Does Your Korean Skincare Need a California Prop 65 Warning?

Your Korean ODM just cleared your first serum run, the COAs look clean, and your US launch date is locked. Then a retailer asks a question that stops you cold: does this need a California Proposition 65 warning? For indie K-beauty founders, Prop 65 is the compliance trap that has little to do with whether your product is safe and everything to do with whether California says you warned people first.

Here is the map for a Korean-made line: what Prop 65 is, which listed chemicals actually show up in K-beauty, when a warning is legally required versus optional, what a compliant warning looks like on a label and an Amazon listing, and the disclosures to pull from your ODM before you ship. Federal rules are a separate track, covered in our FDA requirements for Korean skincare guide.

What Is California Prop 65, and Why Does It Reach Korean Skincare?

Proposition 65 is the California law, formally the Safe Drinking Water and Toxic Enforcement Act of 1986, that requires a clear and reasonable warning before a business knowingly exposes anyone in California to a chemical the state has listed as causing cancer, birth defects, or other reproductive harm. The Office of Environmental Health Hazard Assessment (OEHHA) maintains the Prop 65 list, which runs to roughly 900 chemicals and is updated at least once a year.

Prop 65 reaches Korean skincare because it turns on the point of sale, not the country of manufacture. If a California consumer can buy your product, on a shelf or online, the warning duty attaches to you as the brand. MFDS approval in Korea and MoCRA registration in the US do not exempt a product, because they answer different questions. Federal FDA rules govern labeling and facility registration, while Prop 65 is a state chemical-warning regime layered on top of them. A formula can be fully legal to sell and still owe a California warning.

The Listed Chemicals Most Likely to Touch a K-Beauty Formula

A short list of chemicals accounts for most Prop 65 exposure in skincare. Retinol and retinyl esters are listed for developmental toxicity when daily dosage exceeds 10,000 IU or 3,000 retinol equivalents, a listing that dates to 1989 (OEHHA retinol listing). Heavy metals such as lead, arsenic, cadmium, and mercury appear as trace contaminants in botanical extracts, clays, and some pigments. 1,4-dioxane rides in as a byproduct of ethoxylated surfactants. Titanium dioxide is listed only as airborne, unbound particles of respirable size, and a court has held that businesses do not need to warn about titanium dioxide in cosmetics, though loose powders and aerosol sunscreens can still raise the airborne question (OEHHA titanium dioxide fact sheet).

When Does a Product Actually Need a Warning?

A warning is required only when a person's exposure to a listed chemical is high enough to cross the state safe harbor level. For carcinogens that threshold is the No Significant Risk Level, or NSRL; for reproductive toxicants it is the Maximum Allowable Dose Level, or MADL. If your product keeps exposure below the safe harbor, no warning is required. Exposure is about dose and use pattern, not the mere presence of a chemical, so a trace of lead below the MADL does not by itself trigger a duty to warn.

This is why blanket warnings are a mistake. Founders without exposure data often default to warning on everything just in case, which can dampen conversion and, in some cases, invite the attention of enforcers who read a warning as a concession. The defensible path is the opposite: get the numbers, run the exposure math against the safe harbor, and warn only where the analysis says you must.

What a Compliant Warning Looks Like on Label and Online

A compliant warning uses California's safe harbor content, which names at least one listed chemical and points to the state site. The standard long-form warning reads like this:

The short-form warning changed. As of January 1, 2025, a short-form warning must name at least one chemical and may use "WARNING," "CA WARNING," or "CALIFORNIA WARNING," and enforcement of the new format begins January 1, 2028, with sell-through for products made before then (OEHHA safe harbor amendments). Just as important for K-beauty, the warning must also appear on the web listing before purchase, not only on the package. That online duty is what trips up Amazon and DTC sellers, and it pairs with the federal label rules in our US labeling compliance guide.

How Should Founders Handle Prop 65 With a Korean ODM?

Handle Prop 65 at sourcing, before the purchase order, because that is where you have the most pull over disclosure. A practical protocol looks like this:

1. Pull a full ingredient list with dosages and function from the ODM, not only the INCI names.
2. Request heavy-metal and contaminant testing, a certificate of analysis covering lead, arsenic, cadmium, and mercury, plus 1,4-dioxane where ethoxylated surfactants are used.
3. Map each ingredient and contaminant against the current OEHHA list.
4. Estimate exposure per use and compare it to the NSRL or MADL safe harbor, and bring in a toxicologist or Prop 65 specialist where the numbers are close.
5. Decide the path: warn, reformulate to swap the trigger, or document that exposure sits below safe harbor.
6. If you warn, place compliant text on the label and on every California-facing listing.

A Korean ODM that already ships to the US can usually produce this data, but you have to ask for it by name. Building it into your sourcing brief matters more than any single ingredient choice, a point we make in our US market launch playbook.

Common Mistakes Indie Founders Make With Prop 65

The recurring errors are predictable. Founders assume MoCRA or MFDS covers Prop 65, when the three are separate. They slap a blanket warning on every product instead of assessing exposure. They put the warning on the box but forget the website, which is where enforcers often look first. They trust an INCI list without asking for contaminant testing, so heavy metals in a "clean" botanical extract go unseen. They miss the 2025 short-form change and keep printing an outdated warning. And they treat compliance as a one-time task rather than re-checking when OEHHA updates the list.

Frequently Asked Questions

Does an FDA MoCRA registration cover Prop 65?
No. MoCRA is a federal law on facility registration and product listing, while Prop 65 is a California warning law about specific listed chemicals. Meeting one says nothing about the other, and a MoCRA-registered product can still owe a California warning.

Do I need a Prop 65 warning if I only sell on my own website, not Amazon?
If a California resident can buy your product, the warning duty can attach, and it must appear on the listing before purchase. Selling direct rather than on a marketplace does not remove the obligation.

Is a Prop 65 warning an admission that my product is unsafe?
No. A warning reflects the presence of a listed chemical above a safe harbor exposure level, not a finding that the product is dangerous. Many everyday products carry warnings for trace exposures.

What is the penalty for missing a Prop 65 warning?
Penalties can reach $2,500 per day per violation, and private enforcers can bring an action after serving a 60-day notice of violation (California Prop 65 Warnings site). Most cases settle, but the cost and distraction are real.

Does natural or clean beauty exempt me from Prop 65?
No. Natural botanicals can carry heavy-metal contaminants such as lead or arsenic, which are listed chemicals. A clean or vegan claim does not change the exposure math or the warning duty.

By Liz Song, K-beauty sourcing consultant. Reviewed for accuracy by ALTA MEET's formulation consulting team.