EPA Used Flawed Methodology to End Regulation of Smog-Forming Chemical, Says NRDC

Last week, the Environmental Protection Agency took several chemicals off its list of regulated, smog-forming, volatile organic compounds (VOCs). VOCs react in sunlight to form ground-level ozone, or smog, a major lung irritant. The agency decided that the newly delisted chemicals do not cause enough ozone to require regulation.

One of the chemicals, tertiary butyl acetate, known by its acronym TBAC, is used in making pharmaceuticals, pesticides and other products. The agency contended that TBAC is much less reactive than other VOCs and, as a result, does not significantly contribute to smog. The agency said it wants industry to use TBAC instead of more reactive solvents.

NRDC has taken a close look at the methodology EPA used to delist TBAC and found that it violates basic rules of chemistry. The organization is not alone in that view. Even the former director of EPA's Office of Air Quality Planning and Standards has said that the agency's methodology is wrong.

But the issue is much bigger than TBAC. Not only did EPA reward one company at the expense of public health, it set a precedent for future administration giveaways to industry.

EPA's Regulation of VOCs

The Clean Air Act requires EPA to regulate emissions of chemicals that contribute to smog formation, including so-called volatile organic compounds. VOCs are carbon compounds that react with other chemicals in the atmosphere to form smog. EPA and states require companies to limit their emissions of VOCs, and to comply with various VOC reporting provisions.

EPA determines which compounds to regulate as VOCs by comparing each compound's reactivity to that of the agency's regulatory benchmark, ethane. Compounds that are more reactive than ethane are deemed VOCs; those that are less reactive are labeled "negligibly reactive" and exempted from VOC emissions limits and monitoring and reporting requirements.

To date, EPA has identified 48 negligibly reactive chemicals. For all but two, the agency performed the reactivity comparison on a molecule-by-molecule basis, analyzing whether a certain number of molecules of the compound would, under particular reaction conditions, produce more or less ozone than the same number of molecules of ethane.

The Exceptions: Acetone and TBAC

In 1995 EPA unaccountably exempted a compound, acetone, which is more reactive than ethane on a per-molecule basis. To reach this insupportable decision, the agency focused on the fact that a gram of acetone forms less ozone than a gram of ethane. In other words, EPA changed its units from per-molecule to per-gram for this particular reactivity analysis.

The change is baseless. Reactivity depends solely on the number of molecules available for a reaction, not the weight of those molecules. Changing units enabled the agency to place fewer molecules of the heavier acetone in its imaginary reaction chamber (because one gram of acetone comprises fewer molecules than one gram of the lighter ethane), thus generating fewer imaginary molecules of ozone. Voila! Acetone appears less reactive than ethane.

In late 1999, the agency again proposed adopting this flawed per-gram approach to assessing reactivity, this time to exempt TBAC from VOC regulations. The TBAC proposal came in response to a petition submitted on behalf of the chemical's manufacturer, Lyondell, by the company's attorneys at Latham & Watkins - a group that included Jeffrey Holmstead, then a chemical industry lobbyist and now EPA assistant administrator for air. (Holmstead recused himself from the TBAC matter when he joined the agency.)

Responding to Lyondell's petition at a meeting of EPA officials and Lyondell representatives, John Seitz, then-director of EPA's Office of Air Quality Planning and Standards, noted that the "reactivity per mole[cule] basis is the correct technical basis for comparing compounds to ethane for exemption purposes," and that "exempting TBAC on a gram basis" in reliance on the acetone rule "would be perpetrating an error." (Docket item III-E-04, summary of August 9, 2000, meeting.) The proposed TBAC rule made the same point: "[T]he per-mole[cule] basis is the proper scientific basis to use in comparing reactivity to ethane for decisions concerning negligible reactivity." (Air Quality: Revision to Definition of Volatile Organic Compounds - Exclusion of t-Butyl Acetate, 64 Fed. Reg. 52,731, 52,734.)

EPA even acknowledged the flaws in its reasoning in last week's final rule. The agency conceded that a " 'reactivity per mole[cule]' comparison … is more consistent" with historical practice and "arguably more environmentally protective than a 'reactivity per [gram]' comparison" and admitted that using a reactivity-per-molecule approach would preclude an exemption for TBAC (which is 50 percent more reactive than ethane on a per-molecule basis). (Revision to Definition of Volatile Organic Compounds - Exclusion of t-Butyl Acetate, http://www.epa.gov/airlinks/pdfs/tbac.pdf, at 6, 13 (TBAC Exemption)).

In the end, however, EPA granted Lyondell's request that TBAC be exempted from VOC limits without providing any rationale, let alone a scientifically defensible one, for using a per-gram reactivity approach. As a result, public exposure to TBAC and TBAC-created smog will no longer be regulated.

More Unscientific Mumbo Jumbo

EPA's unfounded reliance on the reactivity-per-gram approach is only one of many flaws in its recent decision to exempt TBAC from regulation. For example:

  • Splitting the baby: Acknowledging that on a per-molecule basis, TBAC is 50 percent more reactive than ethane, EPA compromised by continuing to define TBAC as a VOC for purposes of monitoring, reporting, and state VOC inventory purposes, while ceasing to define it as a VOC for emissions control purposes. In other words, the agency first used flawed science to justify lifting TBAC emissions limits, and then assuaged its conscience by observing that TBAC's " 'closeness' to EPA's [per-molecule] reactivity exemption line requires the agency to retain certain emission reporting requirements" for the chemical. (TBAC Exemption at 6-7.) EPA failed, however, to explain how this unprecedented and hardly Solomonic approach will protect the public from TBAC exposure - especially since the rule prevents states from taking credit for TBAC emissions reductions, thereby discouraging them from adopting TBAC-specific control measures.

  • Voodoo economics: EPA made additional missteps when it attempted to justify the TBAC exemption by resorting to "economics." Noting that TBAC is less reactive and possibly also less toxic than toluene and xylene, two common industrial solvents, the agency reasoned that exempting TBAC from VOC controls will encourage manufacturers to substitute TBAC for those solvents, producing net public health benefits. EPA pointed to no legal authority for deregulating one smog-forming chemical in the hope that it would prompt industries to reduce their use of other smog-forming chemicals - unsurprising, since no such authority exists. Moreover, the agency provided no data to support its speculation that manufacturers will substitute TBAC for toluene and xylene, rather than simply augmenting their use of those two highly regulated chemicals with the now-unregulated TBAC. Further, the agency responded to one commenter's observation that TBAC is considerably more expensive than either toluene or xylene (and is therefore an unlikely substitute for either chemical) with the following Economics 101 fallacy: If TBAC is exempted from VOC controls, "demand for TBAC is expected to increase, … driving down costs." (TBAC Exemption at 20 (emphasis added)).
  • Pollute first, ask questions later: Finally, the agency conceded that it is "concern[ed]" about TBAC's toxicity (TBAC Exemption at 18), but brushed aside those concerns and exempted the chemical from Clean Air Act controls rather than erring on the side of caution and keeping the controls in place until further toxicity research is completed. EPA then reassured the public (1) that Lyondell has promised to "work with EPA to perform the … testing needed" to assess TBAC's toxicity, and (2) that the company will voluntarily "limit [its] annual production of TBAC … [u]ntil the testing program is completed and evaluated … to ensure that significant chronic ambient exposures will not occur." (TBAC Exemption at 18-19.) Rest assured: Lyondell is guarding the henhouse door.

In sum, the TBAC exemption is nothing short of a scientific and economic con job, coupled with a hollow PR announcement about Lyondell's public spirit.

Is this Con Job Just the Beginning?

Of even more concern, the TBAC exemption likely is a strategic step in the Bush administration's larger campaign to undermine clean air protections. In the rule itself, EPA suggests that it may adopt the untenable reactivity-per-gram approach for all of its future VOC reactivity determinations, and that future petitioners that seek VOC exemptions "should expect their petitions to be reviewed under a new policy." (TBAC Exemption at 24.) In short, EPA clearly hopes the public will overlook the glaring flaws in its TBAC exemption, leaving the agency free to use that exemption as a precedent for future giveaways to companies like Lyondell.