The Safe Drinking Water and Toxic Enforcement Act of 1986, commonly known as California’s Proposition 65, continues to evolve in response to scientific developments, litigation trends, and regulatory priorities. Designed to protect public health, Prop 65 requires businesses to provide warnings when consumers may be exposed to chemicals known to cause cancer or reproductive or developmental harm.
On December 8, 2025, California made important updates to the Proposition 65 chemical list. These changes will affect businesses, consumers, and compliance strategies across multiple industries.
The Challenge with Proposition 65
Proposition 65 was created to protect public health by ensuring transparency around exposure to harmful chemicals. However, its application has led to several ongoing challenges:
- Nearly every product sold in California seems to carry a Prop 65 warning. These over-broad warnings appear on a wide range of products, leading many consumers to ignore them entirely.
- Labelling rules are complex and expensive to implement. Requirements vary depending on the chemical involved and the route of exposure.
- Regulators and courts continuously adjust how the law is applied, creating uncertainty for businesses trying to remain compliant.
Key Benefits of the December 8, 2025, Update
Despite the challenges, the latest update reflects California’s effort to align Proposition 65 with current scientific understanding:
- N-Methyl-N-Formylhydrazine has been officially listed as a carcinogen, meaning it is now legally recognized as a substance that causes cancer.
- Bisphenol S (BPS), a common substitute for BPA, has gained a developmental toxicity endpoint in addition to its previously listed reproductive endpoints. This completes its classification across major reproductive and developmental risks.
- For products such as thermal receipt paper that may contain BPS, the Office of Environmental Health Hazard Assessment (OEHHA) has issued guidance to clarify how these listings should be addressed.
These updates matter because they provide consumers with clearer information about harmful chemicals, allow businesses to plan for compliance deadlines, and help regulators keep the law aligned with the latest science.
Effects on Businesses
The December 2025 updates have direct implications for companies selling products in California:
- Product formulations and labeling must be reviewed, particularly for products that may contain N-methyl-N-formylhydrazine or BPS.
- Businesses should estimate potential chemical exposures and determine whether a Proposition 65 warning will be required.
- For the new carcinogen listing, warning requirements begin on December 8, 2026, giving businesses time to prepare.
As a result, Proposition 65 warnings are expected to become more specific, helping Californians and visitors better understand which chemicals pose which risks.
Compliance Impact Across the Supply Chain
Manufacturers, distributors, and retailers can expect increased compliance-related activities, including:
- Product testing to determine chemical content and exposure levels
- Updates to product labels, websites, and packaging
- Reformulation of products to avoid warning requirements where feasible
The December 8, 2025 Proposition 65 update reinforces California’s continued commitment to grounding regulatory decisions in current science. For businesses selling into California—and for consumers who rely on warning labels—the message is clear: Proposition 65 compliance is not static, and expectations continue to evolve.
To reduce risk, businesses must stay informed, assess products proactively, and adapt compliance strategies early. Partnering with experienced compliance experts like ComplianceXL can help organizations navigate Prop 65 updates efficiently, reduce enforcement and litigation risks, and align compliance efforts with broader public health objectives.
FAQs:
1. What is Proposition 65?
Proposition 65 is a California law that requires warnings when products expose consumers to chemicals known to cause cancer or reproductive harm.
2. What chemicals were added in December 2025?
N-methyl-N-formylhydrazine was added as a carcinogen, and Bisphenol S (BPS) was listed for developmental toxicity.
3. When do the new warning requirements take effect?
For both chemicals, warning requirements begin on December 8, 2026.
4. Do all products need new labels immediately?
No. Businesses have time to assess product formulations and update labels before the effective date.
5. Why do so many products carry Proposition 65 warnings?
Because the chemical list includes hundreds of substances, many businesses apply warnings broadly to reduce litigation risk, even when actual exposure risk may be low.
