Prop 65 is enforced differently from FDA or FTC regulations. Private plaintiffs — individuals or organizations — can bring enforcement actions and are entitled to attorney fees and civil penalties of up to $2,500 per day per violation. The result is a plaintiff's bar that actively monitors supplement and food products for unlabeled chemicals, making Prop 65 a significant litigation risk for brands that haven't assessed their exposure.
How Prop 65 Works
Under California Health and Safety Code Section 25249.6, businesses with 10 or more employees must provide a "clear and reasonable warning" before knowingly and intentionally exposing any individual to a chemical on the Prop 65 list. The list currently contains over 900 chemicals.
A warning is required when:
A listed chemical is present in the product
The exposure exceeds the "safe harbor" level established by OEHHA (the California Office of Environmental Health Hazard Assessment)
The exposure comes from intentional addition or is a known component
Common Prop 65 Chemicals in Supplements and Food
Several chemicals on the Prop 65 list appear frequently in supplements and food products:
Lead: Present in many botanical ingredients, particularly root-based herbs, at levels that may trigger warning requirements. California has pursued numerous Prop 65 actions against supplement brands for lead in herbal products.
Cadmium: Another heavy metal found in botanical ingredients, particularly mushrooms, leafy vegetables, and root herbs.
Arsenic: Found in rice-based products, certain seafood-derived ingredients, and some botanical extracts.
Mercury: Present in fish-derived ingredients (fish oil, shark cartilage).
Acrylamide: Forms in foods heated at high temperatures; relevant for some food products.
Titanium dioxide: Used as a whitening agent in supplement coatings and some food products; listed as a Prop 65 carcinogen (by inhalation).
DEHP and other phthalates: Can leach from plastic packaging.
Safe Harbor Levels and How They Work
OEHHA establishes Maximum Allowable Dose Levels (MADLs) for reproductive toxicants and No Significant Risk Levels (NSRLs) for carcinogens. If daily exposure from a product is below the MADL or NSRL, no warning is required — even if the chemical is detectable.
For lead, the MADL is 0.5 micrograms per day. This is extremely low — and is why many herbal supplement products that test positive for trace lead at levels that wouldn't concern FDA (which focuses on safety thresholds) still require Prop 65 warnings for California sales.
The Warning Label Requirement
If a Prop 65 warning is required, it must use specific OEHHA-approved language (updated in 2018). The current required warning format for most products:
WARNING: This product can expose you to [chemical name], which is known to the State of California to cause [cancer / birth defects or other reproductive harm]. For more information go to www.P65Warnings.ca.gov.
Warnings must appear on the product label, in online product listings for California consumers, or on point-of-sale displays. The 2018 update requires that the specific chemical(s) be named in the warning — generic "Prop 65 chemicals" warnings are no longer compliant.
Prop 65 Testing Protocol
Brands selling in California should:
Test finished products for common Prop 65 chemicals using accredited laboratories
Calculate daily consumer exposure based on recommended serving size
Compare exposure to relevant MADLs and NSRLs
Apply warnings where exposures exceed safe harbor levels
Maintain testing records — which serve as a defense in plaintiff enforcement actions
Testing can also support a "no significant risk" defense. If a brand can demonstrate that exposure from its product falls below safe harbor levels, it has a complete defense against Prop 65 enforcement.
Prop 65 is a litigation risk, not just a labeling issue
California's private enforcement model means Prop 65 exposure exists wherever supplement brands ship to California — which, for DTC brands, is effectively everywhere they sell online. Truli tracks Prop 65 list updates, flags ingredients with known Prop 65 chemical associations, and helps brands identify products that may need testing or warning language before entering the California market.
A note from Truli: Truli is not a law firm, and this article does not constitute or contain legal advice or create an attorney-client relationship. When determining your obligations and compliance with respect to relevant laws and regulations, you should consult a licensed attorney.
