See PANUPS updates service, for complete information.
Both methyl bromide and methyl iodide are fumigants, gas pesticides injected into soils to kill all living things before a field is planted. "This is an archaic, unsustainable approach," remarked Pesticide Action Network's Senior Scientist Dr. Susan Kegley. "We know so much more now about soil pests, plant pathology and plant breeding than when fumigants were first introduced in the 1920s. EPA should be helping farmers move into the future by expanding the use of new integrated pest management techniques, not replacing one deadly chemical with another." Kegley also points out that fumigation is an inherently risky technology that endangers farm workers, contaminates groundwater, and threatens schools and communities surrounding fumigated fields. With new techniques, however, some organic farms can produce even greater yields per acre than fields treated with fumigants.
The chemical industry is seeking to maintain a market for soil fumigants even as EPA is beginning to recognize the full extent of their toxicity, as well as the difficulty of controlling them once they are released. Methyl bromide is already subject to a global phase out under the Montreal Protocol as a destroyer of the earth's stratospheric ozone layer. Methyl bromide is also an acute respiratory poison, strongly linked with prostate cancer, implicated in Parkinson's Disease and other neurological illnesses, and responsible for many injuries and deaths. "One time I just couldn't stand the gas. My throat hurt, and I had to run from the field to get a breath of air," remembers Jorge Fernandez, a farm worker whose exposure to the gas resulted in chronic respiratory and neurological problems so severe he can no longer support his family--simply talking leaves him dizzy and gasping for breath.
Methyl iodide may be even more hazardous to human health than methyl bromide. Cancer researchers have used methyl iodide in laboratories to induce cancer in cells. Researchers using methyl iodide use great caution, transferring small quantities from sealed tubes with syringes under special ventilation hoods to prevent its release into the air. The state of California lists it as a carcinogen under Proposition 65.
When EPA found that methyl iodide caused thyroid tumors, however, it invoked 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 used only a single paper to come to this conclusion--a questionable 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 large and significant changes in thyroid hormone levels, which are closely tied to metabolic disorders. EPA did not evaluate potential adverse effects that might arise from these changes. Other animal studies evaluated by EPA indicated that methyl iodide causes respiratory tract lesions, neurological problems, and miscarriages.
The State of New Jersey's Fact Sheet cautions laboratory workers exposed to high levels of methyl iodide that the chemical can irritate eyes, burn and blister the skin, and cause coughing and shortness of breath as well as nausea, diarrhea, and vomiting. High exposures may also cause a buildup of fluid in the lungs leading to death. According to the National Institutes of Health, in one case a chemical plant worker exposed to methyl iodide developed symptoms of central nervous system poisoning and died.
If methyl iodide is injected into soil as a fumigant, even tarps will not be able to keep it from escaping into the open air and endangering nearby farmworkers and communities. EPA's human health assessment optimistically recommends that workers handling methyl iodide be required to wear respirators, and that buffer zones the size of several football fields may be necessary to keep the poisonous gas from drifting into nearby communities. But on many farms, agricultural workers are regularly denied basic safety equipment, and growers have objected strenuously to buffer zones of any size. Under actual agricultural conditions, methyl iodide cannot be safely used.
Meanwhile, researchers and farmers have made great progress in improving the productivity and cost effectiveness of growing crops without fumigants. Non-chemical methods include choosing locally appropriate resistant varieties, rotating crops, planting cover crops, soil solarization to control pathogens and weeds, hand-pulling weeds, and using traps and predator species to minimize insect damage. Studies at the University of California at Davis comparing organic strawberry fields to fumigated plots found that the organic fields actually enjoyed higher yields, and both methods produced a profit. In Florida, soil solarization achieved by trapping the sun's heat with plastic covers produced 23% greater tomato yields than neighboring farms that used fumigants. Studies in many countries in Europe, Latin America and other regions are finding successful alternatives as well. These safe and ecological practices can be greatly expanded.
Join scientists, organic growers and public health advocates in calling on EPA to deny registration of methyl iodide for use as a soil fumigant. Take action by sending your comment to EPA before February 21st, 2006.
Mendez, Elizabeth and Jeffrey L. Dawson. 2006. Human Health Risk Assessment: Iodomethane. Office of Pesticide Programs Health Effects Division, US EPA, Docket ID # EPA-HQ-OPP-2005-0252-0002, EPA Public Docket, http://www.regulations.gov/fdmspublic-rel11/component/main
New Jersey Department Of Health and Senior Services. Hazardous Substance Fact Sheet: Methyl Iodide. http://www.state.nj.us/health/eoh/rtkweb/1266.pdf
National Institutes of Health, US National Library of Medicine. Haz-Map Occupational Exposure to Hazardous Agents.
McSherry, Lucius and Katherine Mills. 2005. "Strawberry and Tomato Farming Without Fumigants and Other Toxic Pesticides" in August 2005 Global Pesticide Campaigner, Pesticide Action Network North America.