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Assessing and Managing Chemicals under TSCA

Persistent, Bioaccumulative, and Toxic (PBT) Chemicals under TSCA Section 6(h)

Under the Toxic Substances Control Act (TSCA), as amended by the Frank R. Lautenberg Chemical Safety for the 21st Century Act, EPA has new authorities to regulate certain existing chemicals. Section 6(h) directs EPA to take action on certain persistent, bioaccumulative, and toxic (PBT) chemicals.

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EPA’s Requirements and Authorities under TSCA Section 6(h)

TSCA section 6(h) requires EPA to take expedited regulatory action under section 6(a) without a risk evaluation for PBT chemicals from the 2014 update of the TSCA Work Plan for Chemical Assessments that meet a specific set of criteria laid out in section 6(h).

The Agency must examine various ways in which exposure to PBT chemicals that meet the criteria outlined in section 6(h) are likely under the “conditions of use.” The conditions of use are the circumstances, as determined by the EPA Administrator, under which a chemical substance is intended, known or reasonably foreseen to be manufactured, processed, distributed in commerce, used or disposed of. Under the conditions of use for each PBT chemical, EPA will characterize the exposures to humans and the environment.

Once peer-reviewed and released for public comment, this information will be used to address, by regulatory action, the risks of injury to health and the environment posed by the PBT chemicals EPA identifies as meeting the requirements of section 6(h) and reduce exposure to the extent practicable. EPA must propose a rule to reduce exposures from these PBT chemicals to the extent practicable no later than June 22, 2019, with a final rule to follow no more than 18 months later.

Identified PBT Chemicals and Conditions of Use

As a first step in the TSCA section 6(h) process, five PBT chemicals were identified for action by EPA according to statutory criteria. These five PBT chemicals will be the subject of the rule discussed in the preceding section. EPA first looked to chemical substances identified in the 2014 update of the TSCA Work Plan for Chemical Assessments that met the criteria for persistence and bioaccumulation described in the statute and based on the 2012 TSCA Work Plan Chemicals Methods Document. Read more about the statutory criteria.

The following five PBT chemicals are identified under the conditions specified in TSCA section 6(h):

  • Decabromodiphenyl ethers (DecaBDE), used as a flame retardant in textiles, plastics, wiring insulation, and building and construction materials;
  • Hexachlorobutadiene (HCBD), used as a solvent in the manufacture of rubber compounds and as hydraulic, heat transfer or transformer fluid;
  • Pentachlorothiophenol (PCTP), used as a mercaptan (sulfur) cross-linking agent to make rubber more pliable in industrial uses;
  • Phenol, isopropylated, phosphate (3:1), used as a flame retardant in consumer products and as lubricant, hydraulic fluid, and other industrial uses; and
  • 2,4,6-Tris(tert-butyl) phenol, an antioxidant that can be used as a fuel, oil, gasoline or lubricant additive.  

Two additional PBT chemicals met the TSCA section 6(h) criteria; however, manufacturers for these substances submitted timely requests to EPA for risk evaluations pursuant to section 6(h)(5) and are therefore not subject to the rulemaking effort. As a result of the requests, two chemicals (Ethanone, 1-(1,2,3,4,5,6,7,8-octahydro-2,3,5,5-tetramethyl-2-naphthalenyl) and Ethanone, 1-(1,2,3,4,5,6,7,8-octahydro-2,3,8,8-tetramethyl-2-naphthalenyl)) are excluded from the expedited action requirements under TSCA section 6(h).

Use Documents for Identified PBT Chemicals

EPA is providing background information to the public for each of the five PBT chemicals. These use documents provide a preliminary summary of available information collected by EPA on the manufacturing (including importing), processing, distribution in commerce, use, and disposal of each chemical. This is based on existing data available to EPA, including information collected under the Chemical Data Reporting rule, information from other Agency databases, other U.S. Government agencies, publicly available information from states, and a review of published literature.

Read the use documents for the five PBT chemicals identified for expedited regulatory action under TSCA section 6(h).  

Opportunities for Public Input

Letter Peer Reviews of Exposure and Hazard Information

EPA is conducting letter peer reviews of exposure and hazard information for the five PBT chemicals. EPA will also be accepting written comments on the charge questions and other documents to be considered by the peer reviewers. These materials are available in docket EPA-HQ-OPPT-2018-0314. Written comments on these materials must be submitted by July 23, 2018 to be considered by the letter peer reviewers. Though the peer reviewers may not be able to fully consider written comments submitted after July 23, 2018, EPA will consider all comments submitted on or before August 17, 2018.

Learn more about the letter peer reviews.

Small Business Advocacy Review (SBAR) Panel

EPA solicited nominations from individuals who represent small businesses, small governments, and small not-for-profit organizations to provide input to a Small Business Advocacy Review (SBAR) panel on the Agency’s development of a proposed rule by June 2019 to reduce exposures from the five PBT chemicals.

The Agency asked for self-nominations directly from the small entities that may be subject to the rule requirements and other representatives, such as trade associations, that exclusively or at least primarily represent potentially regulated small entities.

Nominations were due by March 22, 2018. For more information on how to apply, visit:


On Thursday, September 7, 2017, at 2 pm EDT, EPA hosted a webinar, “Use Information for Persistent, Bioaccumulative, and Toxic (PBT) Chemicals Under TSCA Section 6(h).” This webinar provided background on the new requirements for PBT chemicals under amended TSCA and explained to interested parties the process for gathering use and exposure information the five PBT chemicals.

Public Dockets

EPA has established public dockets for each of the five PBT chemicals to facilitate receipt of information on exposure and use which may be useful to the Agency’s rulemaking effort. To read the comments EPA received, visit the docket for each chemical.

The docket numbers can be found in the table below.

Additional Information, Docket Numbers and Agency Contacts for PBTs

Chemical CAS Number Docket ID Number Background Documents Agency Contact
Decabromodiphenyl ethers (DecaBDE) CASRN 1163-19-5 EPA-HQ-OPPT-2016-0724 Use Document for DecaBDE Cindy Wheeler
Phone: (202) 566-0484
Pentachlorothiophenol (PCTP) CASRN 133-49-3 EPA-HQ-OPPT-2016-0739 Use Document for PCTP Marc Edmonds
Phone: (202) 566-0758
Hexachlorobutadiene (HCBD) CASRN 87-68-3 EPA-HQ-OPPT-2016-0738 Use Document for HCBD Marc Edmonds
Phone: (202) 566-0758
Phenol, isopropylated, phosphate (3:1) CASRN 68937-41-7 EPA-HQ-OPPT-2016-0730 Use Document for Phenol, isopropylated, phosphate (3:1) Ingrid Feustel
Phone: (202) 564-3199

2,4,6-Tris(tert-butyl) phenol CASRN 732-26-3 EPA-HQ-OPPT-2016-0734 Use Document for 2,4,6-Tris(tert-butyl) phenol Peter Gimlin
Phone: (202) 566-0515