卤代苯的分子连接性指数与其毒性的QSAR研究

[目的]探明卤代苯类化合物对水生生物的致毒机理,为化学品环境风险的评价提供依据。[方法]采用细菌生长抑制试验,测定了17种卤代苯类化合物对长江水中混合细菌的慢性毒性。选用价分子连接性指数法对毒性数据进行定量结构活性关系（QSAR）研究。[结果]测得了17种卤代苯类化合物的MATC值,毒性范围为4.31（氯苯）~5.25（1,2,4三-氯苯）。卤代苯类化合物对长江水细菌的慢性毒性主要与苯环上取代基的种类、数目有关。取代基对毒性的贡献表现为：Br〉C l〉NH2〉OH。取代基数目越多,化合物毒性越强。[结论]方程-lgMATC=1.1906XVPC-0.3723XVP＋4.611能够很好的描述卤代苯类化合物对长江水细菌的慢性毒性。     

The toxicity of cyromazine to Chironomus zealandicus (chironomidae) and Deleatidium sp. (leptophlebiidae)

The toxicity of cyromazine and a commercial formulation, ‘Vetrazin’®, to Chironomus zealandicus (thummi) Hudson and Deleatidium sp. was investigated. Under acute test conditions, the LC₅₀ values for each species were quite comparable. For C. zealandicus, the value varied according to instar, 100–400 mg litre^?1 for second- and third-instar to 1000–10000 mg litre^?1 for older fourth-instars. For the one size class of Deleatidium tested (c.10 mm long), the value was 300–400 mg litre^?1. High control mortalities of C. zealandicus limit that species' usefulness as an acute bioassay candidate. Under chronic test conditions, cyromazine showed a high toxicity to eggs or early-instar larvae of C. zealandicus. The maximum acceptable toxicant concentration for cyromazine against C. zealandicus was approximately 17.5 μg litre^?1. The possibility of water contamination at this level is discussed. Whole-of-life chronic tests with C. zealandicus indicated that the most susceptible stage was in the egg or soon after larval emergence. These results highlight the dangers of using short-term acute toxicity results to formulate environmental exposure limits for modern pesticides that do not have dysfunction of the nervous system as their mode of action.