It should, however, be noted that in rats sulfide enhances the toxicity of molybdenum so it cannot be assumed that soluble or more reactive molybdenum-sulfur compounds will be nontoxic. Inhalation of dusts of molybdenum trioxide and the more soluble molybdates produced toxic effects. As with other fine powders inhalation of quantities of molybdenum dust can be dangerous. As with the stainless steel, molybdenum confers corrosion resistance. Workers handling metals in welding and steelmaking are expected to have higher levels of trace metals.
Trends are often more informative than concentrations at one time.
Molybdenum and vanadium are often found to be elevated among workers exposed to metals who show no evidence of clinical illness. The toxicity is due to hydrochloric acid produced during hydrolysis of the compound and not to molybdenum. Molybdenum pentachloride is a hazardous chemical and, if proper precautions are not taken, its industrial use involves danger of acute intoxication. There were no health problems in the production of MoCl 5 at the former Climax Langeloth refinery and the Ann Arbor Laboratory. Molybdenum pentachloride should be considered as a non-immunotoxic and a weak, nonspecific contact irritant.