Prop 65 testing for supplements and food

What is Proposition 65?

Proposition 65 is California's Safe Drinking Water and Toxic Enforcement Act of 1986. It requires the state to keep a list of chemicals known to cause cancer or reproductive toxicity, revised and republished at least once a year; the edition checked for this page is dated 31 July 2026. A business that knowingly exposes people in California to a listed chemical must first give a "clear and reasonable" warning, unless the exposure falls under an exemption such as a level at or below the safe harbor.

The rule is about exposure, not presence. A product can contain a listed chemical and need no warning if the daily exposure is low enough. Food, including dietary supplements, has its own warning rules in Title 27 of the California Code of Regulations (sections 25607.1 and 25607.2).

Which Prop 65 chemicals matter most for supplements and foods?

Selected entries on the Prop 65 list. Source: OEHHA, Proposition 65 List of Carcinogens or Reproductive Toxicants, 31 July 2026.

The four metals come into products mainly through ingredients: plants and minerals take them up from soil and water. Acrylamide is different. FDA describes it as forming from sugars and the amino acid asparagine in plant-based foods, such as potato and cereal-grain foods, during high-temperature cooking like frying, roasting and baking, so it matters for roasted, baked and fried products. Aflatoxins are mold toxins, covered on the mycotoxin testing page. The full list has hundreds of entries, so check it against your ingredients.

How is Prop 65 exposure calculated?

The regulations define exposure as a concentration multiplied by a rate of intake. For a product you eat or swallow:

Daily exposure (µg/day) = concentration (ppm, which is µg/g) × grams of product consumed per day

For consumer products, the intake rate is the reasonably anticipated rate for average users of the product, not the general population (Title 27, sections 25721 and 25821). Cancer exposures are assessed as lifetime exposure; reproductive exposures use the pattern and duration relevant to the effect. Only the exposure from your own product counts, not exposure from other sources.

Example with made-up numbers: a gummy weighing 2.5 g, two a day (5 g per day), with a lead result of 0.08 ppm gives 0.08 × 5 = 0.4 µg/day. For a full worked table across all four metals, see heavy metal limits.

For food, a chemical that is naturally occurring is not counted as an exposure to the extent the business can show it came from the environment the food was grown in, and only to the extent it could not be avoided by good agricultural or manufacturing practice (section 25501). Whether that applies to a given ingredient is a legal question, and it needs background data, not only a test result.

What are the safe harbor levels for the key chemicals?

Prop 65 safe harbor levels in µg/day. Source: OEHHA NSRL and MADL list; Title 27, California Code of Regulations, sections 25705, 25709 and 25805.

Figures checked against the sources below on 3 November 2026; rules change, so confirm the current version before relying on them.

An NSRL is set at one excess cancer case in 100,000 people over a lifetime; a MADL is set so that exposure at 1,000 times the level would have no observable effect. When a chemical has both, the exposure has to be under each one. OEHHA notes that settlement agreements in enforcement actions can set negotiated levels for specific cases, and that a business may use another level if it can show it is scientifically valid. For ICH Q3D and FDA figures and a worked example across four metals, see heavy metal limits.

Warning or reformulation: what are the options?

• Show the exposure is below the safe harbor level. No warning is needed for that chemical. This depends on test results and a realistic intake rate.
• Give a warning. The safe harbor wording for food and supplements begins "WARNING:" (or "CA WARNING:" or "CALIFORNIA WARNING:") and reads, for lead as a reproductive toxicant, "Consuming this product can expose you to chemicals including lead, which is known to the State of California to cause birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov/food." On a food label it must be set off in a box. Acrylamide has its own approved wording.
• Reformulate. Change the ingredient, supplier or serving size so the exposure drops below the level, then confirm with new results.

In the supply chain, a manufacturer can put the warning on the label or send written notice and warning materials to the retailer's authorized agent, renewed every year while the product is sold in California. Retailers carry the duty only in set cases, such as their own brands.

What role does lab testing play in Prop 65?

The Prop 65 rules describe a calculation, not a lab method. Testing supplies the concentration, and the label supplies the intake. A useful Prop 65 data set has:

• a result for each listed chemical of concern, with units and the limit of quantitation;
• an LOQ low enough for your serving size: at 5 g a day, 0.5 µg/day of lead equals 0.1 ppm, so the method has to quantify well below that;
• finished-product results, because a blend can exceed a level when no single ingredient does;
• arsenic reported as total or inorganic, since the safe harbor level is for inorganic arsenic;
• results tied to a lot number, repeated after supplier or formula changes.

Verified Analytical Laboratory tests products for heavy metals by ICP-MS and for aflatoxins under contaminant testing, and issues a Certificate of Analysis for each sample. Tell us the serving size, servings per day and the chemicals you need covered, and we will recommend a panel from the analytes listed on the heavy metals and contaminant testing pages and confirm the method and sample amount with your quote.

Questions about this page

Sources: OEHHA: Proposition 65 List of Carcinogens or Reproductive Toxicants (31 July 2026) · OEHHA: Proposition 65 No Significant Risk Levels (NSRLs) and Maximum Allowable Dose Levels (MADLs) · FDA: Acrylamide
Last reviewed: 3 November 2026