Prop 65 Warning Requirements: Do You Need One?

California's Proposition 65 warning requirements trip up a lot of importers. Here's a practical decision framework so you can figure out what applies to your products — and what your labels actually need to say.

You're browsing Amazon and notice a brass doorknob with a cancer warning label. A doorknob. Welcome to Proposition 65.

If you've ever imported consumer products that end up in California — and many do — you've probably encountered Prop 65 in some form. Maybe a retailer asked for a Prop 65 compliance letter. Maybe your freight forwarder flagged it. Maybe you just saw the warnings on every competitor's listing and thought, "Do I need one of those?"

The answer, as with most things in compliance, is "it depends." But unlike most regulatory gray areas, Prop 65 actually has a fairly clear decision framework once you understand how it works. Let's walk through it.

What Is California Proposition 65?

Proposition 65, officially the Safe Drinking Water and Toxic Enforcement Act of 1986, requires businesses to warn California consumers about significant exposures to chemicals that cause cancer, birth defects, or other reproductive harm. The state maintains a list of these chemicals — several hundred of them; check OEHHA's current list — managed by the Office of Environmental Health Hazard Assessment (OEHHA).

The key word there is "significant." Prop 65 doesn't ban products containing listed chemicals. It requires a clear and reasonable warning when a product exposes someone to a listed chemical above certain threshold levels. For carcinogens, that threshold is called the No Significant Risk Level (NSRL). For reproductive toxicants, it's the Maximum Allowable Dose Level (MADL).

Here's the twist that catches most importers off guard: the burden of proof is on you. If someone sues (and Prop 65 has a private right of action, meaning anyone can sue), you have to prove your product's exposure is below the threshold. You don't get the benefit of the doubt. This is why so many companies slap warnings on everything — it's cheaper than testing, and it's definitely cheaper than defending a lawsuit.

Does Prop 65 Apply to You? A Practical Decision Framework

Not every importer needs to lose sleep over Prop 65. Here's a quick decision tree:

1. Does your product reach California? If you sell on Amazon, Walmart.com, or any national retailer — yes. If you sell D2C and ship to California — yes. If you only sell in-person at a single store in Maine — maybe not, but good luck guaranteeing that forever.
2. Does your business have 10 or more employees? Companies with fewer than 10 employees are exempt. This is based on total headcount, not California employees.
3. Does your product contain or expose users to a listed chemical? This is the big question. Common culprits: lead in metals and ceramics, cadmium in jewelry and pigments, phthalates in soft plastics, BPA in food contact materials, formaldehyde in textiles and wood products.
4. Is the exposure above the safe harbor level? If your product contains a listed chemical but exposure is below the NSRL or MADL, no warning is required. But proving that requires testing.

If you answered yes to the first three and aren't sure about the fourth, you either need to test or you need to warn. Many importers choose the warning route because it's more practical — but there are good reasons to test, which we'll get to.

Safe Harbor Warnings: Short-Form vs Long-Form

In 2018, California overhauled its Prop 65 warning requirements. The old days of a vague "this product contains chemicals known to the State of California to cause cancer" are over. Well, sort of. The new regulations introduced two formats, and amendments that took effect January 1, 2025 changed the short-form wording:

Long-form warning: Must include the word "WARNING" in all caps and bold, a triangle warning symbol, the specific chemical name(s), the type of harm (cancer, reproductive harm, or both), and a URL to www.P65Warnings.ca.gov. Example:

WARNING: This product can expose you to chemicals including lead, which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Short-form warning: A shorter version that goes on the product label. Must still include "WARNING" in all caps and bold, the triangle symbol, the name of a chemical, and the P65Warnings URL, using one of the phrasings set out in the regulation. Example:

WARNING: Risk of cancer and reproductive harm from exposure to lead. See www.P65Warnings.ca.gov.

The short-form option is a lifesaver for importers whose products or multilingual packaging leave little room on the label. But here's the catch: the older short form with no chemical name (“WARNING: Cancer — www.P65Warnings.ca.gov”) is only allowed for products manufactured and labeled before January 1, 2028. The short form also has to meet the type-size and prominence rules — never smaller than 6-point type.

The Chemicals Importers Encounter Most Often

Out of the hundreds of chemicals on the Prop 65 list, a handful are responsible for most of the compliance headaches importers face. Here's the greatest hits:

• Lead — the undisputed champion. Found in brass, solder, ceramics, vinyl, painted surfaces, and electronics. If you import anything metal, you're probably dealing with lead.
• Cadmium — common in jewelry, pigments (especially reds and yellows), plastics, and rechargeable batteries.
• Phthalates (DEHP, DINP, others) — plasticizers used in soft PVC, vinyl products, some inks and adhesives. Also restricted under CPSIA in children's toys and child care articles.
• Bisphenol A (BPA) — found in polycarbonate plastics, epoxy linings in cans, thermal receipt paper.
• Formaldehyde — used in textile finishes, composite wood products, and some adhesives.
• Acrylamide — forms during high-temperature cooking processes; relevant for food importers.

If your product category intersects with any of these chemicals, Prop 65 is almost certainly on your radar — or should be. And if you're managing compliance across multiple regulations like PFAS disclosure requirements at the same time, the overlap gets interesting fast.

Prop 65 for Amazon and E-Commerce Sellers

This is where things get especially tricky for modern importers. Prop 65 requires that warnings be provided before or at the time of purchase. For brick-and-mortar retail, that means on the product or shelf. For e-commerce, the safe harbor calls for the warning on the product page (or a clearly marked “WARNING” link there), or otherwise prominently displayed before the customer completes the purchase.

Amazon has its own Prop 65 policy for sellers — check Seller Central for its current requirements. If you sell on Amazon and your product requires a warning, sellers typically:

• Include the Prop 65 warning text in your product listing (typically in the product description or a dedicated attribute field)
• Include the warning on the product itself or its packaging
• Some sellers also add warnings to packing slips or package inserts, though this alone doesn't satisfy the "before purchase" requirement

Online sales are not a gap in enforcement. The Attorney General, district attorneys, some city attorneys, and private plaintiffs (after a 60-day notice) can all bring Prop 65 actions, and the Attorney General's office publishes Prop 65 enforcement reporting.

If you sell on Shopify, WooCommerce, or any other platform, the same rules apply. The warning needs to reach the customer before they complete the purchase. The safe harbor methods are a warning on the product display page, a clearly marked “WARNING” hyperlink on that page that links to the warning, or a warning otherwise prominently displayed before checkout — one the customer doesn't have to search for.

How to Generate Compliant Prop 65 Labels

Getting the label right requires attention to detail. Here's the practical checklist:

1. Identify the chemicals — Review your product materials, request Safety Data Sheets (SDS) from suppliers, and/or get third-party testing done. You need to know which listed chemicals are present.
2. Determine the warning type — Cancer, reproductive harm, or both. This depends on which chemical(s) you've identified and their classification on the OEHHA list.
3. Choose long-form or short-form — The short form is for the product label and must use the current wording. When in doubt, use long-form.
4. Include all required elements — "WARNING" in bold caps, the triangle symbol, chemical name(s), harm type, and the P65Warnings.ca.gov URL.
5. Apply it everywhere it's needed — Product, packaging, product listing (for e-commerce), catalog, or any other point-of-sale material.

The formatting requirements are surprisingly specific. The warning symbol has to be a particular size relative to the text. The word "WARNING" needs to be in a specific format. And if you're producing labels for multiple products with different chemicals, managing this manually across your catalog gets old very quickly.

This is one of the reasons we built Prop 65 label generation directly into Aleph. You tell the platform which chemicals are relevant to each product, and it drafts the warning text from them. Check the result against the current safe harbor rules before you print — California does update them, as the January 1, 2025 short-form amendments showed.

And because Prop 65 is rarely the only regulation an importer deals with, Aleph ties your Prop 65 warnings into the same platform where you manage your Children's Product Certificates, your FSVP documentation, and the PFAS test reports you keep on file. One product, one dashboard, across the regulations Aleph tracks.