Risk Evaluation for 1,3-Butadiene

In December 2024, EPA released the draft risk evaluation for 1,3-butadiene for public comment and peer review. EPA designated 1,3-butadiene as a high priority chemical in December 2019 and the chemical is currently undergoing risk evaluation.

Find other information about other chemicals undergoing risk evaluations under TSCA.

On this page:

Risk Evaluation Findings
Background on 1,3-Butadiene
Uses of 1,3-Butadiene
Recent Activities and Opportunities for Public Comment
Draft Risk Evaluation and Supporting Documents

Risk Evaluation Findings

EPA’s draft risk evaluation preliminarily shows that 1,3-butadiene presents an unreasonable risk of injury to human health for workers and the general population (including fenceline communities) from inhalation exposure. 1,3-Butadiene is associated with health effects such as reduced birthweight pregnancies, blood and immune system disease, and leukemia.

EPA preliminarily determined that 1,3-butadiene presents an unreasonable risk of injury to human health for workers and the general population (including fenceline communities). Workers may be exposed to 1,3-butadiene when making products or otherwise using 1,3-butadiene in the workplace. Activities like non-routine laboratory technician maintenance activities can also expose workers to 1,3-butadiene through inhalation, which significantly contributes to unreasonable risk. 1,3-Butadiene presents unreasonable risk to the general population, including fenceline communities, when 1,3-butadiene is released into the environment and people breathe it in.

The draft risk evaluation preliminarily shows that consumer uses do not significantly contribute to the unreasonable risk presented by 1,3-butadiene because reasonably available evidence suggests that 1,3-butadiene only exists at trace concentrations in consumer products and articles and is not expected to degrade and expose consumers. The draft risk evaluation also preliminarily shows that there is no unreasonable risk of injury to the environment.

Background on 1,3-Butadiene

1,3-Butadiene (CASRN 106-99-0) is a colorless gas with a mild odor similar to gasoline, and it is highly flammable. Information from the 2016 Chemical Data Reporting (CDR) for 1,3-butadiene indicates the reported production volume is between 1 and 5 billion lbs/year (manufacture and import).

Uses of 1,3-Butadiene

In the final scope, EPA identified conditions of use associated with the manufacturing (including importing); processing; distribution in commerce; industrial, commercial and consumer uses; and disposal of 1,3-butadiene, for example:

As an intermediate in the manufacturing of adhesive, synthetic rubber, organic fiber, plastic material and resin, paints and coatings, and other chemical product and preparation manufacturing;
As an intermediate in the manufacturing of petroleum, petrochemical, and solid rocket fuels;
In adhesives and sealants;
In fuels and related products;
As a laboratory chemical;
In automotive care products;
In lubricants and lubricant additives;
In paints and coatings; and
In plastic and rubber products (including rubber tires).

The above listed conditions of use are ways that a person or the environment could be potentially exposed to this chemical. However, when conducting a risk evaluation, EPA also considers the hazards (i.e. health effects or environmental impacts) that could occur from coming in contact with a chemical.

Recent Activities and Opportunities for Public Comment

In December 2024, EPA released the draft risk evaluation for 1,3-butadiene public comment and peer review. In March 2025, EPA released a supplement to the risk evaluation describing a preliminary refinement of cancer risk estimates from exposure to 1,3-butadiene in air from releasing facilities. These refined facility specific risk estimates provide important updated estimates for incorporation into the risk evaluation.

The current comment period is set to close on March 5, 2025. EPA is extending the comment period for an additional 15 days. Comments can be submitted to docket EPA-HQ-OPPT-2024-0425 at regulations.gov until March 20, 2025. In order to give the peer reviewers on the Science Advisory Committee on Chemicals (SACC) time to review any additional comments received, EPA rescheduled the February 4, 2025, virtual preparatory meeting to March 25, 2025, and the February peer review virtual meeting to April 1-4, 2025. View the SACC website for more information on these meetings, including the registration links and information about how to provide oral comments during the meetings.

In August 2020, EPA published a final scope document outlining the hazards, exposures, conditions of use, and the potentially exposed or susceptible subpopulations the agency expects to consider in its risk evaluation. The agency released the draft scope in April 2020 and took public comments on the draft document.

As EPA continues to move through the risk evaluation process there will be additional opportunities for public comment, including a public comment period on the draft risk evaluation. In addition to public comment periods, EPA will continue to engage with stakeholders as it refines the risk evaluation and stakeholders should reach out to EPA via the staff contact to engage with EPA.

Draft Risk Evaluation and Supporting Documents

Read the Federal Register notice.