September 15, 2005

Industry Gears Up To Fight EPA Air Toxics Listing For Hydrogen Sulfide

Risk Policy Report Daily News

A number of industry sectors are gearing up to challenge a possible EPA listing of hydrogen sulfide (H2S) as a hazardous air pollutant (HAP) in the agency's air toxics program, fearing the move could prompt new emissions control requirements, industry sources say.

These sources believe that a number of upcoming scientific studies commissioned by industry groups and industry-funded research centers will bolster their argument that even if the substance is deemed to harm human health, its exposure to the general public is so small that it does not warrant such a listing.

EPA staff is considering whether to recommend to senior officials that the agency list H2S in what would mark the first time the agency has added an air toxic to the list of 188 HAPs Congress codified in 1990 amendments to the Clean Air Act. That consideration, which is in response to a 1999 environmentalist petition for EPA to list the substance as a HAP, is based on recent ambient and emissions data provided by more than a dozen states. Environmentalists and some EPA staff say ambient measures mean the substance is not currently well controlled.

But industry sources believe new studies funded by various sectors may help form a counterargument against listing the substance, which can cause death at high concentrations and respiratory problems at low exposure levels.

The American Chemistry Council-funded CIIT Centers for Health Research is close to completing its tests on whether H2S causes adverse health effects and if so, what those effects may be. A CIIT source says the group has been working on tests of the substance since 1999, and that the tests have been funded in part by the American Petroleum Institute and the American Forest and Paper Association, both groups representing industries that emit H2S.

The studies, which test H2S' impacts on rats, are helping CIIT scientists reach a preliminary consensus that nasal exposure and the creation of lesions in the nose are the most significant effects of exposure to the substance. “We're trying to support [the EPA] risk assessment for H2S and the majority of our focus is on the nose, because nasal exposure seems to be the most significant endpoint” the source says.

CIIT intends to submit its studies to EPA once completed, but already preliminary results “keep pointing” to the suggestion that H2S inhibits the enzyme cytochrome oxidase, which can injure a cell's ability to generate energy necessary for life, the source says. At extremely high doses of H2S, the substance “acts like cyanide” and can kill, although it does not accumulate in the body and these risks are based on significant short-term exposure.

There are three ways to be exposed to H2S; from accidental exposure, from workplace exposure in different types of businesses that release the substance, such as paper production, and from ambient levels from naturally occurring sources. However, workplace and ambient levels of the substance are likely very low, the source believes.

Scientists in other industry sectors are also working on further studies of the substance to provide more data on health effects and exposure levels, one pulp and paper industry source says.

Most of the new studies should be completed by the fall, the source adds. “Our hope is that EPA considers all the data and looks at the latest health science before deciding whether [H2S] should be regulated or not,” the source says, adding that certain industry sectors are currently collecting estimates on their emissions of the substance.

A wide range of industries -- including oil and gas, agriculture, chemical, pharmaceutical and pulp and paper -- emit the chemical and are likely to oppose any attempt by EPA to add the substance to the list of HAPs because listing would subject sources emitting H2S to maximum achievable control technology requirements for controlling emissions, agency sources have said.

Industry groups are confident that the substance is already well controlled onsite at facilities and does not escape into the wider community at levels that would pose a public health threat, according to the pulp and paper industry source. “The obligation on the agency is to determine that there are sufficient exposures that are widespread enough that the risks [of exposure] are significant,” the source says.

Although H2S is emitted during certain industry processes, the substance is captured by facilities that emit it, the source says. Companies control emissions of H2S and prevent it from escaping into the wider community, and therefore the substance's presence in the air may not be of sufficient concern to warrant EPA staff recommending listing it as a HAP, the source adds.

An oil and gas industry source argues that H2S emissions are “completely contained” on-site and says the industry already has very stringent mitigation practices in place to address such emissions. The likelihood of H2S being a widespread air pollutant affecting public health is “little to none. . . . Refiners have very stringent measures used internally for dealing with it,” the source says.

Additionally, the substance's presence during manufacturing and other processes may be “inherent” and already at the point where it may not be technically possible to further reduce H2S emissions, the pulp and paper industry source believes. “It doesn't make much sense to list it if there's not much one can do to reduce emissions.”

One EPA source says the agency has been examining the substance's health effects since the original list of HAPs was finalized, and says that the most recent data provided by states on the possible widespread public health effects of H2S has prompted staff to consider recommending that the agency start the process to list it as the 189th federally recognized HAP. The substance escaped being listed as a HAP 15 years ago because of opposition from the oil and gas industry, despite EPA’s attempts to include it at the time, the source said.

Environmentalists are optimistic EPA will press ahead with a rulemaking to list H2S as a HAP. One activist says, “This administration has generally been weak on air pollution issues, but periodically we win one.

A second activist says the chances of EPA trying to list H2S are “very good . . . there's a lot of information out there that hydrogen sulfide is a very common toxic pollutant, and not just for people living near places like refineries. People need to understand and have a greater awareness” of the threat of the substance. Greater public awareness of the health threats of H2s may increase pressure on EPA to advance with a listing, the source adds.