EPA Publishes Background Documents for Five PBT Chemicals

Persistent, bioaccumulative, and toxic chemicals (PBTs) receive expedited attention under the amended Toxic Substances Control Act (TSCA). The Environmental Protection Agency (EPA) recently released background documents for five substances that it regards as PBTs. These five chemicals will go through a separate track for “exposure and use assessments” under section 6(h) of TSCA, instead of full risk assessments for other chemicals evaluated under section 6(b). EPA must propose rules to restrict these chemicals by June 22, 2019. These background documents are the first step toward those exposure and use assessments. 

Background on Section 6(h) of TSCA

The Frank R. Lautenberg Chemical Safety for the 21st Century Act (LCSA) extensively amended TSCA in June 2016. Among other changes, the LCSA revamped section 6 of TSCA by crafting a new three-step regulatory process for most existing chemicals under section 6(b): prioritization, risk evaluation, and risk management.

However, in the LSCA, Congress also designed a separate “expedited action” track for the risk management of PBTs. This appears in section 6(h) of TSCA. Under that provision, by June 22, 2019, EPA must propose risk management rules for TSCA Work Plan chemicals that score high for persistence or bioaccumulation and high or moderate for the other (using the TSCA Work Plan Chemicals Methods Document (2012) or successor scoring system), so long as EPA determines that exposure to such chemicals under the conditions of use is likely to either the general population, a potentially exposed or susceptible subpopulation, or the environment. Unlike for other chemicals assessed under section 6(b), EPA does not have to conduct a risk evaluation of section 6(h) chemicals. It must, however, conduct an exposure and use assessment. The final rule must be published within 18 months after publishing the proposal. In selecting restrictions, EPA is directed to reduce exposure to the extent practicable. Excluded from this provision are metals and metal compounds; chemicals for which EPA has completed a TSCA Work Plan problem formulation; chemicals for which EPA has initiated a review under section 5; and chemicals for which EPA has entered into a testing consent agreement under section 4. 

Nine chemicals ostensibly met the scoring criteria, but for various reasons, EPA reduced the list to five chemicals. It announced these five chemicals in October 2016. They include the following:

  • Decabromodiphenyl ethers (decaBDE), CAS No. 1163-19-5;
  • Hexachlorobutadiene (HCBD), CAS No. 87-68-3;
  • Pentachlorothiophenol (PCTP), CAS No. 133-49-3;
  • Phenol, isopropylated, phosphate (3:1) (according to EPA, this name describes multiple chemicals); and
  • 2,4,6-Tris(tert-butyl) phenol, CAS No. 732-26-3.

DecaBDE was a subject of a 2012 proposed SNUR and test rule. EPA’s Spring 2017 regulatory agenda identified the effort to promulgate a final SNUR and final test rule for decaBDE as “inactive.” 

EPA Gets Started Under Section 6(h)

In August 2017, EPA announced that it had opened rulemaking dockets for each of the five section 6(h) chemicals. Each docket contains a background document on manufacturing, processing, distribution, use, and disposal of a section 6(h) chemical. The dockets are available at these links:

The background documents are available here: 

According to the posting memo in each of the dockets, EPA will accept public comments on these background documents until December 9, 2017.

These documents are generally organized based on the five life-cycle stages of the chemicals’: manufacturing (including importing), processing, distribution, use, and disposal. EPA relied on a range of publicly available information, including the information from the Chemical Data Reporting program, the Toxic Release Inventory program, various other governmental databases, patent records, published literature, data and policies from other countries, and general internet search. The background documents present, among other things, known information about manufactured and distributed quantities, involved industrial sectors, existing regulations and policies, certain branded products distributed in commerce, and most importantly, identified uses.

Each of the five chemicals has a variety of uses. Below are the non-exhaustive summaries of certain uses mentioned in the background documents of the five chemicals. 


EPA indicated that decaBDE may be used as a flame retardant in textiles, electronic equipment, and building and construction materials, as well as certain other products:

  • Carpets, upholstery fabric, back coatings, cushions, mattresses, tents;
  • Plastic components in electrical appliances and equipment such as stereos, computers, televisions, circuit boards, casings, and cable insulation;
  • Fabrics of automobiles and aircraft and wood in building materials;
  • Children’s products such as bibs, bracelets and necklaces, sportswear, undergarments, socks and shoes, craft materials, blankets, and dolls and other toys; and
  • Products for laboratory or research use.


EPA found PCTP to be used in peptizers, which are mercaptan (sulfur) cross-lining agents to make rubber more pliable in industrial uses.

According to EPA, patent records show that certain golf balls may include PCTP. Other historical or potential identified uses include producing a particular type of soil fungicide; extracting naphthalene; and manufacturing butadiene rubber, isoprene rubber, natural rubber, and other rubber materials. PCTP is also said to be used for laboratory and research purposes.


HCBD is considered as a byproduct of chemical manufacturing but can be recovered or recycled for commercial purposes. EPA indicated that HCBD may be processed for uses as:

  • Plastic additives;
  • Protective coatings;
  • Prepared in solvent as analytical standards;
  • Part of the recovery system for chlorine-containing gases at chlorine plants; and
  • Chemical intermediates in the production of rubber, chlorofluorocarbons, and lubricants.

Identified industrial uses, historical or potential, include:

  • Heat transfer liquid;
  • Reactant in chemical syntheses;
  • Organic solvent;
  • Wash liquor for hydrocarbon removal;
  • Chlorine recovery;
  • Rubber vulcanization;
  • Manufacture of aluminum and graphite rods;
  • Manufacture of carbon spheres;
  • Manufacture of photopolymerized films; and
  • Preparation of organosilicon polymers.

Identified commercial and consumer uses, historical or potential, include:

  • Pesticides/agricultural fumigants;
  • Insecticides;
  • Algicide;
  • Herbicide;
  • Hydraulic fluid;
  • Gyroscope fluid;
  • Laboratory reagent;
  • Children’s clothing and headgear; and
  • Drywall.

Phenol, Isopropylated, Phosphate (3:1)

This name includes chemicals with a family of structures in which each of the three aryl groups has at least one isopropyl group. EPA identified this group of chemicals as widely used for both flame retardant and lubricating properties. 

Identified typical flame retardant uses include, but are not limited to, electronics and electrical devices, building and construction materials, furnishings, and transportation. EPA presented the following examples:

  • TVs, computers/computer accessories, phones, washers and dryers, circuit boards, electrical cables, and other various household appliances;
  • Insulation materials, paints and coatings, wood products, roofing components, composite panels, and fixtures;
  • Foam upholstery, curtains, carpets, and any fabrics that house them; and
  • Fabrics, foams, carpets, electrical equipment, and bumpers in airplanes, trains, and automobiles.

EPA also identified the uses in adhesives, lubricants, oils, paints, epoxy resins, and plasticizers. EPA also represented that the chemicals can be added into formulated mixtures for the processing of lubricant products and liquid flame retardants. 

2,4,6-Tris(Tert-Butyl) Phenol

Two primary use categories EPA identified for this chemical are reactants or intermediates in basic organic chemical manufacturing, as well as fuels and related products:

  • EPA indicated that the chemical is a reactant, intermediate, and product in organic chemical manufacturing, as well as an antioxidant in the manufacturing of plastics, resins, and other materials; and
  • The chemical is also said to be for fuel and other purposes, including as an ingredient in automobile fuel injector cleaners, and lubricant additives and fuel additives in gasoline and jet fuel. EPA represented that these fuel additive products are available for automotive, marine, or miscellaneous small engine use.

For all five chemicals, EPA recognized that the background documents only present information currently available to EPA. It solicited more information regarding the manufacturing, processing, use, distribution, and disposal of these chemicals. EPA is specifically interested in the following types of information:

  • Functional uses for the chemicals;
  • Types of products that contain the chemicals;
  • Industry sectors that use the chemicals;
  • Volumes of the chemicals used;
  • Discontinued or phased out uses;
  • Exposure scenarios for the chemicals; and
  • Articles in which the chemicals are found.

Next Step

The five chemicals have a wide range of uses. Accordingly, companies should carefully determine whether their activities may involve any of these substances. Because the section 6(h) process is different from the regular section 6(b) process, and the resulting section 6(a) risk management regulations may be more restrictive, affected companies may want to become informed and active for section 6(h) chemicals.

Comments on the background documents are due on December 9, 2017. The posting memos indicate that comments may be submitted through the rulemaking portal, or mail, or hand delivery. Because EPA will perform exposure and use assessments before rulemaking, potentially affected companies should consider taking the opportunity to submit their use and exposure information in comments on the background documents.