State regulators are set to approve the use of a highly toxic pesticide that would replace a soil fumigant that is being phased out because of the damage it does to the ozone layer.
State officials have received thousands of comments, largely from organized e-mail campaigns, in opposition to a proposal to allow the use of methyl iodide. The comment period runs through June 29.
If approved, the pesticide would likely be used mostly on the strawberry fields around Salinas and Watsonville, and Southern California regions around Oxnard and Santa Maria. It is a fumigant that is usually injected into the soil before strawberries, nursery plants and nut trees are planted.
It is meant to kill almost everything in the soil.
The substance is considered so dangerous that chemists are careful to use only small amounts in their laboratories and only with extreme care.
"Because of methyl iodide's high volatility and water solubility, broad use of this chemical in agriculture will guarantee substantial releases to air, surface waters and groundwater, and will result in exposures to many people," dozens of scientists wrote to the U.S. Environmental Protection Agency before the chemical was approved by the federal government in 2007.
More recent studies commissioned by state regulators turned up equally dire warnings about the potential threat to public health and, in some cases, the lack of knowledge about what the chemical might do.
"Based on the data available, we know that methyl iodide is a highly toxic chemical and we expect that any anticipated scenario for the agricultural or structural fumigation use of this agent would result in exposures to a large number of the public and thus would have a significant adverse impact on the public health," a committee of scientists commissioned to review the pesticide for use in California reported in February.
The committee also was alarmed at a lack of reliable data on the potential of methyl iodide to contaminate groundwater.
The modeling they looked at "indicated the potential for unacceptably high levels of iodide to accumulate in water supplies," the committee wrote.
Still, the Department of Pesticide Regulation is proposing to approve use of methyl iodide after the June 29 public comment deadline. But it would impose several restrictions not required in other states that are meant to minimize health risks.
Those requirements include larger buffer zones around fumigated fields and the use of higher quality tarps.
It would also require county officials to issue permits, limit application rates and impose other restrictions.
In an e-mail, Lea Brooks, assistant director of the Department of Pesticide Regulation, said the restrictions will allow safe use of the pesticide.
Department documents contend people would not be exposed to methyl iodide at harmful levels and that the pesticide will not get into food or drinking water.
Methyl iodide is expected to replace the use of methyl bromide, a fumigant that is being phased out because of an international agreement to reduce the use of ozone-depleting chemicals.
In 2009, the EPA gave the maker of methyl iodide an award for protecting the ozone, saying the chemical could replace "some 85 percent of the current soil fumigation use of methyl bromide," according to state officials.
The federal government has approved methyl iodide for use in 46 states. Florida has also approved its use.
Up to now, however, it has not been approved in California.
"This is the No. 1 pesticide of concern that we've worked on in the last five years, at least," said Paul Towers, state director for the Pesticide Watch Education Fund.
"You can imagine the possibility of this pesticide drifting onto those farmworkers, on children on the playgrounds, and getting into groundwater," Towers said.
In addition to being used for strawberries, nuts and nursery plants, methyl iodide would be registered for use to treat soil for a handful of other crops, including tomatoes, stone fruits, vines, peppers and turf.
Mike Taugher covers the environment. Contact him at 925-943-8257.
Comments on the proposal to approve methyl iodide for use in California are due June 29. They may be mailed to: Pesticide Registration Branch, Department of Pesticide Regulation, P.O. Box 4015, Sacramento, CA 95812. E-mail: firstname.lastname@example.org.