Patch testing with sodium tungstate.

Hard metal contains about 90% tungsten carbide. In an investigation of the skin of 853 individuals who are still working or had previously worker in hard metal manufacture, sodium tungstate was included in a patch test with a panel of substances from the environment of the employees. No allergic reactions to tungstate were found. However, irritant pustular reactions appeared in 2.0% of the patch tests. The pustular reactions were often reproducible.