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EPA Issues Final TSCA Test Rule Requiring In Vitro Dermal Absorption

Date: Apr 27, 2004


On April 26, 2004, the U.S. Environmental Protection Agency (EPA) issued a final test rule under section 4(a) of the Toxic Substances Control Act (TSCA) that requires certain manufacturers, importers, and processors of 34 chemicals to conduct in vitro dermal absorption rate testing. 69 Fed. Reg. 22,402. 1 Among the chemicals designated for testing include vinylidene chloride, p-xylene, ethylene dichloride (EDC), pentane, tetrahydrofuran, and n-heptane. The U.S. Department of Labor's Occupational Safety and Health Administration (OSHA) will analyze the data collected under the testing program and use it to determine whether "skin designations' should be developed to better communicate potential toxicity risks to workers exposed to these chemicals. The rule is effective May 26, 2004.

Section 4(a) of TSCA authorizes EPA to require the development of data relevant to assessing the risk to health and the environment posed by exposures to chemical substances and mixtures. The agency determined the following about the 34 chemicals listed in the rule:

    (1)they are produced in substantial quantities;
    (2)there is or may be substantial human exposure to them;
    (3)existing data is insufficient to determine or predict their health effects; and
    (4)testing is necessary to develop such data.

Generally, those who are subject to this section 4 test rule fall into one of two groups: Tier 1 or Tier 2.

  • Tier 1 encompasses manufacturers (and importers) who would initially be required to comply with the rule. Such compliance involves notifying the agency of an intent to conduct testing, conducting the testing, and submitting the test data (or an application for a possible exemption) to EPA.


  • Tier 2 typically includes those who would not have to initially comply with the rule, such as processors, "small volume' manufacturers of less than 500 kg (1,100 lbs) per year, and "R&D" manufacturers of small quantities for research and development purposes. However, this final rule expands the breadth of the Tier 2 category by including several more manufacturers (and importers): byproduct manufacturers, impurity manufacturers, manufacturers of naturally occurring substances, manufacturers of non-isolated intermediates, and manufacturers of listed components of "Class 2" substances.2 Persons in Tier 2 are not initially required to comply with the test rule, but can be notified by EPA that they are required to do so.

If you are in Tier 1 with respect to a chemical substance subject to the rule, you must, for each test required under the rule for that chemical substance, either submit to EPA a letter of intent to test or apply to EPA for an exemption from testing. The letter of intent to test or the exemption application must be received by EPA no later than June 25, 2004. Note that issuance of this final test rule also subjects the 34 chemicals listed in the rule to the export notification requirements of section 12(b) of TSCA. 40 C.F.R. Part 707 Subpart D. For additional information on TSCA section 12(b) export notification requirements, see the Keller and Heckman LLP article entitled "TSCA Section 12(b) Export Notification Requirement Gets Teeth."

If you have any questions regarding this article, please do not hesitate to contact Tom Berger at (202) 434-4285 or berger@khlaw.com.

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1http://www.epa.gov/fedrgstr/EPA-TOX/2004/April/Day-26/t9409.htm

2 Class 2 substances are chemical substances having a chemical composition that cannot be represented by a specific, complete chemical structure diagram because such a substance generally contains two or more different chemical species (not including impurities).