On July 25, 2024, the US Environmental Protection Agency (EPA) proposed to designate acetaldehyde (CASRN 75-07-0), acrylonitrile (CASRN 107-13-1), benzenamine (CASRN 62-53-3), vinyl chloride (CASRN 75-01-4), and 4,4-methylene bis(2-chloroaniline) (MBOCA) (CASRN 101-14-4) as high-priority substances for risk evaluation under the Toxic Substances Control Act (TSCA). A high-priority designation marks the first step toward EPA performing a risk evaluation of a chemical, which could lead to a risk management regulation imposing significant restrictions on uses of the chemical, including products containing the chemical. Companies involved in the manufacture, import, processing, distribution, use or disposal of these widely used chemicals or products containing them should take note that EPA is considering them for potential evaluation and restrictions in the future.

High Priority Chemicals

Under TSCA Section 6, a high-priority substance is a substance that EPA determines “may present an unreasonable risk of injury to health or the environment” because of potential hazard and exposure under the conditions of use, including an unreasonable risk to potentially exposed or susceptible subpopulations. In proposing the five chemicals for high-priority designation, EPA considered their conditions of use and production volume or changes in conditions of use and production volume over time, hazard and exposure potential, and impacts to potentially exposed or susceptible subpopulations, including children, consumers, workers, and overburdened communities. The chemicals’ persistence and bioaccumulation and whether they are stored near significant sources of drinking water are also relevant criteria.

If EPA finalizes its proposed high-priority designations for these substances, EPA will proceed to release scoping documents defining the scope of the risk evaluations and will conduct risk evaluations to determine whether the substances present an unreasonable risk to human health or the environment. If EPA does find that the substance presents an unreasonable risk, EPA must propose risk management rules, such as bans, worker protection programs, concentration limits, labeling, notification, and other restrictions to the extent necessary to eliminate the unreasonable risks. EPA must complete the risk evaluation process within 3-3.5 years and the risk management process within 2 years of the final risk evaluation.

Notably, EPA has been significantly delayed in these timelines for other high-priority substances that are still undergoing risk evaluations. There are currently 24 high-priority chemicals that are still undergoing the risk evaluation process. EPA has announced the goal of releasing more information about high-priority substances earlier in the process to attempt to gather more data on uses from stakeholders about high-priority chemicals, resulting in more efficient and informed risk evaluations and risk management rules.

Uses of the Five High Priority Chemicals

EPA released high priority designation documents for each of the five chemicals. The documents detail why under the statutory criteria EPA believes they warrant a high priority designation. In particular, EPA outlines the conditions of use of each chemical that it is aware of based on publicly available data such as TSCA Chemical Data Reporting (CDR) rule data, Toxics Release Inventory (TRI) exposure data, safety data sheets, and other EPA databases. Below, we outline the conditions of use that EPA has identified in these high-priority designation documents.

Companies should be aware that these uses are likely to be included in risk evaluations for these chemicals and potentially regulated in the future:

Acetaldehyde

Acetaldehyde is used as an intermediate in chemical, petrochemical and adhesive manufacturing, as well as an intermediate in packaging (excluding food packaging). It has commercial uses in adhesives, sealants, plastic and rubber products, golf and sports turf, agricultural non-pesticidal products, and paper products. Additionally, EPA identified acetaldehyde in commercial use for construction and building materials, including paper articles; metal articles; stone, plaster, and cement; and glass and ceramic materials.

Acetaldehyde is also used in consumer paints and coatings, plastic and rubber products, paper products, leather cleaning products, surface cleaners, wood polish, car degreaser and wax, motor oil, caulking, surface sealer, drywall, home insulation, automobile components, imaging products such as cameras and camcorders, displays, projectors, audio equipment, broadcasting systems, harnesses, cables, sheets, films, blankets, jewelry, clothing, and children’s products such as toys and games.

Acrylonitrile

Acrylonitrile is used primarily in the manufacturing and processing of plastics, paints, fibers, rubber, petrochemicals, adhesive and sealant, and other chemicals. Acrylonitrile is used as an intermediate and a monomer in manufacturing chemical products such as plastic material and resins, synthetic rubber, organic fibers, and paints and coatings. Other conditions of use of acrylonitrile include soaps and detergent manufacturing; surface active agent manufacturing; photographic film, paper, plate and chemical manufacturing; petroleum refineries; bulk gasoline terminals; pulp and paper; ferrous metals, and as a solvent in degreasing.

Consumer products reported to contain acrylonitrile include auto adhesives, batteries, multipurpose adhesive, printer inks, paint/stain products, surface sealers and upholstery, glues, coloring pens, corrective fluid, food packaging, clothing, textiles, furnishings, audio equipment, automobile construction, automobile equipment, battery cases, broadcasting systems, carbon fiber, displays, fans, imaging products such as cameras and camcorders, optical units, projectors, and nitrile gloves. EPA also identified acrylonitrile uses in several children’s products, including craft supplies, toys, games, bibs, and clothing.

Benzenamine

Benzenamine (also referred to as aniline) is used as an intermediate in chemical, petrochemical, pesticide, fertilizer, and other agricultural chemical, plastics, resins and synthetic dyes and pigment manufacturing. Benzenamine is also processed as a reactant in dyes in synthetic dye and pigment manufacturing and dyes in textiles, leather, and apparel manufacturing. Benzenamine is a processing aid and heat transfer agent for several industrial uses. It is also used in inks, toner, color products, rubber tires, textile (fabric) products, as well as furniture and furnishings, including soft plastic articles and leather articles.

Other conditions of use of benzamine include brightener in paper manufacturing, soaps and detergents, pH regulators, water treatment products, degreasing, and industrial surface coating and solvent use. Additionally, benzamine is present in consumer products such as fabric, jewelry, paints and coatings, fuels, batteries, speaker systems, audio equipment, imaging products such as cameras and camcorders, broadcasting systems, cable parts, magnetics, switch holders, seals, housings, ink, optical whitening agents, and children’s products such as toys and apparel.

Vinyl chloride

Vinyl chloride is primarily used to manufacture and process plastic materials such as polyvinyl chloride (PVC), plastic resins, and other chemicals, many of which are used for pipes and insulating materials. It is used as an intermediate, binder, and monomer in plastic material and resin manufacturing, as well as an intermediate in manufacturing products such as adhesives, industrial gas, and petrochemicals. Additional conditions of use of vinyl chloride include other basic inorganic chemical manufacturing, plastics, rubber products, unlaminated plastics film and sheet (except packaging) manufacturing, pulp and paper, ferrous and non-ferrous metals, degreasing, and industrial surface coating and solvent use.

Consumer products reported to contain vinyl chloride include adhesives and sealants, paints and coatings, furniture and furnishings, floor coverings, fabric, agricultural and food packaging, medical devices, vinyl wallcovering and roofing, upholstery, instrument and door panels, convertible tops, swimming pool and industrial liners, sporting goods, luggage, briefcases, accessories, adhesives, glues, inks, and children’s products such as toys and apparel.

4,4-methylene bis(2-chloroaniline) (MBOCA)

MBOCA is used in plastic material, resin, synthetic rubber, and paint and coating manufacturing. It is also used as a plasticizer in plastic and rubber products. Other MBOCA uses include degreasing and industrial surface coating and solvent use; processing as a curing agent (epoxy resins); and as an intermediate in polyurethane elastomers to produce polyurethane foams. Additionally, MBOCA may be present in consumer products such as golf balls, robot wheels, roller skate wheels, high-load wheels for platform and tool-box carts, sports boots, shoe soles, belts, belts and rollers used in computer printers and photocopy machines, paper, and corrugated cardboard.

Comment Period

EPA is interested in receiving comments on these proposed high priority designations that would inform its hazard and exposure assessment, as well as identify conditions of use it could include in a risk evaluation. Comments must be received on these proposed designations on or before October 23, 2024. Companies who use these chemicals may want to provide EPA with data about how they use these chemicals in their facilities, including what current worker protections are used or whether there are restrictions or limitations on how the substance is used in consumer products, so that EPA can have the most updated information about the real-world applications of these substances.