Methyl Iodide as a Pesticide?


from “Cal Governor to Review Methyl Iodide Use” Alexander Law Group on March 29, (

I’m an organic chemist by trade, so it’s atypical for me to be overly concerned with toxic agents in the environment. I recall preparing to carry out a routine experiment in 2006 with a reagent called methyl iodide. Any chemist knows that this reagent is a carcinogen, given its role in regulation of gene expression, and is highly volatile, an altogether nasty profile. It was therefore a complete shock to me when I saw that the EPA was planning on approving methyl iodide for use as a fumigant pesticide.

Imagine my surprise in 2011, when methyl iodide officially became an approved fumigant throughout the US. California was a hotbed of contention over this decision; however, in 2010 state government officials approved its use theredisregarding the concerns of their own scientific review board. How did this happen?  To be honest, the EPA and Arysta LifeScience, the commercial vendor of MIDAS (marketed name for methyl iodide), carried out significant due diligence in order to evaluate and predict the toxicity of methyl iodide to humans at doses that are likely to be encountered during application and following incorporation into water supplies. But here is the problem; we don’t know enough about what this chemical can do, and what we do know about it tells us to stay away. This is a situation when even a scientist must look beyond the data and infer from their own intuition that the risk-benefit ratio is off.

In 2012, on the back of litigation and outcry by advocacy groups such as the Pajaro Valley Federation of Teachers (PVFT), it appears as if Arysta has ended sales of MIDAS in the US, however, they continue to carry out worldwide distribution. There is clearly still work to be done.


2 Responses to “Methyl Iodide as a Pesticide?”

  1. sbfph Says:

    I think your post is incredibly interesting and touches on some very pertinent issues within environmental health. Specifically, this idea of how chemicals are tested and how safety levels are determined. It is interesting when the company creating the product carries out the due diligence studies. I think that an impartial third party should conduct toxicity testing; specifically an organization that has no financial ties to the outcome of the study. Unfortunately, with the way research is currently funded, this can be incredibly challenging and does not always happen. I would be interested in learning more about how the EPA determines the safety of various drugs and how many studies are actually needed. In addition, this case demonstrates how even when chemicals are deemed unsafe for the United States, the chemicals will still be used overseas. This is something we still see in the case of lead, as it continues to be used in gasoline in developing countries. It is a shame that often when it comes to industrialization and development environmental concerns do not make the priority list.

  2. ekane3 Says:

    I agree that there should be a more impartial way to assess the impact of these chemicals in the environment. If the EPA is constantly out-gunned on issues like pesticides and fertilizers, perhaps the FDA could help. These chemicals change the food that we eat in some way, shape, or form. We don’t know exactly what these modifications are and we don’t know what the effects are in humans or animals. Maybe some inter-agency collaboration would benefit the public in scenarios like this?

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