Clothianidin and honeybees: No longer a conspiracy theory
A pesticide commonly used in the U.S. is banned in many countries — including the one that produces it — and is contributing to the dwindling honeybee population.
Tuesday, May 10, 2011 - 21:55
In last week's article, I addressed the dwindling honeybee population, caused by colony collapse disorder, and the danger that this poses for environmental equilibrium. To expand on this topic, consider one of its documented causes: a pesticide called clothianidin.
Clothianidin has been widely used on corn — the largest U.S. crop, blanketing 88 million acres of United States farmland — since 2003. Produced by German chemical company Bayer, the pesticide earned $262 million in sales in 2009 alone. It is so widely used in the States, that many suppliers even sell seeds pre-treated with it.
However, despite its ubiquity here, clothianidin is a highly controversial pesticide. It has been banned in France, Italy, Slovenia and, ironically, even Bayer's home country, Germany.
What makes it so dangerous? Like other members of the neonicotinoid family of pesticides, clothianidin gets "taken up by a plant's vascular system and expressed through pollen and nectar," according to Pesticide Action Network of North America (PANNA). That effect makes it highly toxic to a crop's pests — and specifically harmful to pollen-hoarding honeybees, which have experienced mysterious annual massive die-offs (known as colony collapse disorder) here in the United States since at least 2006. So the honeybees feasting on the bounty of pollen produced by the millions of acres of corn are also directly ingesting the toxic pesticide.
PANNA and Beyond Pesticides recently leaked a document indicating that EPA scientists have warned administrators not to allow this product on the market. In this memo, two scientists in the EPA's Environmental Fate and Effects Division — ecologist Joseph DeCant and chemist Michael Barrett — noted:
"Clothianidin's major risk concern is to nontarget insects (that is, honey bees). Clothianidin is a neonicotinoid insecticide that is both persistent and systemic. Acute toxicity studies to honeybees show that clothianidin is highly toxic on both a contact and an oral basis. An incident in Germany already illustrated the toxicity of clothianidin to honeybees when allowed to drift off-site from treated seed during planting. EFED expects adverse effects to bees if clothianidin is allowed to drift from seed planting equipment. Because of this and the uncertainty surrounding the exposure and potential toxicity through contaminated pollen and nectar, EFED is recommending bee precautionary labeling."
Despite this recommendation, the EPA has continued to allow clothianidin to be marketed in the U.S.
Clothianidin's spread in North America
Let's take a closer look at the timeline of this approval. In February 2003, the EPA's Environmental Fate and Effects Division (EFED) withheld registration of clothianidin, declaring that it wanted scientific evidence that it wouldn't harm bee populations. Scientists were concerned that clothianidin's effects were "persistent" and "toxic to honeybees" and noted the "potential for expression in pollen and nectar of flowering crops."
However, in April 2003, the EFED granted Bayer "conditional" approval to sell its product. The "condition" placed by EPA scientists was that Bayer must conduct a "chronic life cycle study" of the pesticide’s effect on bee populations by December 2004. With their "conditional registration" in hand, Bayer introduced clothianidin to the U.S. market in spring 2003. Farmers throughout the Corn Belt planted seeds treated with clothianidin, and billions of plants began producing pollen rich with this toxic pesticide.
In March 2004, Bayer requested an extension of the study deadline and the EPA granted the chemical company until May 2005 to complete its research. After a series of delays, requests, and extensions, the study was not completed until August 2007. Unfortunately, this long-awaited study was deeply flawed for several reasons.
First, the EPA allowed Bayer to conduct the study in Canada instead of the U.S. Second, they used the product on canola instead of corn. Third, the test regions were placed far too close to the control regions to retain autonomy. The researchers created several 2.47-acre fields planted with clothianidin-treated seeds and matching untreated control fields, and placed hives at the center of each. The test and control fields were planted as closely as 968 feet apart and the bees were allowed to roam freely. The problem is that bees forage in a range of 1.24 to 6.2 miles — meaning that the test bees and control bees had access to each other's fields.
With these scientifically flawed testing conditions, the researchers unsurprisingly found "no differences in bee mortality, worker longevity, or brood development occurred between control and treatment groups throughout the study." In short, a contaminated study produced contaminated results.
Tom Theobald, the Colorado beekeeper who obtained the leaked memo, assessed the study harshly. According to Mr. Theobald, "Imagine you're a rancher trying to figure out if a noxious weed is harming your cows. If you plant the weed on two acres and let your cows roam free over 50 acres of lush Montana grass, you're not going to learn much about that weed."
In April 2010, after assessing the results of this study, the EPA quietly granted Bayer unconditional registration for clothianidin. In the leaked memorandum from 2010, DeCant and Barret invalidated the Bayer-funded study. Referring to the pesticide, the authors write:
"A previous field study [i.e., the Bayer study] investigated the effects of clothianidin on whole hive parameters and was classified as acceptable. However, after another review of this field study in light of additional information, deficiencies were identified that render the study supplemental. It does not satisfy the guideline 850.3040, and another field study is needed to evaluate the effects of clothianidin on bees through contaminated pollen and nectar. Exposure through contaminated pollen and nectar and potential toxic effects therefore remain an uncertainty for pollinators."
As concern mounts that clothianidin is harming honeybees, James Frazier, Professor of Entomology at Penn State says, "If the Bayer study is the core study the EPA used to register clothianidin, then there's no basis for registering it." He has urged the EPA to withdraw registration to avoid unnecessary risk to a critical player in our ecosystem — as have the governments of Germany, France, Italy and Slovenia. According to the German Federal Agriculture Institute, "It can unequivocally be concluded that poisoning of the bees is due to the rub-off of the pesticide ingredient clothianidin from corn seeds." The U.S. should join these nations in banning a lethal pesticide that poses serious risks to our environment.
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