Overloading of lung clearance chronic exposure of experimental animals to particle

Rats and hamsters inhaled different mineral dusts (TiO2, fly ash from coal fired power plants, man made mineral fibres) or combustion products (cigarett smoke, diesel or gasoline motor exhaust, coal oven exhaust). The effect of exposure on the clearance kinetics of labelled particle of high(59) Fe2O3 was investigated. This probe aerosol was inhaled for one hour at different times of the chronic exposure. Lung clearance was measured by the decrease of the gamma-activity in the thoracic area for up to 80 days after this procedure. Chronic exposure was continued during this time. Results show an increase of the half-time of the deep lung clearance in animals which were exposed to a particle concentration of 3-14 mg/cubicmeter for several months. The gaseous components of the combustion products were of minor importance in respect to lung clearance