EPA Releases Draft Risk Evaluation for D4

EPA’s draft risk evaluation for the chemical D4 finds that inhalation and dermal exposure presents “unreasonable” risk to workers in 23 conditions of use, including processing it as a reactant; incorporating it into mixtures, formulations, or reaction products; and the industrial use of solvents, paints, and coatings that contain D4. According to EPA, exposure to D4 is likely to be hazardous to the female reproductive system. The draft risk evaluation does not account for the use of personal protective equipment, and the agency notes that PPE use may be sufficient to mitigate exposures.

D4, the common name for octamethylcyclotetrasiloxane, is used to make other silicone chemicals and as an ingredient in some personal care products. Between 750 million and 1 billion pounds of D4 are produced annually in the United States.

The draft risk evaluation includes an “existing chemical occupational exposure value” for inhalation exposures to D4 of 0.307 ppm, or 3.73 mg/m3, as an eight-hour, time-weighted average. EPA describes this determination as a “risk-only” value that does not account for the feasibility of achieving it.

Neither OSHA nor NIOSH has published an exposure limit for D4. In 2014, the Occupational Alliance for Risk Science (OARS) published a workplace environmental exposure level for D4 of 10 ppm as an eight-hour TWA. WEEL values are air concentrations believed to protect most workers from negative health effects resulting from occupational chemical exposure.

Comments on the draft risk evaluation will be accepted through Nov. 17. For more information about D4, review the draft risk evaluation.

EPA has produced “draft charge questions” (PDF) for the agency’s Science Advisory Committee on Chemicals (SACC) to consider when conducting peer review of the D4 draft risk evaluation. On Nov. 18, EPA will hold a virtual meeting intended to provide opportunities for SACC and the public to discuss the draft charge questions. SACC will discuss the draft risk evaluation as a whole during a virtual public meeting scheduled for Dec. 2–5. More information is available from the EPA website.