Any poisonous or deleterious substance added to any food except where the substance is required in the production thereof or cannot be avoided by good manufacturing practice shall be deemed to be unsafe for purposes of the application of subdivision 4059(1)(B) of this title; but when the substance is so required or cannot be so avoided, the Board shall adopt rules limiting the quantity therein or thereon to such extent as the Board finds necessary for the protection of public health, and any quantity exceeding the limits so fixed shall also be deemed to be unsafe for purposes of the application of subdivision 4059(1)(B) of this title. While such a rule is in effect limiting the quantity of any such substance in the case of any food, the food shall not, by reason of bearing or containing any added amount of the substance, be considered to be adulterated within the meaning of subdivision 4059(1)(A) of this title. In determining the quantity of the added substance to be tolerated in or on different articles of food, the Board shall take into account the extent to which the use of the substance is required or cannot be avoided in the production of each such article and the other ways in which the consumer may be affected by the same or other poisonous or deleterious substances. (Added 1959, No. 172, § 13, eff. May 12, 1959; amended 1959, No. 329 (Adj. Sess.), § 27, eff. March 1, 1961; 2015, No. 23, § 111.)