Agency’s assumptions do not serve the public interest

As a member of the National Nanotechnology Initiative (NNI), the EPA has undersigned a top NNI goal—to “disseminate information on where the Federal Government can directly assist in the transfer and commercialization of nanotechnology-enabled products.”  But the EPA also has a higher purpose—implementation of federal laws intended to protect human health and the environment.  While these two objectives are not necessarily in conflict, there are instances where EPA’s approval of a nanoproduct has raised legal objections by third parties.  It has been left to the courts to determine if the Agency is meeting its statutory obligations or exceeding its lawful powers to expand the role of nanotechnology in commerce. 

Regarding one material—nanosilver used as an antimicrobial ingredient to preserve certain commercial products—the U.S. Court of Appeals for the 9th Circuit has twice ruled that the Agency has not met the requirements of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA).  The first ruling in November 2013 found that the EPA improperly determined that nano-silver-treated textiles posed no significant risk to young children.  The second decision, issued May 30, 2017, focuses less on risk than on EPA’s obligation to conditionally register pesticides only if the public interest is served.  The 9th Circuit agreed with the EPA that the risk posed by a nanosilver product was acceptable.  However, the panel also found that the EPA failed to establish how the product met the FIFRA requirement that a conditional registration be in the public interest. 

NSPW-L30SS

The product at the core of the recent case—an antimicrobial called NSPW-L30SS (NSPW)—was developed by Nanosilva LLC for incorporation into non-food-contact plastics that may then be used in textiles.  According to the National Institutes of Health, the antibacterial function of silver has long been known and has found a variety of applications because its toxicity to human cells is lower than the toxicity of bacteria.  In 2010, Nanosilva applied to the EPA to register NSPW.  Five years later, the Agency conditionally registered NSPW.  Conditional registrations are authorized under FIFRA Section 3(c)(7)(C) provided the EPA makes four findings:

• The pesticide contains an active ingredient not contained in any currently registered pesticide.
• A period reasonably sufficient for generation of required data has not elapsed since the EPA first imposed the data requirement.  (That is, all the data submission requirements for full registration have not been met.)
• Use of the pesticide during such period will not cause any unreasonable adverse effect on the environment.
• Use of the pesticide is in the public interest.

Based on the information received, the EPA said it was able to find that use of NSPW during the 4-year conditional-registration period would not cause unreasonable adverse effects and would be in the public interest because it could reduce the amount of silver in the environment.

The petition

EPA’s proposed conditional registration of NSPW was first challenged in public comments by the Natural Resources Defense Council (NRDC), the Center for Food Safety, and the International Center for Technology Assessment (petitioners).  When the Agency went ahead anyway and conditionally registered the product, the petitioners sued in the 9th Circuit.

The suit did not contest EPA’s finding that use of NSPW will not cause unreasonable adverse effects. But the panel noted that the petitioners did not concede that NSPW is “safe.”  Moreover, based on a blog by an NRDC scientist, the petitioners’ most pressing concern is that the EPA granted the conditional registration “without having first completed all the health and safety studies required by law.”  Such studies are essential before any kind of registration is allowed, the blog continues, particularly for nanopesticides.  These products offer advantages such as reactivity speeds that pesticides made with conventionally sized ingredients cannot match.  They also pose unique risks such as the ability to penetrate deeper into living tissue. 

What the petitioners did assert is that the EPA failed to establish that conditional registration of NSPW is in the public’s interest—that is, that the benefits of conditional registration outweigh the risks.

Understanding public interest

In finding that use of NSPW was in the public interest, the EPA considered nanosilver’s application rate, mobility and release, and toxicity. The Agency said its “record” showed that NSPW’s maximum authorized application rate of 30 parts per million (ppm) is many times lower than the application rates for conventional silvers in pesticides, which range from 132 to 11,000 ppm.  The EPA added that nanosilver in NSPW has low mobility because it is attached by strong bonds to a larger particle and leaches silver into the environment at levels below what measuring instruments can detect. This is the basis for the Agency’s public interest defense.

The panel points out that FIFRA does not define the public-interest requirement.  In cases where a statute is silent on matters that are critical to a judicial ruling, the courts often seek direction in the legislative history of the statute.  Here, the panel cited a 1977 report in which a Senate committee stated that a conditional registration could be issued if the pesticide could mitigate a significant pest control problem that cannot be mitigated with fully registered products.

The court also notes comments by Senator Patrick Leahy, a sponsor of the conditional registration amendment, who said the provision “would be reserved to the truly exceptional case.” Leahy also indicated that the public-interest requirement should be met by a more stringent test than what is required for fully registered pesticides. 

One problem the EPA faced in this case is that there is no evidence for the type of public emergency the legislative history views as justification for a conditional registration.  Rather, the EPA found that use of NSPW is in the public interest because it has the “potential” to reduce the amount of silver released into the environment.  The EPA based this conclusion on the three “factual premises” described below.  The court found two of these premises valid but could not agree with the third.

Application rate

Premise: NSPW has a lower application rate (i.e., it uses less silver) than conventional-silver pesticides. 

After the EPA proposed the conditional registration of NSPW, petitioners commented that the increased toxicity of nanosilver outweighs any benefits that may be gained from its lower application rate. The EPA agreed that “nano-scale silver can potentially be more toxic than ionic silver alone.” But the Agency cited evidence suggesting that nanosilver would not be “sufficiently more toxic to raise risk concerns when taking into account leaching rates for the proposed uses.” For NSPW incorporated into plastics, the EPA said nanosilver would have to be “on the order of 5 to 53 times more toxic” than conventional silver to raise concerns. For textiles, the Agency said nanosilver would need to be “on the order of 19 to 190 times more toxic.”

“Petitioners appear to attack these conclusions as too probabilistic,” stated the court. “Nevertheless, on substantial evidence review, the EPA need not present evidence to support an outcome with certainty; it only needs to present such relevant evidence as a reasonable mind might accept as adequate to support a conclusion.  We defer to the EPA on this matter as it is making predictions, within its area of special expertise, at the frontiers of science.”

Mobility

Premise: NSPW has a lower mobility rate and is less likely to release silver into the environment in detectable quantities. 

Petitioners argued that this finding relied on a plastic-leaching study the EPA had previously found deficient.

“But the EPA’s finding does not rely solely on the plastic-leaching study,” responded the panel. “The EPA also relied on an undisputed textile-leaching study which also demonstrated low release levels. Further, the EPA noted, the nanosilver in NSPW ‘is complexed to a larger particle that is then embedded into a polymer. The submitted leaching studies show that nanosilver is unlikely to be released in quantities above the detection limit from this polymer. Absent release from the polymer, the mobility of nanosilver in [NSPW] is greatly reduced.’”

Environmental releases

EPA: Use of NSPW is in the public interest because it has the “potential” to reduce the amount of silver released into the environment.

The court notes that this premise derives from two assumptions: First, current users of conventional-silver pesticides will replace pesticides with NSPW (the substitution assumption); and second, NSPW will not be incorporated into new products to the extent that such incorporation would increase the amount of silver released into the environment (the no-new-products assumption).

Neither assumption impressed the panel. 

First, says the court, the EPA cited no evidence to support its substitution assumption.  The Agency contended that substitution will occur as a logical outgrowth of the historical trend of pesticide users shifting their purchases from company to company. The panel said the EPA based this assumption on data from 1983. “[Even] if we did consider the general description of the pesticide market as it existed in 1983, we have no way of knowing from the record whether that description is applicable to the current and narrower markets for silver-based pesticides and materials preservatives,” said the court.

Under the no-new-products assumption, the Agency argued that there is no evidence to suggest that NSPW will be incorporated into new products. 

“EPA’s no-new-products assumption must be weighed against its substitution assumption,” responded the panel. “On the one hand, the EPA assumes that current users of conventional-silver pesticides will switch to NSPW. On the other hand, it assumes that the benefits of NSPW will not also invite manufacturers to incorporate NSPW into new products. The EPA assumes, moreover, that the costs of switching to NSPW are not prohibitive, while it also assumes that the costs of adding NSPW will discourage new incorporations during the conditional-registration period.”

The panel said the EPA did not support this assumption. “Here, if the EPA’s substitution and no-new-products assumptions are incorrect, NSPW may increase the amount of silver released into the environment and contravene the identified public interest,” said the court.  “For example, the EPA permits NSPW and conventional-silver pesticides to be incorporated into certain plastic furniture under their current registrations. That does not mean, however, that every plastic furniture product actually incorporates a silver-based pesticide. Furniture A may use a conventional-silver pesticide as a materials preservative, but Furniture B may not. If NSPW is added to Furniture B, but Furniture A continues to use the conventional-silver pesticide, there would be a net increase in the amount of silver incorporated into Furniture A and B.”

The panel wrote that the EPA did not need to evaluate every possible alternative scenario that may occur when determining that a conditional registration is in the public interest.  “But the EPA may not satisfy the requirement by simply finding that a pesticide has the ‘potential’ to be in the public interest—especially where the pesticide also has the ‘potential’ to contravene the public interest,” the panel concluded. [emphasis added]. “Accordingly, where an essential premise of a public-interest finding is only supported by bare assumptions, as in the present case, we will find substantial evidence lacking.”

Based on its evaluation of EPA’s assumptions, the panel vacated the conditional registration of NSPW.

The 9th Circuit’s opinion in NRDC et al. v. EPA is here.