"...paper concludes the EPA, in its risk assessment used to register a raft of neonic products over the past two decades, "underestimates toxicity by 1.5 to 10 fold if the intent of the exercise is to protect most species, not merely mallards and bobwhites." For the most vulnerable bird species, they found, consuming even two corn seeds coated with Bayer's blockbuster neonic clothianidin can have lethal effects.
"The authors point to several instances of EPA scientists raising serious concerns about the ecological impacts of these pesticides, only to see them registered anyway. Back in 2003, when the EPA was first considering registering Bayer's clothianidin, an agency risk assessment concluded that "exposure to treated seed through ingestion might result in chronic risk to birds and mammals, especially mammals where consumption of 1-2 seeds only could push them to an exposure level at which reproductive effects are expected," the authors report. The assessment also described the chemical as persistent and mobile, with "potential to leach to groundwater as well as runoff to surface waters." So what happened to clothianidin? A "plethora of registered uses for clothianidin followed in quick succession," they report. The pesticide is now used on corn, soybeans, cotton, pears, potatoes, tree nuts, mustard greens, and more.
"Mineau's paper notes in passing that the EPA also identified potential threats from clothianidin to bees as early as 2003, adding, however, that the pollinator issue is "outside the scope of the current review." I told the sordid tale of clothianidin's march through EPA registration despite its own scientists' bee concerns in this 2010 post.
"But the most pernicious effect of neonics on birds may be indirect: By leaching into water and accumulating in streams and ponds, neonics also attack a major component of birds' food supply: insects that hang out in water, what Mineau calls the "bottom of the aquatic food chain." The EPA has severely underestimated the risk to such insects, they charge. For the neonic imidacloprid, they argue, a "scientifically defensible reference level" to gauge when the pesticide causes harm to insects is 0.2 ug/l. "European regulators acknowledge that acute effects are likely at levels exceeding 0.5 ug/l," they write. "In contrast, the EPA’s regulatory and non-regulatory reference levels are set at 35 ug/l."
Special Thanks to "Mother Jones"