On August 13, 2026, the US Environmental Protection Agency (EPA) released its draft risk evaluation for o-dichlorobenzene (CASRN 95-50-1) under Section 6 of the Toxic Substances Control Act (TSCA), preliminarily finding an unreasonable risk of injury to human health from 14 of the 24 conditions of use evaluated. The finding is driven by occupational exposure, and a 60-day public comment window is now open in docket EPA-HQ-OPPT-2018-0444 on regulations.gov.
The solvent, produced at 100,000 to 500,000 lbs/year under the 2016 Chemical Data Reporting rule, is used mainly in manufacturing dyes, paints and pigments, and in cleaning, degreasing and paint-thinning products. EPA designated it a high-priority chemical in December 2019 and initiated the risk evaluation the same month, making this draft a scheduled milestone in the existing-chemicals work plan rather than a surprise action.
What did EPA conclude about worker risk?
EPA preliminarily determined that o-dichlorobenzene presents unreasonable risk to workers across 14 conditions of use, and to occupational non-users (ONUs) from 7 of those same uses. Workers may be exposed through inhalation and dermal contact during manufacturing, processing and commercial use, and the agency identified respiratory toxicity and liver toxicity as the primary non-cancer hazards. EPA used transcriptomic data developed with the National Institute of Environmental Health Sciences (NIEHS) to inform the hazard assessment.
The draft is notable for what it excludes. EPA did not preliminarily identify any unreasonable risk for consumers, the general population (including fenceline communities), or the environment from the evaluated TSCA uses. It has moderate to robust confidence in the worker estimates and robust confidence in the general-population and environmental assessments. Critically, the worker risk determinations do not assume the use of personal protective equipment (PPE); the draft notes that appropriate engineering controls and PPE can reduce exposures and mitigate risk, which will shape any later risk-management rule.
Which conditions of use trigger unreasonable risk, and which do not?
The draft splits the 24 evaluated conditions of use into risk and no-risk buckets. Eight uses do not significantly contribute to unreasonable risk: domestic manufacturing, plastics converting, plastics compounding, use of laboratory chemicals, use in paint thinners and removers, use in solid air care products, use as a fuel additive, and use in sheep-branding fluid.
| Outcome | Conditions of use | Exposed population |
|---|---|---|
| Unreasonable risk | 14 of 24 COUs | Workers (14 COUs), occupational non-users (7 of those) |
| No unreasonable risk | 8 COUs | Workers, consumers, general population, environment |
The Federal Register notice and supporting technical documents are filed under the same docket. These preliminary conclusions apply only to the TSCA conditions of use evaluated in the draft; uses excluded under TSCA section 3(2)(B) were not assessed.
Who must act, and by when?
TSCA compliance and EHS leads at US manufacturers, processors and downstream industrial users of o-dichlorobenzene are the directly affected audience. The immediate obligation is procedural: submit comments and exposure data within the 60-day window that opened on August 13, 2026. EPA is specifically seeking input on occupational exposure scenarios, exposure controls, and other data that may inform the final evaluation.
Because the draft determinations do not credit current PPE use, facilities that handle the solvent should not assume their existing controls will be treated as adequate in the final evaluation. The comment period is the point at which a company can place its real-world exposure-control data on the record before EPA moves to binding risk management.
What comes after the comment period?
EPA has signaled it will move quickly to finalize the risk evaluation after comments close. If the agency continues to find unreasonable risk, it will then propose risk-management actions under TSCA Section 6 to reduce or eliminate unsafe workplace exposures, which could include use restrictions, exposure limits, or PPE and engineering-control mandates. The draft does not alter any existing protections, regulations, or risk-management measures already in place for the chemical; all current safeguards remain in effect while the evaluation is finalized.
For context, two 2024 TSCA Section 6 risk-management rules (methylene chloride and chrysotile asbestos) remain under Fifth Circuit review, and EPA is still finalizing the broader framework rule (RIN 2070-AL27) that will govern how future risk evaluations like this one are scoped. Companies tracking o-dichlorobenzene should treat this draft as the leading edge of a risk-management rule, not a closed assessment.
Continuous, per-jurisdiction monitoring of the TSCA docket surfaces a draft like this the day it publishes, before any binding obligation attaches.
Take advantage of this real-time watch
Next steps. Confirm whether your facility manufactures, processes or uses o-dichlorobenzene in one of the 14 flagged conditions of use; review your inhalation and dermal exposure controls against the draft's respiratory and liver-toxicity findings; and file comments or exposure data in docket EPA-HQ-OPPT-2018-0444 before the 60-day window closes.
