Comparative in vitro cytotoxicity of volcanic ashes from Mount St. Helens, El Chichon, and Galunggung.
Physical characteristics and in-vitro cytotoxicity of volcanic ash obtained from three different volcanoes were studied. Volcanic ash samples were collected 45 miles away from the El Chichon (EC) eruption of June 3, 1982, 15 miles from the Mount Saint Helens (MSH) eruption of May 18, 1980, and 160 and 165 miles, respectively, from the May 5 and June 3, 1982 eruptions of Galunggung (GLG-1 and GLG- 2). Particles less than 10 micrometers in diameter were separated and analyzed for silica concentration, morphology, elemental composition, area equivalent diameters, and concentration by number percentage. In-vitro cytotoxicity studies were conducted on sheep erythrocyte cell preparations and cellular integrity studies were done using rat alveolar macrophages. Total silica content of the ash samples was determined to be 1.5% for MSH, 1.36% for GLG-1, 1.95% for GLG-2, and 1.72% for EC. Higher concentrations of magnesium, silica, sulfur, calcium and iron were seen in ash from GLG-1 compared with the other samples. A linear relationship was seen between hemolysis and increasing ash concentration for all samples. Fifty percent hemolytic concentrations were highest for the MSH and GLG-2 eruptions. All samples were cytotoxic to macrophages after 2 hours, but ash from GLG-1 was more potent than the others. Few if any effects on macrophage cell viability were seen with any of the samples. Microscopic analysis revealed that particles from all samples were readily phagocytized. The authors conclude that volcanic ash has moderate cytotoxic activity.