The California Department of Pesticide Regulation (DPR) has taken the next step in its initiative to reduce the amount of volatile organic compounds (VOCs) that are released into the air from pesticides. Late last summer, DPR proposed to cancel the registrations of 27 pesticide products that were on the agency’s hit list because the registrants had failed to comply with DPR orders to submit plans to reduce VOC emissions from their liquid products to a 20 percent level, or to justify their exemption from that DPR goal.

“Some of these were voluntary cancellations,” says Bob Ehn, with R3 Ag Consulting LLC, a Clovis-based firm that provides research, registration and regulatory services to the crop protection chemical industry. “None of these are major-use products and in total, the agricultural chemical industry stepped up and provided DPR with the needed information. It’s not time to panic yet,” he added.

More than 700 products were originally identified in two VOC notices issued by DPR and most registrants of these products provided responses acceptable to DPR, the agency reports. Acceptable responses would be an intent to reformulate to create a product with acceptable VOC emissions, a label change to reduce the amount and/or frequency of product use, or a delivery system that would reduce emissions.

DPR launched its Pesticide Air Initiative in May to reduce VOCs in pesticides that contribute to smog. The goal is to reduce emissions from emulsifiable concentrate (EC) formulations and fumigants to meet state air quality standards by 2008, at which time regulations will be in place. Although pesticides account for only 6 percent of all VOCs in California, all sources must be addressed to meet the standards.

Reaction issue

VOCs are an issue because they react with nitrous oxides (NOx) to create ozone, which is regulated by the Clean Air Act. In California, five areas have been designated “non-attainment,” meaning they do not meet federal air standards. These areas are Sacramento Metro, San Joaquin Valley, Southeast Desert, Ventura, and South Coast. In the San Joaquin Valley, the major ag sources of VOCs are livestock waste, pickup trucks and cars, prescribed burning, pesticides and consumer products. These add up to 54.4 percent of all VOCs in the area. Of these, pesticides contribute only 6.3 percent.

At a series of air quality workshops held by DPR in August, Jerry Campbell, assistant director of DPR, stated that certain fumigants are responsible for 50-90 percent of pesticide VOCs in California. Because reformulation of fumigant products is not possible, the agency wants growers to reduce reliance on fumigants, find ways to reduce emissions, and reduce the frequency and/or amount of fumigant applied.

According to Campbell, DPR will require certain low-emission application methods, or prohibit certain high-emission methods. The agency is also considering other mitigation measures such as requiring applicators to have a pest control operator (PCO) license. Also under consideration is restricting fumigant use in three nonattainment areas — San Joaquin Valley, Southeast Desert, and Ventura — during the first two weeks in May and the last two weeks in October to reduce emissions during the peak ozone season of May-October.

Close evaluation

Campbell added that DPR may evaluate fumigants more closely, including fumigant reactivity considerations. He pointed out that different fumigants create different amounts of ozone.

Methyl bromide, for instance, accounts for 76 percent of VOC emissions in the Ventura nonattainment area, while in the Southeast Desert nonattainment area, metam-sodium accounts for 49 percent of VOC emissions, according to DPR’s calculations. Other fumigants that head the list for VOC emissions are metam-potassium, 1,3-dichloropropene, and chloropicrin.

On the other hand, fumigants such as aluminum phosphide, which contains phosphine gas, is not an ozone depleter.

The agency’s Randy Segawa, program supervisor for environmental monitoring, addressed the workshop on EC formulations. “Liquid products contribute about 35 percent of the pesticide VOC inventory in the San Joaquin Valley,” he reported. To reduce these emissions, the agency is requiring manufacturers to either reformulate products to lower the VOC potential, or to show DPR how they intend to reduce the VOC potential by method, timing, or rate and frequency of application. Some products, such as pheromones, will be exempted because volatility is essential for effectiveness.

According to consultant Bob Ehn, there are other exemptions for products that may be above the 20 percent VOC requirement, but have other characteristics that would allow the product to still be used. “For instance, a product that although volatile above 20 percent, if it does not react with sunlight to form ozone, or if the product is immediately incorporated into the soil, it could be exempt.”

Reformulation, mitigation

Reformulation is one way to resolve the VOC emission problem, according to Ehn, and mitigation is another way. “For example, trifluralin, which has a VOC of 60-70 percent, will volatilize in the air, but once incorporated, trifluralin does not contribute to VOC emissions. Manufacturers will probably have to demonstrate this to DPR down the line in order to maintain labels,” he says.

“Another way to mitigate emissions is through label modifications that would change the timing of herbicides and fumigants application, where possible, to outside the critical May to October window, or making applications during those hours of the day when air is unstable, which allows better spray droplet deposition and less problems with inversions. Other possible label changes could be the frequency of application and the total volume of application allowed within a season.”

According to Ehn, DPR is expected to make a decision on these proposed restrictions to products soon.

“Reformulation is an obvious fix,” he says, “but it may not be technically or economically feasible in some cases. DPR has also proposed a requirement that if one registrant that has a liquid formulation with a VOC greater than 20 percent reduces the VOC to “X” percent, all other registrants of that active ingredient with a liquid formulation have to meet that same level, even though the formulation method used to reach that level may not be available to other registrants because the process is patent-protected.

“I see some of the generic manufacturers playing a big role in this issue because of their skill and expertise in manufacturing and formulation,” Ehn adds.

One example is United Phosphorus Inc. (UPI) a manufacturer and marketer of post-patent products for ag and specialty markets.

“We are in the process of developing dry flowable formulations of our pyrethroid products,” says Donnell Guy, director of technical services for UPI. “This includes the active ingredients bifenthrin, cypermethrin, and permethrin. We expect these products to reach the market next year.”

Guy adds that, fortunately, “volatility is not necessary for these pyrethroid products to be effective insecticides, so we are not compromising efficacy. We were evaluating these formulations already because of the inherent advantages of dry vs. liquid formulations so that we could offer added value to the grower. But the VOC issue in California has created a sense of urgency in bringing these products to market.”

During the public comment period at the Sacramento air quality workshop conducted by DPR, the point was made that the industry has to be careful not to substitute products with lower toxicity, which could lead to resistance issues. Another undesirable side-effect could be the substitution of products that, while they have a lower VOC emission, they might also be less effective, leading to more applications and in the final analysis, more emissions than the product it replaced. And more applications, it was pointed out, mean more passes with tractors, leading to added potential VOCs from a different source.

While one of DPRs goals for reducing VOC emissions is to use new technology, such as targeted sprayers, Jim Wells of the Environmental Solutions Group and former head of DPR, said “we welcome methods to reduce VOCs if they can be used effectively and economically for growers looking at alternative products with lower emissions.”