Even though the U. S. Environmental Protection Agency (EPA) has given final approval for use of a new pesticide, regulators in California and other states are taking a closer look at the substance's potential adverse health effects before allowing the chemical to be used, according to an article in Chemical&Engineering News. 

In the article, C&EN Associate Editor Britt E. Erickson notes that EPA first considered approving the pesticide, methyl iodide, in 2006 as a replacement for methyl bromide.   Methyl iodide has several advantages over methyl bromide. It is more reactive and therefore too unstable to make it to the upper atmosphere to damage the ozone layer and it is a low-boiling liquid rather than a gas.   New concerns are that, if improperly utilized, methyl iodide is toxic to nerve cells and may carry a risk of thyroid damage, cancer, and other adverse health effects.   

Some states are doing their own assessments.  Florida finished its assessment and approved the use of methyl iodide, requiring additional safety measures beyond those required by EPA.

One environmental group and some independent scientists opposed EPA's approval of the pesticide, alleging that EPA had been secretive during the review process, failing to fully consider the chemical's health effects, and they pointed to an apparent conflict of interest involving the pesticide's manufacturer.

States like California and Florida had their own concerns about the pesticide's safety and decided to do their own risk assessments before allowing use of methyl iodide. Florida finished its assessment and approved the use of methyl iodide last July, but not before requiring additional safety measures beyond those required by EPA. California's assessment is still ongoing, the article notes.