(Beyond Pesticides, October 4, 2007) On September 28, 2007, the Environmental Protection Agency (EPA) delayed approval of the pesticide methyl iodide, a highly toxic replacement chemical for the ozone-depleting methyl bromide (also called iodomethane), after more than 50 prominent scientists objected that the chemical was too dangerous. The decision surprised environmentalists who assumed the pesticide would most likely be registered despite opposition. According to EPA, it now “will address recent questions prompted by the pending registration of iodomethane.”
On September 24, 2007, scientists across the country — including six Nobel prize winners, alarmed by the prospect of registering methyl iodide as a pesticide, issued a letter to EPA Administrator Stephen Johnson urging the Agency not to sanction the broad use of methyl iodide now or at any time.
“The gratifying thing is that EPA has been responsive to people who are really concerned about this,” Robert Bergman, a University of California at Berkeley professor who organized the scientists’ letter, told the Associated Press. The letter criticized EPA’s scientific analysis, calling for an independent scientific review of the agency’s assessment.
Methyl iodide and methyl bromide are injected into the soil at rates of 100-400 pounds per acre to kill soil-borne pests. Because of the high application rates and gaseous nature of these chemicals, they drift away from the application site to poison neighbors and farmworkers. EPA’s analysis evaluated possible buffer zones around fields and concluded that bystander exposure would not be significant. It said farmworkers could protect themselves sufficiently with respirators.
The Montreal Protocol, a 1992 commitment by the world’s nations that includes the phase out methyl bromide – one of the five deadly pesticides targeted by Cesar Chavez and the United Farm Workers – gave hope that farmworkers and others would finally stop being put at risk by this deadly pesticide. Unfortunately, EPA is not only backpedaling on this, but is also facilitating the chemical industry and agribusiness efforts to introduce methyl iodide, a fumigant that may be even more hazardous to human health than methyl bromide.
The state of California lists methyl iodide as a carcinogen under Proposition 65. EPA found that methyl iodide caused thyroid tumors–and introduced a previously unheard of cancer ranking of “Not likely to be carcinogenic to humans at doses that do not alter rat thyroid hormone homeostasis.” The EPA’s Cancer Assessment Review Committee came to this conclusion using only a single study””in which 62-66% of the rats in both the control and the high dose group died during the experiment. In addition to thyroid tumors, the study showed significant changes in thyroid hormone levels, which are closely tied to metabolic disorders. Other animal studies evaluated by EPA also indicated that methyl iodide causes respiratory tract lesions, neurological effects, and miscarriages.