On June 3, 2025, the Fifth Circuit heard oral argument in a case consolidating industry and Sierra Club challenges to EPA’s regulation of methylene chloride under the Toxic Substances Control Act (TSCA).  The panel generally appeared to doubt EPA’s justification for banning certain uses of the solvent and imposing stringent workplace restrictions.

The background for East Fork Enterprises Inc. v. EPA, No. 24-60256, is discussed in a previous blog post.  It looks likely that this will be the first case in which a court of appeals rules on the merits of a TSCA risk management rule since EPA was granted expanded authority to regulate existing chemicals with the 2016 Lautenberg amendments to TSCA.

Undefended Policies

The industry petitioners’ attorney urged the court to rule on two Biden-era policies that the Trump EPA has declined to defend: the agency’s decision not to assume that workers use PPE, and its “single determination” approach to findings of unreasonable risk.

One judge asked the industry attorney whether there had been any statistical surveys or epidemiological work to determine the number of workers affected by methylene chloride, suggesting that EPA should base its review in terms of “reality.”  The industry attorney replied that isolated incidents were noted in the record, but that they should be considered against the size of the country.  “That there have been a given number of incidents is not enough to tell you the scale of the risk,” he said.

When a judge suggested that EPA’s use of conservative “uncertainty factors” helps the agency extrapolate from human studies in a way that “protect[s] those…most at risk,” the industry attorney pushed back.  “The uncertainty factors are going far beyond that…it is protective factor times protective factor times protective factor, and they’re doing that in a part of the analysis that is quite separate from what they’re doing for vulnerable populations,” he said.

Another judge inquired about the economics of the methylene chloride industry, claiming that “it’s not irrelevant to understand what the scope of the market is” when determining whether a regulation is reasonable.

Scientific Evidence

To defend its decision to impose significantly stricter worker exposure limits than OSHA, EPA argued that OSHA’s standard was based on cancer findings, rather than “the most common adverse effect, adverse liver effects.”  This drew pushback from one judge, who claimed that liver effects had only been found in animals, not humans.

“If you’re going to really show that there’s toxicity to the liver, it seems to me that you have to show toxicity to the liver, and that requires epidemiological testing, doesn’t it?” the judge said.  “EPA is tasked with finding unreasonable risk, and unreasonable risk, from a scientific standpoint, when you’re talking about humans, is epidemiology.”

EPA’s attorney acknowledged that “human studies are the first place you look” but said that “when [EPA doesn’t] have concrete information, they have to look [to] animals.”  Earlier in the argument, EPA’s attorney noted that animal testing allows for dissection, unlike human studies—which she argued can make some effects, like the early stages of liver disease, more apparent.

Both EPA and Sierra Club also pointed to the Lautenberg amendments’ explicit directive that EPA consider worker risks as evidence that Congress did not intend for EPA to defer to OSHA’s existing limitations.

“I Survived”

In a notable exchange, one judge expressed concern with the breadth of the risk management rule: “It’s hard to say that any party can verify that they have never given a bit of methylene chloride to their friend who’s refinishing old furniture, a subject for which I’m particularly sensitive, because I’ve done it, and I survived.”

EPA’s attorney replied that the rule permits continued use of methylene chloride for furniture refinishing for another five years because no adequate alternative currently exists.  “This is not a case where EPA was just unilaterally deciding, ‘we don’t like this chemical, we’re going to regulate so there’s zero risk,’” she said.

EPA was also sharply pressed on the applicable standard of review.  “We noticed that EPA’s brief didn’t cite a single case that relied on the substantial evidence standard [used by TSCA] as opposed to the lower arbitrary and capricious standard,” a judge observed.

Sierra Club Arguments

The panel also appeared skeptical about the Sierra Club’s arguments, which claim that EPA’s regulations did not properly protect fenceline communities or address risks to the ozone layer.

“It’s a very, very, very, stringent regulation…I mean, what do you mean?” one judge asked.

When EPA noted that methylene chloride emissions are regulated under the Clean Air Act, one judge asked, “How does Sierra Club have a justification for coming in on this regulation at all, vis-à-vis fenceline communities, because this regulation does not cover ambient air emissions?”

EPA’s attorney responded that this was why risks to fenceline communities were not evaluated in the original 2020 risk evaluation for methylene chloride—though those risks were considered in a 2022 revision.

During rebuttals, the Sierra Club was also pressed about EPA’s one-in-a-million cancer benchmark.  “One in a million is pretty darn small…where’s the science that supports one in a million of anything being unreasonable?” one judge asked.

The Sierra Club’s attorney said that the benchmark was supported by the Science Advisory Committee on Chemicals (SACC), prompting the judge to respond, “We did a little looking at that, and it looked like some…members of the [SACC] had also themselves received EPA grants.”

But the Sierra Club argued that it does create a conflict of interest, because other members had been funded by methylene chloride manufacturers.  “I think EPA aims for a diverse range of views on the SACC,” its attorney said.