EPA published draft Toxic Substances Control Act (TSCA) risk evaluations on August 10 for o-dichlorobenzene and p-dichlorobenzene, two chlorinated solvents used across manufacturing, printing, and consumer product formulations. The agency's preliminary determination is that both chemicals present unreasonable risk to human health, driven primarily by specific industrial and commercial conditions of use rather than by the chemicals' presence in a product generally. That determination is not final. EPA is now asking manufacturers, processors, and users to supply the operational detail that feeds its exposure models, including worker schedules, monitoring data, and how personal protective equipment actually gets used on the floor.
Comments on both chemicals are due October 9, with submissions filed separately to each chemical's docket at regulations.gov. The two evaluations share a structure but not an origin story: o-dichlorobenzene is a liquid solvent used in dyes, inks, and degreasers, while p-dichlorobenzene is a solid that sublimates directly into vapor and shows up in air fresheners, mothballs, and abrasive grinding wheels. EPA is treating the underlying science as settled enough to skip a separate peer review round, since the methodology already went through Science Advisory Committee scrutiny on earlier chemical evaluations this year.
o-Dichlorobenzene Questions Center on Ink, Dry Cleaning, and Septic Tank Use
For o-dichlorobenzene, EPA wants current information on five specific activities: domestic manufacturing, its use as a reactant in chemical processing, its role in ink and toner formulation, its use as a spot cleaner in the dry cleaning and furnishings industry, and its presence in consumer septic and cesspool tank cleaners. That last category caught EPA's attention because product availability and use instructions for septic cleaners containing the chemical are not well documented in the agency's existing data.
EPA is also revisiting a modeling approach borrowed from an automotive refinishing standard to estimate inhalation exposure during paint and coating work, and it wants feedback on whether that model fits the way o-dichlorobenzene is actually sprayed and handled in the field. Companies running any of these processes have a narrow window to put facility-specific numbers into the record before those assumptions harden into a final risk determination.
p-Dichlorobenzene's PPE and Shift-Timing Data Gap
The p-dichlorobenzene evaluation leans harder on real-world PPE practices. EPA already holds test order data on exposure controls but says it needs more on glove use specifically, including how common gloves are during commercial handling and what materials workers actually wear. The agency is also asking whether monitoring data from a handful of sites can reasonably stand in for facilities running similar processes elsewhere, and whether its assumptions about dermal exposure hold up for workers who are near the chemical but not directly handling it.
A more technical question involves how EPA converts short-duration exposure readings into the longer time-weighted averages its risk math depends on, along with whether a generic particulate model fits a chemical that behaves as both a solid and a vapor. None of this changes the underlying hazard science. It does determine how conservative or realistic the final workplace risk picture ends up being, which is exactly the leverage point EHS teams have during this comment window.
If the final evaluations retain the unreasonable-risk finding, both chemicals move into TSCA Section 6(a) risk management, with another public comment opportunity before any rule takes effect. That sequencing means the immediate task for affected facilities is evidentiary, not compliance planning: getting accurate operating data on record now shapes what kind of restrictions, if any, follow later.
