21 CFR §184.1265

1. (a)Cuprous iodide (copper (I) iodide, CuI, CAS Reg. No. 7681-65-4) is a pure white crystalline powder. It is prepared by the reaction of copper sulfate with potassium iodide under slightly acidic conditions.
2. (b)The ingredient must be of a purity suitable for its intended use.
3. (c)In accordance with § 184.1(b)(2), the ingredient is used in food only within the following specific limitations:
4. (d)Prior sanctions for this ingredient different from the uses established in this section do not exist or have been waived.