What is Proposition 65?

Proposition 65 is a California law requiring businesses to provide a clear warning before knowingly exposing people in California to chemicals the state lists as causing cancer or reproductive harm. The list includes hundreds of substances found in many ordinary products. For sellers, it means that if your product can expose a California customer to a listed chemical above the relevant threshold, you generally must provide the prescribed warning. It is a right-to-know law, enforced largely through private lawsuits.

Does Prop 65 apply to online sellers outside California?

Yes, if you sell and ship products to customers in California, the law can reach you regardless of where your business is located. It is about exposing people in California, not about where the seller sits. That is why ecommerce sellers nationwide and beyond need to consider Prop 65: shipping into the state brings you within its scope, and marketplaces like Amazon have their own requirements layered on top.

What happens if I ignore Prop 65?

Prop 65 is enforced heavily through private lawsuits, and noncompliance can lead to costly settlements and penalties, a whole cottage industry exists around enforcement actions. At the same time, over-warning on products that do not need it has its own downsides. The sensible path is a genuine assessment of which products require warnings and compliance with the actual requirements, rather than either ignoring the law or slapping warnings on everything out of fear.

Field Guide Compliance-safe marketing

Prop 65 warnings for ecommerce sellers

Q: How do I comply with Prop 65?

Determine whether your products can expose California customers to a listed chemical above the safe-harbor threshold, which often requires understanding your materials and may need testing or supplier information. If a warning is required, provide it in the prescribed form and placement, including on the product listing for online sales. Because the analysis is product-specific and legally consequential, many sellers get qualified guidance rather than guessing. Do not apply warnings blindly or omit them blindly.

California's Prop 65 reaches any seller who ships into the state, and getting it wrong invites costly lawsuits. Here is what it actually requires, who it applies to, and how to handle it sensibly, not fearfully.

August 4, 2026 7 min read

Prop 65 ecommerce exposure is the California rule that surprises out-of-state sellers: ship a product to a California customer and you can fall within its scope no matter where your business sits. It is a right-to-know law about chemical exposure, enforced largely through private lawsuits, which is why getting it wrong is expensive and why a cottage industry exists around suing noncompliant sellers. Here is what it actually requires and how to handle it sensibly rather than fearfully.

What Prop 65 ecommerce compliance requires

A Proposition 65 warning is required before a business knowingly exposes people in California to chemicals the state lists as causing cancer or reproductive harm. The list runs to hundreds of substances found in many ordinary products. For a seller, the practical meaning is: if your product can expose a California customer to a listed chemical above the relevant threshold, you generally must provide the prescribed warning, in the prescribed form and placement.

Prop 65 is not about whether your product is dangerous. It is about whether it can expose a California customer to a listed chemical, and whether you warned them. Those are different questions.

Why it reaches sellers everywhere

It follows the product, not the business

The law is about exposing people in California, so it can reach you wherever you are located if you ship there. Selling into the state brings you within scope, which is why California Prop 65 sellers include ecommerce brands nationwide and beyond, not just businesses based in the state.

Marketplaces add their own layer

Platforms impose their own requirements on listings, and Prop 65 Amazon rules in particular mean compliance is both a legal matter and a marketplace-policy matter. Getting the warning right on the listing is part of keeping the listing healthy and live, the same compliance discipline that governs the rest of your regulated selling.

Handling it sensibly

Assess your products honestly

Determine whether each product can expose California customers to a listed chemical above the safe-harbor threshold. This often requires understanding your materials and may need supplier information or testing. The assessment is product-specific, there is no shortcut that applies to your whole catalog at once.

Warn correctly where required, not everywhere

Where a warning is required, provide it in the prescribed form and placement, including on the product listing for online sales. Where it is not, blanket over-warning has its own downsides. The goal is accurate compliance, not fear-driven labels on everything.

Prop 65 for ecommerce sellers

Understand that shipping into California brings you within scope
Assess each product for exposure to listed chemicals above thresholds
Gather material and supplier information, test where needed
Provide the prescribed warning where required, correctly placed
Meet marketplace-specific Prop 65 requirements on listings
Avoid both ignoring the law and reflexive over-warning
Get qualified guidance for product-specific decisions

Prop 65 is part of the broader compliance-marketing reality of selling regulated and physical products: the rules that, handled well, become routine, and handled poorly, become lawsuits and suspended listings. The operators who treat it as a manageable, product-specific assessment, rather than a panic, keep both the regulators and the marketplaces satisfied.

If you sell physical products into California and are unsure of your Prop 65 exposure, working through which products need warnings and how to comply is exactly the kind of risk-reducing work a Growth Audit can help scope.