Tuesday, June 15, 2010

The horror! Methyl iodide as an approved pesticide??

I recall hearing a couple of years ago that California was considering using methyl iodide as a replacement for methyl bromide, which has been used extensively as a pesticide for crops, such as strawberries, but has also been wreaking havoc on the ozone layer. So, methyl bromide is being phased out, but what to replace it with? Apparently, Arysta LifeScience has been pushing the use of methyl iodide as a soil fumigant, which should work similarly but not affect the ozone layer. In 2007, the EPA actually approved its use, despite the warnings from many chemists who said they were "astonished" that the EPA was considering "broadcast releases of one of the more toxic chemicals used in manufacturing into the environment."

I personally used methyl iodide in grad school, but I always took great precautions -- gloves, fumehood, syringes to transfer. This is not something you want to get on yourself. It is routinely used to methylate DNA. Can you say, "cancer"? Methyl iodide is 6 times more toxic than methyl bromide. It's still very volatile, so there is a serious inhalation risk. If used on crops, it will contaminate the air and the water, and most likely poison farm workers and people living in the vicinity (especially downwind).

A report from the California Scientific Review Committee in 2009 concluded that there was no good way to use methyl iodide safely and that its use would have a significant adverse impact on public health. Yet, on April 30, 2010, California actually proposed using methyl iodide as a pesticide for use in agriculture. What are these people thinking?? If nothing is done, methyl iodide will become legal for California farmers to use after June 29.

Interesting facts: 47 States have licensed the use of methyl iodide, and 11 states have used it at least once. It has been used mostly on strawberries and sometimes on tomatoes and peppers.

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