California Prop 65 Warning Labels Explained

1. What Is Proposition 65?

Proposition 65, officially the Safe Drinking Water and Toxic Enforcement Act of 1986, is a California state law codified at California Health & Safety Code §§ 25249.5–25249.14. It requires businesses with 10 or more employees to provide "clear and reasonable" warnings before knowingly and intentionally exposing anyone in California to chemicals known to cause cancer, birth defects, or other reproductive harm.

The Chemical List

The Office of Environmental Health Hazard Assessment (OEHHA) maintains the Proposition 65 chemical list. As of 2026, it includes over 1,050 substances known to the State of California to cause cancer, birth defects, or reproductive harm. The list is updated at least annually, though OEHHA may add chemicals at any time throughout the year.

• Chemicals are listed under two categories: carcinogens and reproductive toxicants (some appear on both)
• Listings are based on findings by authoritative bodies such as IARC, the US EPA, the FDA, and OEHHA's own Carcinogen Identification Committee or Developmental and Reproductive Toxicant Identification Committee
• Once listed, a chemical is rarely delisted — the list has grown continuously since 1987

Who Does It Apply To?

Prop 65 is a California state law, but it effectively applies to all sellers shipping products to California — including businesses based in other US states and international sellers. If a product reaches a California consumer, the warning obligation applies regardless of where the seller is located.

2. Which Products Need Prop 65 Warnings?

Any product that exposes California consumers to a listed chemical above the applicable "safe harbor" threshold requires a Prop 65 warning. There is no exemption based on product type — the law applies to all consumer products, food, beverages, environmental exposures, and occupational settings.

Candles and Wax Melts

Paraffin wax combustion produces several Prop 65-listed chemicals. Even soy-based and coconut-based candles generate listed substances when fragranced and burned. The primary concern is combustion byproducts, not the wax itself.

• Benzene — listed carcinogen; produced during incomplete combustion of hydrocarbons
• Toluene — listed reproductive toxicant; present in combustion emissions and certain fragrance compounds
• Formaldehyde — listed carcinogen; a common combustion byproduct of organic materials
• Carbon black (airborne, unbound) — listed carcinogen; generated as soot particulate
• Styrene — listed carcinogen; can be emitted from fragranced candles during burning

Cosmetics, Soap, and Personal Care Products

Cosmetics and soap products may contain Prop 65-listed chemicals through fragrance ingredients, preservatives, colorants, or contaminants. Listed chemicals commonly found include:

• Titanium dioxide (airborne, unbound) — listed carcinogen; used as a white pigment in soap and cosmetics
• Diethanolamine (DEA) — listed carcinogen; found in some surfactants
• Formaldehyde — listed carcinogen; released by certain preservative systems (DMDM hydantoin, quaternium-15)
• Cocamide DEA — listed carcinogen; used as a foaming agent

Essential Oils

Several naturally occurring compounds in essential oils appear on the Prop 65 list:

• Pulegone — listed carcinogen; found in peppermint and pennyroyal essential oils
• Safrole — listed carcinogen; present in sassafras, basil, and nutmeg oils
• Methyleugenol — listed carcinogen; found in basil, lemongrass, and tarragon oils
• Beta-myrcene — listed carcinogen; a common terpene in many essential oils including lemongrass, hops, and bay laurel

Common Listed Chemicals by Product Category

3. The 2025 Short-Form Warning Changes

This is the most significant Prop 65 compliance update in years. Effective January 1, 2025, OEHHA amended the safe harbor warning regulations to require that short-form warnings must now include at least one chemical name. The previous generic short-form warning that omitted chemical names is no longer compliant.

What Changed

Under 27 CCR § 25603, the amended regulations require short-form warnings to identify at least one listed chemical by name. Businesses have a transition period until January 1, 2028 to update existing product labels, packaging, and signage. However, all new products introduced after January 1, 2025 should use the updated format immediately.

Old Short-Form (No Longer Compliant After January 1, 2028)

New Short-Form (Required — exact safe harbor text per 27 CCR § 25603)

Note: businesses may also use "CA WARNING" or "CALIFORNIA WARNING" as the signal word instead of "WARNING" — useful for products sold in multiple states to clearly identify the warning as California-specific.

Long-form warnings already required naming specific chemicals, so businesses using the long-form format are largely unaffected by this change. The practical impact falls on businesses that relied on the shorter, generic warning language — which was common on small product labels where space is limited.

Key Transition Dates

4. Safe Harbor Warnings — Exact Text

"Safe harbor" warnings are specific warning formats prescribed by OEHHA in 27 CCR §§ 25601–25607.2. Using the exact safe harbor text provides legal protection — it creates a presumption that the warning is "clear and reasonable" as required by the statute. Custom or modified warnings do not receive this presumption and are more vulnerable to legal challenge.

Long-Form Warning (Consumer Products)

If a product contains both carcinogens and reproductive toxicants, the warnings can be combined into a single statement listing both endpoints.

Short-Form Warning (Post-2025)

The Warning Symbol

Safe harbor warnings must include a triangular warning symbol (⚠) in a contrasting color — typically black on yellow, or black on white. The symbol must precede the word "WARNING." OEHHA provides downloadable symbol files on the P65Warnings.ca.gov website. The symbol is recommended for all product categories and is mandatory for on-product consumer goods warnings.

Formatting Requirements

• "WARNING" must be in all caps and bold
• The warning must be prominently displayed and easily readable
• Minimum type size requirements apply — generally no smaller than the largest type size used for other consumer information on the product (with a minimum of 6-point font)
• The warning must be set off from surrounding text by a border or use a contrasting color to ensure conspicuousness
• The URL www.P65Warnings.ca.gov must be included in all safe harbor warnings

5. NSRLs and MADLs — Safe Harbor Thresholds

Prop 65 does not require warnings for every trace amount of a listed chemical. OEHHA publishes quantitative "safe harbor" exposure thresholds: No Significant Risk Levels (NSRLs) for carcinogens and Maximum Allowable Dose Levels (MADLs) for reproductive toxicants. If a business can demonstrate that its product exposes consumers to listed chemicals below these thresholds, no warning is required.

How NSRLs and MADLs Work

• NSRL (carcinogens): The exposure level posing no significant cancer risk, defined as one excess case of cancer in 100,000 individuals exposed over a 70-year lifetime
• MADL (reproductive toxicants): One-thousandth (1/1,000th) of the No Observable Effect Level (NOEL) determined from animal or human studies
• The burden of proof is on the business — if sued, the business must demonstrate that exposure falls below these levels
• Not all listed chemicals have established NSRLs or MADLs — for chemicals without published thresholds, any detectable exposure may trigger the warning requirement

Key NSRLs and MADLs for Candle and Cosmetics Chemicals

The Cost of Testing

For candles, demonstrating that combustion emissions fall below NSRLs requires burn chamber testing — specialized laboratory analysis that measures chemical concentrations in emissions during simulated consumer use. This testing typically costs $5,000 to $15,000 per product, depending on the number of chemicals analyzed.

Because of this cost, most small candle sellers choose to provide Prop 65 warnings rather than invest in testing to prove exemption. This is a legitimate compliance strategy — the warning does not mean the product is dangerous, only that it may expose consumers to listed chemicals.

6. Who Must Comply?

Prop 65 applies to any business with 10 or more employees that manufactures, produces, distributes, or sells products in California. The employee threshold is the only size-based exemption.

Key Compliance Rules

• The 10-employee count includes all employees, not just those based in California — a company with 10 employees in Texas that sells on Amazon to California customers must comply
• Online sellers shipping to California are subject to Prop 65, regardless of where the business is physically located
• Government entities are exempt from the warning requirement (but not the discharge prohibition)
• Businesses with fewer than 10 employees are exempt from the warning requirement, but NOT from the prohibition on discharging listed chemicals into drinking water sources

Enforcement: Private Lawsuits

Prop 65 enforcement is unusual because it relies primarily on private enforcement actions, not government inspections. The statute contains a "bounty hunter" provision that allows any private individual or organization to sue a business for Prop 65 violations after providing 60 days' notice to the California Attorney General, the relevant district attorney, and the alleged violator.

• Penalties: Up to $2,500 per day per violation
• Typical settlements for small businesses: $50,000 to $100,000+, including attorney fees, penalties, and injunctive relief
• Several law firms and organizations specialize in filing Prop 65 enforcement actions — they actively search for products without proper warnings
• In 2024 alone, over 700 Prop 65 settlement notices were filed with the California AG's office
• The 60-day notice period gives businesses a window to cure the violation before a lawsuit is formally filed

The "Knowing and Intentional" Standard

The warning requirement is triggered when a business "knowingly and intentionally" exposes a person to a listed chemical. Courts have interpreted "knowingly" broadly — a business is deemed to have knowledge if the presence of the chemical is known in the industry or scientific community, even if the specific business did not test its own product. For well-known product categories like candles, cosmetics, and essential oils, the "knowing" element is generally presumed.

7. How to Display Prop 65 Warnings

The warning must be provided through a method that is "clear and reasonable," meaning the consumer is likely to see and understand it before exposure. For consumer products, this generally means before purchase.

Acceptable Warning Methods

E-Commerce Requirements

For online sales, the Prop 65 warning must be provided before the purchase is completed — not just in the shipping box or on a packing slip. The warning must appear on the product page itself, where the consumer can see it before adding the item to their cart.

• Amazon: Requires Prop 65 warnings in product listings for California-bound goods. Sellers must add the warning text to the product detail page or use Amazon's "California Proposition 65 Warning" field
• Etsy: Sellers should include Prop 65 warning text in the product description for items that may ship to California
• Shopify / custom sites: Add the warning to the product page — many sellers use a dedicated section below the product description
• An email confirmation or post-purchase notice is NOT sufficient — the warning must be presented before the transaction

Formatting for Conspicuousness

• The warning must be in a type size no smaller than the largest type used for other consumer information on the product
• Minimum 6-point font for on-product warnings
• The warning must be enclosed in a box or otherwise set off from surrounding text
• The triangle warning symbol and the word "WARNING" in bold capitals are required elements for safe harbor compliance
• Background color or border contrast should ensure the warning is not obscured

8. Prop 65 and International Sellers

Non-US sellers shipping products to California must comply with Prop 65. There is no exemption based on the seller's country of origin. If the product reaches a California consumer, the warning obligation applies.

Practical Approach for International Sellers

Many international sellers add Prop 65 warnings to all US-bound products rather than trying to implement California-specific labeling. This is simpler from a logistics standpoint — it avoids the need to maintain separate labeling for California-destined and non-California-destined shipments.

• Adding a Prop 65 warning to a product shipped to other US states causes no legal issue — the warning is permitted everywhere, just required in California
• Some sellers include a Prop 65 insert card in all US orders to minimize label redesign costs
• For e-commerce, a Prop 65 warning on every US-facing product page is the simplest approach

Prop 65 vs. EU CLP vs. Canadian WHMIS / CCCR

Prop 65 warnings serve a fundamentally different purpose than EU CLP hazard labels or Canadian CCCR / WHMIS requirements. They are not interchangeable.

A product sold in California AND the EU AND Canada may need three separate warning systems — Prop 65 text, CLP pictograms and statements, and CCCR/WHMIS labeling. Each serves a distinct regulatory purpose and has its own prescribed format.

9. Compliance Checklist

Assessment

• Confirm whether your business has 10 or more employees (if fewer, the warning requirement does not apply)
• Identify all listed chemicals in your products — review SDSs, raw material specifications, and known combustion byproducts
• Determine whether exposure exceeds applicable NSRLs / MADLs (or decide to warn rather than test)
• Check OEHHA's current chemical list for any newly added substances relevant to your product category
• Document your assessment — keep records of how you determined which warnings are needed

Labeling

• Use the safe harbor warning format (long-form or updated short-form with chemical name)
• Include the triangle warning symbol and bold "WARNING" text
• Name at least one listed chemical in the warning (required for both long-form and post-2025 short-form)
• Include the URL www.P65Warnings.ca.gov
• Ensure warning meets minimum type size and conspicuousness requirements
• If using the old short-form, update to the new format before January 1, 2028

E-Commerce

• Display Prop 65 warning on each product page where the consumer can see it before purchase
• Add the warning to your Amazon listing's Prop 65 field (if selling on Amazon)
• Include the warning in Etsy product descriptions (if selling on Etsy)
• Ensure the warning is visible without requiring the customer to click "expand" or "read more"
• Verify that the warning appears on mobile as well as desktop product pages
• Do NOT rely solely on shipping inserts, packing slips, or post-purchase emails for Prop 65 compliance

10. Common Mistakes

Prop 65 compliance errors are among the most common sources of enforcement actions against small consumer goods sellers. These are the mistakes that most frequently lead to 60-day notice letters and lawsuits.

Using the Old Short-Form Without Chemical Names

After the 2025 amendment, short-form warnings must include at least one chemical name. Businesses that continue using the old generic "chemicals known to the State of California to cause cancer" language without naming a specific chemical will lose safe harbor protection after January 1, 2028. Update labels now rather than waiting for the transition period to expire.

Assuming Small Online Sellers Are Exempt

The 10-employee threshold is the only size-based exemption. There is no revenue threshold, no "small business" carveout for online-only sellers, and no exemption based on sales volume. A 15-person Etsy business shipping candles to California is subject to the same Prop 65 requirements as a major retailer.

Not Providing Warnings Before Purchase Online

Including a Prop 65 warning on a packing slip, in the shipping box, or in a post-purchase email is not sufficient for e-commerce. The warning must be visible on the product page before the consumer completes the purchase. This is one of the most frequently litigated e-commerce issues under Prop 65.

Using EU CLP Warnings as a Substitute

EU CLP hazard labels (GHS pictograms, H-statements, P-statements) do not satisfy Prop 65. They address different regulatory requirements, use different formats, and are based on different classification criteria. A product with a compliant EU CLP label still needs a separate Prop 65 warning for California sales.

Ignoring the Private Lawsuit Enforcement Mechanism

Unlike most regulations enforced by government agencies, Prop 65 enforcement is driven by private plaintiffs. Businesses that assume "no one will notice" are taking a significant risk — dedicated enforcement organizations and law firms actively monitor products sold online and in retail for Prop 65 compliance. Settlements routinely exceed $50,000 and can reach six figures, making non-compliance far more expensive than adding the required warnings.