The chemical speciation of particulate Cr has a significant influence on its environmental impact, with Cr/sup 6 +/ compounds of greatest current concern. A novel analytical regimen was evaluated for the determination of the concentration, speciation, and potential bioavailability of environmental Cr by using the example of ferrochrome smelter dust. Various wet chemical extractions were compared for possible use in the routine environmental monitoring of bioavailable Cr and Cr/sup 6 +/. Roughly half of the total Cr in the primary smelter dust was extractable by routine acid/base leaching (bioavailable), of which about 40% was Cr/sup 6 +/. The Cr/sup 6 +/ exists as Cr/sub 2/O/sub 7//sup 2 -/ or CrO/sub 4//sup 2 -/ and predominates in submicron particles probably formed during smelting. The remainder of the Cr is primarily insoluble Cr/sub 2/O/sub 3/ which is located in large particles similar to the original chromite ore.