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Health Effects of Dust from Owens (dry) Lake, California

Potential Health Hazards of Owens Lake Dust
(Reheis et al., 2003)

Mineral dusts from the desiccated playa of Owens Lake, Calif., contain elevated concentrations of many metals known to have toxic effects. To assess the element sources and possible hazards to humans, other animals, and plants, we are (1) analyzing trace-element contents of the fine-grained mineral and soluble fractions of deposited dust, playa sediment, and aerosol samples collected during dust storms, and (2) repeating these analyses by extracting the same samples using solutions that are surrogates for human lung and gastric fluids.

Dusts and aerosols are strongly enriched in sulfate from soluble sodium sulfate in playa sediment: elemental S concentrations in saline dust events can be as much as 10% by weight. Potentially toxic elements in the <50 µm fraction of deposited dust include (conc. in ppm): As (10-50), Cr (17-56), Cu (<22), Mo (0.5-3), Ni (<16), Pb (50-400), Sb (6-14), Th (10-16), and U (3-8). Leach tests of the dusts using water and simulated lung fluids (20:1 fluid:dust by wt., 24 hr mixing) show these metals are quite soluble and bioavailable (i.e., dissolved As, Mo, and U as much as 2700, 650, and 170 g/L, respectively).

Dust-deposition rates of some metals and sulfates in Owens Valley equal or exceed rates in industrialized areas of the world. Much Owens Lake dust is <10 µm in diameter, and SEM studies reveal abundant submicron particles. Given composition, size, and deposition rates (1991-1998 average of 150 g/m²/yr of fine dust at one site), a large fraction of these metals could be transported hundreds of kilometers and easily respired. Terminal lake basins such as Owens Valley could be globally important sources of metal-bearing dusts. The health and ecological effects of soluble alkaline sulfate aerosols are poorly known but of potential concern.

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