Methyl Iodide - Unsafe at Any Speed

June 18, 2010

By: Assemblymember Bill Monning

The decision of the California Department of Pesticide Regulation (DPR) to support the registration of the pesticide methyl iodide is irresponsible because its proposed mitigations will not avert potentially devastating health and environmental impacts.  The proposed registration is misplaced in light of compelling evidence presented by the external scientific peer review committee commissioned by DPR.  Once methyl iodide is approved, there will be no turning back from its dangerous and potentially lethal effects.  Workers and families in rural regions deserve protection from this highly volatile and toxic pesticide.  The only means to protect public health and the environment is to prohibit the use of methyl iodide in California.

Methyl Iodide, the proposed replacement chemical for the ozone-depleting chemical methyl bromide, is a known carcinogen, a neurotoxin, and a thyroid toxicant that can disrupt fetal development and cause miscarriages.  It is used to create cancer cells for scientific research and is a groundwater contaminant.

While DPR’s Notice of Proposed Regulation boasts that the proposed restrictions on the use of methyl iodide are tougher than those adopted by the federal Environmental Protection Agency (EPA), DPR’s acceptable exposure limits are 100 times higher than the exposure limits recommended by DPR’s own toxicologists.  To protect public health and safety, field applications require the covering of treated areas with a tarpaulin material called Virtually Impermeable Film.  The practice of tarping fields is not fool proof.  Winds, vehicles, animals, and people can damage the tarps allowing gas to vent and expose workers, neighboring schools, hospitals, and residential areas to unintended exposures. 
One of the most troubling aspects of the proposed registration of methyl iodide is the gap that exists between the practice of real world applications and the expectation voiced by the manufacturer that as long as label warnings and use restrictions are followed, there will be no problems.  In my experience representing victims of unintended pesticide exposures, it is the real world conditions of weather, human error, and insufficient testing that have resulted in human tragedies following acute and chronic exposures.  The risks of application in rural areas include potential long term health consequences of a chronic nature such as respiratory, neurological, and systemic illnesses.

As a representative of agricultural and urban areas, I am keenly aware of the balancing test that must be applied.  I believe that in the short term, the State of California should commit to further review of the synergistic impacts of methyl iodide and chloropicrin, the potential impacts of raising the permissible exposure limits by a factor of over 100, and the short and long term impacts on water and air resources.

At the end of June, DPR will be completing its review of the application to register methyl iodide as an alternative to methyl bromide.  Based upon the findings of the independent scientific peer review committee, the conclusions of the National Academy of Sciences…which includes six Nobel Laureates, and testimony presented before the Legislature, I am convinced that methyl iodide should not be registered for use in California.

It is unconscionable for DPR to proceed with the registration of  methyl iodide when its own scientists have presented unequivocal evidence of extreme risk and insufficient data collection.  The California Department of Pesticide Regulation has an immense responsibility to prioritize the health interest of the public and should reconsider its provisional decision to register methyl iodide.  To do anything less would be arrogant and irresponsible.  

Assemblymember Bill Monning represents the 27th Assembly District, which includes the cities of Capitola, Santa Cruz and Scotts Valley in Santa Cruz County; as well as the cities of Carmel, Marina, Monterey, and Seaside in Monterey County; and the city of Morgan Hill in Santa Clara County.  You can reach him through his website:
For Your Information - The public comment period on the registration of methyl iodide by the California Department of Pesticide Registration has been extended until June 29, 2010.  Should you have comments, please send them to: