Prop 65 (California)

Proposition 65, officially the Safe Drinking Water and Toxic Enforcement Act of 1986, requires businesses to provide warnings about significant exposures to chemicals that cause cancer, birth defects, or reproductive harm. The list of covered chemicals now exceeds 900 substances and includes materials common in consumer products: lead, cadmium, phthalates, BPA, acrylamide, and wood dust. The law applies to any product sold in California, regardless of where the seller is based.

For hardware founders, Prop 65 is uniquely dangerous because of its enforcement mechanism. Unlike FCC or CE, which are enforced by government agencies, Prop 65 allows private citizens and law firms to sue for violations and collect a share of the penalties. This has created an ecosystem of "bounty hunter" plaintiffs’ firms that test consumer products for Prop 65 chemicals and file lawsuits — often targeting small and medium-sized brands that are less likely to fight back. A Prop 65 lawsuit can cost $10,000–$50,000+ to settle, regardless of whether your product actually poses a health risk.

The core requirement is a "clear and reasonable" warning before exposure to a listed chemical. For consumer products, this typically means a warning label on the product or its packaging. The warning must name at least one chemical that triggered it. A standard compliant warning reads: "WARNING: This product can expose you to chemicals including [name of chemical], which is known to the State of California to cause cancer. For more information go to www.P65Warnings.ca.gov." The warning must be in English and in any other language used on the product labeling.

Which products need warnings? Any product that exposes a consumer to a listed chemical above the "safe harbor" level. Safe harbor levels are established for some but not all listed chemicals. For lead, the safe harbor is 0.5 micrograms per day for reproductive toxicity. For cadmium, it is 4.1 micrograms per day. For phthalates like DEHP, it is 310 micrograms per day for adults. If your product contains a listed chemical and there is no established safe harbor level, you must provide a warning if exposure exceeds zero — a very low bar.

The exposure pathway matters. Carcinogens are evaluated for exposure by ingestion, inhalation, and dermal contact. Chemicals that cause reproductive harm are evaluated for exposure by all routes. A lead-containing solder joint sealed inside a plastic housing is less likely to trigger exposure than lead in a surface coating that a child could mouth. The risk is not the presence of the chemical — it is whether a consumer can be exposed to it.

Testing is typically done by ICP-MS (Inductively Coupled Plasma Mass Spectrometry) analysis to quantify total heavy metal content, and GC-MS (Gas Chromatography–Mass Spectrometry) for phthalates. A Prop 65 screen costs $300–$800 per product, depending on the number of materials and the chemicals tested. Many labs offer a combined CPSIA + Prop 65 panel that covers both federal children’s product requirements and California’s warning requirements.