Solubility of Metals in Windblown Dust from Mine Waste Dump Sites

Abstract

Threshold limit values for metal compounds are listed for specific salts, for fumes or dusts, or for soluble or insoluble compounds. The values for soluble compounds are usually lower than for insoluble compounds, reflecting the greater ability of the soluble compounds to enter the body and cause systemic toxicity. Neither the chemical composition nor the solubility of metals in windblown dust from mine waste dump sites is usually known. Four such sites in Butte, Montana, were investigated. Arsenic, cadmium, copper, manganese, and lead in windblown dust as a function of particle size and of solubility in simulated fluids of the lungs, stomach, and intestines were measured. Lead compounds showed the poorest solubility except for the samples from the Corra site. Manganese, cadmium, and copper compounds tended to be reasonably soluble in both simulated lung and stomach fluids. Arsenic compounds only had significant solubility in the acidic simulated stomach fluids. Only manganese showed reasonable solubility in simulated intestinal fluid. For the investigation of metals in dust samples of unknown composition, it is recommended that duplicate samples be obtained, one for total metal content and the other for dissolution in acidic simulated stomach fluid. Significant differences in metal content between the two samples should be taken into account to assess the potential hazard for systemic toxicity.