On March 1, 2012, US EPA announced that it has finalized a new plan for identifying which existing chemicals should undergo comprehensive risk assessment under the Toxic Substances Control Act (TSCA).  US EPA also announced that, using this new plan, it has identified  83 existing chemicals for further risk assessment, with 7 of those chemicals slated for assessments in 2012.  US EPA first inititiated stakeholder discussion on how best to address future risk assessments last fall when it asked for public comment through an on-line forum, webinar, and stakeholder meeting on its August 2011 two-step plan for identifying existing chemicals for risk assessment.  

As noted in the final plan announced and posted on US EPA's website, the first step of the plan identifies potential risk assessment candidates through evaluation of the following factors:  carcinogenicity; PBT factors (persistence, bioaccumulation, and toxicity); children's health; neurotoxicity; children's product use; and biomonitoring status.  Over 1200 chemicals were identified through this initial step.  US EPA then removed from that list chemicals that "did not meet the intent of the prioritization criteria, they were not subject to action under TSCA, or they were already the subject of TSCA action."  Chemicals removed through that screening process included:  pesiticides; drugs, hormones, and pharmacalogical chemicals; certain radiological materials; complex process streams, byproducts not commercially produced; polymers; gases, common naturally ocurring chemicals, and combustion products; common oils or fats and simple plant extracts; explosive, pyrophoric, or extremely reactive or corrosive chemicals; metals principally identified as toxic to the environment; and chemicals already the subject of Action Plans or signiciant regulation under TSCA (Benzidene Dyes, BPA, HBCD, MDI, Nonylphenol and Nonylphenol Ethoxylates, PBDEs, PCBs, PFCs, Phthalates, Short-chain Chlorinated Paraffins, and TDI).  After removing such chemicals, 345 chemicals remained at the end of the first step of the screening plan.

For the second step of the screening plan, US EPA applied a numeric algorithm to derive "scores" for the chemicals based on:  hazard; exposure; and potential for persistence and bioaccumulation.  The "Hazard" score was based on evaluation of both human health and environmental toxicity concerns using US EPA's Alternatives Assessment Criteria for Hazard Evaluation.   The "Exposure" score was based on evaluation of chemical use, general population and environmental exposures, and release information, including information from US EPA's Toxics Release Inventory (TRI) and Inventory Update Reporting data (IUR - now called Chemical Data Reporting (CDR)).   The "Persistence/Bioaccumulation" score was based on evaluation of chemical half-life and bioaccumulation/bioconcentration (measured or estimated BAF/BCF) data or similar calculations.  The total Hazard, Exposure, and Persistence/Bioaccumulation scores for the chemicals under review were then sorted into overall "High," "Moderate," and "Low" groups.  Through this process, 83 chemicals received "High" rankings and have, therefore, been designated as the first TSCA Work Plan Chemicals.  The complete list of these 83 chemicals is available here.  

Of the initial 83 TSCA Work Plan Chemicals, US EPA then selected 7 chemicals for risk assessment in 2012, based on evaluation of the following factors:  1) Whether the chemical was ranked "High"; 2) Whether the chemical reflects more than one of the factors identified in step one of the plan; 3) Whether the chemical might benefit from some preliminary work to assure that the risk assessment is targeted and scoped appropriately; 4) Whether the chemical is the subject of an existing assessment;  and 5) Agency work load considerations, including timing of work needed on specific chemicals and existing commitments for assessment.  The 7 chemicals identified for TSCA risk assessment during 2012 are: 

  1. Antimony & Antimony Compunds
  2. 1,3,4,6,7,8-Hexahydro-4,6,6,7,8,8,-hexamethylcyclopenta [g]-2-benzopyran (HHCB)
  3. Long-Chain Chlorinated Paraffins (C18-20)
  4. Medium-Chain Chlorinated Paraffins (C14-17)
  5. Methylene Chloride
  6. N-Methylpyrrolidone
  7. Trichloroethylene (TCE)

As for the function of the upcoming risk assessment work, US EPA stated in its new "Existing Chemicals Program: Strategy" document that its chemical assessments "may include evaluation of alternatives.  If an assessment indicates significant risk, EPA will evaluate and pursue appropriate risk reduction actions.  If an assessment indicates no significant risk, EPA will conclude its current work on that chemical."  US EPA also noted that "additional chemicals will be added to the work plan as more data are developed and more chemicals screened."