Absorption and excretion of cobalt in the hard metal industry

Absorption and excretion of cobalt in the hard metal industry was investigated by means of ambient air and urine measurements in three factories with high levels of environmental cobalt pollution. In the presence of poor hygiene conditions and permission to smoking during work, there was no relationship between cobalt ambient air and cobalt urine concentrations. Such a finding was therefore attributed to a substantial skin contact. A simple experiment of skin exposure to freshly mixed or waste powder on volunteers identified a ten-fold increase of cobalt in urine in the post-exposure samples, thus confirming the contribution of dermal exposure as a route of entry. An improvement in the hygiene of the working conditions helped to investigate the relationship between exposure and excretion level. Cobalt uptake through the different routes of entry may be substantial, and requires a more prolonged exposure-free period so that the excretion rate can be reduced to the reference population level.