Alarmed that popular insecticides that end up in urban streams are killing tiny aquatic creatures, California's pesticide agency is conducting a review that is likely to lead to restrictions on many products used on lawns and gardens.
The chemicals, pyrethroids, are man-made versions of natural compounds in chrysanthemum flowers. Their use has skyrocketed in the past few years as U.S. consumers and exterminators search for less-toxic alternatives for dangerous insecticides already banned.
But last fall, a UC Berkeley scientist reported that pyrethroids are polluting streams in Northern California suburbs, wiping out crustaceans and insects vital to ecosystems.
Mary-Ann Warmerdam, director of the state Department of Pesticide Regulation, said Thursday that notices will be sent next month to manufacturers of about 600 pyrethroid products informing them that the state is reevaluating their use. That kicks off a process that will probably culminate in new regulations, and perhaps bans of some products in California.
"We've got the caution flag out," Warmerdam said. "This is a shot across the bow to the manufacturers that we found a reason for concern and you need to provide us with data to either eliminate the concern, reformulate your products or consider taking them off the market."
Allan Noe, a spokesman for CropLife America, representing pesticide manufacturers, said Thursday that the companies were unaware of California's intentions but will cooperate with its requests. He said the industry does not agree that there are toxicity problems but is analyzing the way the products are used.
"The valuable contributions that pyrethroids make through agricultural and urban uses are many and these benefits need to be considered," Noe said.
The compounds, particularly one called permethrin, are prevalent in lawn products and household and pet sprays, as well as in insecticides sprayed by exterminators and farmers. Also, many cities and counties spray a pyrethroid for mosquito control to prevent the spread of West Nile virus.
Although they poison nerve cells of invertebrates, the compounds are among the least toxic insecticides for humans and other mammals as well as birds. That is why they have replaced the organophosphate insecticides diazinon and chlorpyrifos, which were phased out by the EPA because they are particularly hazardous for children.
