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，关于有机溶剂毒性的实验研究需要让实验动物暴露在精确浓度的有机溶剂中。我们尝试制作一套小型实验动物的自动溶剂暴露系统，以便准确地获得有序的浓度，并且可以清洁地喂养动物，以减轻劳动，进行长期实验。暴露系统主要由四个带有粪便清洗装置的暴露室、四个使用商用电动燃油喷射器（EFIs）的蒸发器、一个带有自动蒸汽采样电磁阀的蒸汽探测器和一个带有记录仪的微机组成。燃烧室内的浓度由火焰电离检测器（FID）连续检测，每隔3分钟反馈给微机。当浓度与预定值偏差超过5%时，自动调整。一次暴露中正己烷和甲苯的时间加权平均浓度（TWAs）在10 ppm正己烷时与有序浓度的偏差在2%以内，超过6%。TWAs在长。正己烷和甲苯的长期暴露值与有序暴露值的偏差在4%以内波动。两种有机溶剂可同时在实验室内暴露。实验结果表明，该暴露系统能够准确地产生溶剂蒸汽，并且易于清洁地喂养实验室小动物，适合长期实验。

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.