As part of its effort to reduce the environmental impact associated with mining and metallurgical operations, the Bureau of Mines used a modified form of the Environmental Protection Agency's extraction procedure toxicity test on copper reverberatory slags that contained low, medium, and high levels of the impurity elements as, pb, sb, bi, and zn. All tests resulted in extracts that did not exceed those limits published in the May 19, 1980, federal register; therefore, these solid wastes were designated as nonhazardous for most landfill disposal situations. However, arsenic and lead levels disturbingly close to the allowable limits--and even higher levels of copper and zinc, for which there are no established limits-- leached from the high-impurity-element granulated slags. These slags should be handled in such a way so as to minimize the possibility of water contamination. One baghouse dust was tested according to the EPA procedure and found to exceed the extract limits by a factor of 10. This solid waste may be considered hazardous.