On the recordMarch 8, 2006
If the FDA has not established a tolerance or limit for a particular poisonous or deleterious substance in food, the State is free to make its own determination of what quantity of that substance should be held to adulterate the food. If, however, there is an FDA established tolerance or limit, the State would then need to follow the tolerance or limit in its enforcement of State law. If FDA has finally determined that there should not be a tolerance or limit, then in that instance also the State would need to follow the Federal policy.
Source
govinfo.gov
