Wu Jigang, Laird David A
Department of Agronomy, Iowa State University, Ames, Iowa 50011, USA.
Environ Toxicol Chem. 2003 Feb;22(2):261-4.
In vivo transformation of chlorpyrifos to chlorpyrifos oxon is believed to be a prerequisite for this insecticide to display acute toxicity to organisms. We discovered that active chlorine dispersed in water causes the rapid abiotic transformation of chlorpyrifos to chlorpyrifos oxon. The proposed mechanism for the transformation is an electrophilic attack by hypochlorous acid (HOCl) on the thion (P=S) double bond of chlorpyrifos followed by desulfuration of chlorpyrifos to its oxon analog. The pH of a Cl-aqueous solution controls the speciation of HOCl and hypochlorite (OCl-) in water and thereby influences the transformation process. Chlorpyrifos oxon is a potent anticholinesterase that is about 1,000 times more toxic than chlorpyrifos. Because chlorination is commonly used for treatment of domestic water supplies, the findings raise a new concern about the safety of domestic use of chlorpyrifos products.
毒死蜱在体内转化为毒死蜱氧磷被认为是该杀虫剂对生物体显示急性毒性的先决条件。我们发现，分散在水中的活性氯会导致毒死蜱迅速非生物转化为毒死蜱氧磷。提出的转化机制是次氯酸（HOCl）对毒死蜱的硫酮（P=S）双键进行亲电攻击，随后毒死蜱脱硫生成其氧磷类似物。含氯水溶液的pH值控制水中HOCl和次氯酸盐（OCl-）的形态，从而影响转化过程。毒死蜱氧磷是一种强效抗胆碱酯酶，其毒性比毒死蜱高约1000倍。由于氯化常用于处理家庭供水，这些发现引发了对毒死蜱产品家庭使用安全性的新担忧。
