Risk Evaluation for o-Dichlorobenzene

In August 2026, EPA released the draft risk evaluation and associated technical support documents for o-dichlorobenzene under the Toxic Substances Control Act (TSCA) for public comment. 

EPA will accept public comments on the draft risk evaluation for 60 days in the o-dichlorobenzene TSCA docket (EPA-HQ-OPPT-2018-0444) at www.regulations.gov.

EPA designated o-dichlorobenzene as a high priority chemical in December 2019 and the chemical is currently undergoing risk evaluation.

Find other information about other chemicals undergoing risk evaluations under TSCA. 

On this page:

• What is o-Dichlorobenzene? 
• Draft Risk Evaluation for o-Dichlorobenzene
• Draft Risk Evaluation and Supporting Documents

What is o-Dichlorobenzene?

o-Dichlorobenzene (CASRN 95-50-1) is a colorless liquid, with a pleasant, aromatic odor. The primary uses for o-dichlorobenzene are in the manufacturing of dyes, paints, and pigments and in products used for cleaning, degreasing, and painting. Information from the 2016 Chemical Data Reporting (CDR) for o-dichlorobenzene indicates the reported production volume is between 100,000 and 500,000 lbs/year.

Draft Risk Evaluation for o-Dichlorobenzene?

EPA is preliminarily determining that o-dichlorobenzene presents an unreasonable risk of injury to human health driven by 14 of 24 evaluated conditions of use (COUs). These preliminary risk findings are driven by occupational exposures, including risks to workers from 14 COUs and risks to occupational non-users (ONUs) from 7 of those COUs. EPA did not preliminarily identify any significant contribution to unreasonable risk for consumers, the general population, including fenceline communities, or the environment from the evaluated TSCA conditions of use. EPA also preliminarily identified eight COUs that do not significantly contribute to unreasonable risk, including 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. For COUs with unreasonable risk to workers, these preliminary risk determinations do not reflect the use of personal protective equipment (PPE); however, as the draft risk evaluation shows, appropriate engineering controls and PPE can reduce exposures and mitigate risk.

The draft risk evaluation found that workers may be exposed to o-dichlorobenzene through inhalation and dermal contact during manufacturing, processing, and commercial uses. EPA identified respiratory toxicity and liver toxicity as the primary non-cancer hazards associated with exposure and used transcriptomic data developed in collaboration with the National Institute of Environmental Health Sciences (NIEHS) to inform the hazard assessment. EPA preliminarily determined that no unreasonable risk is expected for consumers, the general population through ambient air or drinking water exposure, or aquatic and terrestrial organisms. EPA has moderate to robust confidence in the worker risk estimates and robust confidence in the general population and environmental assessments. EPA is seeking public comment and additional information on occupational exposure scenarios, exposure controls, and other data that may inform the final risk evaluation. These preliminary conclusions apply only to the TSCA conditions of use evaluated in this draft risk evaluation; uses excluded under TSCA section 3(2)(B) were not assessed.

EPA will move quickly, after public comment, to finalize the risk evaluation. Should EPA continue to find unreasonable risk, EPA will then propose risk management actions under TSCA to reduce or eliminate unsafe workplace exposures.

EPA emphasizes that this evaluation is draft and does not represent a final Agency determination regarding the risks posed by this chemical. The findings and conclusions may change based on feedback received during the public comment period. Additionally, the release of a draft evaluation does not alter or impact any existing protections, regulations, or risk management measures currently in place for this chemical. All current safeguards remain in place.

Draft Risk Evaluation and Supporting Documents

View the Federal Register Notice and supporting documents in TSCA review docket EPA-HQ-OPPT-2018-0444. 

• Draft Risk Evaluation for o-Dichlorobenzene (pdf) (3.21 MB)
• Draft Human Health and Environmental Hazard Assessment for o-Dichlorobenzene (pdf) (4.72 MB)
• Draft Chemistry, Fate, Release, and Exposure Assessment for o-Dichlorobenzene (pdf) (6.23 MB)
• Data Quality Evaluation Information for Human Health Hazard Animal Toxicology for o-Dichlorobenzene (pdf) (1.54 MB)
• Draft Data Quality Evaluation Information for Human Health Hazard Epidemiology for o-Dichlorobenzene (pdf) (450.37 KB)
• Draft Data Quality Evaluation Information for Environmental Hazard for o-Dichlorobenzene (pdf) (4.11 MB)
• Draft Data Quality Evaluation Information for Dermal Absorption for o-Dichlorobenzene (pdf) (243.88 KB)
• Draft Data Extraction Information for Environmental Hazard and Human Health Hazard Animal Toxicology and Epidemiology for o-Dichlorobenzene (pdf) (1.31 MB)
• Draft Benchmark Dose Modeling Results for o-Dichlorobenzene (pdf) (4.61 MB)
• Draft Candidate Analog and Toxicity Values to Support ReCAAP Analysis for o-Dichlorobenzene (xlsx) (175.06 KB)
• Draft Transcriptomic Assessment for o-Dichlorobenzene and p-Dichlorobenzene (pdf) (4.46 MB)

Additional technical support files for the draft risk evaluation of o-Dichlorobenzene (zip)