Prop 65 and Dietary Supplements: What Brand Owners Need to Know
California's Proposition 65 (the Safe Drinking Water and Toxic Enforcement Act of 1986) requires businesses to provide warnings when they expose consumers to chemicals that the state has listed as causing cancer, birth defects, or other reproductive harm. If you sell supplements in California — including online — this law applies to you.
How Prop 65 Applies to Supplements
Prop 65 maintains a list of over 900 chemicals. If your supplement contains any listed chemical above the No Significant Risk Level (NSRL) for carcinogens or the Maximum Allowable Dose Level (MADL) for reproductive toxics, you must provide a "clear and reasonable" warning — or face penalties of up to $2,500 per day per violation.
Critically, Prop 65 applies to any business selling products in California — not just companies headquartered there. If your e-commerce store ships to California, you are subject to Prop 65.
Which Supplement Ingredients Trigger Prop 65?
The most common Prop 65 chemicals found in supplements include:
- Lead — found in calcium, botanical, and mineral supplements due to soil contamination
- Cadmium — common in rice-based, zinc, and cocoa powders
- Arsenic — present in kelp, seaweed, and some protein powders
- Mercury — fish oil and marine-sourced ingredients
- DEHP — used in some plastic packaging that leaches into capsules
Even "natural" and "organic" supplements can contain Prop 65 chemicals at levels requiring a warning. Browse all Prop 65 listed substances to check your formula.
How the NSRL and MADL Thresholds Work
A warning is only required if exposure exceeds the threshold:
- NSRL (carcinogens): The level at which a chemical would cause one excess case of cancer in 100,000 people over a lifetime. For lead, this is 15 µg/day.
- MADL (reproductive toxics): The level at which no observable reproductive effect is seen, divided by 1,000 for safety. For lead, this is 0.5 µg/day.
If your product's daily exposure is below both thresholds, no warning is required. But note: Prop 65 thresholds are often far lower than FDA action levels, which is why products that are "FDA compliant" can still need Prop 65 warnings.
How to Screen Your Formula
- List every ingredient — including excipients, fillers, and processing aids.
- Cross-reference the Prop 65 list — check each ingredient against the 900+ listed chemicals at our Prop 65 directory.
- Estimate daily exposure — calculate the amount of each listed chemical a consumer ingests per serving.
- Compare against NSRL/MADL — if exposure exceeds the threshold, apply a warning label.
- Use the safe harbor warning — OEHHA provides approved warning language. Use it verbatim.
This guide is for informational purposes only and does not constitute legal or regulatory advice. Prop 65 compliance involves complex risk assessments — consult a qualified attorney or regulatory expert for your specific product. Not affiliated with the State of California OEHHA. IngredientCompliance is an independent tool operated by Gerim-Sterling LLC.