The U.S. Environmental Protection Agency (EPA) published on July 1, 2019, a Federal Register notice announcing the availability of the 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). 84 Fed. Reg. 31315. EPA states that the purpose of the risk evaluations is to determine whether a chemical substance presents an unreasonable risk to health or the environment under the conditions of use, including an unreasonable risk to a relevant potentially exposed or susceptible subpopulation. EPA states in its press release that in the draft risk evaluation for HBCD, it did not find unreasonable risk to the general population, consumers, workers, or the environment. According to the press release, in the draft risk evaluation for 1,4-dioxane, EPA states that while it did not find unreasonable risk to the environment, the data “show there could be unreasonable risks to workers in certain circumstances.” EPA states: “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.” EPA is submitting these same documents to the TSCA Science Advisory Committee on Chemicals (SACC) for peer review. SACC will hold a five-day in-person meeting on July 29-August 2, 2019, to consider and review these draft risk evaluations. Preceding the in-person meeting, there will be a three-hour preparatory virtual meeting on July 10, 2019, for SACC to consider the scope and clarity of the draft charge questions for the peer reviews. Comments on the draft risk evaluations are due August 30, 2019.
EPA states in the Federal Register notice that it is seeking public comment on all aspects of the draft risk evaluations, “including any conclusions, findings, determinations, and the submission of any additional information that might be relevant to the science underlying the risk evaluations and the outcome of the systematic review” associated with HBCD and 1,4-dioxane. In addition to any new comments on the draft risk evaluations, EPA asks that commenters resubmit or clearly identify any previously filed comments, modified as appropriate, that are relevant to the risk evaluations and that the submitter feels have not been addressed.
EPA is also submitting these same documents to SACC for peer review. According to EPA, all comments submitted to the dockets for consideration by SACC by the comment deadline will be provided to the SACC peer review panel, which will have the opportunity to consider the comments during its discussions.
TSCA Section 6, as amended by 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.”
Draft Risk Evaluation for HBCD
EPA’s fact sheet on the draft risk evaluation for HBCD provides the following chemical description:
- A flame retardant used primarily in construction materials, which may include structural insulated panels (SIPS);
- Use has declined dramatically over the past few years, primarily due to the use of replacement chemicals; and
- Domestic U.S. manufacturers have indicated complete replacement of HBCD in their production lines.
According to the fact sheet, EPA looked at the following conditions of use associated with the manufacturing (including import), processing, distribution, use, and disposal of HBCD:
- Importation for manufacturing;
- Processing of flame retardants used in custom compounding of resin;
- Processing of flame retardants used in plastics product manufacturing;
- Recycling of foam and resin panels;
- Building and construction materials;
- Automobile replacement parts;
- Recycled plastics; and
- Disposal of construction and demotion waste.
EPA made the following initial determinations on risk:
- No unreasonable risks for the general population, including consumers and children. HBCD is no longer domestically manufactured or imported in the U.S. and has been replaced by other chemicals. Calculated risk estimates are below levels of concern.
- No unreasonable risks to workers or occupational non-users. Again, HBCD is no longer domestically manufactured or imported in the U.S. and has been replaced by other chemicals. The use of HBCD does not present unreasonable risks to workers and applies to both those workers who come in direct contact with HBCD, as well as those who use the chemical but do not come in direct contact.
- No unreasonable risk to the environment. For all the conditions of use included in the draft risk evaluation, EPA found no unreasonable risks to the environment from HBCD.
EPA notes that “[t]hese initial determinations may change as our assessment becomes more refined through the public and peer review process.” EPA’s web page on the draft risk evaluation for HBCD includes a number of supporting documents, as well as the charge questions for SACC.
Draft Risk Evaluation for 1,4-Dioxane
EPA’s fact sheet for 1,4-dioxane includes the following chemical description:
- Used primarily as a solvent in a variety of commercial and industrial applications such as in the manufacture of other chemicals, as a processing aid, in laboratory chemicals, and in adhesives and sealants.
- No consumer uses for 1,4-dioxane were reported in the U.S. in the 2016 Chemical Data Reporting (CDR). EPA did not find evidence of consumer uses besides presence as a contaminant in consumer products, and as explained in the problem formulation document for 1,4-dioxane, such activities will be considered in the scope of the risk evaluation for ethoxylated chemicals.
- 2016 CDR data show only two manufacturers were producing or importing more than 1 million pounds of 1,4-dioxane in the U.S. in 2015.
According to the fact sheet, in the draft risk evaluation, EPA looked at 14 conditions of use associated with the manufacturing (including import), processing, distribution, use, and disposal of 1,4-dioxane, including:
- Processing aids (not otherwise listed) (270,000 pounds (lbs.));
- Functional fluids in open and closed systems (<150,000 lbs.);
- Laboratory chemicals (<150,000 lbs.);
- Adhesives and sealants (professional film cement);
- Spray polyurethane foam;
- Printing and printing compositions;
- Disposal of waste materials containing 1,4-dioxane; and
- Dry film lubricant.
The fact sheet states: “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.” The fact sheet lists the following initial determinations on risk:
- No unreasonable risks to occupational non-users. EPA found no unreasonable risks to workers in the general area of 1,4-dioxane use but not directly in contact with the chemical;
- Unreasonable risks to workers in certain circumstances. These initial determinations are based on a draft assessment of the reasonably available information and are not EPA’s final determinations on whether this chemical presents unreasonable risks under the conditions of use. EPA states that it will use the feedback received from the public and peer review processes to inform the final risk evaluations; and
- No unreasonable risk to the environment. For all the conditions of use included in the draft risk evaluation, EPA found no unreasonable risks to the environment from 1,4-dioxane.
EPA notes that “[t]hese initial determinations may change as our assessment becomes more refined through the public and peer review process.” EPA’s web page on the draft risk evaluation for 1,4-dioxane includes a number of supporting documents, as well as the charge questions for SACC.
The two chemicals most recently assessed by EPA are more complicated and data-rich than Pigment Violet 29 (PV29). The page counts alone reflect this. Where the risk evaluation for PV29 had just over 40 pages, the newly released risk evaluations are considerably longer, with 407 and 570 pages for 1,4-dioxane and HBCD, respectively. The more robust databases and the more complex pattern of hazards, exposures, and uses will help to demonstrate more specifics of EPA’s TSCA Section 6(b) approach to hazard and exposure assessment and risk characterization.
We note a few points to consider as EPA progresses the risk evaluations and moves on to risk management. For HBCD, EPA’s assessment seems to be predicated on the phase-out in the market. If there truly is no longer any manufacturing or importing of HBCD, EPA may propose a Significant New Use Rule (SNUR) barring future manufacture or import (a “dead chemical SNUR”). Such a SNUR would effectively lock the door to future HBCD use.
For 1,4-dioxane, EPA deferred assessing risk from the presence of 1,4-dioxane as an impurity in consumer products, focusing instead on intentional uses. This seems to us to be a sensible approach since EPA only found potential risk in workplace settings. It is unlikely that exposures to low levels in consumer products will reach a level that would trigger concerns. Also, EPA will have an opportunity to review the exposure to 1,4-dioxane impurities in an ethoxylated surfactant when EPA evaluates the risk associated with the surfactant. By deferring review of 1,4-dioxane-as-impurity, EPA also defers having to address the more complicated truth that a significant amount of the use of surfactants is in personal care products that are excluded from TSCA authority.
EPA identified potential risk to workers, even considering that workers would use personal protective equipment (PPE) such as gloves and respirators. It is surprising that exposures would be sufficiently high to trigger concerns when using PPE. 1,4-Dioxane may lead EPA to impose specific worker protection requirements that are more stringent than what would otherwise be required by the Occupational Safety and Health Administration (OSHA).
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