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Chemical Regulation

Industry requests safety review of cyclic siloxane

US EPA considers evaluating risks of D4 under the Toxic Substances Control Act

by Britt E. Erickson
April 19, 2020 | APPEARED IN VOLUME 98, ISSUE 15



Octamethylcyclotetrasiloxane (D4), a cyclic organosilicon chemical used as an intermediate to make numerous commercial and consumer products, does not pose risks to human health or the environment, according to a risk assessment conducted by a group of six chemical manufacturers. The companies, represented by the Silicones Environmental, Health, and Safety Center (SEHSC), which is part of the American Chemistry Council, submitted their evaluation to the US Environmental Protection Agency earlier this year. The group is requesting that the EPA conduct its own evaluation of the chemical under the Toxic Substances Control Act (TSCA).

Revisions to TSCA enacted in 2016 allow a manufacturer to ask the EPA to conduct a risk evaluation for certain uses of a chemical that are of interest to the manufacturer. In December 2019, the agency granted requests from industry to evaluate two phthalates—diisononyl phthalate and diisodecyl phthalate. Those evaluations are ongoing. The EPA announced the D4 evaluation request April 8. If the agency grants the request, it must then decide whether to use any of the information included in the industry’s evaluation.

D4 is found in a wide range of products, including adhesives, paints, plastics, rubber, automotive parts, and soaps and detergents. The six chemical manufacturers considered these uses in their assessment, as well as uses outside the scope of TSCA, such as personal care products and food contact materials, which are regulated by the Food and Drug Administration.

“Based on a thorough risk evaluation SEHSC included in its submission to EPA, the silicones industry continues to believe that no regulatory restrictions on D4 are needed,” Karluss Thomas, senior director of SEHSC, says in a statement.

In January 2019, the European Chemicals Agency (ECHA) proposed restricting the sale of products containing D4 in the European Union, citing the chemical’s persistence and ability to bioaccumulate. ECHA has already restricted D4 in wash-off personal care products, such as shampoos and shower gels, to no more than 0.1% by weight.

The EPA plans to begin accepting public comments on the request to evaluate D4 by June 11. Once the agency publishes that notice in the Federal Register, the public will have at least 45 days to provide input.



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