September 9, 2021

EPA Requests Feedback on Scope Document for D4 Risk Evaluation

EPA is soliciting public input on a draft document that describes the scope of a proposed risk evaluation of octamethylcyclotetra-siloxane (D4), a chemical used in some personal care products and to make other silicone chemicals. The document includes a description of the scientific approaches EPA will use in its risk evaluation, a model of D4’s potential hazards and exposures, and a plan for assessing its risks to human health and the environment. The risk evaluation, which was requested by several companies that manufacture the chemical, is intended to determine whether D4 presents unreasonable risk of injury to health or the environment under the chemical’s conditions of use. Comments may be submitted to the docket on on or before Oct. 25, 2021.

According to the scope document, the total production volume of D4 in 2015—the most recent year for which data are available—was between 750 million and 1 billion pounds. No occupational exposure limits for D4 have been established by OSHA, NIOSH, or ACGIH.

In 2014, the Occupational Alliance for Risk Science published a Workplace Environmental Exposure Level (WEEL) of 10 ppm as an 8-hour time-weighted average for D4. According to the OARS website, WEELs are health-based guidelines that identify air concentrations intended to protect most workers from adverse health effects related to occupational chemical exposures.

The draft scope document and other materials related to the D4 risk evaluation are available from EPA’s website.