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Biological Chemistry

Methyl Iodide Fumigant

December 8, 2008 | A version of this story appeared in Volume 86, Issue 49

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THE ARTICLE on methyl iodide has me shaking my head (C&EN, Oct. 27, page 28). Every organic chemist in the world should shudder at the thought of producing massive amounts of methyl iodide to fumigate soil. Methyl iodide is one of the strongest alkylating agents known. As a result, its use raises serious health issues for all living organisms.

Clearly, the farm industry needs a fumigant, but this chemical is not selective and would be more persistent in the environment than the more volatile methyl bromide, which admittedly needs to be replaced. Is there anyone organizing our resistance to methylating the world?

Steven Fleming

I WAS A LITTLE disappointed in the article concerning the soil fumigant methyl iodide. It seemed to me to be biased toward the antichemical groups that oppose its registration and use.

Methyl iodide as a soil fumigant is used to control soil fungi, bacteria, nematodes, and weeds. As to the carcinogenicity of methyl iodide, please take a look at 13th edition of the Merck Index. Methyl iodide was delisted in 1989 by the National Toxicology Program due to the International Agency for Research on Cancer's reevaluation of it as unclassifiable as to its human carcinogenicity. Nothing new has since been published that I am aware of. California's list of substances known to be carcinogens includes substances in everyday use such as gasoline. A warning is posted on every gas pump.

Bob Bergman is a superb chemist and a friend. I am surprised that he wouldn't know that there are numerous commercial uses of pheromones in the control of insects. The analogy to orphan drugs is cute but not on target.

Two general approaches to the control of plant diseases that do not involve the use of agricultural chemicals are being actively researched in most plant pathology departments and in plant biology departments around the world. These approaches are the genetic modification of crop plants and the use of biological control organisms. Neither of these approaches has reached the stage where chemical fumigants could be replaced.

All of the researchers involved in these projects think that, one day, chemicals will be replaced by one or more of these technologies. I have the same hope. At this point in time, however, chemicals are needed to provide food.

James Sims
Riverside, Calif.



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