The EPA has preliminarily found that both dichlorobenzenes present unreasonable risk to human health, and it opened the file on them in December 2019
December 2019.
That is when the Environmental Protection Agency designated o-dichlorobenzene and p-dichlorobenzene as high priority substances for risk evaluation under the Toxic Substances Control Act. The draft risk evaluations arrived on Friday and publish on Monday, six years and seven months later, and they carry a finding. The agency writes that it "preliminarily determined, based on the weight of scientific evidence, that o-dichlorobenzene and p-dichlorobenzene present unreasonable risk to human health driven primarily by certain COUs analyzed in the draft risk evaluations." COU is the agency's shorthand for a condition of use.
Comments close on 9 October.
What the two chemicals are for
The notice describes the ortho isomer as a clear to pale yellow liquid used industrially as a solvent in dyes and pigments, in lubricant and degreaser products, and in inks and paint strippers. Consumer uses it lists include lubricants and degreasers, air care products, ceramics glazing and cleaning products. The agency then asks a question that says more than the list does. It wants comment on consumer and occupational use as a cleaner for septic and cesspool tanks, and on septic tank cleaner products specifically, including their availability, ingredients and use instructions.
The para isomer is described as a colorless to white crystalline solid with a strong, pungent odor that passes straight from solid to vapour at room temperature. It goes into thermoplastic manufacture, into solvents, and into air care products as continuous-action air fresheners. On this one the agency asks about abrasive grinding wheels, about how common the chemical is in laboratories, and about whether and how gloves are used during commercial use in air care products.
Neither description names a household product. The evaluations behind them were not read for this brief, and no exposure figure appears in the notice.
The peer review the agency is not running
Buried under the request for comment is a procedural line worth reading twice.
EPA says external peer review is not needed on the draft risk evaluations, nor on the chemistry, fate, release and exposure assessments underneath them. Two reasons are given. The draft hazard assessments already went to the Science Advisory Committee on Chemicals in April, with a virtual public meeting in June. And the methodologies were peer reviewed before, in the published risk evaluations for 1,1-dichloroethane, 1,3-butadiene and phthalates, and in the draft screening level approach for fenceline communities from January 2022.
So the science advisory committee has seen how the hazard was assessed. It will not see the evaluation that the hazard assessment feeds, and the 60 day comment period is what stands in its place.
What comes next, and what does not
A draft is not a restriction. The notice sets out the sequence plainly: EPA weighs the comments and the committee's input, publishes final risk evaluations, and only a final finding of unreasonable risk sends a chemical to risk management under section 6(a), for the conditions of use that drove the finding. Any restriction proposed there gets its own comment period.
One feature of the statute shapes everything above it. A TSCA risk evaluation is made without consideration of costs or non-risk factors. Whatever the two evaluations conclude, price is not in them.
Status
Comments on either chemical are due on or before 9 October 2026, to docket EPA-HQ-OPPT-2018-0444 for the ortho isomer and EPA-HQ-OPPT-2018-0446 for the para.
