EPA Publishes Final Risk Evaluation for HBCD

On September 24, 2020, the U.S. Environmental Protection Agency (EPA) published the final risk evaluation for cyclic aliphatic bromide cluster (HBCD). EPA found unreasonable risks to the environment from six out of 12 conditions of use and unreasonable risks to workers and occupational non-users (ONU) from the processing, use, and disposal of HBCD, largely from building and construction materials. EPA’s website states “EPA did not find unreasonable risks to the general population or consumers.” Nevertheless, in the risk evaluation document, EPA did find unreasonable risk from fish ingestion at the high-end exposure in one scenario. The unreasonable risk determinations in HBCD’s final risk evaluation represent a substantial change in response to public comments and peer review compared to the draft assessment in which EPA did not make unreasonable risk findings to health or the environment for any of the conditions of use evaluated.

EPA’s next step in the process required by the Toxic Substances Control Act (TSCA) is to develop a plan to reduce or eliminate the unreasonable risks found in the final risk evaluation. EPA states that it “is moving immediately to risk management for this chemical and will work as quickly as possible to propose and finalize actions to protect workers, occupational non-users, and the environment.” EPA states that the action it could take to address these risks includes regulating how HBCD is used or limiting or prohibiting the manufacture, processing, distribution in the marketplace, use, or disposal of HBCD, as applicable. As with any chemical product, EPA “strongly recommends that users of products containing HBCD continue to carefully follow all instructions on the product’s label and safety data sheet.” EPA notes that this is the third final risk evaluation that it has issued and that it plans to issue the seven remaining final risk evaluations by the end of 2020.

Background

TSCA Section 6, as amended by the Frank R. Lautenberg Chemical Safety for the 21st Century Act (Lautenberg Act), requires EPA to conduct risk evaluations to “determine whether a chemical substance presents an unreasonable risk of injury to health or the environment, without consideration of costs or other nonrisk factors, including an unreasonable risk to a potentially exposed or susceptible subpopulation identified as relevant to the risk evaluation by the Administrator, under the conditions of use.” The statute identifies the minimum components EPA must include in all risk evaluations. For each risk evaluation, EPA must publish a document that outlines the scope of the risk evaluation to be conducted, which includes the hazards, exposures, conditions of use, and the potentially exposed or susceptible subpopulations that EPA expects to consider. Each risk evaluation must also: (1) integrate and assess available information on hazards and exposure for the conditions of use of the chemical substance, including information on specific risks of injury to health or the environment and information on relevant potentially exposed or susceptible subpopulations; (2) describe whether aggregate or sentinel exposures were considered and the basis for that consideration; (3) take into account, where relevant, the likely duration, intensity, frequency, and number of exposures under the conditions of use; and (4) describe the weight of the scientific evidence for the identified hazards and exposure. The risk evaluation must not consider costs or other nonrisk factors. A detailed summary and analysis of the final risk evaluation rule is available in our June 26, 2017, memorandum, “EPA Issues Final TSCA Framework Rules.”

Risk Evaluation for HBCD

According to the final risk evaluation, EPA evaluated the following twelve conditions of use for HBCD:

• Importation of HBCD;
   
• Processing of flame retardants: use in custom compounding of resin and solder paste;
   
• Processing of flame retardants: use in manufacture of extruded polystyrene (XPS) and expanded polystyrene (EPS) foam; use in manufacture of structural insulated panels; use in automobile replacement parts from XPS and EPS foam;
   
• Processing: recycling of XPS and EPS foam, resin, panels containing HBCD; electronics waste;
   
• Processing: recycling of electronics waste containing high impact polystyrene (HIPS) that contains HBCD;
   
• Distribution: activities related to distribution;
   
• Use in building and construction materials;
   
• Use in automobile replacement parts;
   
• Use in plastic and other articles;
   
• Use in other formulated products and articles, e.g., adhesives, coatings, textiles, and electronics;
   
• Disposal of construction and demolition waste; and
   
• Disposal of other formulated products and articles, e.g., adhesives, coatings, textiles, and electronics.
   

EPA made the following final risk findings on this chemical. EPA states that in making these unreasonable risk determinations, it considered the hazards and exposure, magnitude of risk, exposed population, severity of the hazard, uncertainties, and other factors.

• EPA found no unreasonable risks to the general population: According to EPA, the general population could be exposed to HBCD either through releases to water and air, through waste disposal, or aggregate general background exposure to HBCD not related to any particular use of the chemical. EPA states that it found no unreasonable risks to the general population from releases to air and water, including drinking water.
   
• EPA found no unreasonable risks to consumers: EPA states that HBCD does not pose an unreasonable risk for use of consumer articles and products or where distributed in commerce. EPA identified no bystanders for HBCD.
   
• EPA found unreasonable risks to the environment from six conditions of use: EPA assessed the impact of HBCD on aquatic and sediment-dwelling species through surface water and sediment exposures, and on terrestrial species. After reviewing these data, EPA states that it found that the import, processing, recycling, commercial use, consumer use, and disposal of HBCD presents unreasonable risks to the environment for growth and development effects, reproductive effects, and mortality. EPA identified unreasonable risks for both acute and chronic exposure scenarios, including potential risks due to trophic transfer of HBCD to higher levels in the food chain due to the chemical’s bioaccumulation and persistence in the environment.
   
• EPA found unreasonable risks to workers and ONUs from two conditions of use involving the use and disposal of HBCD in building and construction materials: EPA states that it found unreasonable risks to workers and ONUs from the use of HBCD in building and construction materials like insulation. According to EPA, unreasonable risks to workers and ONUs can come from both short- and long-term inhalation exposure when personal protective equipment (such as respirators) is not used. The most robust and sensitive endpoints of concern involved acute and chronic inhalation exposure resulting in reproductive/developmental effects and effects on thyroid hormone levels. EPA considered the thyroid hormone changes to be the primary effect resulting from acute and chronic exposure to HBCD, as such changes are associated with all of the other observed downstream endpoints.
   

Because of the Ninth Circuit Court of Appeals ruling in Safer Chemicals Healthy Families v. U.S. Environmental Protection, the risk evaluation includes uses of HBCD that are no longer manufactured, processed, or distributed for use in products and the disposal of those products, otherwise known as “legacy uses” and “associated disposal,” respectively. Accordingly, EPA’s risk evaluation included additional assessments on these uses: general population exposure to HBCD in dust and indoor air released from HBCD-containing products, and articles that are still in use but for which the manufacture, processing, and distribution for such use has ceased. EPA considers these exposures as “background” exposures.

Commentary

As readers recall, there are ten chemicals included in the first tranche of risk evaluations required by the Lautenberg Act. This is the third risk evaluation EPA has issued in final; the first two evaluations were for methylene chloride and 1-bromopropane. According to EPA, the risk evaluations on the remaining seven chemicals are planned for completion by the end of 2020.

The HBCD risk evaluation determined that unreasonable risks to health were presented by a number of conditions of use that EPA evaluated, including compounding of HBCD into XPS, processing of HBCD/XPS mixtures, manufacturing parts from XPS containing HBCD, installation and demolition of building materials containing HBCD, and formulation of flux or solder paste. EPA identified risks from both dermal and inhalation exposure. In some cases, EPA identified unreasonable risk from inhalation even when using respirators with an assigned protection factor of 10 (e.g., an N95 or half-face respirator). In addition, and for the first time in a final risk evaluation, EPA found unreasonable risks to the environment. This determination concerned six conditions of use of HBCD, including: import; processing the chemical as a formulation, mixture, or reaction product; processing the chemical into articles; recycling; commercial installation of building/construction materials; and disposal (demolition). These unreasonable risk determinations involved both acute and chronic exposures to aquatic and terrestrial organisms and, based on HBCD’s persistent, bioaccumulative, and toxic (PBT) characteristics, EPA identified potential risks from trophic transfer along the food chain.

EPA did not find unreasonable risks for the general population and consumers from most conditions of use. In one of its tables, EPA identified one condition of use that lead to an unreasonable risk from fish ingestion at the high-end of exposure. EPA nevertheless states: “Based on risk estimates of exposure to HBCD for various PESS including subsistence fishers and newborns less than 1 year old, EPA did not find unreasonable risk of exposure to HBCD.”

EPA did not find unreasonable risks for workers and ONUs for a number of conditions of use and for the environment for six conditions of use. The six conditions of use that EPA determined do not present unreasonable risk for either health or the environment include: processing: recycling (of electronics waste containing HIPS that contains HBCD); distribution; commercial/consumer use: other -- replacement automobile parts; commercial/consumer use: other -- plastic and other articles; commercial/consumer use: other -- formulated products and articles; and disposal of formulated products and articles. As required by TSCA, the “no unreasonable risk” determinations will be issued by order under Section 6(i)(1).

Risk management efforts will now commence regarding the six conditions of use for which EPA found unreasonable risks, and a final Section 6(a) regulation is required to be issued within three and one half years. In addition, for the conditions of use that were determined not to present an unreasonable risk, these decisions represent final agency actions that are subject to legal challenge. Given the scope of the changes made by EPA in the final risk evaluation response to comments and peer review, it remains to be seen if there will be legal challenges to EPA’s remaining determinations of no unreasonable risk. The petitioners in the Ninth Circuit Court will undoubtedly closely review this risk evaluation and assess whether EPA has sufficiently included legacy uses and other background exposures.