California regulators eye insect sprays, weed killers

An unprecedented review of compounds found in bug sprays, weed killers, pet shampoos and tick powder is under way by state environmental regulators. The effort has received little attention from the public–carbon gas emissions and liquefied natural gas are dominating current environmental news coverage–but it is the most extensive study of its kind and is likely to continue through 2008.

“This is a proactive initiative by this department on its own authority,” said Glenn Brank of the Department of Pesticide Regulation, which is conducting the review. “There was no single event that kicked this off, but we were already moving in this direction. We’ve been collecting data and monitoring streams.” At least three of those streams were in nearby Roseville, where the presence of pyrethroids became an issue last August. The DPR review began September 1.

One goal of the review by DPR, which licenses pesticides in California, is to protect water quality in urban streams, which can be tainted by waste runoff that contains organism-killing pyrethroids. Studies have shown that synthetic pyrethroids linger in water and may raise the toxicity level, although its precise impact is in dispute. A natural form of the same compound, which comes from chrysanthemum flowers, dissipates more readily and is not being targeted by the study, which is looking at the products produced by more than 120 manufacturers in a multimillion-dollar industry.

Only pesticides that are registered by DPR are allowed to be used in the state. Ultimately, the information collected in the review of pyrethroids–the tongue-twister is pronounced “pie-REE-throydz”–will be used to determine whether the products will continue to be licensed. They already are licensed now. The study, officially called a “re-evaluation,” seeks to determine whether the products containing pyrethroids should continue to be licensed. It is a critical distinction, because pyrethroids are widely used in products familiar to consumers.

For environmentalists and public-health experts, pyrethroids present something of a dilemma.

They have been used effectively in mosquito control against such maladies as the West Nile Virus, and they replaced earlier, more harmful compounds such as organophosphates, which were widely used in Diazinon. But pyrethroids also destroy micro-organisms in water, and their impacts can be aggravated by the way the products are used in the home. For example, over-watering the lawns or misapplying the weed killers can affect the level and intensity of the runoff, and thus the amount of pyrethroids that ultimately enter urban streams.

Some environmentalists believe that pyrethroids were adopted too quickly as alternatives to earlier compounds, and now that they are widely used it is more difficult to remove them from the market.

“This situation indicates a basic problem with our system of regulating toxics,” said Gary Patton of the Planning and Conservation League. “You have a very open door to put things out [in the market] without a lot of advance study. When somebody suspects there is a problem, you try to shut the door from behind.
“But we should follow the precautionary principle,” he said. “We should make it more difficult to get through the door in the first place.”

Indeed, pesticide manufacturers believe that urban environmental impacts of pyrethroids can be eased by simply following the directions on the label. They hope that the ultimate result of the DPR review–which companies believe will take four to six years, after hearings and final decisions are reached–will be to address usage issues, rather than require reformulating the products. The industry and the DPR already have created a joint working group to exchange information on the issue.

“Pyrethroids were developed and produced because the organophosphates were so toxic,” said Richard Cornett of the Western Plant Health Association, which represents manufacturers of pesticides, weed killers and fertilizers.
“What it boils down to is that the industry is working very closely with DPR,” he added.

For manufacturers, the bottom line is whether they will be required to reformulate their products, a costly process, or take them off the shelves entirely. Another possibility is that several makers will combine to share research and development costs, an expensive prospect that can force some from the market.

“If they have to go through a tremendous amount of formulation, it will cost millions and millions of dollars. But we cooperating with the DPR. If that is what it takes to make sure that that water is safe, than that is what we’re going to do,” Cornett said.

Contact John Howard at

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