Development of exposure chamber for investigation of inhaled chronic health effect of airbone particles

由于工作和大气环境中粉尘控制的改善，对吸入性粉尘的慢性健康影响的调查已变得比急性影响重要得多。因此，在动物实验中，暴露室中的粉尘浓度和粒度分布必须长时间保持恒定。此外，期望颗粒是未团聚的且均匀分散的。本研究开发了一种新型流化床粉尘发生器，该发生器具有连续螺旋进料器和溢流管，可用于长期慢性吸入毒性研究。该发电机具有以下优点：1.可以长时间运行。2.粉尘浓度可任意改变。3.可以产生多种气溶胶粒子。4.本研究采用Wister雄性大鼠对由粉尘发生器、暴露室和气液固分离器组成的吸入系统进行了为期一年的粉煤灰气溶胶暴露实验，结果表明：1.暴露室内一年的日平均浓度为38.5 <+！->11.1 mg/ <m^3>（高暴露组）和5.0 <+！->2.1 mg/ <m^3>（低暴露组）。实验过程中，暴露室内粉煤灰气溶胶的质量中值空气动力学直径为2.7 <micro>m.在暴露的大鼠肺中观察到大量的粉煤灰颗粒.通过对粉煤灰中铝含量的分析，定量测定了粉煤灰的体载量.本研究所开发之吸入系统，对于探讨吸入粉尘之慢性健康效应，具有相当之应用价值。

As a result of improved dust control in work and atmospheric environments, investigations of the chronic health effects of inhaled dust have become much more important than the acute ones. In animal experiments, therefore, the dust concentration and size distribution in the exposure chamber must be kept constant over a long period. Also, it is desirable that the particles be unagglomerated and evenly dispersed. In this study a new fluidized bed dust generator with continuous screw feeder and overflow pipe was developed for long-term chronic inhalation toxicity studies. This generator has the following advantages:1. It is possible to operate for a long time.2. The dust concentration can be changed arbitrarily.3. Many kinds of aerosol particles can be generated.4. Maintenance and operation are easy.The performance of inhalation system, consisted of dust generator, exposure chambers and gas-liquid-solid separator, were investigated by Wister male rats exposed to coal fly ash aerosol for one-year.The following results were observed.1. The daily average concentrations in the exposure chamber for one-year were 38.5 <+!-> 11.1 mg/ <m^3> (high exposure group) and 5.0 <+!-> 2.1 mg/ <m^3> (low exposure group).2. The mass median aerodynamic diameter of coal fly ash aerosol in the exposure chamber was 2.7 <micro> m during the exposure.3. Many coal fly ash particles were observed in exposed rat lung.4. The body burdens of coal fly ash were measured quantitatively by an analysis of aluminium contained in coal fly ash.5. The deposed coal fly ash in exposed rat lung was significantly incresed.I believe that the inhalation system developed in this study is extremely useful for investigating chronic health effects of inhaled dusts.