Dow AgroSciences is determined to defend Lorsban (chlorpyrifos) from those who seek to destroy it. That's what Jesse Richardson, Dow AgroSciences Product Technology Specialist, stated emphatically at a California Alfalfa and Forage Association (CAFA) breakfast during the 2008 California Alfalfa & Forage Symposium in San Diego, Calif.

“There are certain segments of our society, especially here in California, that have determined it's their job to put chlorpyrifos under extreme scrutiny,” Richardson says.

CAFA is also actively involved in protecting the chlorpyrifos label. “CAFA has been working hard to oppose some people in the environmental movement who are trying to basically take all the organophosphates away from us, but in particular, chlorpyrifos,” says Philip Bowles, CAFA board member and president of Bowles Farming in Los Banos, Calif. “They wanted it to be listed as a Prop 65 carcinogen and wanted to put many other restrictions on the use of the chemical. That would force us to rely more heavily on much more broad-spectrum insecticides such as pyrethroids which wouldn't be to anyone's benefit. We're fighting that fight.”

Today, chlorpyrifos is one of the most attacked crop protection materials on the market. Richardson says nothing has changed about the characteristics of chlorpyrifos since he joined the Dow AgroSciences team in 1986.

“In 1986, terms to describe chlorpyrifos would have been ‘low mammalian toxicity vs. competitive standards’, ‘not a skin irritant and not a skin sensitizer’, ‘broken down and excreted through the urine in humans with a half-life of about 24 hours’. It's ‘not a mutagen’. It's ‘not a carcinogen’. If you look at the way chlorpyrifos should be described today, it's exactly the way it was described in 1986,” he says.

What has changed in the past 22 years is the loss of numerous crop protection materials and the addition of numerous others.

“Basically, the way this occurred was that environmental groups would sue regulatory agencies,” Richardson says. “Those agencies would have to respond, and consequently over time, we saw a loss of a number of our major products that we depended on for insect control.”

While chlorpyrifos once occupied a rather innocuous position toward the middle of the line in terms of environmental scrutiny, it's now very close to the front of the line, and environmentalists are firing at will.

“When you are a product with a broad label, excellent pest spectrum, you want to be as far away from the front of that line as you can possibly be because the guys at the front of the line are getting all the attention,” he says. “The problem is that you don't even have to be at the very front of the line because a lot of these products that are still hanging on — the labels have been so reduced — that they're really not as significant as they used to be. Lorsban, on the other hand, still has a very robust label. It's the No. 2 insecticide used in the world, and consequently gets a lot of attention.”

Chlorpyrifos is currently under re-evaluation by DPR for surface water issues as a result of detections in surface waters in California at very minute concentrations. “We're talking about concentrations in parts per trillion which we couldn't even detect 15 years ago,” Richardson says.

The biological organism used to detect chlorpyrifos is a water flea that is sensitive to the active ingredient at about 40 parts per trillion. The state of California has requested a goal of keeping all detections in waterways at less than 14 parts per trillion for chlorpyrifos.

That's the equivalent of four tablespoons of Lorsban in a 10 million gallon tank,” Richardson says.

Chlorpyrifos recently came under fire by the Pesticide Action Network of North America (PANNA) and the National Resources Defense Council (NRDC). The two organizations petitioned EPA and requested that EPA pull all the chlorpyrifos tolerances in North America.

“When you pull tolerances, you're basically canceling the product,” Richardson says. “Their argument had partially to due with atmospheric concentrations of chlorpyrifos in the Central Valley, the surface water issue and a number of other issues. We had no choice but to respond.”

In other regulatory entanglements, Cal-EPA in late 2007 was forced to consider listing chlorpyrifos as a Prop 65 product mainly for developmental and reproductive toxicity.

“Most recently The National Marine Fisheries Service, as a result of being sued by PANNA and NRDC, was forced to come up with a biological opinion, prematurely, without really doing a very good job on the research,” Richardson says. “What they basically said was there was potential damage from chlorpyrifos to salmon and steelhead populations throughout the West, and there were implications to the Endangered Species Act. They were recommending that we curtail chlorpyrifos applications throughout the Western states.”

“When you have a product under this kind of scrutiny, the question is why should we continue to defend chlorpyrifos? It's very, very expensive. Dow AgroSciences has spent millions of dollars recently doing all we can to defend this product,” Richardson says.

The first reason, according to Richardson, is that Lorsban and Lock-On are important tools for alfalfa growers. “About 1.5 million acres of crops that are treated with Lorsban or Lock-On in the state of California, and 37 percent of all chlorpyrifos acres in California are alfalfa,” he says.

Additionally, it's an important option for insecticide resistance management because it gives growers an alternate class of chemistry to fight pests.

“The third reason that we should defend Lorsban is because we can,” he says. “We have a very robust database worldwide. We've had labeled uses for 40 years. We have credible data on worker safety and we have over 3,600 reports defending chlorpyrifos. It's been registered in about a 100 counties, and its labeled uses have been reviewed favorably by U.S. EPA.”

Finally, Lorsban buffers other products from environmental activism, according to Richardson. “Those products that are close to the front of the line are being pummeled by environmental activists and, as a result, by regulators. Lorsban used to be way back in the line in 1986. Now Lorsban is at the front of the line. If Dow AgroSciences gives in to poor science and environmental activism as a result of political expediency instead of good science, we set a precedent for all those other products that are further back in line and how they're going to be treated.”

Dow AgroSciences and CAFA continue to vigorously defend the registration of chlorpyrifos. To date, along with other commodity groups, they have effectively combated the PANNA/NRDC petition. As a result of this collaborative effort, based on good science and sound arguments, chlorpyrifos tolerances were not pulled.

“Recently, Cal-EPA made a decision about Prop 65 as far as chlorpyrifos is concerned,” Richardson says. “They gave us a clear recommendation in all three categories — developmental toxicity, male reproductive toxicity and female reproductive toxicity.”

As for the National Marine Fisheries Services, “We are tracking this one closely,” Richardson says.