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Technology Transfer Network - OAR Policy and Guidance





  • On December 13, 2005, the Environmental Protection Agency (EPA) issued a final rule that removes methyl ethyl ketone (MEK) from the list of toxic air pollutants the Agency is required to regulate under the Clean Air Act.
  • After extensive technical review and consideration of public comments, EPA has concluded that potential exposures to MEK that is emitted from certain industrial processes may not reasonably be anticipated to cause human health or environmental problems.
  • MEK is used as a solvent in the surface coatings industry, specifically in manufacturing vinyl lacquers, some lacquers and acrylics. Industries also use MEK for producing adhesives, magnetic tapes, printing inks, degreasing and cleaning fluids, as a dewaxing agent for lubricating oils and as an intermediate in the production of antioxidants and perfumes.
  • EPA reviewed MEK exposure and health effects in response to a petition from the American Chemistry Council and completed an analysis to determine if there were grounds to grant the petition.
  • EPA's final rule removes MEK from a list of 188 air toxics for which EPA is required to develop national, technology-based emissions control standards. However, emissions of MEK will continue to be regulated as a volatile organic compound because of its contribution to the formation of ground-level ozone (smog). Facilities emitting MEK in areas not meeting national ambient air quality standards for ozone remain subject to volatile organic compound emissions limits through other Clean Air Act programs.

  • The Clean Air Act requires EPA to regulate 188 compounds that are listed as toxic air pollutants.
  • The law allows EPA to consider petitions to modify the list, by adding or removing substances. To date, EPA has removed caprolactam (1996), long chain glycol ethers (2000), and ethylene glycol monobutyl ether (2004) from the air toxics list. The Agency denied a petition to remove methanol from the air toxics list in 2001.
  • Any person may petition EPA to modify the air toxics list by adding or removing one or more substances. Petitioners seeking to remove a substance must demonstrate that there are adequate data to determine that emissions, outdoor concentrations, bioaccumulation, or atmospheric deposition of the substance may not reasonably be anticipated to damage human health or the environment.
  • Once EPA receives a petition, it conducts two reviews: a completeness review to determine whether there is sufficient information on which to base a decision; and a technical review to evaluate the merits of the petition.
  • During the technical review, EPA considers both information contained in the petition and information received from the public to determine whether the petition satisfies the requirements of the Clean Air Act. Once that comprehensive review is complete, EPA decides whether to propose removing the substance from the air toxics list.
  • The American Chemistry Council submitted its original petition in November 1996 and provided additional materials in August 1998.
  • In July 1999, EPA published a Federal Register notice announcing that the petition was complete and requesting technical information on the toxicity and health effects of MEK. EPA received fewer than 20 comments in response to that announcement.
  • In May 2003, EPA proposed to remove methyl ethyl ketone (MEK) from the list of toxic air pollutants the Agency is required to regulate under the Clean Air Act. After carefully considering the 57 comments received on the proposal and reviewing scientific data demonstrating MEKs low toxicity, EPA has taken final action to delist MEK as a hazardous air pollutant.
  • In a separate action on June 30, 2005, EPA published a final rule to remove the requirement for companies to report MEK emissions to the EPA’s Toxics Release Inventory (TRI).
  • In March of 1998, EPA denied a petition to remove MEK from the TRI list. The American Chemistry Council challenged EPA's decision in U.S. District Court for the District of Columbia.
  • On March 26, 2004, the District Court upheld EPA’s petition denial on the basis that EPA’s denial of the petition was lawful and appropriate. The American Chemistry Council appealed the District Court’s decision to the D.C. Circuit Court of Appeals.
  • On May 10, 2005, the D.C. Circuit Court vacated the District Court's decision and remanded "... so that it can direct EPA to delete MEK from the TRI." The Circuit Court issued its mandate on June 13, 2005.
  • Copies of the original petition and its supporting information are available for public inspection and copying at the following address: U.S. Environmental Protection Agency, Air and Radiation Docket and Information Center (6102), 1200 Pennsylvania Avenue, NW, Washington, DC 20460.
  • For further information including the final rule and the Federal Register notice once published, go to EPAs web site at https://www.epa.gov/ttn/oarpg. Click on recent actions.

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