toxic effects therefore remain an uncertainty for pollinators."

Some beekeepers and activists have now asked the EPA to reverse its clothianidin approval. An EPA spokesperson told Grist's Tom Philpott that clothianidin will again be on sale this spring.

According to the EPA's website, the clothianidin review has been moved back to 2012.

Image: Flickr/Jack Wolf.

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