In late May, EPA issued a notice seeking comment on a proposal to list n-propyl bromide (nPB) as an unacceptable replacement for ozone depleting substances (ODSs) in adhesive and aerosol applications. At the same time, EPA listed nPB as an acceptable alternative to ODSs in metal, precision, and electronics cleaning and proposed to list it as an acceptable replacement under specific use conditions for coating applications. ODSs used in these applications include methyl chloroform (1,1,1-trichloroethane), chlorofluorocarbon (CFC)–113, and hydrochlorofluorocarbon (HCFC)–141b.

The nPB determinations were made as part of EPA’s Significant New Alternatives Policy (SNAP) program. The SNAP program implements Section 612 of the Clean Air Act, which requires EPA to evaluate replacements for ODSs to ensure they minimize risk to human health and the environment. A number of substances – including methylene chloride, perchloroethylene, and trichloroethylene – have previously been listed as acceptable under the SNAP program. A comprehensive list of replacements is available on EPA’s SNAP web site.

Because the Occupational Safety and Health Administration has not established a workplace exposure limit for nPB, EPA used its authority under Section 612 to evaluate the human health risks associated with use of nPB in the workplace. According to the EPA notice, "the preponderance of the data indicate that exposure levels sufficient to protect against male reproductive effects . . . would be in a range from 18 to 30 [parts per million, or] ppm, in the range of 17 to 22 ppm to protect against female reproductive effects . . . and at approximately 20 ppm for effects related to reproductive success." These values are somewhat higher than the Threshold Limit Value (TLV^®) of 10 ppm established by the American Conference of Governmental Industrial Hygienists (ACGIH) in 2006.

EPA had proposed in June 2003 to establish an acceptable exposure limit (AEL) of 25 ppm, for an 8-hour time weighted average, as part of an acceptability determination for nPB. Based on the available information, EPA has concluded that "the great majority of users of nPB in metals cleaning, electronics cleaning, and precision cleaning have been able to attain exposure levels of well below 25 ppm . . . with their existing equipment." As a result, the final determination for nPB use in metal, electronics, and precision cleaning applications does not include an AEL.

EPA’s decision to list nPB as acceptable in cleaning applications applies to use of the solvent in metal, precision, and electronics cleaning equipment, and does not apply to its use in hand wipe and aerosol cleaners. The decision also does not apply to drycleaning applications.

EPA proposal to list nPB as an unacceptable substitute for ODSs in adhesives and aerosols is based on its determination that likely worker exposures in these end uses may pose unacceptable risks to human health when compared with other substitutes that are available. Current aerosol uses of nPB are believed to include lubricants and cleaning fluids for electrical or electronic equipment, aircraft maintenance, and synthetic fiber production. EPA believes the solvent also is used in laminate and foam adhesives.

EPA is proposing to list nPB as acceptable for certain coating applications for which the Agency has received exposure data indicating that the solvent can be used safely in that application. Currently, only one coatings application would be considered acceptable under the proposal. Parties interested in additional coating applications would have to make a separate submission for SNAP approval.

Comments on the proposed acceptability determinations are due by July 30.

The ink had barely dried on EPA’s amendments to the halogenated solvent cleaning (degreasing) standard before Pennsylvania’s Department of Environmental Protection (PA DEP) filed a petition for review in the US Court of Appeals for the DC Circuit. Although the PA DEP has yet to file a statement of issues with the Court, press releases from the Department and the Governor’s office indicate that the state is concerned about the exemption for narrow tube manufacturers that EPA granted in the rule. PA DEP’s concerns with the exemption for narrow tube companies, several of which are located in the state, also are outlined in a petition for reconsideration PA DEP filed with EPA in mid June.

As described in the May/June issue of the Update, EPA promulgated amendments to the national emission standard for degreasing in early May. The amendments establishing a facility-wide emissions limit for each of the chlorinated solvents from degreasing operations at all facilities except those involved in narrow tube or aerospace manufacturing and those operating continuous web cleaners. In its petition to EPA, PA DEP argues that the exemptions were not a "logical outgrowth" of EPA’s August 2006 proposed rule and, therefore, were not subject to appropriate public review and comment.

According to recent reports, EPA has already agreed informally to reconsider aspects of the rule. An official decision is expected in August. A decision to reconsider parts of the May 2007 rule will affect the nature and timing of the DC Circuit’s consideration of the PA DEP challenge. HSIA has intervened in the lawsuit in support of EPA’s decision, as have three narrow tube manufacturers based in Pennsylvania.

More recently, Citizens for Pennsylvania’s Future and the Sierra Club together filed suit to challenge the degreasing rule, as did the Natural Resources Defense Council (NRDC). These lawsuits are expected to be consolidated with the DEP challenge by the DC Circuit. NRDC also filed a petition for reconsideration with EPA that raises broader issues than the industry exemptions.