On August 28, 2026, the US Environmental Protection Agency (EPA) released its draft risk evaluation for trans-1,2-dichloroethylene under Section 6 of the Toxic Substances Control Act (TSCA), preliminarily finding that 20 of the 25 assessed conditions of use significantly contribute to unreasonable risk to human health. The solvent (CASRN 156-60-5), produced at 1 million to 5 million lbs/year according to the 2024 Chemical Data Reporting cycle, is used mainly in processing and in formulations for cleaning and degreasing. The finding opens a 60-day public comment window in docket EPA-HQ-OPPT-2018-0465 and starts the Section 6 risk-management pathway that follows a final unreasonable-risk determination.
The draft is not a final Agency determination, and EPA stresses that it does not alter any existing protections, regulations, or risk-management measures for the chemical. For US manufacturers, processors, formulators and industrial users of trans-1,2-dichloroethylene, it is nevertheless the signal to assess their own conditions of use and weigh in during the comment period, because the same use-by-use findings will shape the binding rule that follows.
Which conditions of use does the draft find unreasonable?
Unreasonable risk is driven primarily by non-cancer inhalation exposure to workers and occupational non-users (ONUs). EPA preliminarily finds that 19 conditions of use contribute to risk for workers, and that 13 of those also contribute to risk for ONUs. One consumer use, as a cleaner or degreaser, contributes to unreasonable risk based on acute and intermediate non-cancer inhalation exposure.
EPA did not preliminarily identify unreasonable risk for the general population, including fenceline communities, or for the environment under the conditions of use evaluated. It found no unreasonable risk from dermal exposure to workers, ONUs, or consumers. Five conditions of use do not significantly contribute to the determination: distribution in commerce, disposal, laboratory chemical use, use in semiconductor and photovoltaic processing aids, and consumer use of polymer foam propellants.
| Finding | Conditions of use | Primary driver |
|---|---|---|
| Unreasonable risk (20 of 25) | 19 worker uses, 13 of which also affect ONUs, plus 1 consumer cleaner/degreaser use | Non-cancer inhalation |
| No unreasonable risk (5 of 25) | Distribution, disposal, laboratory chemical use, semiconductor and photovoltaic processing aids, consumer polymer foam propellant use | Not significant |
| Out of scope of the finding | General population, fenceline communities, environment, dermal exposure | No unreasonable risk identified |
Who must act, and by when?
EHS and regulatory compliance leads at US chemical manufacturers, formulators and industrial users of trans-1,2-dichloroethylene are the directly exposed audience. The immediate obligation is procedural: EPA will accept public comments for 60 days in docket EPA-HQ-OPPT-2018-0465 at regulations.gov. Comments can challenge the conditions-of-use findings, the exposure assumptions, or the scope, and EPA explicitly notes that the findings and conclusions may change based on feedback received.
In parallel, affected companies should map their own conditions of use against the 20 that drive the draft determination, because the same use-by-use logic will carry into risk management. Companies whose operations fall under the five use categories EPA cleared should document why, since that distinction is what keeps a use out of the subsequent rule.
What happens after the comment period closes?
EPA will move quickly under TSCA to finalize the risk evaluation after public comment. Should the Agency continue to find unreasonable risk, EPA will then propose risk-management actions under TSCA Section 6 to address the unsafe workplace exposures identified. Section 6 risk-management rules can restrict or prohibit the manufacture, processing, distribution, use, or disposal of a chemical, so a final unreasonable-risk finding puts trans-1,2-dichloroethylene on track to binding use restrictions, not merely a labelling change.
This draft is a chemical-specific evaluation, distinct from the awaited TSCA framework rule (RIN 2070-AL27) that would revise the procedural rules for risk evaluations themselves. The two move on separate tracks: one rewrites how EPA evaluates chemicals, the other determines what happens to this specific solvent.
Continuous, per-jurisdiction real-time monitoring surfaces a draft like this the moment EPA publishes it, before trade press echoes it.
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What to do next
Three concrete steps. First, confirm whether your operations use trans-1,2-dichloroethylene in any of the 20 conditions of use EPA flagged, and gather exposure data to file in the comment docket before the 60-day window closes. Second, check whether any of your uses fall under the five cleared categories and document the basis, so the distinction survives into risk management. Third, brief your EHS and procurement teams now, because a final unreasonable-risk finding will feed directly into a Section 6 risk-management rule that can restrict the solvent's use. Obsidian tracks this docket and the downstream Section 6 rulemaking as they develop.
