EPA Publishes Final Risk Evaluation for Cyclic Aliphatic Bromide Cluster

On September 24, 2020, a final risk evaluation for cyclic aliphatic bromide cluster was released by the U.S. Environmental Protection Agency (EPA). This evaluation is part of the Agency’s ongoing efforts to help protect the environment and human health. In this blog post, we discuss this evaluation and several of the key findings associated with it.

About Cyclic Aliphatic Bromide Cluster

Also known as hexabromocyclodecanes (HBCD), cyclic aliphatic bromide cluster is a non-volatile solid comprised of three related chemicals:

  • hexabromocyclododecane
  • 1,2,5,6,9,10-hexabromocyclododecane
  • 1,2,5,6-tetrabromocyclooctane
Substance NameCAS Registry Number

Source: U.S. Environmental Protection Agency

While it has had several industrial uses, including the manufacture of solder and automobile replacement parts, its principal use has been as a flame retardant in polystyrene foam. Several routes of exposure to HBCD are possible, although dermal and inhalation exposure are the primary methods.

Cyclic aliphatic bromide cluster is persistent, bioaccumulative, and toxic (PBT). Given its classification as a persistent organic pollutant, it is (as of 2018) no longer produced in this country. Additionally, many other countries have already banned HBCD use and manufacture.

It should be noted that for this risk evaluation, cyclic aliphatic bromide cluster refers to hexabromocyclododecane and/or to 1,2,5,6,9,10-hexabromocyclododecane, as use conditions for 1,2,5,6-tetrabromocyclooctane were not identified.

Key Findings

The EPA's final risk evaluation for HBCD yielded several key findings, based on anassessment of 12 conditions of use.

  • Unreasonable risks to the environment were found (for six of the 12 conditions of use)
  • No unreasonable risks to the general population were found
  • No unreasonable risks to consumers were found
  • Unreasonable risks to workers and occupational non-users were found, particularly when dealing with materials in construction

Chemicals Requiring Risk Evaluation

HBCD represents the third of the first group of ten chemical substances (those requiring risk evaluation under the Frank R. Lautenberg Chemical Safety for the 21st Century Act (Lautenberg Act)) for which a final evaluation has been issued by the EPA. The Agency intends to complete the remainder of these risk evaluations by year’s end.

Access to Vital Information

Information gleaned from chemical risk evaluation is essential in efforts to help protect human and environmental health. Equally important is having a deep understanding of chemical substances, their properties, and their many uses.

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