Fumigants in California: Let's Avoid a Sophie's Choice Between Toxic Chemicals
Posted February 22, 2011
I'm headed up to Sacramento today to testify at a joint hearing of the California Assembly on the Public Health and Environmental Risk of Methyl Iodide. Here's a preview of part of my testimony:
Methyl bromide - a fumigant pesticide that is heavily used on California strawberries - is a chemical of very serious concern because of its known destruction of the stratospheric ozone layer. It is a public health and environmental imperative to reduce and phase out the use of this fumigant, and doing so will prevent thousands of skin cancer cases and ophthalmologic cataracts in the U.S. alone every year. However, the principles of green chemistry that we have embraced in California require that we assess alternatives to dangerous chemicals, and by doing a proper alternatives assessment, we can avoid the problem of regrettable substitutions – where hasty adoption of an easy alternative opens up an entirely new set of serious problems. I’m sorry to say that methyl iodide would be a highly regrettable substitution.
Use of methyl iodide instead of methyl bromide creates a Sophie’s choice: Trading off protection of the ozone layer against serious risk to groundwater resources; trading off a reduction in skin cancers for an increase in thyroid and other cancers. Methyl iodide also exhibits a remarkable propensity to target the brain and nervous system, and damage the developing fetus; it also has a dramatic affinity for damaging DNA in living cells, all of which makes physicians and toxicologists very worried about the workers who may be handling this chemical, as well as the communities living near where it is applied. In short, if we allow methyl iodide to be used in California, we will all regret it.
As a scientist, I was very impressed with California’s process for evaluating methyl iodide. The DPR staff scientists did a very good job evaluating the toxicity of this chemical, the stellar Scientific Review Committee made excellent recommendations for improvements, many of which were ultimately incorporated into DPR’s final risk assessment. But then something rather strange occurred. In the waning days of the previous administration, a decision to register the chemical was rushed through -- a decision which flies in the face of all of the excellent scientific work that was done over the prior two years, and that fails to comport in any way, shape, or form with the scientific facts that are on the table.
In fact, the level that DPR now allows for exposures to the general public corresponds to 100-times the level that DPR itself determined was the maximum safe exposure for risk of fetal death. The cancer risk level for workers is 8-fold higher than DPR’s maximum acceptable cancer risk, and the risk of neurological effects at the levels that DPR decided to allow ranges from 5-fold higher than the safe upper limit calculated by DPR itself (for infants and children), to 3-fold higher for applicators. I have a table in my testimony that provides all of these number comparisons. Dr. Ron Melnick a member of the Committee who was a toxicologist with the National Institutes of Health calculated that exposure to DPR’s allowable level of methyl iodide (32 ppb) for just one month per year would still far exceed California’s no significant risk level for cancer.
In my view, these numbers mean that people will get sick and injured, possibly in large numbers, if this chemical comes into widespread use in California agriculture. It’s hard to stand by quietly and watch this happen.
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