An updated U.S. population dietary exposure assessment for 4-methylimidazole (4-MEI) from foods containing colour and from formation of 4-MEI through thermal treatment of foods

The current study updates the U.S. Food and Drug Administration’s dietary exposure assessment for 4-methylimidazole (4-MEI), a constituent of caramel colouring. The FDA study was published in 2018 and was based on food consumption data from U.S. National Health and Nutrition Examination Survey (NHANES) 2009-2012 cycles. This study incorporates 4-MEI levels currently found in beverages (Tier 1, based on industry reported levels), removes from the assessment foods that no longer contain caramel (Tier 2, based on food labels), and assumes 4-MEI levels in foods being reduced by half to align with the 50% lowering of the Food Chemicals Codex specification limits for 4-MEI in caramel III or IV (Tier 3). Updated food and beverage consumption data from the NHANES 2015-2018 cycles are also used. The cumulative reduction in 4-MEI levels in beverages and foods from industry reformulations results in exposures to added sources (caramel colour) and intrinsic sources (baking or roasting process) being similar. Compared to previous FDA estimates of 0.043 and 0.046 mg day−1 of 4-MEI from added caramel sources for the general population and adults, respectively, this updated assessment shows 4-MEI estimated exposures to be 0.016 and 0.017 mg day−1, when all reductions in foods and beverages are accounted for. When 4-MEI level adjustments were limited to beverages (Tier 1) and labelled food products (Tier 2), prepared meals, breads and rolls, and ice cream and frozen yogurt were the top three contributors to added 4-MEI exposures. As 4-MEI dietary exposure from added caramel continues to decrease, the contribution ranking of the food categories is expected to change.本研究更新了美国食品药品监督管理局（U.S. Food and Drug Administration, FDA）针对焦糖色素（caramel colouring）成分4-甲基咪唑（4-methylimidazole, 4-MEI）的膳食暴露评估。2018年发布的FDA原研究基于美国国家健康与营养检查调查（National Health and Nutrition Examination Survey, NHANES）2009-2012周期的食物消费数据。本次研究纳入了当前饮料中检出的4-MEI水平（Tier 1，基于行业报告水平），移除了评估中不再含有焦糖的食品（Tier 2，基于食品标签），并假设食品中的4-MEI水平降低一半，以匹配食品化学品法典（Food Chemicals Codex）针对III型或IV型焦糖中4-MEI的规格限值下调50%的要求（Tier 3）。同时，本研究还采用了NHANES 2015-2018周期的更新食物与饮料消费数据。通过行业配方调整实现饮料与食品中4-MEI水平的整体降低，使得添加来源（焦糖色素）与内源性来源（烘焙或焙烤过程）的暴露水平趋于一致。相较于FDA此前对普通人群及成人人群从添加焦糖来源摄入4-MEI的评估值（分别为0.043和0.046 mg·天⁻¹），本次更新后的评估显示，当纳入所有食物及饮料的降低措施后，4-MEI的估计暴露量分别为0.016和0.017 mg·天⁻¹。当4-MEI水平调整仅局限于饮料（Tier 1）及标注配料的食品（Tier 2）时，预制餐食、面包及餐包、冰淇淋与冷冻酸奶是添加型4-MEI暴露的前三大贡献来源。随着添加焦糖带来的膳食4-MEI暴露持续降低，各类食品类别的贡献排名预计将发生变化。