The colorant, called cochineal (koch-uh-NEEL) extract or carmine dye, has been used for centuries?dating back at least to the Aztec empire. It is made from female cochineal bugs, which are harvested in Central and South America and the Canary Islands specifically to be made into dye.
The extract is used to dye food, drinks, cosmetics and fibers various shades of red, orange, pink and purple.
Through a bit of medical detective work, U-M allergist James L. Baldwin, M.D., confirmed that cochineal extract triggered life-threatening anaphylactic shock in a patient after she ate a popsicle containing the colorant.
A paper on the subject will be published in the November issue of the peer-reviewed journal Annals of Allergy, Asthma & Immunology.
Ironically, cochineal extract often is not listed on food labels. As an animal product, it is considered a "natural" additive and, therefore, is subject to less stringent labeling regulations than synthetic food dyes.
Baldwin wants more doctors and patients to be aware that the extract may be the cause of unexplained allergic reactions?from mild hives and itchy skin to dangerous anaphylaxis. Only through more awareness, he says, will the medical community be able to determine how many people are sensitive to cochineal extract.
"If we don't look for it," he says, "we're not going to find it."
He does not advocate removing the colorant from the market, and points out that several large studies have found it to be safe and non-toxic. It would be helpful, however, if the FDA required cochineal extract and carmine to be listed as an ingredient on food labels, he says. The only way people can avoid allergic reactions is to avoid the substance they're allergic to?but that's often impossible if the food labels don't list the substance. Currently, some food labels identify carmine or cochineal extract as an ingredient, but other foods containing the additive simply say "color added," "artificial color," or "artificial color added."
About 18 months ago, Baldwin treated an emergency room patient suffering from anaphylactic shock?a rare, severe and life-threatening allergic reaction that usually occurs in response to an insect sting or injected drug.
"She came in with hives, asthma and virtually no blood pressure," Baldwin says.
The patient was stabilized and Baldwin learned that her dramatic allergic reaction occurred after she ate a red popsicle. A skin test confirmed the woman was allergic to the frozen dessert?but to which of its ingredients? After further research and testing, Baldwin determined the popsicle contained two "natural" color additives, and the patient demonstrated a severe allergic sensitivity to one of them?cochineal extract.
The doctor also learned that the woman had routinely experienced hives and itchy skin after applying blush, a cosmetic that often contains cochineal extract.
Baldwin scoured references?including an old Spanish monograph, FDA regulations, the Handbook of U.S. Colorants for Foods and Drugs, and even an article on cochineal bugs in Ranger Rick magazine. He learned about the extract's long history as a colorant, widespread use today, manufacturing process, regulatory classification and chemical makeup. He also discovered that on rare occasions it had been suspected?though not confirmed?as the cause of anaphylactic shock and asthma in workers who processed the extract.
Physicians often confirm the results of allergy skin tests through a radioallergosorbent test (RAST), which detects antigens produced in the body in response to an allergen. Baldwin could not administer a RAST for cochineal extract, however, because no such test has been developed for the additive.
Instead, he took an unusual step?one which had never been taken before with cochineal extract or carmine. Along with a colleague, Dr. Alice Chou, he conducted a Prausnitz-Kustner (P-K) test to confirm that his patient carried cochineal antibodies and was, indeed, allergic to the food dye.
A P-K test involves making a serum from the patient's blood and injecting it in the skin of a person who is not allergic to the substance being tested. P-K tests are rarely administered anymore because of concern over blood-borne infections, but in this case the patient's husband agreed to have her serum injected into the skin on his arms.
The result: the patient's husband demonstrated an allergic sensitivity to cochineal extract in the spots on his arms where the serum was injected.
That, combined with the results of the woman's skin test, confirmed that her anaphylaxis was triggered by the colorant.
Since then, Baldwin and other allergists at the U-M have confirmed cochineal sensitivity in two more patients.
EDITORS: For more information or to schedule an interview with Dr. Baldwin, call Dave Wilkins or Pete Barkey in the U-M Medical Center Department of Public Relations, (313) 764-2220.