Risk Evaluation for 1,3,4,6,7,8-Hexahydro-4,6,6,7,8,8-hexamethylcyclopenta [g]-2-benzopyran (HHCB)

In April 2026, EPA released the draft risk evaluation and associated technical support documents for 1,3,4,6,7,8-Hexahydro-4,6,6,7,8,8-hexamethylcyclopenta [g]-2-benzopyran (HHCB) under the Toxic Substances Control Act (TSCA) for public comment. EPA designated HHCB as a high priority chemical in December 2019 and the chemical is currently undergoing risk evaluation.

Find other information about other chemicals undergoing risk evaluations under TSCA.

On this page:

Draft Risk Evaluation for HHCB
What is HHCB?
Uses of HHCB
Recent Activities and Opportunities for Public Comment
Draft Risk Evaluation and Supporting Documents
Review of HHCB Prior to the Lautenberg Act

Draft Risk Evaluation for HHCB

EPA is preliminarily determining that HHCB does not present an unreasonable risk of injury to human health or the environment under the conditions of use, including manufacturing, processing, distribution, commercial and consumer use, and disposal. This preliminary determination applies to workers, consumers, and the general population (including subsistence fishers and Tribal populations), as well as ecological receptors.

This draft risk evaluation incorporates a fit-for-purpose, tiered approach that refines screening assessments only when indicated; long term aggregate exposure scenarios for workers and consumers (including an infant scenario); refined fish bioaccumulation modeling using KABAM and a kinetic mass-balance model (ADMEB) alongside measured data; and an updated human health hazard basis using an OECD 443 extended one-generation reproductive toxicity study (decreased offspring body weight as the noncancer point of departure). While some screening-level chronic ecological risk quotients were greater than 1 but less than 3, the overall weight of evidence (modeled and measured concentrations with stated uncertainties) did not indicate risk. EPA did not evaluate uses of HHCB that are not subject to TSCA (e.g., cosmetics, certain personal care products, medical devices, food additives), and as such the conclusions in the draft risk evaluation do not apply to those uses.

What is HHCB?

HHCB (CASRN 1222-05-5) is a viscous, or thick, liquid . The primary use of HHCB is as an odor agent for fragrances, for instance, air care products and cleaning products. Total production volume of HHCB in 2015 was between 1 million and 10 million pounds.

Uses of HHCB

In the final scope, EPA identified conditions of use associated with the manufacturing (including importing); processing; distribution in commerce; commercial and consumer uses; and disposal of HHCB, for example:

Processing to incorporate HHCB into a formulation, mixture, or reaction products, and to incorporate HHCB into articles;
In air care products (e.g., aroma chemicals, air fresheners in motor vehicles, scented candles, aerosols and spays);
In cleaning and furnishing care products (e.g., all-purpose cleaners and bathroom cleaners);
In laundry products (e.g., laundry detergent and fabric softener);
In plastic and rubber products; and
In paper products.

The above listed conditions of use are ways that a person or the environment could be potentially exposed to this chemical. However, when conducting a risk evaluation, EPA also considers the hazards (i.e. health effects or environmental impacts) that could occur from coming in contact with a chemical.

Recent Activities and Opportunities for Public Comment

In April 2026, EPA released the draft risk evaluation for public comment and peer review by the agency’s Science Advisory Committee on Chemicals (SACC). Upon publication of a Federal Register notice, EPA will accept public comments on the draft risk evaluation for 60 days via the TSCA docket EPA-HQ-OPPT-2018-0430 at www.regulations.gov.

In August 2020, EPA published a final scope document outlining the hazards, exposures, conditions of use, and the potentially exposed or susceptible subpopulations the agency expects to consider in its risk evaluation. The agency released the draft scope in April 2020 and took public comments on the draft document.

As EPA continues to move through the risk evaluation process there will be additional opportunities for public comment, including a public comment period on the draft risk evaluation. In addition to public comment periods, EPA will continue to engage with stakeholders as it refines the risk evaluation and stakeholders should reach out to EPA via the staff contact to engage with the agency.

Draft Risk Evaluation and Supporting Documents

Read the Federal Register Notice and view the supporting documents in EPA-HQ-OPPT-2018-0430.

Additional technical support files for the draft risk evaluation of HHCB (zip)

Review of HHCB Prior to the Lautenberg Act

Prior to the Frank R. Lautenberg Chemical Safety for the 21st Century Act, EPA completed a risk assessment for HHCB and published the following information: