California Proposition 65 compliance has become more complex in 2026 following the December 2025 addition of two significant chemicals to the state's official list of substances known to cause cancer or reproductive harm. The Office of Environmental Health Hazard Assessment (OEHHA) announced on December 5, 2025 that Bisphenol S (BPS) and N-Methyl-N-Formylhydrazine are now subject to California's strict warning requirements, creating immediate compliance obligations for manufacturers, importers, and retailers whose products contain these substances and are sold or distributed in California.

For compliance leaders, product safety teams, and executive decision-makers, understanding California Proposition 65 compliance requirements is essential to avoiding costly enforcement actions, protecting brand reputation, and maintaining California market access. With businesses facing a 12-month compliance window from the December 8, 2025 effective date, organizations must act now to assess product portfolios, evaluate exposure risks, and implement warning protocols by December 2026. Companies lacking AI-powered compliance infrastructure and systematic regulatory monitoring face significant challenges meeting this timeline while managing broader environmental compliance obligations.

This comprehensive guide explains what changed in California Proposition 65, which industries are most affected by the new chemical listings, compliance timelines and enforcement risks, and how organizations can prepare for 2026 requirements while building scalable capabilities for ongoing Proposition 65 obligations.

Table of Contents

1. What Changed in California Proposition 65 (December 2025 Update)

2. Understanding the Newly Listed Chemicals and Their 2026 Impact

3. Who Must Comply: Industry-by-Industry Breakdown

4. California Proposition 65 Compliance Timelines and the 12-Month Warning Window

5. Enforcement Risks, Penalties, and Executive-Level Exposure

6. 2026 California Proposition 65 Compliance Action Checklist

7. How Certivo Simplifies California Proposition 65 Compliance

1. What Changed in California Proposition 65 (December 2025 Update)

California Proposition 65, formally known as the Safe Drinking Water and Toxic Enforcement Act of 1986, requires businesses to provide clear and reasonable warnings before knowingly and intentionally exposing individuals to chemicals that California has identified as causing cancer, birth defects, or other reproductive harm. The December 2025 update added two chemicals to the official Proposition 65 list, expanding the scope of substances subject to warning requirements.

The December 8, 2025 Effective Date

OEHHA's announcement on December 5, 2025 established December 8, 2025 as the official listing date for both chemicals. This date triggers the 12-month compliance clock, giving businesses until December 8, 2026 to implement required warning protocols for products containing these substances at exposure levels exceeding safe harbor thresholds.

Organizations treating this as a distant 2027 concern misunderstand the immediate compliance imperative. The 12-month window requires:

• Product portfolio assessment (Q1 2026) - Identifying products potentially containing newly listed chemicals

• Exposure evaluation (Q1-Q2 2026) - Determining whether exposure levels exceed safe harbor limits

• Warning implementation (Q2-Q3 2026) - Developing and deploying compliant warning labels and protocols

• Supply chain verification (ongoing) - Confirming supplier chemical disclosures and reformulation timelines

Companies deferring California Proposition 65 compliance activities until late 2026 face severe time pressure and potential enforcement exposure beginning December 9, 2026.

Why These Chemical Additions Matter

The addition of Bisphenol S and N-Methyl-N-Formylhydrazine represents more than routine list updates. These chemicals appear in products across multiple industries, creating widespread compliance obligations that extend far beyond traditional chemical manufacturing sectors.

Official regulatory source (OEHHA): https://oehha.ca.gov/proposition-65/proposition-65-list

2. Understanding the Newly Listed Chemicals and Their 2026 Impact

Bisphenol S (BPS) - CAS No. 80-09-1

Listed for: Reproductive toxicity (developmental toxicity)

Bisphenol S has emerged as a common substitute for Bisphenol A (BPA) following widespread BPA restrictions and consumer demand for "BPA-free" products. The irony of this Proposition 65 listing is that many manufacturers reformulated products to eliminate BPA only to introduce BPS—now itself listed for reproductive toxicity.

Common BPS Applications:

• Thermal paper - Cash register receipts, airline boarding passes, event tickets

• Plastics and polymers - Polycarbonate and epoxy resin alternatives marketed as BPA-free

• Coatings - Can linings, food packaging coatings, protective coatings

• Personal care products - Some cosmetics and toiletries

• Consumer goods - Products marketed as BPA-free alternatives

The BPS listing creates particular challenges for organizations that invested in BPA-to-BPS reformulation as a "safer alternative" strategy. These companies must now either:

• Implement Proposition 65 warnings for BPS-containing products

• Reformulate again to eliminate both BPA and BPS

• Conduct exposure assessments demonstrating levels below safe harbor thresholds

Organizations in consumer goods and packaging materials sectors face particularly urgent BPS compliance requirements given widespread use in products sold through California retail channels.

N-Methyl-N-Formylhydrazine - CAS No. 758-17-8

Listed as: Carcinogen

N-Methyl-N-Formylhydrazine is primarily encountered as a chemical intermediate in pharmaceutical manufacturing and specialty chemical production. While less widely distributed in consumer products than BPS, this substance's carcinogen classification creates strict warning requirements where exposure occurs.

Potential N-Methyl-N-Formylhydrazine Applications:

• Pharmaceutical intermediates - Chemical synthesis processes in drug manufacturing

• Specialty chemicals - Industrial chemical production

• Research chemicals - Laboratory and R&D applications

The carcinogen designation means organizations cannot avoid warnings through exposure assessments showing levels below reproductive toxicity thresholds—any exposure exceeding carcinogen safe harbor levels triggers warning requirements.

Why "BPA-Free" Is No Longer Sufficient Marketing

The BPS listing demonstrates a critical compliance principle: substituting one restricted chemical with a structurally similar alternative does not guarantee regulatory or safety advantages. Organizations marketing products as "BPA-free" must now verify that BPS (and other bisphenol alternatives like BPF, BPAF) are either absent or present only below Proposition 65 safe harbor levels.

This pattern extends beyond Bisphenols to other chemical classes where "regrettable substitution" creates ongoing compliance challenges. Companies need proactive chemical tracking systems that assess alternatives against current and emerging regulatory restrictions rather than reactively responding to each new listing.

3. Who Must Comply: Industry-by-Industry Breakdown

California Proposition 65 compliance applies broadly to any business with 10 or more employees that causes exposure to listed chemicals in California through:

• Products manufactured or sold in California

• Products imported into California

• Workplace exposures at California facilities

• Environmental releases affecting California residents

Plastics and Polymer Manufacturers

Businesses producing or processing BPS-containing plastics face immediate California Proposition 65 compliance obligations. This includes:

• Polycarbonate plastic manufacturers marketing BPA-free alternatives

• Epoxy resin producers using BPS

• Plastic compounding operations incorporating BPS

• Injection molding facilities processing BPS-containing resins

Manufacturers must verify whether finished products contain BPS at levels exceeding 0.3 micrograms per day exposure (the current safe harbor level for developmental toxicity), requiring either product reformulation or warning implementation.

Consumer Goods and Household Products

Consumer product companies selling BPS-containing goods into California markets must implement warnings or reformulate. Affected categories include:

• Kitchenware and food storage containers

• Water bottles and beverage containers

• Food service items and utensils

• Household storage and organization products

• Baby products and children's items

Consumer goods manufacturers face particular enforcement pressure as consumer advocacy organizations actively pursue Proposition 65 settlements for products lacking required warnings.

Electronics and Electrical Equipment

Electronic products may contain BPS in:

• Component coatings and enclosures

• Circuit board materials

• Display technologies

• Protective casings marketed as BPA-free

Electronics manufacturers must assess BPS presence in components and determine whether consumer or workplace exposure triggers warning requirements.

Packaging Materials Manufacturers

The packaging industry faces widespread BPS compliance challenges given use in:

• Food contact coatings replacing BPA epoxy

• Thermal paper for receipts and labels

• Protective packaging films

• Can linings and beverage container coatings

Organizations producing packaging materials for California food and beverage markets must verify BPS compliance across product lines and implement supplier verification programs ensuring upstream chemical compliance.

Chemical Manufacturers and Distributors

Chemical companies manufacturing, importing, or distributing BPS or N-Methyl-N-Formylhydrazine face direct Proposition 65 obligations including:

• Warning requirements for chemical products sold in California

• Downstream customer notification regarding Proposition 65 status

• Safety Data Sheet (SDS) updates reflecting California listings

• Workplace exposure warnings for California facilities

Retailers and Importers

California retailers and importers share Proposition 65 compliance responsibility for products they sell, creating due diligence obligations to:

• Verify supplier Proposition 65 compliance before accepting products

• Implement point-of-sale warnings for non-compliant products

• Maintain documentation demonstrating compliance efforts

• Remove non-compliant products lacking warnings after the 12-month grace period

Major California retailers increasingly require suppliers to provide Proposition 65 compliance certifications as condition of doing business, making California Proposition 65 compliance a market access requirement rather than optional regulatory obligation.

4. California Proposition 65 Compliance Timelines and the 12-Month Warning Window

California Proposition 65 provides a 12-month grace period from the official listing date before enforcement of warning requirements begins. For the December 8, 2025 BPS and N-Methyl-N-Formylhydrazine listings, the compliance timeline follows:

Understanding the 12-Month Window

The 12-month compliance period is not an extension or optional timeline—it represents the maximum time businesses have to achieve compliance before enforcement begins. Organizations should not interpret this as 12 months to start working on compliance, but rather 12 months to complete:

Product Portfolio Assessment (Months 1-2)

• Inventory all products sold in California

• Identify products potentially containing BPS or N-Methyl-N-Formylhydrazine

• Prioritize high-volume or high-risk products for immediate attention

Exposure Evaluation (Months 2-4)

• Determine chemical concentrations in products

• Calculate reasonably anticipated exposure levels

• Compare exposure to safe harbor levels

• Engage laboratories for testing where supplier data is unavailable

Strategic Decision-Making (Months 3-5)

• Decide whether to warn, reformulate, or discontinue products

• Assess economic implications of each strategy

• Coordinate with suppliers on reformulation timelines

• Develop implementation plans

Warning Implementation (Months 5-10)

• Design warning labels compliant with Proposition 65 requirements

• Obtain regulatory review if necessary

• Produce new packaging or labels

• Coordinate warning deployment across distribution channels

Verification and Documentation (Months 10-12)

• Confirm warnings are properly displayed

• Maintain compliance documentation

• Train customer service and sales teams

• Prepare for potential enforcement inquiries

Organizations lacking automated compliance tracking discover timeline pressures too late, rushing through critical assessment and implementation phases that require methodical execution.

Safe Harbor Levels and Exposure Assessment

California Proposition 65 compliance does not require warnings for all products containing listed chemicals—only those causing exposure exceeding "safe harbor" levels. OEHHA establishes safe harbor levels representing daily exposure amounts below which warnings are not required.

For developmental toxicity (BPS classification):

• Current safe harbor: 0.3 micrograms per day maximum allowable dose level (MADL)

For carcinogens (N-Methyl-N-Formylhydrazine classification):

• Safe harbor determined by "no significant risk level" (NSRL) calculated to represent negligible cancer risk

Organizations must calculate reasonably anticipated consumer exposure considering:

• Chemical concentration in products

• Frequency and duration of product use

• Routes of exposure (dermal, ingestion, inhalation)

• Vulnerable populations (children, pregnant women)

Exposure assessments require technical expertise and conservative assumptions to withstand regulatory scrutiny and potential litigation challenges.

5. Enforcement Risks, Penalties, and Executive-Level Exposure

California Proposition 65 enforcement operates through a unique "private attorney general" mechanism allowing private parties and advocacy organizations to file lawsuits against businesses violating warning requirements. This creates enforcement risks extending beyond traditional government regulatory actions.

Notices of Violation and the 60-Day Notice Requirement

Proposition 65 enforcement typically begins with a Notice of Violation (NOV) alleging non-compliance. The NOV must provide 60-day advance notice to:

• The alleged violator

• California Attorney General

• District attorneys and city attorneys for jurisdictions where violations occurred

The 60-day notice period allows parties to negotiate settlements before formal litigation commences. Most Proposition 65 cases settle during this pre-litigation period, creating substantial costs even without trial.

Civil Penalties and Settlement Amounts

Proposition 65 violations carry civil penalties up to $2,500 per violation per day. With "per day" calculated from the date warning obligations began (December 9, 2026 for newly listed chemicals), penalties accumulate rapidly.

A single product sold continuously in California for one year without required warnings theoretically creates:

• 365 days × $2,500 = $912,500 in potential penalties (per product)

In practice, settlement amounts vary widely but commonly include:

• Civil penalties - negotiated amounts typically lower than maximum statutory penalties

• Reformulation commitments - agreements to remove listed chemicals within specified timelines

• Attorney fees and costs - plaintiff attorney compensation often exceeding civil penalties

• Compliance verification - ongoing monitoring and reporting requirements

• Public notification - settlement terms published creating reputational impacts

The Private Enforcement Landscape

Proposition 65's private enforcement mechanism has created an active ecosystem of:

• Consumer advocacy organizations pursuing public interest litigation

• Bounty hunter law firms filing hundreds of cases annually

• Testing laboratories analyzing products for Proposition 65 violations

• Settlement mills generating revenue through high-volume NOV campaigns

Organizations selling consumer products into California face near-certain Proposition 65 enforcement pressure if products contain listed chemicals without proper warnings. The question is not if but when enforcement occurs.

Executive and Corporate Liability

While Proposition 65 violations typically result in corporate liability, executive officers and board members face indirect exposure through:

• Shareholder derivative actions alleging failure to implement adequate compliance systems

• Securities litigation if material Proposition 65 exposures are not disclosed

• Reputational damage from public settlement disclosures

• Customer relationship impacts when major retailers disqualify suppliers

For publicly traded companies, significant Proposition 65 settlements may constitute material events requiring disclosure, creating investor relations and SEC reporting implications.

Enforcement Timeline After December 2026

Beginning December 9, 2026, businesses selling BPS or N-Methyl-N-Formylhydrazine-containing products in California without compliant warnings face immediate enforcement risk. Advocacy organizations and plaintiff attorneys actively monitor newly listed chemicals, filing NOVs shortly after grace periods expire.

Organizations should anticipate:

• Q1 2027: Initial NOVs filed against high-visibility consumer product companies

• Q2-Q3 2027: Settlement negotiations and precedent-setting agreements

• Q4 2027 onward: Expanded enforcement as plaintiff firms replicate successful strategies

Companies achieving California Proposition 65 compliance by December 2026 avoid this enforcement wave while competitors face settlement costs, reformulation mandates, and market disruption.

6. 2026 California Proposition 65 Compliance Action Checklist

Organizations subject to California Proposition 65 requirements should implement these compliance actions immediately:

☑ Conduct Comprehensive Product Portfolio Assessment

Inventory California Market Products:

• Identify all products manufactured, imported, sold, or distributed in California

• Include products sold online reaching California consumers

• Prioritize high-volume products and product lines generating significant California revenue

Assess BPS and N-Methyl-N-Formylhydrazine Presence:

• Review product formulations and material specifications

• Flag products marketed as "BPA-free" as high-risk for BPS presence

• Identify plastic, coating, and thermal paper products requiring evaluation

• List chemical manufacturing or pharmaceutical products potentially containing N-Methyl-N-Formylhydrazine

☑ Engage Suppliers for Chemical Disclosure

Launch Systematic Supplier Verification:

• Develop standardized chemical disclosure requests covering newly listed substances

• Distribute requests to material, component, and chemical suppliers

• Establish response deadlines allowing time for validation before December 2026

• Implement automated supplier engagement workflows

Validate Supplier Responses:

• Verify chemical identity and concentration data

• Request supporting documentation for BPS or N-Methyl-N-Formylhydrazine claims

• Flag incomplete or inconsistent responses requiring follow-up

• Escalate non-responsive suppliers through procurement channels

☑ Conduct Exposure Assessments

Determine Exposure Levels:

• Calculate reasonably anticipated consumer exposure based on product use

• Consider concentration, frequency, duration, and exposure routes

• Compare calculated exposure to safe harbor levels (0.3 μg/day MADL for BPS developmental toxicity)

• Engage qualified toxicologists for complex exposure scenarios

Document Assessment Methodology:

• Preserve exposure calculations and supporting assumptions

• Maintain chemical concentration data and product use scenarios

• Create defensible documentation for regulatory or litigation challenges

☑ Develop Compliance Strategy

Evaluate Compliance Options:

Option 1: Implement Warnings

• Design Proposition 65-compliant warning labels

• Coordinate warning implementation across packaging, signage, and online channels

• Train customer service and sales teams on warning requirements

• Maintain warning compliance documentation

Option 2: Reformulate Products

• Identify alternative materials eliminating BPS or N-Methyl-N-Formylhydrazine

• Conduct testing validating alternatives meet performance requirements

• Update product specifications and manufacturing processes

• Verify reformulated products comply with all applicable regulations

Option 3: Discontinue Products

• Assess economic viability of warning or reformulation strategies

• Phase out products where compliance costs exceed revenue potential

• Manage inventory drawdown and customer transition

☑ Implement Warning Protocols (If Applicable)

Design Compliant Warnings:

• Use OEHHA-approved warning language and symbols

• Ensure warnings are clear, reasonable, and prominently displayed

• Adapt warnings to product type (consumer products, workplace, environmental)

• Review warning designs against regulatory requirements

Deploy Warnings Across Channels:

• Update product packaging and labels

• Implement point-of-sale warnings for retail locations

• Add website warnings for online sales

• Coordinate with distributors and retailers on warning compliance

☑ Establish Ongoing Monitoring

Track Proposition 65 List Updates:

• Monitor OEHHA announcements for new chemical listings

• Assess impacts of new listings on product portfolios

• Implement continuous regulatory intelligence capabilities

• Participate in industry association information sharing

Maintain Compliance Documentation:

• Organize supplier chemical disclosures by product and supplier

• Retain exposure assessments and toxicology evaluations

• Preserve warning implementation records

• Document reformulation activities and testing results

Organizations implementing centralized compliance data management transform Proposition 65 from reactive crisis response to systematic, scalable capabilities.

☑ Prepare for Enforcement Scenarios

Develop Response Protocols:

• Establish procedures for responding to Notices of Violation

• Identify qualified Proposition 65 legal counsel

• Create settlement negotiation guidelines

• Prepare communications strategies for public disclosure

Train Cross-Functional Teams:

• Brief product development teams on Proposition 65 implications for new products

• Train procurement staff on supplier chemical verification

• Inform sales teams on compliance status and customer inquiries

• Update executive leadership on enforcement risks and financial exposure

7. How Certivo Simplifies California Proposition 65 Compliance

Certivo provides manufacturers, importers, and retailers with an AI-powered compliance management platform specifically designed for California Proposition 65 requirements and broader chemical regulatory obligations:

AI-Driven Chemical Tracking and List Monitoring

Certivo creates comprehensive visibility into Proposition 65-listed chemicals across product portfolios:

• Chemical-level substance tracking linking listed chemicals to specific products and formulations

• Automated list monitoring alerting teams immediately when new chemicals are added to Proposition 65

• Impact assessment identifying affected products when new listings occur

• Historical tracking maintaining compliance status as regulations evolve

Organizations achieve the chemical intelligence required for rapid Proposition 65 response without manual regulatory monitoring creating awareness gaps.

Automated Proposition 65 Compliance Assessment

Certivo streamlines Proposition 65 compliance evaluation:

• Product portfolio screening identifying products potentially containing newly listed chemicals

• Exposure assessment support organizing data required for safe harbor calculations

• Compliance status tracking showing which products require warnings, reformulation, or no action

• Deadline management ensuring timely compliance before 12-month grace periods expire

The platform eliminates manual compliance assessments that consume weeks and introduce evaluation errors.

Intelligent Supplier Declaration Management

Certivo automates supplier chemical disclosure verification:

• Standardized disclosure templates aligned with Proposition 65 requirements

• Automated supplier engagement distributing requests and tracking responses

• Validation rules ensuring supplier data includes required chemical information

• Supplier performance analytics identifying high-risk suppliers requiring escalation

Organizations scale supplier verification across hundreds of suppliers without manual tracking creating bottlenecks.

Multi-Regulation Visibility and Cross-Compliance

Certivo provides unified visibility across California Proposition 65 and other chemical regulations:

• Jurisdiction-specific tracking showing compliance status for Prop 65, REACH, RoHS, TSCA

• Cross-regulatory data reuse leveraging chemical data across multiple frameworks

• Comparative analysis identifying products subject to multiple restrictions

• Global compliance readiness supporting operations across regulatory jurisdictions

Organizations investing in Proposition 65 compliance build scalable infrastructure supporting broader environmental regulatory requirements.

Warning Implementation and Documentation

Certivo supports warning compliance execution:

• Warning requirement tracking identifying products needing warnings

• Implementation workflows coordinating warning deployment across teams

• Documentation management organizing compliance evidence for enforcement defense

• Audit readiness maintaining records demonstrating due diligence

Organizations respond to Notices of Violation with complete, organized documentation rather than scrambling to assemble evidence during settlement negotiations.

Proactive Compliance Intelligence

Certivo's AI continuously monitors California Proposition 65 regulatory developments:

• OEHHA announcement tracking monitoring new chemical listings and regulatory updates

• Enforcement precedent analysis identifying compliance trends and settlement patterns

• Industry impact assessment tracking how competitors address Proposition 65 challenges

• Strategic planning support informing reformulation and product development decisions

The platform eliminates manual regulatory monitoring that creates gaps between policy changes and organizational awareness.

Cross-Functional Collaboration

Certivo connects teams across compliance, product development, procurement, and legal functions:

• Role-based access providing relevant Proposition 65 data to each stakeholder

• Workflow automation routing compliance tasks to appropriate teams

• Notification systems alerting teams to deadline-driven actions

• Executive dashboards giving leadership visibility into compliance status and enforcement exposure

The platform transforms California Proposition 65 compliance from isolated compliance activities to coordinated, enterprise-wide capabilities.

Conclusion

California Proposition 65 compliance in 2026 requires immediate action from businesses manufacturing, importing, or selling products containing Bisphenol S or N-Methyl-N-Formylhydrazine in California markets. The December 8, 2025 listing of these chemicals triggered a 12-month compliance window ending December 8, 2026, creating urgent obligations to assess product portfolios, evaluate exposure risks, and implement warning protocols or reformulate products.

Organizations deferring California Proposition 65 compliance activities until late 2026 face severe time pressure to complete complex exposure assessments, supplier verification, and warning implementation before enforcement begins December 9, 2026. The unique private enforcement mechanism means compliance failures attract immediate litigation from advocacy organizations and plaintiff attorneys who actively monitor newly listed chemicals.

Beyond these specific chemical listings, effective Proposition 65 compliance requires ongoing monitoring of OEHHA announcements, systematic supplier verification programs, and scalable chemical tracking infrastructure that adapts as the Proposition 65 list expands. Companies investing in AI-powered compliance platforms build capabilities supporting continuous regulatory readiness rather than reactive crisis response to each new listing.

The question is not whether your organization will achieve California Proposition 65 compliance by December 2026. The question is whether you will build the compliance infrastructure required for sustained California market access as chemical regulations continue evolving.

Ready to transform your California Proposition 65 compliance approach? Contact Certivo to see how AI-powered compliance automation helps organizations meet 2026 deadlines while building scalable chemical regulatory infrastructure.