Running a Prop 65 exposure assessment

Proposition 65 does not require a warning for an exposure that the business can show poses no significant risk (for a chemical listed as causing cancer) or has no observable effect at 1,000 times the level in question (for a chemical listed as causing reproductive toxicity). The burden of showing that is on the business (Health and Safety Code 25249.10(c)). An exposure assessment is how you make that showing.

The two levels an exposure is compared against:

• NSRL (No Significant Risk Level) — for carcinogens: the level calculated to result in one excess case of cancer in an exposed population of 100,000, assuming lifetime exposure at that level (27 CCR 25703(b)).
• MADL (Maximum Allowable Dose Level) — for reproductive toxicants: the no-observable-effect level divided by 1,000 (27 CCR 25801(b)).

What an assessment usually needs:

1. Concentration — how much of the listed chemical is in the product, from a lab test
2. How the product is used — how much of it a person contacts, eats, or breathes in during typical use
3. Route of exposure — oral (food, mouthing), skin contact, or inhalation
4. Frequency — how often and for how long the product is used

The estimated exposure is then compared with the chemical's NSRL or MADL. The Prop 65 regulations set rules for how that estimate is made, so if you have not done one before, this is work for a qualified consultant or lab.

TIP: Keep the assessment on file even when it concludes no warning is required. If you receive a 60-day notice, it is your evidence that the exposure was below the level.

WARNING: The state must revise and republish the chemical list at least once a year (HSC 25249.8(a)). Recheck an old assessment when the list or the product changes. Aleph does not calculate exposure; it records the Prop 65 answers you enter for each product.