Fabric Pesticide Rules Survive Circuit Scrutiny

SAN FRANCISCO (CN) - The 9th Circuit upheld most of the EPA's approval of a fabric antimicrobial that environmentalists claim will end up in infants' mouths.

Swiss high-tech company HeiQ manufactures the antimicrobial pesticide AGS-20, marketed in Europe as Pure. HeiQ says that the "unique silver microcomposite" is applied topically to fabric, "making it possible to keep garments naturally odor-free for the lifetime of the product."

The EPA granted conditional registration for AGS-20 under the Federal Insecticide, Fungicide and Rodenticide Act in 2011, despite finding that it could expose workers, consumers and the environment to silver ions, and that nanosilver could break away from AGS-20 particles.

It nevertheless concluded that "human health or ecological risk from exposure to silver ions derived from AGS-20 treated textiles is not of concern."

The Natural Resources Defense Council petitioned the 9th Circuit in January 2012 to overturn the EPA decision, claiming that the agency had ignored its comments regarding products for infants and children.

At a hearing earlier this year, an appellate panel acknowledged the risks of nanosilver and grilled the EPA over its seemingly incongruous finding of "unknown risks" and "no adverse risks. The agency had estimated the potential leeching exposure at 35 percent when a child chews or wears treated textiles.

In its opinion Thursday, however, a majority upheld the EPA's decision to use 3-year-olds in its risk assessment rather than infants whom the NRDC argued would be more adversely affected by the pesticide.

"The agency's guidelines state that past assessments of the effects of dermal and non-dietary oral exposure to a pesticide have found that toddlers between three and five years old are the most vulnerable subpopulation," Judge Jay Bybee wrote for the majority. "By using the body weight of an average three-year old, the agency selected the lightest - and hence most vulnerable - member of the subpopulation specified in its guidelines. This is wholly consistent with the agency's general approach: it routinely uses the body weight of three-year olds to evaluate the risk of dermal and oral exposure to pesticides such as AGS-20 that are applied to textiles."

Furthermore, the EPA showed that aggressive chewing - with teeth - unleashed more nanosilver particles than an infant would by simply sucking or mouthing the fabric, according to the ruling.

But the judges vacated the EPA's finding that exposure to AGS-20 for periods of less than six months posed no risk concern, charging the agency with using funky math to support its conclusions. Under the EPA's own guidelines, an actual margin of exposure must exceed the agency's target - and not equal to or less than - to qualify as risk-free.

"The notable finding is that the aggregate margin of exposure for a surface-coated textile is 1,000," Bybee wrote. "Under the EPA's own rule of decision, there is a risk concern requiring mitigation when the short- or intermediate-term margin is less than or equal to 1,000. EPA seemingly overlooked its rule in describing its findings. The agency wrote that 'all of these margins are greater than the target of 1,000 indicating that the risk for short- and intermediate-term exposure to toddlers who wear and chew on AGS-20 treated textiles is not of concern.' One page later, EPA noted that 'aggregating the dermal and oral daily doses for children yielded margins ranging from 1,000 to 3,600, which is not of concern because they exceed the target margin of 1,000.' These statements are not supported by substantial evidence because a calculated margin of exposure of 1,000 poses a risk concern given that it is less than or equal to the target of 1,000."

Bybee also rejected the EPA's explanation of the variance: It rounded up the dosages to five decimal places and skewed the actual exposures lower than the target.

"Importantly, the oral dose (0.00047) has five digits after the decimal point and the dermal dose (0.000027) has six digits after the decimal point," he wrote. "The sum of these two numbers - which is the aggregate daily dose - can have no more than five digits after the decimal point because of the rule that 'when measured quantities are added or subtracted, the number of decimal places in the result is the same as that in the quantity with the greatest uncertainty and hence the smallest number of decimal places,'" Bybee wrote, citing "Chemistry: Principles and Reactions 12."

The ruling continues: "EPA correctly offered an aggregate daily dose with five digits after the decimal point (0.00050). EPA's data is not precise enough to allow it to 'unround' this number to 0.000497, as it attempts to do in its supplemental brief. The data available in the decision document only permit us to conclude that the aggregate dose is 0.00050, which means that the aggregate margin of exposure is 1,000, and not 1,006."

The panel refused, however, to entertain NRDC's argument that the agency shirked its duty by failing to consider other potential sources of nanosilver exposure in its risk assessment. Such an assessment isn't required for the conditional approval of pesticides not used on food, according to the ruling.

"Here, there is no data whatsoever on whether other types of nanosilver are chemically similar to AGS-20," Bybee wrote. "In urging EPA to conduct an aggregate risk assessment, NRDC is effectively attempting to short circuit the statutory scheme for conditional registration by forcing AGS-20 into the unconditional registration process where EPA proceeds on a 'chemical by chemical basis.' It is true that EPA might conduct a full data review sufficient to support an unconditional registration where, as here, it receives 'applications for registration of a new active ingredient.' But unconditional registration is not required as FIFRA expressly provides that EPA 'may conditionally register a pesticide containing an active ingredient not contained in any currently registered pesticide.'"

U.S. District Judge Lynn Adelman, sitting by designation from Milwaukee, Wis., said the potential risks of nanosilver alone warrant granting NRDC's petition.

"As the majority explains, the EPA's conclusion that aggregate dermal and oral exposure to textiles surface-coated with AGS-20 poses no risk concern is not supported by substantial evidence," Adelman wrote. "That being so, it follows that the EPA has failed to demonstrate that its determination that AGS-20 will not have an unreasonable adverse effect on the environment is supported by substantial evidence. Accordingly, the EPA's conditional registration of AGS-20 cannot stand. Because the only relief requested in the NRDC's petition is setting aside the conditional registration, it follows that the NRDC's petition should be granted in full."

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