16 CFR §260.9

1. (a)It is deceptive to misrepresent, directly or by implication, that a product, package, or service is free of, or does not contain or use, a substance. Such claims should be clearly and prominently qualified to the extent necessary to avoid deception.
2. (b)A truthful claim that a product, package, or service is free of, or does not contain or use, a substance may nevertheless be deceptive if:
   1. (1)The product, package, or service contains or uses substances that pose the same or similar environmental risks as the substance that is not present; or
   2. (2)The substance has not been associated with the product category.
3. (c)Depending on the context, a free-of or does-not-contain claim is appropriate even for a product, package, or service that contains or uses a trace amount of a substance if:
   1. (1)The level of the specified substance is no more than that which would be found as an acknowledged trace contaminant or background level 47 ;
   2. (2)The substance's presence does not cause material harm that consumers typically associate with that substance; and
   3. (3)The substance has not been added intentionally to the product.