Chemical metabolism and toxicity to early life stages of fish

烷基多环芳烃（具有一个或多个烷基侧链的多环芳烃）存在于原油、杂酚油以及河流和港口的污染沉积物中。烷基多环芳烃是根据它们的母体结构和侧链上的碳数来分类的。有十多个类，其中一个类，如烷基菲，可能包括500多个侧链上有1到4个碳的独特化合物。虽然研究很少，但它们占原油中多环芳烃总量的90%以上，并对埃克森瓦尔迪兹号石油泄漏事件的渔业造成了影响。它们被鱼类迅速吸收，并产生细胞色素p450 （CYP1A）酶。这些酶将氧添加到烷基多环芳烃中，作为其排泄的第一步。然而，氧合可能产生比母体化合物更有害的代谢物。因此，更快的排泄会带来更大毒性的风险，表现为循环衰竭和胚胎和幼虫死亡，这是生命中最敏感的阶段。

Alkyl polycyclic aromatic hydrocarbons (PAH with one or more alkyl side chains) are found in crude oil, creosote, and contaminated sediments of rivers and harbours. Alkyl PAH are classified according to their parent structures and to the numbers of carbons in side chains. There are more than a dozen classes, and a single class, such as alkyl phenanthrenes, may include more than 500 unique compounds with 1 to 4 carbons in side chains. While little studied, they comprise more than 90% of total PAH in crude oil, and contributed to the impacts on fisheries of the Exxon Valdez oil spill. They are rapidly taken up by fish, which respond by producing cytochrome-P450 (CYP1A) enzymes. These enzymes add oxygen to alkyl PAH as the first step in their excretion. However, oxygenation may create metabolites that are more harmful than the parent compound. Hence, faster excretion carries a risk of greater toxicity, which is expressed as circulatory collapse and death of embryos and larvae, the most sensitive life stages.