In December 2016, the U.S. Environmental Protection Agency (EPA) published the first 10 chemical substances for evaluation under the Toxic Substances Control Act (TSCA), which was revised in June 2017 through Congress via the Frank R. Lautenberg Chemical Safety Act. These 10 substances were selected from 90 chemicals listed in the 2014 update of EPA’s TSCA Work Plan for Chemical Assessments.
One of the 10 substances selected was asbestos, a naturally-occurring fibrous mineral. In February 2014, EPA convened a public meeting to obtain input to assist them in establishing the scope of the risk evaluations under development for the 10 substances. In June 2017, EPA provided new rules, guidance, and scoping documents for risk evaluation of these chemicals, including for asbestos.
Scoping Document for Risk Evaluation of Asbestos
The scoping document for asbestos – defined as including all six asbestos fiber types (chrysotile, crocidolite, amosite, anthophyllite, tremolite, and actinolite) – identifies the conditions of use, hazards, exposures, and potential susceptible populations.
- Conditions of Use – Imported asbestos is used almost exclusively in the chlor-alkali industry for manufacture of semi-permeable diaphragms and, less so, in the use of sheet gaskets as containment seals during the manufacture of titanium dioxide. These industries were identified as known processors/users. Other “evidence of use” industries included gaskets and packing, adhesives and sealants, roof and non-roof coatings, oilfield equipment, and aftermarket friction products.
- Hazards – EPA described both environmental hazards and human health hazards (non-cancer, cancer, and genotoxic). Lung cancer and mesothelioma were the primary focus, with “suggestive evidence” for cancer of the pharynx, stomach, and colorectum.
- Exposures – Environmental and human exposures were discussed. Human exposures include occupational (direct and indirect), consumer, and general population exposures. Although dermal and oral exposure routes were discussed, inhalation was considered the most likely exposure route. Indoor and outdoor air pathways were noted in conceptual site models.
- Potentially Susceptible Populations – EPA identified the following as potentially exposed or susceptible subpopulations: workers and occupational non-users (indirectly exposed), consumers and bystanders of consumer use, and individuals living or working near point sources (manufacturing, processing, use or disposal sites). Specialty groups such as fire fighters were also noted.
Much of the use of asbestos in the United States was diminished in the 1970s and 1980s with the development of suitable alternatives for certain applications, and asbestos has not been mined or otherwise produced in the U.S. since 2002. As such, legacy uses (e.g., pipeline wrap, cement sheets, shingles, clutch facings, floor tiles) and associated legacy disposals were specifically excluded from the scope of the risk evaluation. “Libby amphibole” associated with vermiculite ore near Libby, Montana, was also excluded.
How Can Exponent Help?
- Exponent is a multi-disciplinary engineering and scientific consulting firm that brings together more than 90 different disciplines to solve important engineering, science, regulatory, and business issues facing our clients.
- Exponent has considerable experience in various aspects of asbestos-related research, including expertise in the disciplines needed to evaluate health risks associated with different types of asbestos exposures. Exponent’s consultants can help you evaluate exposures and health effects in the occupational, para-occupational, bystander, and domestic environment.
- Exponent’s TSCA regulatory consultants can help you evaluate your product in anticipation of scoping documents being published and, once published, determine if your product is subject to exemptions included in the rule and how to comply with recordkeeping and reporting requirements under the new rule.
- Our regulatory and health consultants can prepare exposure estimates based on the use pattern, evaluate existing data on environmental and health effects, and provide advice concerning acquisition of additional data.
- Exponent can assist in evaluating and re-formulating historical products for purposes of exposure simulation, and has expertise in visualizing and characterizing asbestos-containing products in our technical laboratories.