California OEHHA Issues Notice of Intent
Listing Welding Fumes via Labor Code Mechanism
5/20/2026 (OEHHA Published: May 8, 2026)
This notice relates to the chemical listing framework under California’s Proposition 65 (Safe Drinking Water and Toxic Enforcement Act of 1986).
The California Office of Environmental Health Hazard Assessment (OEHHA) has determined that welding fumes meet the criteria for listing under the applicable regulatory framework.
What Are Welding Fumes?
Welding fumes are a mixture of airborne particles and gases generated during welding operations. They may contain metal components such as chromium, nickel, and manganese, among others. Long-term inhalation exposure has been associated with potential health risks.
Regulatory Framework Under Proposition 65
The listing of chemicals under Proposition 65 is governed by a combination of California health and labor law provisions.
Health and Safety Code Section 25249.8(a) incorporates provisions of California Labor Code Section 6382(b)(1) into the Proposition 65 listing mechanism.
Under this framework, substances identified by authoritative bodies such as the International Agency for Research on Cancer (IARC) may be included as chemicals "known to the State of California to cause cancer."
Labor Code Section 6382(b)(1) covers substances identified by IARC as carcinogenic to humans or experimental animals.
Detailed implementing regulations are set forth in Title 27 of the California Code of Regulations, Section 25904, under which OEHHA evaluates whether listing is legally required.
OEHHA Evaluation and Classification of Welding Fumes
OEHHA has evaluated welding fumes and determined that they meet the criteria for listing under Proposition 65, pursuant to 27 CCR §25904(b)(1).
This determination is based in part on the scientific evaluation conducted by the International Agency for Research on Cancer (IARC).
In 2018, IARC Monographs Volume 118 classified welding fumes as Group 1 (carcinogenic to humans).
IARC further concluded that there is sufficient evidence of carcinogenicity in humans associated with welding fume exposure.
Relevant Developments at the U.S. EPA
The U.S. Environmental Protection Agency (EPA) continues to assess industrial emissions, including constituents of welding fumes, in the context of Hazardous Air Pollutants (HAPs).
There is increasing regulatory and scientific attention on exposure control and emission reduction in industrial settings.
Implications for Businesses
For companies manufacturing or exporting products to the United States, or conducting business in California, evaluating welding fume exposure pathways is an important compliance consideration.
Proposition 65 is widely recognized as a litigation-driven regulatory framework.
As a result, businesses may need to consider warning requirements, supply chain responsibilities, and contractual risk allocation.
Accordingly, companies are encouraged to assess potential exposures early and implement appropriate compliance and risk management measures.
