Effects of electrostatic charge on the pulmonary deposition of mineral dust aerosols inhaled by rats

Mineral dusts usually become electrostatically charged during mechanical dispersal into the air. The effects on deposition of several such dusts within the lung were investigated by measuring the amounts of dust retained in groups of rats exposed, respectively, to a normally charged dust cloud and to a cloud with reduced charge. No significant effect was found for the isometric dusts of quartz or titanium dioxide, nor for mica-a flaky dust. These results are compared with previous results for asbestos where the lung burden had been significantly and substantially increased by the electrostatic charge. Theoretical calculations of the relative magnitude of electrostatic image forces acting on (and associated drift velocities of) a charged particle within the lung also indicate that these forces may be more significant for fibrous dusts than for isometric or flaky dusts.