Urinary beta 2 microglobulin in the biological monitoring of cadmium workers

Urinary beta 2 microglobulin (beta 2m) estimation has been added to an existing pre-employment and periodic medical surveillance programme for cadmium workers. Pre-employment values were measured in 203 men not occupationally exposed to cadmium. The overall geometric mean was 76 microgram/l (adjusted to specific gravity 1016): a significantly higher level of 96 microgram/l was found in the specimens stored continually at -20 degrees C after voiding, compared with 73 microgram/l in specimens that thawed during transport. Sodium azide had been added to all specimen bottles. Employees exposed to cadmium pigments at various stages of their manufacture had no evidence of raised urinary beta 2m despite exposures above 50 microgram/m3 for up to 11 years. This is believed to be due to the insolubility of the compounds. Five known cases of cadmium induced proteinuria whose exposure ceased up to 15 years ago had raised urinary beta 2m concentrations. Moderately raised concentrations were found in seven others with a history of cadmium oxide exposure and in whom proteinuria has never been detected. The place of urinary beta 2m in the health care of cadmium workers is discussed and the question of correct management of a cadmium worker with a high beta 2m is raised.