Tests found dangerous levels of the compound iodide in groundwater near where an agricultural pesticide had been applied that is pending approval in California, according to a report completed in Florida, where the pesticide is already in use.
The report, which was circulated by environmental and farmworker advocacy groups seeking to stop the pesticide methyl iodide from being registered for use in California, also found high concentrations of the fumigant in the air near its application. Methyl iodide is included on California's list of cancer-causing chemicals.
The findings "should be wake-up call that methyl iodide should not be registered here and that registration should be canceled in Florida and nationwide," said Anne Katten, pesticide and workplace safety specialist for the California Rural Legal Assistance Foundation.
Methyl iodide's Tokyo-based manufacturer, Arysta LifeScience Corp., funded the pesticide safety study as a condition of the chemical's approval for use on Florida farms.
Arysta business development chief Jeff Tweedy criticized the groups' analysis of the data, saying the fumigant was not to blame for the high groundwater iodide levels and that the air concentrations were below levels tentatively approved by the California Department of Pesticide Regulations.
"They're misrepresenting the product," Tweedy said of the groups. Tweedy noted that tests taken before and after an application of the pesticide did not show an increase.
However Florida agriculture officials said it's too early to be sure that the iodide found in the water was not caused by methyl iodide.
The study found that groundwater near fumigated fields in Sarasota County, one of two Florida sites tested, contained iodide concentrations between 6 and 1,500 times those typically found in fresh water and between 2 and 2 ½ those found in sea water.
High levels of iodide, a component of broken down methyl iodide, can cause thyroid disease and could contribute to miscarriages, fetal death and developmental disabilities, said Susan E. Kegley, a scientist with the Pesticide Action Network.
A 1-year-old child who drank a liter of the Sarasota site's groundwater would also be getting 20 percent more iodide than the Centers for Disease Control considers safe for that age, Kegley said.
The study also found methyl iodide levels in the air near the pesticide's applications that exceeded those endorsed by a scientific review panel that reported to California's Pesticide Regulation Department, although they are within levels to which the department ultimately gave tentative approval in April.
The U.S. Environmental Protection Agency affirmed methyl iodide for use in most of the country in 2007, but California regulators opted to put it through their own registration process.
Pesticide regulation spokeswoman Lea Brooks said the department's final decision on the pesticide is not expected until later this year.
Brooks said the department had not seen the Florida monitoring data, but would consider them as part of its final decision on the pesticide, which is not expected until later this year.
California's $1.6 billion strawberry industry would probably be the main user of methyl iodide, which is promoted as a substitute for methyl bromide. Methyl bromide is being phased out under an international treaty because it depletes the earth's protective ozone layer.
Methyl iodide's current users are growers of tomatoes, peppers, eggplants and other crops in Florida and other Southeastern states.
Davis Daiker, scientific evaluation administrator at Florida's agriculture department's pesticides bureau, said his agency was still reviewing the study.
He said a water well in Sarasota County showed high iodide levels after two subsequent methyl iodide applications nearby, but another well in Miami-Dade County, near the site of just one application, showed normal levels.
Daiker said he would be paying close attention to whether the Miami-Dade County well's iodide levels increased after repeated applications.
"It really is premature to try to evaluate at this point the meaning of those results," he said.
Daiker also said the nearby air concentrations fell within levels considered safe in his state.
A message left with the EPA was not immediately returned. The agency is reviewing components of California's approval process to see if they have any bearing on its own earlier approval of the compound.