CUPROUS IODIDE
Cuprous iodide is a copper(I) iodide inorganic compound used in very limited food applications in the United States regulated under specific FDA provisions.
What It Is
Cuprous iodide is a binary inorganic compound consisting of copper in its +1 oxidation state and iodide anions. It is recognized as a white crystalline powder when pure and may be identified by the CAS registry number 7681-65-4. In regulatory listings under U.S. food law, it is described by these identifiers and appears in FDA regulations that define permitted direct food substances, even though its application in food is highly specific and limited to particular contexts. The compound has been evaluated by the U.S. Food and Drug Administration as part of Title 21 of the Code of Federal Regulations, and its inclusion there reflects its regulated use as a source of dietary iodine under narrowly defined conditions in salt and feed grade products. In chemical nomenclature it is categorized among the copper halides, and typical references list common synonyms including copper(I) iodide and Cuprous iodide. While this section focuses on its identity as an additive or direct food substance under U.S. food law, cuprous iodide also has broader industrial and synthetic applications outside of the food supply.
How It Is Made
The synthesis of cuprous iodide for regulatory or industrial use typically involves basic inorganic precipitation reactions involving a soluble copper(II) salt and a source of iodide. In one standard route, an aqueous solution of copper sulfate is mixed with an iodide donor such as potassium iodide under controlled conditions, leading to the immediate formation of the cuprous iodide precipitate, which is then filtered and dried. Regulatory specifications in food contexts require that the final product be of a purity appropriate for its intended use, and manufacturers producing food‑grade material must follow good manufacturing practices and quality controls to ensure that impurities and potential contaminants are minimized. This process, while straightforward in an industrial chemistry setting, must be adapted to food regulatory requirements when the compound is intended for feed or human salt fortification. Because this is an inorganic salt, the manufacturing process does not involve complex organic synthesis steps, and purity criteria are critically assessed in regulatory review to ensure consumer safety.
Why It Is Used In Food
In food regulation, cuprous iodide is authorized for use in a very narrow set of circumstances, primarily as a source of dietary iodine. In the United States under Title 21 of the CFR, it appears in Section 184.1265 with an explicit limitation that it may be used as a source of dietary iodine in table salt and animal feed at a defined maximum level. Iodine fortification of salt is a common nutritional strategy to prevent deficiency disorders, and the inclusion of cuprous iodide under this regulation reflects its technical function in providing the iodine nutrient. Its role in feed is similarly to deliver iodine necessary for animal health. It is not used for flavor, color, or other typical additive functions but rather strictly as a nutrient source under defined regulatory parameters. The narrow scope of use underscores why the compound does not appear widely across food categories but remains listed due to this specific functional contribution in fortified products.
Adi Example Calculation
Because an internationally recognized numeric ADI value for cuprous iodide was not identified in authoritative additive evaluation sources during this research, a quantitative example calculation cannot be presented here. In general, if an ADI were available, a calculation would illustrate how an individual’s body weight and daily intake of a fortified food containing the compound relate to that ADI. Such examples can help clarify how regulatory use limits translate into real‑world consumption, but without a confirmed numeric ADI, this section remains descriptive rather than quantitative.
Safety And Health Research
Safety evaluations of cuprous iodide as a food additive focus on its nutrient delivery role rather than potential toxicological effects at levels encountered in fortified food. In the U.S., regulatory review for its affirmation as GRAS under Section 184.1265 reflects an assessment that the permitted exposure is safe for the intended use, which is to contribute iodine to prevent deficiency. This assessment includes consideration of toxicological data relevant to copper and iodine compounds generally, and ensures that levels used in salt do not exceed safe intake thresholds. Because the compound is used in trace amounts for nutrient fortification, exposure to consumers via fortified food is low. Research on health effects of iodine and copper intake typically informs consideration of such additives, but no broad toxicological conclusions specific to cuprous iodide beyond its regulated context were available in authoritative additive evaluation summaries at the time of writing. It is important to distinguish between general hazard information for inorganic copper compounds and the safety evaluation specific to its nutrient function under regulatory allowances.
Regulatory Status Worldwide
In the United States, cuprous iodide is explicitly listed in Title 21 CFR Section 184.1265 as a direct food substance affirmed as generally recognized as safe for a specific use as a source of dietary iodine in table salt and animal feed at a maximum level of 0.01 percent. This regulatory citation indicates that it has undergone safety review by the FDA for that limited function, and that prior sanctions different from the established uses do not exist or have been waived under this section. It also appears in FDA food contact inventories and additive listings that its CAS number and synonyms, which confirms its regulatory presence. Information about its status in the European Union or under JECFA evaluations could not be confirmed from authoritative additive specification databases during this research, and no clear E‑number listing or international ADI specification could be identified. As such, its global regulatory footprint may differ and users should consult local food law references for jurisdictions outside the U.S. that might permit, restrict, or exclude its use in food or feed products.
Taste And Functional Properties
Cuprous iodide as an inorganic compound does not impart a significant taste or organoleptic property when used in the trace amounts permitted for iodine fortification. Its primary functional contribution in food matrices is as an iodine source rather than as a flavoring or texturizing agent. Because the permitted use levels are extremely low, sensory thresholds for detecting the compound in salt or fortified products are generally not reached in typical applications. In solution, cuprous iodide has very low solubility in water, so formulations using it must account for dissolution behavior and ensure proper dispersion to achieve consistent iodine delivery. Stability under typical food storage conditions is adequate for its nutrient role, but the compound’s chemistry is dominated by its inorganic salt behavior rather than interactions that would significantly influence taste profiles. Its physical characteristics, such as being a crystalline powder, support ease of blending into dry food matrices used for iodization processes.
Acceptable Daily Intake Explained
An Acceptable Daily Intake (ADI) represents an estimate of the amount of a substance that can be ingested daily over a lifetime without appreciable health risk, often set by international bodies such as JECFA or regional regulators. For cuprous iodide specifically, an international numeric ADI could not be confirmed in authoritative additive specification databases during this research, and therefore cannot be stated here. In the U.S. regulatory context, its permitted use level in salt is defined in terms of maximum percentage rather than an ADI for direct comparison. The ADI concept helps consumers and regulators understand safety margins for nutrient sources and additives alike, but in the absence of an identified numeric ADI for this compound from authoritative sources, its safety as a nutrient source is instead guided by the regulatory limits that reflect safe exposure levels.
Comparison With Similar Additives
Cuprous iodide’s functional niche as a source of dietary iodine is similar to other iodine donor compounds used in food fortification, such as potassium iodide or sodium iodide, which also deliver essential iodine in fortified salt products. Compared with these alternatives, cuprous iodide’s permitted use is specific and highly regulated, and other iodine sources may be more commonly referenced or used in different jurisdictions. From a broader perspective, additives that serve nutrient delivery functions differ from flavor enhancers or preservatives in that their primary purpose is to supply essential micronutrients. While potassium iodide and sodium iodide provide iodine without contributing additional elements such as copper, cuprous iodide introduces both copper and iodine into the formulation, which may have implications for formulation chemistry and regulatory acceptance. This comparison underscores that functional similarity does not equate to interchangeability, and regulatory frameworks dictate which forms are acceptable in specific contexts.
Common Food Applications Narrative
Cuprous iodide’s applications in food are limited and highly specific, and they center around nutritional fortification. In the United States, regulatory listings permit its use as a source of dietary iodine in table salt intended to provide an essential micronutrient. This function aligns with longstanding public health practices of iodizing salt to reduce iodine deficiency in populations. Because the compound is permitted only at very low levels under regulatory guidelines, typical consumer products that contain iodized salt may trace that iodine content back to regulated compounds such as cuprous iodide or alternative permitted iodine sources. Beyond salt, its use in animal feed as a nutrient supplement further reflects its role in delivering essential micronutrients rather than functioning as a general additive. It is not commonly found in processed foods outside of these fortification functions, and consumer interest in products that contain iodine often ties back to labeling about iodized salt rather than the specific chemical form used. These applications are technical and reflect regulatory decisions about safe and effective ways to deliver dietary iodine.
Safety & Regulations
FDA
- Approved: True
- Regulation: 21 CFR 184.1265
EFSA
- Notes: No EFSA additive evaluation with numeric ADI readily found
JECFA
- Notes: No JECFA numeric ADI or INS listing was confirmed
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