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Questions & Answers About 4-MEI

What is 4-methylimidazole (4-MEI)?

4-methylimidazole (4-MEI) is a chemical compound that forms as a byproduct at low levels in some foods and beverages during the normal cooking process. For example, 4-MEI may form when coffee beans are roasted and when meats are roasted or grilled. 4-MEI also forms during the manufacturing of certain types of caramel coloring (known as Class III and Class IV caramel coloring).  Class III and Class IV  caramel coloring are the most commonly used food color additives by volume.

Is there a risk from eating foods that contain 4-MEI?

Based on current science, the FDA has no reason to believe that there are any immediate or short-term health risks presented by 4-MEI at the levels expected in food.

What about studies that show 4-MEI to be a carcinogen?

In 2007, the National Toxicology Program (NTP) issued reports summarizing the results of toxicological testing conducted on 4-MEI in rats and mice. A 2-year study in rats was inconclusive regarding carcinogenicity, but a 2-year mouse study showed an increased incidence of certain lung tumors. These NTP studies were conducted in rodents at levels of 4-MEI that far exceed current estimates of human exposure to 4-MEI from the consumption of food with or without the addition of Class III or Class IV caramel coloring.

Has 4-MEI been shown to cause other toxic effects?

In March 2020, NTP published the results of a multi-generation reproductive and developmental study on 4-MEI in rats. These types of toxicity studies are conducted to determine if exposure to a substance is associated with changes in reproduction, fertility, and development in the rats’ offspring. This study showed reproductive and developmental effects in male and female rats at the levels tested, however, the doses used in the study were similar to those used in the earlier carcinogenicity studies and similarly far exceed current estimates of human exposure to 4-MEI from foods.

Does the FDA require manufacturers to disclose whether food products contain Class III and Class IV caramel coloring?

No. The FDA’s regulations require that the labels of food containing non-certified color additives, such as caramel coloring, declare the color additives in the ingredients statement either by name or with a general term such as “artificial color” or “color added” unless otherwise indicated. There is no requirement in FDA’s regulations that the ingredient statement on the label of foods that contain Class III or Class IV caramel coloring list the color additive by name or type. It is therefore not possible, unless voluntarily disclosed, to know based on the label if a food contains Class III or IV caramel coloring. Foods that have “caramel coloring” on a food label do not necessarily contain 4-MEI, because the term “caramel coloring” may be used to describe any class of caramel coloring. Class I and Class II caramel coloring do not contain 4-MEI.

What is the FDA doing about the presence of 4-MEI in caramel coloring?

To ensure that the use of Class III and Class IV caramel coloring in food continues to be safe, the FDA is currently reviewing all available data on the safety of 4-MEI. In 2018, the FDA published an assessment of potential consumer exposure to 4-MEI from the use of Class III and Class IV caramel coloring in food products.

The FDA’s current review, along with this exposure assessment, will help the FDA determine what, if any, regulatory action needs to be taken. Such actions could include setting a limit on the amount of 4-MEI that can be present in Class III and IV caramel coloring. However, in the interim, the FDA is not recommending that consumers change their diets because of concerns about 4-MEI.

Can 4-MEI be eliminated from food products?

Eliminating 4-MEI in food is not feasible because it is formed during normal cooking processes. However, there are examples of manufacturers of Class III and IV caramel coloring who have taken steps to reduce the levels of 4-MEI in their products.

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