(Beyond Pesticides, September 28, 2007) EPA is due to make a decision on methyl iodide, a highly reactive and carcinogenic chemical, for use in crop production as a soil fumigant. Scientists across the country are alarmed by the prospect of registering methyl iodide as a pesticide, and fifty-four chemists and physicians from across the country issued a letter to EPA Administrator Stephen Johnson Monday urging the Agency not to sanction the broad use of methyl iodide now or at any time.â€ś[W]e are concerned that pregnant women and the fetus, children, the elderly, farm workers, and other people living near application sites would be at serious risk if methyl iodide is permitted for use in agriculture,â€ť said the group in the letter. In the chemical community methyl iodide is a well-known cancer hazard due to its ability to mutate DNA, and the scientists are fearful that methyl iodideâ€™s high volatility and water solubility will expose many people to harm if the chemical is used in agriculture.
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. EPAâ€™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.
Environmental and farmworkers groups do not see the risks as reasonable or avoidable and stand firm in their continued resistance against the use of the fumigant. The Pesticide Action Network North America (PANNA), the United Farm Workers (UFW) of America and Beyond Pesticides helped bring methyl iodide to the publicâ€™s attention and organize opposition to the registration earlier this year. EPA refused registration for methyl iodide in April 2006, after the Agency received thousands of public comments opposing the chemical (See â€śStop Methyl Iodide: Donâ€™t let EPA register new carcinogenic pesticideâ€ť).
â€śAn EPA decision to register this chemical would be irresponsible and reckless. Exposure to methyl iodide puts workers and rural residents at greatly increased risk for cancer, thyroid problems, miscarriages and stillbirths,â€ť says Dr. Susan Kegley, senior scientist with PANNA. â€śWhy is it that EPA seems so intent on registering a pesticide that is more toxic than the ones we have now? We need leadership from EPA to move towards sustainable farms that donâ€™t poison their neighbors and workers.â€ť
Internal documents obtained by The Associated Press indicate use of the fumigant may be approved on an interim basis and later reviewed after new safety restrictions are set for a group of fumigants already in use. The scientists who wrote to EPA questioned the Agencyâ€™s safety assessment and asked to delay the decision until the Agencyâ€™s evaluation of methyl iodide could be subject to peer review and scientific scrutiny. â€śU.S. EPA has made many assumptions about toxicology and exposure in the risk assessment that have not been examined by independent scientific peer reviewers for adequacy or accuracy. Additionally, none of U.S. EPAâ€™s calculations account for the extra vulnerability of the unborn fetus and children to toxic insults.â€ť
The new product is MIDAS, a methyl iodide compound manufactured by Tokyo-based Arysta LifeScience Corp., and methyl iodide does break down quickly enough in air to not be considered as a replacement to methyl bromide, an ozone depletor that is scheduled for phase-out according to the Montreal Protocol of 1992. It is not clear that this factor alone negates the hazards of the substance and deems special treatment for its use as a fumigant. 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 â€śNot likely to be carcinogenic to humans at doses that do not alter rat thyroid hormone homeostasis.â€ť The EPAâ€™s Cancer Assessment Review Committee used only a single study to come to this conclusionâ€”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.