EPA publishes the Initiation of Prioritization under the Toxic Substances Control Act

On March 21, 2019, EPA published the Initiation of Prioritization under the Toxic Substances Control Act (TSCA).  In the Federal Register notice, the Agency announced that it is initiating the prioritization process for 20 chemical substances as candidates for designation as High Priority Substances for risk evaluation and 20 chemical substances as candidates for designation as Low Priority Substances for risk evaluation.  Under the amended TSCA High Priority Substance and Low Priority Substance are defined as follows:

  • High Priority Substance.  A chemical substance that EPA determines, without consideration of costs or other non-risk factors, may present an unreasonable risk of injury to health or the environment because of a potential hazard and a potential route of exposure under the conditions of use, including an unreasonable risk to potentially exposed or susceptible subpopulations identified as relevant by EPA.
  • Low Priority Substance.  A chemical that EPA concludes, based on information sufficient to establish, without consideration of costs or other non-risk factors, does not meet the statutory criteria for designation as a High Priority Substance.

The Agency noted that the initiation of prioritization for a substance as a High Priority candidate is not a finding of risk by EPA.

To identify candidates for designation as High Priority Substances, the Agency primarily considered the TSCA Work Plan Chemicals.  EPA then collected information from reasonably available sources.  The Agency evaluated the information across a number of data elements including hazard, exposure, uses, and physicochemical, fate, and transport properties.  Substances were then reviewed for data availability across all data elements.  EPA also considered chemical similarity, similar identified functions (e.g., solvents, phthalates, flame retardants), existing EPA Office of Pollution Prevention and Toxics (OPPT) work (e.g., experience gained from the first ten chemicals to undergo risk evaluation) and other information as identified in available risk assessments (e.g., IRIS, ECHA), and public literature.  In addition, the Agency used information such as the 2016 CDR reported uses and products to inform prioritization.  (EPA noted that the Agency’s  working approach to selecting candidates for designation as High Priority Substances for risk evaluation is outlined in the document, A Working Approach for Identifying Potential Candidate Chemicals for Prioritization.)  

The Agency has identified the following substances as candidates for designation as High Priority Substances candidates:

1.      1,3-Butadiene (CASRN 106-99-0)

2.      Butyl benzyl phthalate (BBP) (1,2-Benzenedicarboxylic acid, 1-butyl 2-(phenylmethyl) ester) (CAS RN 85-68-7)

3.      Dibutyl phthalate (DBP) (1,2-Benzenedicarboxylic acid, 1,2-dibutyl ester) (CAS RN 84-74-2)

4.      1,1-Dichloroethane (CASRN 75-34-3)

5.      1,2-Dichloroethane (CASRN 107-06-2)

6.      1,2-Dichloropropane (CASRN 78-87-5)

7.      Dicyclohexyl phthalate (1,2-Benzenedicarboxylic acid, 1,2-dicyclohexyl ester) (CASRN 84-61-7)

8.      Di-ethylhexyl phthalate (DEHP) (1,2-Benzenedicarboxylic acid, 1,2-bis(2-ethylhexyl) ester) (CASRN 117-81-7)

9.      Di-isobutyl phthalate (DIBP) (1,2-Benzenedicarboxylic acid, 1,2-bis(2-methylpropyl) ester) (CASRN 84-69-5)

10.    Ethylene dibromide (Ethane, 1,2-dibromo-) (CASRN 106-93-4)

11.    Formaldehyde (CASRN 50-00-0)

12.    1,3,4,6,7,8-Hexahydro-4,6,6,7,8,8-hexamethylcyclopenta [g]
-2-benzopyran (HHCB) (CASRN 1222-05-5)

13.    4,4′-(1-Methylethylidene)bis[2, 6-dibromophenol] (TBBPA) (CASRN 79-94-7)

14.    o-Dichlorobenzene (Benzene, 1,2-dichloro-) (CASRN 95-50-1)

15.    p-Dichlorobenzene (Benzene, 1,4-dichloro-) (CASRN 106-46-7)

16.    Phosphoric acid, triphenyl ester (TPP) (CASRN 115-86-6)

17.    Phthalic anhydride (1,3-Isobenzofurandione) (CASRN 85-44-9)

18.    trans-1,2- Dichloroethylene (Ethene, 1,2-dichloro-, (1E)-) (CASRN 156-60-5)

19.    1,1,2-Trichloroethane (CASRN 79-00-5)

20.    Tris(2-chloroethyl) phosphate (TCEP) (Ethanol, 2-chloro-, 1,1′,1”-phosphate) (CASRN 115-96-8)

To identify potential Low Priority Substance candidates, EPA started with the over 30,000 chemicals from the April 2018 interim update of the TSCA active inventory.  EPA identified potential Low Priority Substance candidates by looking for those that present low-hazard across a range of endpoints.  EPA first narrowed the candidate pool to chemicals that had been evaluated by a government body like the US EPA or an Organisation for Economic Co-operation and Development (OECD) member nation.  This created a pool of approximately 1,600 potential Low Priority substances. The Agency then filtered the pool of approximately 1,600 chemicals to approximately 200 substances which have discretely defined structures. Substances with discrete structures were selected to increase confidence in the information on hazards.  EPA further filtered the chemicals with discrete structures and selected those with the most available data, narrowing the pool to about 75 chemicals with low hazard status among an internationally accepted set of endpoints.  The Agency applied a final screen by conducting a literature search to update and verify candidate information for reliability, completeness and consistency. (EPA will make transparent literature search documentation available at the proposal phase for the 20 Low Priority Substance candidates.) 

The Agency has identified the following substances as candidates for designation as Low Priority Substances candidates:

1.      1-Butanol, 3-methoxy-, 1-acetate (CASRN 4435-53-4)

2.      D-gluco-Heptonic acid, sodium salt (1:1), (2.xi.)- (CASRN 31138-65-5)

3.      D-Gluconic acid (CASRN 526-95-4)

4.      D-Gluconic acid, calcium salt (2:1) (CASRN 299-28-5)

5.      D-Gluconic acid, .delta.-lactone (CASRN 90-80-2)

6.      D-Gluconic acid, potassium salt (1:1) (CASRN 299-27-4)

7.      D-Gluconic acid, sodium salt (1:1) (CASRN 527-07-1)

8.      Decanedioic acid, 1,10-dibutyl ester (CASRN 109-43-3

9.      1-Docosanol (CASRN 661-19-8)

10.    1-Eicosanol (CASRN 629-96-9)

11.    1,2-Hexanediol (CASRN 6920-22-5)

12.    1-Octadecanol (CASRN 112-92-5)

13.    Propanol, [2-(2-butoxymethylethoxy)methylethoxy]- (CASRN 55934-93-5)

14.    Propanedioic acid, 1,3-diethyl ester (CASRN 105-53-3)

15.    Propanedioic acid, 1,3-dimethyl ester (CASRN 108-59-8)

16.    Propanol, 1(or 2)-(2-methoxymethylethoxy)-, acetate (CASRN 88917-22-0)

17.    Propanol, [(1-methyl-1,2-ethanediyl)bis(oxy)]bis- (CASRN 24800-44-0)

18.    2-Propanol, 1,1′-oxybis- (CASRN 110-98-5

19.    Propanol, oxybis- (CASRN 25265-71-8

20.    Tetracosane, 2,6,10,15,19,23-hexamethyl- (CASRN 111-01-3)

EPA is providing a 90-day comment period and requests that interested persons voluntarily submit relevant information. Relevant information might include, but is not limited to, information that may inform the screening review (see 40 CFR 702.9(a)).