Development Deregulating system for inhalation exposure to volatile organic chemicals (VOCs) for toxicity testing

使用有机溶剂的工人主要通过吸入接触。因此，对有机溶剂毒性的实验研究需要将实验动物暴露于准确浓度的有机溶剂中。我们尝试制作一种小型实验动物的自动溶剂暴露系统，以便精确地获得有序浓度，并且可以清洁地喂养动物以进行长期实验，并且劳动强度小。暴露系统主要由四个带有粪便冲洗装置的暴露室、四个使用商用电动燃料喷射器（EFIs）的蒸发器、一个带有自动蒸汽取样电磁阀的蒸汽检测器和一个带有记录器的微型计算机组成。通过火焰离子化检测器（FID）连续检测腔室中的浓度，并每3分钟将其反馈到微计算机。当浓度偏离预定值超过5%时，自动调整。正己烷和甲苯在一次暴露中的时间加权平均浓度（TWA）与10 ppm正己烷时的有序值偏差在2%以内，但不超过6%。在正己烷和甲苯长期暴露中，TWA值与有序值的偏差在4%以内波动。两种有机溶剂可以同时暴露在室内。暴露系统被发现足够精确，以产生溶剂蒸气，并足够容易清洁地喂养实验室小动物进行长期实验。

The workers using organic solvents are exposed mainly by inhalation. Therefore, experimental studies on the toxicity of organic solvents need to expose laboratory animals to accurate concentrations of them. We tried to make an automated solvent exposure system for small laboratory animals so that the ordered concentration could be obtained accurately and animals could be fed cleanly for a long-term experiment with a light labor. The exposure system mainly consists of four exposure chambers with feces wash out devices, four evaporators using commercial electric fuel injectors(EFIs), a vapor detector with automatic vapor sampling magnetic valves and a microcomputer with a recorder. The concentration in the chamber is continuously detected by the flame ionization detector (FID) and fed back to the microcomputer every 3 minutes. When the concentration deviate more than 5% from the ordered one, it is automatically adjusted. The time weighted average concentrations(TWAs) of n-hexane and toluene in one exposure were within 2% deviation from the ordered ones exceut 6% at 10 ppm n-hexane. The TWAs in long.term exposure of n-hexane and toluene fluctuated within 4% deviation from the ordered ones. Two kinds of organic solvents could be simultaneously exposed in the chamber. The exposure system was found enough accurate to generate solvent vapor and enough easy to feed laboratory small animals cleanly for a long-term experiment.