- Author: Jeannette E. Warnert
Last week, the California Department of Pesticide Regulation approved the use of methyl iodide as a soil fumigant. The announcement prompted wide media coverage, with many stories noting the fact that a review by a group of scientists empaneled by DPR had recommended against methyl iodide registration.
Over the weekend, the Salinas Californian ran point-counterpoint articles that spelled out the arguments for and against agricultural use of the fumigant. The argument in favor was penned by Jim Sims, the UC Riverside emeritus chemist who first proposed the use of methyl iodide as a soil fumigant.
A few of the points Sims made in his argument were:
- The chemical is not a human carcinogen. It is a rodent carcinogen.
- It has been used in the southeast for nearly three years on more than 15,000 acres with no untoward events reported.
- Methyl iodide is naturally occurring substance, with hundreds of thousands of tons of the compound produced every year by the ocean. Anyone living in coastal regions can expect to inhale methyl iodide as part of their natural environment every day.
- One's risk for being hurt while driving to work is much higher than the risk that one would contract cancer, nerve damage or fetal development problems from exposure to methyl iodide.
The "counterpoint" was written by Susan Kegley of the Pesticide Action Network. Her points included:
- DPR and the Scientific Review Committee noted that a marginally acceptable level of exposure to methyl iodide is 0.3 parts per billion (ppb). In contrast, the level approved by the Department's management is 107 times higher, at 32 ppb.
- The known consequences of methyl iodide exposure at low levels range from late-term miscarriage to thyroid disease. An increased incidence of cancer is also likely from exposure to this recognized carcinogen.
- What we don't know is equally worrisome.
- A recent Florida study documented high levels of iodide in groundwater near fields treated with methyl iodide, compared to normal background levels.