On 17 July 2026, the California Office of Environmental Health Hazard Assessment (OEHHA) added four new carcinogenic substances to the California Proposition 65 list. The newly listed substances are: Welding Fumes Hydrochlorothiazide Voriconazole Tacrolimus The addition of these substances requires manufacturers, importers, distributors, and retailers to review their products and supply chains to determine whether products sold in California may expose consumers or workers to these listed chemicals. Where exposures exceed the applicable safe harbor levels (or where no safe harbor level exists and exposures require assessment), businesses may be required to provide Proposition 65 warnings.
OEHHA will host an in-person and online workshop on July 30, 2026, to discuss potential amendments to the Proposition 65 regulations as part of the Omnibus 2026 pre-rulemaking process. OEHHA will publish potential regulatory amendments on its website prior to the workshop. Stakeholders should monitor for proposed changes that may affect warning requirements, listing procedures, or other compliance obligations.
OEHHA opened a 15-day public comment period on proposed modifications to adopt No Significant Risk Levels (NSRLs) for diethanolamine (dermal route) and 1-bromopropane under Proposition 65. The proposal was originally issued August 22, 2025, with modifications now subject to comment through July 2, 2026. Compliance teams should review exposure scenarios for these chemicals and submit comments if applicable.
At the request of the Personal Care Products Council, OEHHA has extended the public comment period for proposed No Significant Risk Levels (NSRLs) for 1-bromopropane and diethanolamine under Title 27, California Code of Regulations, section 25705(b)(1). NSRLs establish safe harbor levels below which businesses are not required to provide Proposition 65 warnings for exposures to listed carcinogens.
OEHHA released a draft document for public review that summarizes the carcinogenicity data and derives a cancer inhalation unit risk factor (IUR) for acrolein under Proposition 65. The IUR is a quantitative value used to calculate cancer risk from inhalation exposure, which helps businesses determine whether Proposition 65 warnings are required for products or activities involving acrolein exposures.
OEHHA issued a Notice of Intent to list “welding fumes” as a chemical known to the State of California to cause cancer under Proposition 65, using the Labor Code listing mechanism (ministerial listing pathway). OEHHA opened a public comment period running from May 8, 2026 through June 8, 2026. If finalized, the listing would require companies with relevant products/operations (e.g., welding processes, fabricated metal products, equipment, workplace exposures) to assess whether exposures are “significant” and whether Proposition 65 warnings or other risk management actions are needed.
OEHHA published a Notice of Intent (NOI) indicating it intends to list “welding fumes” as a chemical known to the State of California to cause cancer using the Labor Code mechanism incorporated into Proposition 65. OEHHA opened a public comment period (comments due by June 8, 2026). If the listing proceeds, businesses involved in activities, products, or workplaces that may result in significant exposures to welding fumes may need to assess exposure scenarios and potential Proposition 65 warning obligations once any listing becomes effective and applicable warning timelines run.
OEHHA published a Notice of Intent to List (NOIL) indicating it intends to add hydrochlorothiazide, voriconazole, and tacrolimus to the Proposition 65 list as chemicals known to the State of California to cause cancer, using the Labor Code (IARC-based) listing mechanism. OEHHA opened a written public comment period limited to whether IARC sufficiently identified the specific chemicals as human/animal carcinogens. Compliance teams should monitor this action because a final listing would trigger downstream Proposition 65 evaluation and, where applicable, warning/notification obligations for products or exposures involving these substances once listed.
OEHHA issued a request for relevant information regarding the carcinogenicity of ethoprop as part of the Proposition 65 Carcinogen Identification Committee (CIC) process, indicating a potential delisting review pathway. Compliance teams that manufacture, distribute, or sell products that may involve ethoprop should monitor this review because a future delisting decision could change warning obligations, but no delisting has occurred at this stage.
OEHHA has issued a data call-in for ethoprop, seeking relevant scientific information on whether the chemical has been clearly shown to cause cancer. Ethoprop was added to the Proposition 65 list on February 27, 2001 based on EPA's classification as a 'likely' human carcinogen. In 2020, EPA revised this classification, prompting OEHHA to seek public input to determine if ethoprop should remain on the Prop 65 list. This affects companies with products containing ethoprop, including pesticide manufacturers and agricultural suppliers.
OEHHA posted a Request for Relevant Information on the carcinogenicity of ethoprop, indicating the chemical is being referred to the Carcinogen Identification Committee (CIC) for review for possible delisting from the Proposition 65 list. This is not a final delisting, but it is an official step in the delisting evaluation process and invites stakeholders to submit relevant data within OEHHA’s stated information-request window. Compliance teams tracking Proposition 65-listed substances should monitor this proceeding because it could eventually change listing status and related warning/enforcement exposure for ethoprop.
OEHHA posted a request for relevant information on the carcinogenicity of ethoprop and indicated the substance is being referred to the Carcinogen Identification Committee (CIC) for review for possible delisting. This initiates a stakeholder input/data submission process that could ultimately lead to a delisting decision. Compliance teams using ethoprop in products or operations should monitor the review, consider submitting relevant toxicology/exposure data, and be prepared to adjust Prop 65 warning determinations if OEHHA proceeds with delisting or maintains the listing.
OEHHA issued a request for relevant information regarding the carcinogenicity of ethoprop in connection with a Carcinogen Identification Committee (CIC) review that could result in a potential delisting under Proposition 65. Compliance teams should monitor this proceeding because a delisting could change warning/settlement exposure for products/operations involving ethoprop; however, no delisting decision is indicated in the provided sources.
OEHHA added N‑methyl‑N‑formylhydrazine to the Proposition 65 list as a chemical known to cause cancer. Businesses selling products in California should evaluate whether the chemical is present in products or workplace/consumer exposure scenarios and determine if Prop 65 warning, reformulation, or exposure mitigation actions are needed based on anticipated exposure pathways.
OEHHA added N-methyl-N-formylhydrazine to the Proposition 65 list as a carcinogen effective December 8, 2025. The listing was done via the 'State's Qualified Experts' mechanism based on the Carcinogen Identification Committee's determination that this chemical was clearly shown to cause cancer. Businesses have a one-year grace period until December 8, 2026 to provide warnings for significant exposures.
OEHHA’s listing notice for N‑methyl‑N‑formylhydrazine indicates that while the chemical was added to the Proposition 65 list as a carcinogen effective December 8, 2025, the warning requirement for significant exposures takes effect on December 8, 2026 (the 12‑month grace period). Compliance teams should ensure product exposure assessments, labeling/artwork changes, online warning updates, and supply-chain communications are completed ahead of the December 8, 2026 warning-trigger date for this substance.
OEHHA added the developmental toxicity endpoint to the existing reproductive toxicity listing for Bisphenol S (BPS) under Proposition 65. This addition was made via the State's Qualified Experts listing mechanism based on the Developmental and Reproductive Toxicant Identification Committee's determination that BPS was clearly shown to cause developmental toxicity. Products containing BPS sold in California may now require warnings for developmental toxicity exposures in addition to reproductive toxicity.
OEHHA issued an information letter regarding Proposition 65 warning requirements for items such as receipts and shipping labels that may contain bisphenol S (BPS). The letter provides guidance on warning obligations following the listing of BPS for reproductive toxicity endpoints.
OEHHA added the developmental toxicity endpoint to the existing Proposition 65 listing for bisphenol S (BPS) effective December 8, 2025. This expands the reproductive toxicity listing which already included female reproductive toxicity (listed December 29, 2023) and male reproductive toxicity (listed January 3, 2025). Warning requirements for the developmental toxicity endpoint are effective December 8, 2026.
OEHHA added N-methyl-N-formylhydrazine to the Proposition 65 list as a chemical known to cause cancer (effective December 8, 2025). Compliance teams should evaluate whether products, emissions, or workplace activities could expose individuals in California to this substance and whether Prop 65 warnings or exposure assessments are required.