A joint study by Consumer Reports and the Johns Hopkins Center for a Livable Future claims that 4-methylimidazole (4-MEI) exposures “associated with average rates of soft drink consumption pose excess cancer risks exceeding one case per 1,000,0000 exposed individuals, which is a common acceptable risk goal used by U.S. federal regulatory agencies.” Tyler Smith, et al., “Caramel Color in Soft Drinks and Exposure to 4-Methylimidazole: A Quantitative Risk Assessment,” PLOS One, February 2015. Researchers apparently used ultrahighperformance liquid chromatography-tandem mass spectrometry to estimate 4-MEI concentrations in 12 beverages purchased in California and New York City, then assessed exposure levels based on data obtained from the National Health and Nutrition Examination Survey, California Environmental Protection Agency Office of Environmental Health Hazards Assessment (OEHHA) and U.S. Census Bureau.

In addition to ranking 4-MEI concentrations by brand, product and geographic location, the study authors calculated the lifetime average daily dose and lifetime excess cancer risk and burden for consumers. Their results allegedly indicate that “routine consumption of certain beverages” was associated with 4-MEI exposures that exceed the no significant risk level (NSRL) set by California under the Safe Drinking Water and Toxic Enforcement Act of 1986 (Proposition 65), which requires warning labels on beverages with 4-MEI concentrations greater than 29 μg/day.

“Even considering the impact of Proposition 65 on 4-MEI concentrations in beverages, it is worth noting that the NSRL established by OEHHA corresponds to a risk of one cancer per 100,000 people exposed,” the authors argue. “Given that a sizable fraction of the U.S. population consumes these beverages, and high consumption by some persons, a substantial cancer burden may persist even if exposures are reduced to the NSRL nationally. Accordingly, federal regulation to eliminate unnecessary 4-MEI exposures may be needed. [A Food and Drug Administration] intervention, such as maximum levels for 4-MEI in beverages, could be a valuable approach to reducing excess cancer risk attributable to 4-MEI exposure in the U.S. population.” See ConsumerReports. org, February 18, 2015.