食品动物组织中兽药结合残留的毒性

 动物性食品中兽药残留对人类健康的影响日益被人们所重视。动物用药后，其体内可能存在两类残留:第一类是以游离或结合形式存在的原药及其主要代谢物；除高亲脂性化合物外，因代谢和排泄迅速，这些代谢物出现得早，且不在动物体内蓄积。但这些物质具有毒性，且在人体内可生成高度活化的中间产物（亲电子基团、自由基等），导致核酸、蛋白质烷基化、膜脂质过氧化等，从而对消费者具有潜在的危害性；第二类包括出现较晚的共价结合代谢物（结合残留），其排出相对较慢。它们的存在对于靶动物预示着潜在的毒性作用，而对于消费者，由于结合残留在人体内不可能再活化，以及其生物利用度和含量均低，因而可能只显示很低的毒性。

THE TOXICITY OF VETERINARY DRUG RESIDUES AND BOUND RESIDUES IN FOOD-PRODUCING ANIMALS

There are two types of metabolites (residues)in foods prepared from animals treated with veterinary drugs. The first type is represented by the drug itself and/or its primary metabolites as free or conjugated forms. Except for lipophilic compounds, these metabolites generally appear early and are noncumulative, since they are metabolized and eliminated rapidly.These substances may have toxic properties and may be transferred to highly reactive intermediates (electrophiles,free radicals),so they may be potentially toxic for consumers.The second type includes covalently bound metabolites (bound residues) which appear later. These metabolites have lost their reactivity in an irreversible manner and have low bioavailability. They therefore probably represent low toxicity for consumers.