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EPA Releases Two Draft Chemical Risk Evaluations for Public and Science Review

For Release: June 28, 2019

Evaluations Follow Comprehensive TSCA Process to Protect Public Health and Ensure Chemical Safety

Today, the U.S. Environmental Protection Agency (EPA) is asking for public input on draft risk evaluations for cyclic aliphatic bromide cluster (HBCD) and 1,4-dioxane, two of the first ten chemicals undergoing risk evaluation under the amended Toxic Substances Control Act (TSCA). This is the next step in the process required by TSCA toward final risk evaluations for these two chemicals.

Following the comprehensive risk evaluation process required by TSCA ensures our upcoming final risk evaluations are based on the best available science. The draft risk evaluations released today represent the agency’s initial review of the scientific data on these chemicals and will be peer reviewed by independent, scientific experts.

In the draft risk evaluation for HBCD, EPA did not find unreasonable risk to the general population, consumers, workers, or the environment. In the draft risk evaluation for 1,4-dioxane, EPA did not find unreasonable risk to the environment. The data in the draft risk evaluation for 1,4-dioxane does show there could be unreasonable risks to workers in certain circumstances. It is important to note that for the general population, including children, environmental statutes administered by EPA such as the Clean Air Act, the Safe Drinking Water Act, the Clean Water Act, and the Resource Conservation and Recovery Act, adequately assess and effectively manage risks from 1,4-dioxane.

These draft risk evaluations are not final agency actions. EPA will use feedback received from the public and peer review process to inform the final risk evaluations and will keep the public updated on the agency's progress through this process. If EPA's final risk evaluations find there are unreasonable risks associated with these chemicals under specific conditions of use, the agency will propose actions to address those risks within the timeframe required by TSCA. This could include proposed regulations to prohibit or limit the manufacture, processing, distribution in the marketplace, use, or disposal of these chemicals, as applicable.

Upon publication of the Federal Register notice, the draft risk evaluations for the two chemicals will be available for public comment for 60 days. The draft risk evaluations will undergo peer review by the Science Advisory Committee on Chemicals (SACC), the new Federal Advisory Committee required under TSCA, at a July 29- August 2, 2019 meeting. In addition, a preparatory virtual meeting to discuss the scope and clarity of the draft charge questions to the SACC will take place on July 10, 2019.

View the draft risk evaluation for HBCD and a factsheet explaining the draft risk evaluation.

View the draft risk evaluation for 1,4-dioxane and a factsheet explaining the draft risk evaluation.

Learn more about the SACC peer review meeting.


HBCD is a flame retardant and is primarily used in construction materials, which may include structural insulated panels. Use of HBCD has declined dramatically over the past few years, primarily due to the use of replacement chemicals. Domestic U.S. manufacturers have indicated complete replacement of HBCD in their production lines, including the depletion of stockpiles and cessation of export.

1,4-Dioxane is used primarily as a solvent in a variety of commercial and industrial applications, including in the manufacture of other chemicals, as a processing aid, in laboratory chemicals, and in adhesives and sealants. There were no consumer uses for 1,4-dioxane reported in the United States in the 2016 Chemical Data Reporting (CDR), and EPA has not identified any information indicating consumer uses.