SPECIFIC HARMFULNESS OF RESPIRABLE DUSTS FROM WEST GERMAN COAL MINES VI: COMPARISON OF EXPERIMENTAL AND EPIDEMIOLOGICAL RESULTS

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Abstract
Previous epidemiological studies have shown that at a comparable dust exposure the risk of contracting coal workers' pneumoconiosis is less with respirable dust high in ash and quartz than with similar dusts of low ash and quartz contents. Such findings contradict the early results of cellular and animal experiments with respirable dusts from various stratigraphic levels. The quartz and mineral contents of respirable dust correlate positively with its cytotoxicity and also with the mass of dust that penetrates into the pulmonary tissue, the degree of dust dispersion in the lymph nodes and with the formation of collagenous fibres. Quartz is preferentially transferred to the lymph nodes. Such contradiction with epidemiological findings is explained by the assumption that the contribution of fine dusts high in ash content to measurements of dust concentration by tyndallometer or gravimetrically by BAT 1 is disproportionally high in relation to the probability that they will deposit in the alveoli. The reactions of cells, pulmonary tissue and lymph nodes to coal mine dusts are, however, clearly inhibited and delayed, compared with the reactions to pure quartz. The supposed reason for this is that the quartz surfaces of mine dusts are probably covered by intergrowth with coal and other minerals as well as by contamination with organic and inorganic materials. This assumption is supported by microscopical examinations as well as by thermoluminescence tests and scanning Auger microscopy.

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