EPA Draft Risk Review for D4 Chemical

The U.S. Environmental Protection Agency (EPA) has released a draft risk evaluation for Octamethylcyclotetrasiloxane (D4), a widely used silicone chemical present in manufacturing, personal care products, coatings, and adhesives. This evaluation, conducted under the Toxic Substances Control Act (TSCA), assesses potential health and environmental risks associated with D4’s multiple uses.

Preliminary Risk Findings

• Workers: Unreasonable risk identified across 23 conditions of use.
• Consumers: Unreasonable risk found for one condition of use involving paints and coatings.
• Environment: Unreasonable risk in seven conditions of use.
• No Risk: No unreasonable risk preliminarily found in 37 other conditions of use.

Note: These findings do not currently account for personal protective equipment (PPE) use.

Bioaccumulation and Environmental Behavior

• D4 is bioaccumulative, meaning it can accumulate in living organisms.
• Studies suggest low biomagnification, indicating limited increase through the food chain.
• Fish uptake of D4 occurs via water and diet, but metabolism reduces long-term accumulation.

Uses and Exposure Pathways

The evaluation covers:

• Manufacturing, importing, and processing of D4.
• Applications in adhesives, sealants, paints, coatings.
• Use in cleaning, laundry, and dishwashing products.
• Presence in automotive care products.
• Environmental release through waste and disposal.

Public Comment and Scientific Review

• Public Comment Period: Open for 60 days under docket EPA-HQ-OPPT-2018-0443.
• Science Advisory Committee on Chemicals (SACC) Review: Virtual meeting on December 2–5, 2025.
• Preparatory Meeting: November 18, 2025.

Implications for Industry

Companies involved with D4 should monitor the EPA evaluation closely. Potential regulatory actions may include workplace safety enhancements, usage restrictions, or environmental controls. Stakeholders are encouraged to participate in the comment period to contribute data and perspectives.

The draft evaluation marks a significant step in the regulatory scrutiny of D4 under TSCA, emphasizing risks to workers, consumers, and the environment.

Reference: Risk Evaluation for Octamethylcyclotetrasiloxane (D4) - EPA