2013 EPA TSCA Work Plan and Action Plan Risk Assessments and Data Collection Activities
The U.S. Environmental Protection Agency (EPA) is continuing implementation of its Toxic Substances Control Act (TSCA) Work Plan and Action Plan efforts by starting risk assessment activity on seven chemicals in 2013. Six of these chemicals were identified as candidates for risk assessment in the TSCA Work Plan that EPA published in 2012. EPA will also conduct a risk assessment on a seventh chemical, HBCD, in 2013 pursuant to the 2010 TSCA action plan, that describes possible actions including conducting a risk assessment. The sections below explain the risk assessments EPA will be conducting, and data collection activities EPA will be engaging in 2013.
TSCA Work Plan Chemicals
- 2-Ethylhexyl ester 2,3,4,5- tetrabromobenzoate (TBB)
- 1,2- Ethylhexyl 3,4,5,6-tetrabromo-benzenedicarboxylate, or (2-ethylhexyl)-3,4,5,6 tetrabromophthalate (TBPH)
- Tris(2-chloroethyl) phosphate (TCEP)
- Octamethylcyclotetrasiloxane (D4)
- Hexabromocyclododecane (HBCD) and related congeners
In March 2012, EPA released a TSCA Existing Chemicals Strategy and a Work Plan of 83 chemicals as candidates for risk assessment development. As EPA explained in the strategy, “From this work plan list, EPA has identified an initial set of chemicals for which EPA has begun risk assessments in 2012. The Agency will complete some and initiate additional new assessments each succeeding year. The chemical assessments may also include evaluation of alternatives.” The strategy also includes a component to address chemicals beyond those found in the TSCA Work Plan, including continued work on chemical action plans that EPA initiated several years earlier.
The Work Plan was preceded beginning in 2009 by a chemical Action Plan process, which set out to summarize available hazard, exposure, and use information on certain chemicals, outline the risks that each chemical may present, and identify the specific steps the Agency is taking to address those concerns. An action plan was written for HBCD, and EPA has determined that a risk assessment will inform potential actions identified in the plan.
2013 Risk Assessments
The seven 2013 risk assessments will follow an approach similar to that used in 2012. EPA will define the scope of each of the seven assessments to focus on those TSCA-relevant uses of the chemical with significant potential for exposure to humans and/or the environment. EPA anticipates issuing draft risk assessments for public review and comment, and for peer review, as they are completed. At the conclusion of the review process, if an assessment of specific uses indicates significant risk, EPA will evaluate and pursue appropriate risk reduction actions, as warranted. If an assessment indicates no significant risk, EPA will conclude its current work on assessment of those specified targeted uses of that chemical.
Grouping and reviewing chemicals with similar characteristics together, rather than evaluating them individually, may help to address the potential for replacement of chemicals with well-characterized hazards by similar, but unevaluated, alternative substances with similar concerns. Several such situations are being addressed with the first group of Work Plan chemicals that EPA announced in March 2012 and are now in the risk assessment process. Dichloromethane and n-methylpyrrolidone, the two chemicals used as paint strippers were chosen for simultaneous assessment for this reason, as were both the medium and long-chained chlorinated paraffins, which are structurally and functionally related to each other and to short-chained chlorinated paraffins, which are no longer being manufactured.
Three of the Work Plan chemicals and the Action Plan chemical identified for assessment in 2013 are flame retardants. Grouping and evaluating flame retardants with similar characteristics together, rather than individually, will also help EPA with the evaluation of existing data and will support more informed decisions about data gaps and needs. EPA searched its databases and secondary information sources to identify chemicals that also are listed on the TSCA Chemical Substances Inventory (“TSCA Inventory”) that are structurally similar, including precursors and intermediates. Through a literature search and data collection effort, EPA obtained available information for each of these structurally similar chemicals. Collected data included physical-chemical properties, environmental fate and transport, aquatic and mammalian toxicity, occurrence in humans and the environment, and use, market, and regulatory information.
Consistent with its TSCA work plan and action plans, EPA will conduct full risk assessments on TBB, TBPH, TCEP, and HBCD. Information from each of those assessments will be used to determine what can be understood about the biological and environmental behavior of other chemicals in the respective structure-based groups, which currently lack sufficient data for a full risk assessment
TBB and TBPH are members of the brominated phthalates group. Five other members of this group are 2-(2-Hydroxyethoxy) ethyl 2-hydroxy propyl 3,4,5,6 tetrabromobenzenedicarboxylate; 3,4,5,6-Tetrabromo-1,2-benzenedicarboxylic acid, mixed esters with diethylene glycol and propylene glycol; '1,2- (2,3-dibromopropyl) benzenedicarboxylate; and two chemicals whose identities have been claimed confidential, listed here as “Confidential A” and “Confidential B.”
TCEP is a member of the chlorinated members of the halogenated phosphate esters group. Two other members of this group are 2-Propanol, 1,3-dichloro-, phosphate (TDCPP); and 2-Propanol, 1-chloro-, phosphate (TCPP).
HBCD is a member of the cyclic aliphatic bromides group. A second member of this group is 1,2,5,6-Tetrabromocyclooctane.
In its analysis of structure-based flame retardant groupings, EPA identified a fourth flame retardant group, tetrabromo bisphenol A and related chemicals, within which one chemical—4,4’-(l-Methylethylidene)bis(2,6-dibromophenol] or Tetrabromobisphenol A (TBBPA)—has sufficient data to conduct a risk assessment. TBBPA was not identified in the 2012 Work Plan. However, if it ranks sufficiently high when EPA updates its TSCA Work Plan, TBBPA will become a candidate for future risk assessment.
2013 Data Collection Activities
Distinct from the Work Plan and Action Plan effort but as part of the data-gathering element of its broader existing chemicals strategy, in 2013 EPA also will begin environmental fate investigations of eight flame retardants that, using the Work Plan prioritization methodology, ranked high for persistence, bioaccumulation and/or exposure potential, but for which there are not adequate data to conduct risk assessments. These investigations will also help EPA focus its flame retardant data needs. For these chemicals, listed below, EPA will study the mechanisms by which larger molecules may break down into degradants, and how the persistence and bioaccumulation potentials of the degradants compare to those of the parent compounds.
- 1,2,4,5-tetrabromo-3,6-bis(pentabromophenoxy)-benzene or Tetradecabromo-1,4-diphenoxybenzene
- 1,2 bis(Penetabromophenyl) ethane (DBDPE)
- 1,1'-[1,2-Ethanediylbis(oxy)]bis[2,3,4,5,6-pentabromo-benzene] or 1,2-Bis(2,3,4,5,6-pentabromophenoxy) ethane
- 1,1'-[1,2-Ethanediylbis(oxy)]bis[2,4,6-tribromobenzene] or 1,2-bis (2,4,6-Tribromophenoxy) ethane (TBE)
- Benzene,1,3,5-tribromo-2-(2,3-dibromopropoxy) (DPTE)
- Confidential C
- Confidential D
The seven chemicals identified for risk assessment in 2013 are advancing EPA’s existing chemicals strategy by implementing activities identified in its Work Plan and chemical action plans. The review of similar chemicals in related groupings, and the environmental fate investigations for other chemicals, complements the risk assessments by focusing the identification of data needs on chemical classes with members that rank high for specific criteria in the Work Plan methodology, but lack sufficient data to conduct risk assessment.