On November 13, 2024, the U.S. Environmental Protection Agency (EPA) released its final supplement to the risk evaluation and determination for the solvent 1,4-dioxane under the Toxic Substances Control Act (TSCA). The updated assessment no longer assumes that workers are consistently using proper personal protective equipment (PPE), addressing this in the risk management process. The evaluation also highlights gaps in the 2020 review, including the omission of general population exposure via drinking water and air, aggregate risks, and potential impacts on fenceline communities.

Uses, Exposures and Risks Associated with 1,4-Dioxane

1,4-Dioxane (CAS 123-91-1) is a solvent used in a variety of commercial and industrial applications. It is found in laboratories, in cleaning products such as dish soaps and laundry detergents, and in the production or processing of chemicals such as adhesives and sealants. It is often generated as a byproduct in manufacturing processes, leading to its presence as a contaminant in consumer products.

Products containing 1,4-dioxane can contaminate surface water when washed down the drain. Exposure to this chemical may occur through consumer products, workplace environments, or contaminated water and air, often due to industrial or commercial discharges.

EPA has determined that 1,4-dioxane poses an unreasonable risk to workers, nearby communities, and those who may be more sensitive to 1,4-dioxane due to factors such as age or pre-existing health conditions, citing its links to cancer, liver toxicity, and nasal tissue damage. The risks stem from inhalation and skin exposure during industrial use and from its presence as a byproduct in commercial products.

These groups could be exposed to 1,4-dioxane in drinking water, particularly in areas where water sources include smaller or slow-flowing streams that have been contaminated by industrial discharges. Additionally, runoff from households that use products containing 1,4-dioxane, such as dish soap, laundry detergent, and surface cleaners, could contribute to contamination.

1,4-Dioxane does not pose an unreasonable risk to the environment. 

Next Steps

EPA will propose a rule under TSCA Section 6 to protect public health from the identified risks of 1,4-dioxane. In line with TSCA Section 9(b), EPA is coordinating efforts across its agencies, including potential actions under the Safe Drinking Water Act (SDWA), to manage risks related to 1,4-dioxane contamination of drinking water. Both EPA’s Office of Chemical Safety and Pollution Prevention (OCSPP) and Office of Water (OW) are working together to address these concerns.

Additional Information

Conditions of Use identified in the 2020 risk evaluation and 2024 supplement as contributing significantly to unreasonable risk include:

• Manufacture and Import
• Processing (e.g., repackaging, recycling, non-incorporative uses)
• Industrial/Commercial Use (e.g., intermediates, processing aids, metalworking fluids, adhesives, sealants, hydraulic fracturing)
• Consumer Use (e.g., dish soap, laundry detergent, paint)
• Disposal

Conditions of Use that do not significantly contribute to unreasonable risk are:

• Distribution in commerce
• Commercial use of automobile antifreeze, textile dyes, and spray polyurethane foam.

1,3-Butadiene Peer Review Will Follow Suit

On November 14, 2024, EPA announced a call for public comments on candidates to assist the Science Advisory Committee on Chemicals (SACC) in reviewing the draft Toxic Substances Control Act (TSCA) risk evaluation for 1,3-butadiene.

1,3-Butadiene (CAS 106-99-0) is a highly flammable, colorless gas with a gasoline-like odor. It is used in the manufacture of products such as rubber tires, plastics, adhesives, paints, and automotive care products.

The SACC is a scientific peer review body for EPA's Office of Chemical Safety and Pollution Prevention that provides independent advice and recommendations on risk assessments, methodologies, and pollution prevention strategies for chemicals regulated under TSCA.

The peer review will take place in early 2025 and will guide the final risk evaluation.

On October 31, 2024, the U.S. Environmental Protection Agency (EPA) finalized revisions to existing regulations under the Toxic Substances Control Act (TSCA) for two persistent, bioaccumulative, and toxic (PBT) chemicals—Decabromodiphenyl Ether (decaBDE) and Phenol, Isopropylated Phosphate (PIP (3:1)). This new rule aims to address implementation challenges and reduce potential human and environmental exposure to these hazardous substances.

Background

These revisions build on the final rules originally established in January 2021, which targeted five PBT chemicals identified for expedited action under TSCA Section 6(h). Following feedback from stakeholders and further analysis, EPA determined that additional measures were necessary for decaBDE and PIP (3:1). The revisions are designed to clarify compliance requirements, extend certain compliance deadlines, and provide more robust protections particularly in sectors such as agriculture, construction, life sciences, and mining.

Key Changes to the DecaBDE Regulations

DecaBDE (CAS 1163-19-5) is widely used as a flame retardant in a variety of industries, particularly in textiles, electronics, and automotive parts. The updated rule introduces several significant changes:

• Personal Protective Equipment (PPE) Requirements: Companies involved in manufacturing, processing, or distributing decaBDE must now ensure the use of PPE to limit worker exposure.
• Prohibition on Water Releases: The release of decaBDE into water during its manufacture and processing is now banned, reflecting heightened concerns over its environmental impact.
• Extended Compliance for Specific Uses: EPA has extended the compliance deadline for the use of decaBDE in wire and cable insulation for nuclear power facilities, recognizing the critical nature of this application. Similarly, companies must notify authorities when exporting decaBDE-containing materials for nuclear power uses.
• Threshold for Unintentional Presence: The rule allows a minimal presence of decaBDE (less than 0.1% by weight) in products, recognizing the challenges of completely eliminating trace amounts from complex supply chains.

Updates to PIP (3:1) Regulations

PIP (3:1) (CAS 68937-41-7) is commonly used as a flame retardant and plasticizer in hydraulic fluids, lubricants, and electronic components. The revised regulations include:

• Expanded PPE Requirements: Similar to decaBDE, EPA is mandating the use of PPE for handling PIP (3:1) during its domestic manufacturing and processing.
• Phase-Out of Certain Uses: The rule imposes a gradual phase-out of PIP (3:1) for specified applications while allowing exemptions for critical uses, such as wire harnesses and circuit boards, until suitable alternatives are found.
• Exemptions for Replacement Parts: The regulation introduces provisions for the continued use of PIP (3:1) in replacement parts for existing equipment, thereby minimizing disruptions in industries such as aerospace and automotive manufacturing.
• 10-year grace period to phase out the use of PIP (3:1) in parts for new equipment: The extended timeline applies to manufacturing and industrial machinery, commercial electronic equipment, refrigeration, water-heating systems, power-generating equipment, etc.

This allowance is intended to give industries sufficient time to transition to alternatives while maintaining compliance with the new safety standards.

The Agency highlighted the importance of reducing exposure to these toxic substances, which have been linked to adverse health effects, including developmental and neurological harm, as well as environmental damage.

Additional requirements 

The Final rule introduces new workplace safety measures to minimize dermal and respiratory exposure, although certain import and processing applications are exempt. Recordkeeping requirements have been extended from three to five years, with companies now required to have compliance records "readily available" for prompt review, eliminating the previous 30-day grace period.

For continued use of PIP (3:1), companies must update safety data sheets (SDSs) within three months and product labels within 18 months. The rule does not change existing requirements for the other three PBT chemicals regulated under the January 2021 rule: 2,4,6-tris(tert-butyl)phenol (2,4,6-TTBP), hexachlorobutadiene (HCBD), and pentachlorothiophenol (PCTP).

The rule is set to take effect 60 days after its publication in the Federal Register, with extended compliance dates for certain sectors.