Nestmann E R, Lynch B S, Musa-Veloso K, Goodfellow G H, Cheng E, Haighton L A, Lee-Brotherton V M
Food Addit Contam. 2005 Sep;22(9):875-91. doi: 10.1080/02652030500195312.
The discovery of trace levels of semicarbazide (SEM) in bottled foods (especially baby foods) led to a consideration of the safety of this hydrazine compound by regulatory agencies worldwide. Azodicarbonamide, which is used in the jar-sealing technology known as Press On-Twist Off (or Push-Twist/PT) closures for the formation of a hermetic, plastisol seal, partially degrades with the heat of processing to form trace amounts of SEM. This review has evaluated the potential toxicological risks of resulting exposure to SEM and also the benefit of the PT technology (with azodicarbonamide) in the context of possible microbial contamination. It also considers the potential impact on infant nutrition if parents come to the conclusion that commercial baby foods are unsafe. SEM shows limited genotoxicity in vitro that is largely prevented by the presence of mammalian metabolic enzymes. Negative results were found in vivo in DNA alkaline elution, unscheduled DNA synthesis and micronucleus assays. This pattern is in contrast to the genotoxic hydrazines that also have been shown to cause tumours. Carcinogenicity studies of SEM are of limited quality, show a questionable weak effect in mice at high doses, which are not relevant to human exposure at trace levels, and show no effect in the rat. The IARC has assigned SEM as Group 3, 'Not classifiable as to its carcinogenicity to humans'. Based on estimates of exposure to infants consuming baby foods (with the assumption of SEM levels at the 95th percentile of 20 ng g(-1) in all of the consumed 'ready-to-eat' foods) compared with a no observed adverse effect level (NOAEL) in developmental toxicity studies, the margin of safety is more than 21 000. Since the risk of an adverse effect is negligible, it is clear that any theoretical risk is outweighed by the benefits of continuing use of the PT closure (with azodicarbonamide blowing agent) to ensure both the microbial integrity and availability of commercial baby foods as a valuable source of infant nutrition.
瓶装食品（尤其是婴儿食品）中发现痕量的氨基脲（SEM），这使得全球监管机构开始考虑这种肼类化合物的安全性。偶氮二甲酰胺用于一种名为“压扭式”（或“推扭式”/PT）瓶盖的封罐技术，以形成气密的增塑溶胶密封，它在加工过程中会因受热而部分降解，从而形成痕量的SEM。本综述评估了因接触SEM而产生的潜在毒理学风险，以及PT技术（使用偶氮二甲酰胺）在预防微生物污染方面的益处。它还考虑了如果父母认定市售婴儿食品不安全，这可能对婴儿营养产生的潜在影响。SEM在体外显示出有限的遗传毒性，而哺乳动物代谢酶的存在在很大程度上可防止这种毒性。在体内进行的DNA碱性洗脱、非程序性DNA合成和微核试验中均得到阴性结果。这种模式与同样已被证明会致癌的具有遗传毒性的肼类化合物形成对比。SEM的致癌性研究质量有限，在高剂量下对小鼠显示出可疑的微弱影响，但这些高剂量与人类痕量接触无关，且在大鼠中未显示出影响。国际癌症研究机构（IARC）将SEM归类为3类，即“对人类致癌性无法分类”。根据对食用婴儿食品的婴儿的接触量估计（假设所有食用的“即食”食品中SEM水平处于第95百分位数20 ng g⁻¹），与发育毒性研究中的未观察到有害作用水平（NOAEL）相比，安全系数超过21000。由于产生不良影响的风险可忽略不计，显然继续使用PT瓶盖（使用偶氮二甲酰胺发泡剂）以确保市售婴儿食品的微生物完整性和可获得性作为婴儿营养的宝贵来源所带来的益处，超过了任何理论上的风险。
