April 09, 2019

EPA Releases List of 40 Chemicals Undergoing Prioritization for Risk Evaluation

Lynn L. Bergeson

On March 20, 2019, the U.S. Environmental Protection Agency (EPA) released a list of 40 chemicals for which EPA is initiating the prioritization process for risk evaluation. Section 6(b)(2)(B) of the Toxic Substances Control Act (TSCA) requires that, as of three and a half years after enactment (by December 22, 2019), at least 20 high-priority chemicals be undergoing risk evaluations and at least 20 low-priority chemicals be designated by EPA. In a March 21, 2019, Federal Register notice, EPA provides a general explanation of why it chose these chemical substances and information on the data sources that EPA plans to use to support the designation. EPA is providing a 90-day comment period during which interested persons may submit relevant information on these chemical substances. Comments are due June 19, 2019.

High-Priority Candidate Chemical Substances

Last October, EPA released the general approaches that the Office of Pollution Prevention and Toxics (OPPT) may use to identify potential candidate chemicals for prioritization under TSCA. To identify candidates for designation as high-priority substances, EPA primarily looked to the TSCA Work Plan for Chemical Assessments: 2014 Update (2014 TSCA Work Plan) and surveyed the information and checked quality data elements in a step-wise approach intended to ensure “responsible and timely completion of the process according to TSCA timelines.” Additionally, EPA opened dockets for each of the 2014 TSCA Work Plan chemicals, and an additional docket for non-2014 TSCA Work Plan chemicals, to allow for public comment on the prioritization of these chemicals.

EPA evaluated the information across several data elements and reviewed the chemical substances for data availability across all data elements (e.g., hazard, exposure, uses, physicochemical, and environmental fate and transport properties). It considered chemical similarity, similar identified functions (e.g., solvents, phthalates, flame retardants), existing OPPT work (e.g., experience gained from the first ten chemicals to undergo risk evaluation), and other information as identified in available assessments (e.g., Integrated Risk Information System (IRIS) and the European Chemicals Agency (ECHA)) and public literature.

EPA is initiating the prioritization process for the following 20 chemicals as candidates for designation as high-priority substance candidates:

  1. p-Dichlorobenzene;
  2. 1,2-Dichloroethane;
  3. trans-1,2-Dichloroethylene;
  4. o-Dichlorobenzene;
  5.  1,1,2-Trichloroethane;
  6. 1,2-Dichloropropane;
  7. 1,1-Dichloroethane;
  8. Dibutyl phthalate (DBP) (1,2-Benzene-dicarboxylic acid, 1,2- dibutyl ester);
  9. Butyl benzyl phthalate (BBP) - 1,2-Benzene-dicarboxylic acid, 1- butyl 2(phenylmethyl) ester;
  10. Di-ethylhexyl phthalate (DEHP) - (1,2-Benzene- dicarboxylic acid, 1,2- bis(2-ethylhexyl) ester);
  11. Di-isobutyl phthalate (DIBP) - (1,2-Benzene- dicarboxylic acid, 1,2- bis-(2methylpropyl) ester);
  12. Dicyclohexyl phthalate;
  13. 4,4'-(1-Methylethylidene)bis[2, 6-dibromophenol] (TBBPA);
  14. Tris(2-chloroethyl) phosphate (TCEP);
  15. Phosphoric acid, triphenyl ester (TPP);
  16. Ethylene dibromide;
  17. 1,3-Butadiene;
  18. 1,3,4,6,7,8-Hexahydro-4,6,6,7,8,8-hexamethylcyclopenta [g]-2-benzopyran (HHCB);
  19. Formaldehyde; and
  20. Phthalic anhydride.

For all of these, the status is listed as “initiated”––the first step of the prioritization process, and the chemicals are currently undergoing a screening level review of reasonably available information to inform their priority designation.

Low-Priority Candidate Chemical Substances

EPA began with over 30,000 chemicals listed as active on the April 2018 interim update of the TSCA Chemical Inventory. EPA then applied a series of filtering steps to identify potential low-priority substance candidates. EPA identified potential low-priority substance candidates “based on low-hazard, across a range of endpoints, as the initial criterion since EPA knew the data on hazard would be the most readily available.”

EPA’s final screen conducted a literature search to update and verify candidate information for reliability, completeness, and consistency. With a set of high-quality data relevant to a potential designation as a low-priority substance, EPA states that it reduced the candidate pool to 20 chemical substances.

EPA used data sources to obtain “reasonably available” information for evaluating candidate low-priority substances consistent with TSCA section 6(b)(1)(B) and implementing regulations. EPA encourages submission of additional information relevant to low-priority substance designation that stakeholders believe may not be found in the sources used.

EPA is initiating the prioritization process for the following 20 chemicals as candidates for designation as low-priority substance candidates:

  1. 1-Butanol, 3-methoxy-, 1-acetate;
  2. D-gluco-Heptonic acid, sodium salt (1:1), (2.xi.)-;
  3. D-Gluconic acid;
  4. D-Gluconic acid, calcium salt (2:1);
  5. D-Gluconic acid, .delta.-lactone;
  6. D-Gluconic acid, potassium salt (1:1);
  7. D-Gluconic acid, sodium salt (1:1);
  8. Decanedioic acid, 1,10-dibutyl ester;
  9. 1-Docosanol;
  10. 1-Eicosanol;
  11. 1,2-Hexanediol;
  12. 1-Octadecanol;
  13. Propanol, [2-(2-butoxymethylethoxy)methylethoxy]-;
  14. Propanedioic acid, 1,3-diethyl ester;
  15. Propanedioic acid, 1,3-dimethyl ester;
  16. Propanol, 1(or 2)-(2-methoxymethylethoxy)-, acetate;
  17. Propanol, [(1-methyl-1,2-ethanediyl)bis(oxy)]bis-;
  18. 2-Propanol, 1,1'-oxybis-;
  19. Propanol, oxybis-; and
  20. Tetracosane, 2,6,10,15,19,23-hexamethyl-.

For all of these, the status is also listed as “initiated.”

Relevant Information

EPA requests that interested persons “voluntarily submit” relevant information, including but not limited to, information that may inform the screening review conducted pursuant to 40 C.F.R. section 702.9(a) and consistent with the scientific standard of TSCA section 26(h), as stipulated in the notice.

While EPA may consider confidential business information (CBI) when conducting its review under 40 C.F.R. section 702.9(a), EPA “encourages submitters to minimize claims for protection from disclosure wherever possible to maximize transparency in EPA’s screening review.”


None of the chemicals chosen are particularly surprising although the decision to include formaldehyde as a prioritization process candidate may strike some as odd given that it has been under intense scrutiny for years by the IRIS program and OPPT completed rulemaking on formaldehyde in wood products in 2016 (81 Fed. Reg. 89,724). Nonetheless, the TSCA risk-evaluation process is separate and distinct from that under IRIS and it is not unreasonable to start the TSCA process at the beginning looking at all known or reasonably foreseeable conditions of use. Initiation of the TSCA risk evaluation step for formaldehyde requires that EPA designate it as a high-priority substance, an outcome that, while seemingly assured, nonetheless needs to be elicited by the section 6(b) prioritization process. In conducting the risk evaluation on formaldehyde, EPA can and is expected to use the IRIS assessment along with other existing hazard and exposure assessments.

Perhaps the most interesting aspect of the notice concerns the 20 low-priority chemicals that EPA has identified for consideration in the prioritization process. We applaud EPA’s focus on low-hazard substances. It will be easier to support low-risk conclusions if such conclusions can be based solely on a hazard determination, obviating the need for an exposure assessment. The downside in taking this approach is that EPA has left no margin for error in meeting the deadline requirement for designating 20 low-priority chemicals. Readers may recall that section 6(b)(1)(B)(ii), concerning low-priority substances, requires that EPA designate a chemical as a low priorityif [EPA] concludes, based on information sufficient to establish . . . that such substance does not meet” the high-priority standard (emphasis added). The “sufficient to establish” phrase creates a relatively high bar that must be satisfied in designating a low-priority chemical, a decision that is subject to legal challenge (section 19(a)(1)(C)). EPA describes the low-priority candidates as “relatively rich in data on hazard”; EPA must be confident that the information available to it on these 20 chemicals when it comes time to issue its proposal and subsequently to release in final such a designation meets the “sufficient to establish” standard. This means that if, at the end of the prioritization process, EPA cannot meet the “sufficient to establish” standard for any of the proposed low-priority substances, EPA will confront having to designate such substances as high priority and proceed with risk evaluation with additional substances (i.e., more than the expected 30––the first 10 and the 20 proposed high-priority substances). Some readers may recall that section 6(b)(1)(C) allows EPA to extend the prioritization deadline for three months subject to the additional requirement “that if the information available to [EPA] at the end of such extension remains insufficient to enable the designation of the chemical substance as a low-priority substance, [EPA] shall designate the chemical substance as a high-priority substance.” This provision, however, applies to cases for which EPA has required the development of new information under section 4(a)(2)(B), a step that EPA has not initiated on any of these low-priority candidates. It is possible, but not likely, that manufacturers of low-priority substances could complete testing to fill in such data gaps within the total 12 months (including an extension) for prioritization.

Time will tell how EPA handles any “close calls” in proposing and then designating the low-priority chemicals. In the future, EPA might only propose potential low-priority substances when it has capacity to review them as high priority if the supporting data set is insufficient. In addition, taking a number of low-priority substances through the process will give EPA better insight into what data will be necessary to support a low-priority designation. EPA may then begin to exercise its new section 4 authority to require testing on substances that EPA anticipates designating for prioritization to ensure a record exists to support a low-priority conclusion.

Lynn L. Bergeson

Published: April 9, 2019

Lynn L. Bergeson is managing partner of Bergeson & Campbell, P.C. (B&C®), a Washington, D.C., law firm focusing on conventional, nanoscale, and biobased industrial, agricultural, and specialty chemical product regulation and approval matters, and chemical product litigation. Bergeson is president of The Acta Group, with offices in Washington, D.C.; Brussels, Belgium; Manchester, U.K.; and Beijing, China.