Navigating California Proposition 65: Your Quick Guide to the Latest Changes
This blog was originally posted on 4th February, 2026. Further regulatory developments may have occurred after publication. To keep up-to-date with the latest compliance news, sign up to our newsletter.
AUTHORED BY LUISA TORO CORREA, REGULATORY COMPLIANCE SPECIALIST, COMPLIANCE & RISKS
California’s Proposition 65 landscape continues to shift. Recent actions in 2025 by the Office of Environmental Health Hazard Assessment (OEHHA) include new chemical listings, expanded toxicity endpoints, finalized and proposed No Significant Risk Levels (NSRLs), and important updates to warning regulations.
Below is a summary of the most recent Proposition 65 developments and their potential implications for future compliance obligations.
Proposition 65: A Quick Overview
What Is Proposition 65?
California’s Proposition 65, formally known as the Safe Drinking Water and Toxic Enforcement Act of 1986, is a right to know law designed to protect public health. It requires businesses to inform people if they may be exposed to chemicals known to cause cancer, birth defects, or other reproductive harm, and it restricts the discharge of those chemicals into drinking water sources.
Who Oversees the Law?
The law is overseen by the California Office of Environmental Health Hazard Assessment (OEHHA), which maintains the official list of chemicals and develops regulations that explain how the law is applied in practice. OEHHA also establishes “safe harbor” exposure level thresholds, and any levels below these thresholds are generally not subject to warnings.
What About Warning Labels?
One of the most recognizable parts of Proposition 65 is its warning requirement. Detailed regulations specify what qualifies as a “clear and reasonable” warning and provide specific guidance for different products and environments, from consumer goods and food to housing, vehicles, and hospitality settings. Because science and products evolve, the rules are updated regularly through California’s public rulemaking process.
Why Does It Matter?
For businesses, compliance can mean testing products, evaluating exposures, and updating labels. For consumers, Proposition 65 provides greater transparency about potential chemical exposures in everyday life.
Changes to Proposition 65 Warning Regulations
Effective 1 January 2025
OEHHA amended the “Clear and Reasonable Warnings” regulations to make short-form warnings more informative.
Highlights of the key changes include:
- Short-form warnings must include at least one chemical name
- Businesses have three years to transition to the new short-form content
- Short-form warnings are now explicitly allowed for food products
- A 60-day transition period is provided for retailers updating online warnings after manufacturer’s notice
- New tailored safe harbor warnings for: passenger and off-highway motor vehicle parts and recreational marine vessel parts
Chemicals Added to the Proposition 65 List
Bisphenol S (BPS) Added for Male Reproductive Toxicity
Effective 3 January 2025
OEHHA added the male reproductive toxicity endpoint for BPS based on the Developmental and Reproductive Toxicant Identification Committee (DARTIC’s) determination that the chemical was clearly shown to cause male reproductive harm. This expanded the original 2023 listing for female reproductive toxicity.
Bisphenol S (BPS) Added for Developmental Toxicity
Effective 8 December 2025
OEHHA has added the developmental toxicity endpoint to the existing reproductive toxicity listing for bisphenol S (BPS). This action was taken through the “State’s Qualified Experts” mechanism after the DARTIC determined that BPS has been clearly shown to cause developmental toxicity.
N-Methyl-N-Formylhydrazine Listed as a Carcinogen
Effective 8 December 2025
OEHHA added N-methyl-N-formylhydrazine to the Proposition 65 list as a carcinogen via the State’s Qualified Experts mechanism, following a determination by the Carcinogen Identification Committee (CIC).
Vinyl Acetate Listed as a Carcinogen
Effective 3 January 2025Vinyl acetate has been added to the Proposition 65 list as a carcinogen based on the Carcinogen Identification Committee’s (CIC) evaluation.
New No Significant Risk Levels (NSRLs)
Final NSRL Adopted for Titanium Dioxide (Airborne, Unbound Particles of Respirable Size)
Regulation Effective 1 October 2025
OEHHA finalized NSRLs for titanium dioxide (airborne, unbound particles of respirable size) under Title 27, California Code of Regulations, section 25705(c)(2). To qualify for safe harbor protection, both of the following exposure levels must be met:
- Particle Size: ≤10 micrometers NSRL: 440 micrograms per day (µg/day)
- Particle Size: ≤0.8 micrometers NSRL: 44 micrograms per day (µg/day)
The NSRL is based on a National Institute for Occupational Safety and Health (NIOSH) cancer risk assessment using dose-response data from rat studies showing lung tumor development following exposure to respirable titanium dioxide.
Proposed New No Significant Risk Levels (NSRLs) Rule-Making
Proposed on 19 September 2025
OEHHA has proposed new NSRLs under Title 27, section 25705(b):
- 1-Bromopropane: 54 micrograms per day (µg/day). Based on OEHHA cancer potency values from rodent studies
- Diethanolamine (Dermal): 6.4 micrograms per day (µg/day). Applies only to dermal exposure, based on rodent carcinogenicity data
These levels are derived using OEHHA’s established cancer risk assessment methods.
Priority List for Future NSRL Development
Notice Date: 5 June 2025
OEHHA maintains a priority list for developing new or updated NSRLs, with a focus on public health impact, scientific data quality, and coordination with other OEHHA programs.
Current Priority Chemicals: Ethylene oxide; 1-Bromopropane (1-BP); Diethanolamine and Vinyl acetate.
A Notice of Proposed Rulemaking has not been issued.
Request for Information: Reproductive Toxicity of p,pʹ-Bisphenol Chemicals
Data Call-In Period Began 21 October 2025
OEHHA is evaluating p,pʹ-bisphenol chemicals, including ethers and esters, for potential inclusion as reproductive toxicants under Proposition 65 and has begun developing hazard identification materials for these chemicals.
Relevant information regarding p,pʹ-bisphenol chemicals includes, but is not limited to:
- Animal studies on developmental and reproductive toxicity
- Human epidemiological studies
- Mechanistic studies on reproductive or developmental effects
- Pharmacokinetics and biochemical/physiological impact data
Data submission deadline was 1 December 2025 (45-day data call-in period)
Hazard identification materials developed from submitted data will be presented at a future DARTIC meeting for consideration of possible listing.
Looking Ahead: Focus for 2026
In 2026, Proposition 65 shifts from a phase of regulatory transition to active enforcement. As several key grace periods expire and new chemical listings fully take effect, 2026 becomes a crucial year to strengthen your compliance strategy and adhere to the latest requirements.
Ultimately, the goal is to replace uncertainty with verified information. By focusing on accurate data and transparent communication, organizations can manage these changes effectively, minimize legal risks, and continue meeting their obligations in the California market.
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