Question - What is “hard metal” and what is “hard metal disease”?
Answer - The cited source reports “Hard metal is produced by sintering a mixture of powders (typically tungsten carbide and cobalt) to form a tungsten alloy. Variations can include the replacement of tungsten carbide with tungsten, the addition of other metals (yttrium, thorium, copper, nickel, iron, or molybdenum) to achieve specific metallurgical properties, and the omission of cobalt. The term “hard-metal disease” has been coined to describe pulmonary effects resulting from inhaled hard metal dust. It is generally believed that the health effects observed in hard metal workers are the result of exposure to cobalt not tungsten. (https://www.atsdr.cdc.gov/toxprofiles/tp186-c3.pdf; accessed August 2018)