(a) Any added poisonous or deleterious substance, any food additive, any pesticide chemical in or on a raw agricultural commodity or any color additive shall with respect to any particular use or intended use be deemed unsafe for the purpose of application of clause (2) (a) of Section 10(a) with respect to any food, Section 14(a) with respect to any drug or device or Section 18(a) with respect to any cosmetic, unless there is in effect a regulation pursuant to Section 21 of this Act or subsection (b) of this Section limiting the quantity of such substance and the use or intended use of such substance conforms to the terms prescribed by such regulation. While such regulation or a regulation under the Federal Act relating to such substance is in effect, a food, drug or cosmetic shall not, by reason of bearing or containing such substance in accordance with the regulation, be considered adulterated within the meaning of clause 1, Section 10(a), Section 14(a) or Section 18(a).(b) The Director, when public health or other considerations in this State so require, is authorized to adopt, amend or repeal regulations, whether or not in accordance with regulations promulgated under the Federal Act, prescribing therein tolerances for any added poisonous or deleterious substances, for food additives, for pesticide chemicals in or on raw agricultural commodities for direct human consumption or manufactured food products or for color additives, including, but not limited to, zero tolerances and exemptions from tolerances in the case of pesticide chemicals in or on raw agricultural commodities for direct human consumption or manufactured food products and prescribing the conditions under which a food additive or a color additive may be safely used and exemptions where such food additive or color additive is to be used solely for investigational or experimental purposes.