Welling W, de Vries J W
Department of Aquatic Systems, DLO The Winand Staring Centre for Integrated Land, Soil, and Water Research, Wageningen, The Netherlands.
Ecotoxicol Environ Saf. 1992 Feb;23(1):64-75. doi: 10.1016/0147-6513(92)90022-u.
The bioconcentration kinetics of chlorpyrifos (O,O-diethyl O-3,5,6-trichloro-2-pyridyl phosphorothioate) in guppies (Poecilia reticulata) were investigated. A static exposure was used to study the uptake of the compound. The amount absorbed was calculated from the difference in disappearance rates from the water phase in aquaria with and without fish. The uptake rate was found to be first-order with respect to the exposure concentration, and amounts to ca. 38 ml g-1 (fish) hr-1. The elimination rate was studied in separate experiments. Guppies were first given the opportunity to accumulate chlorpyrifos and, following transfer to clean water, the clearance of the compound was measured by determining the residual chlorpyrifos in the fish. It was found that the elimination rate was first-order with respect to the concentration in fish, but depended slightly on the length of the preexposure period. The half-life of tissue chlorpyrifos varied from 31 to 38 hr. Release of unchanged chlorpyrifos turned out to be negligible relative to the amount eliminated. This indicates that metabolic breakdown is the only pathway for elimination. From the kinetic rate parameters, a bioconcentration factor was calculated of about 1700. This value is very similar to that measured directly after an 8-day semistatic exposure. A two-compartment model is proposed to describe the kinetics of the bioconcentration process. The conditions limiting the applicability of the indirect method for measuring the toxicokinetics of chlorpyrifos are discussed.
研究了毒死蜱（O,O-二乙基-O-3,5,6-三氯-2-吡啶基硫代磷酸酯）在孔雀鱼（孔雀鱼）中的生物富集动力学。采用静态暴露法研究该化合物的摄取情况。吸收量通过有鱼和无鱼水族箱中水相消失率的差异来计算。发现摄取速率相对于暴露浓度为一级，约为38 ml g-1（鱼）hr-1。在单独的实验中研究了消除速率。首先让孔雀鱼有机会积累毒死蜱，然后转移到清洁水中，通过测定鱼体内残留的毒死蜱来测量该化合物的清除率。发现消除速率相对于鱼体内的浓度为一级，但略取决于预暴露期的长度。组织中毒死蜱的半衰期在31至38小时之间。相对于消除量，未变化的毒死蜱释放量可忽略不计。这表明代谢分解是消除的唯一途径。根据动力学速率参数，计算出生物富集因子约为1700。该值与8天半静态暴露后直接测量的值非常相似。提出了一个两室模型来描述生物富集过程的动力学。讨论了限制毒死蜱毒代动力学间接测量方法适用性的条件。
