IMMUNOGLOBULIN LEVELS IN WORKERS EXPOSED TO INORGANIC MERCURY

The serum immunoglobulin (IgG, IgM and IgA) concentrations of 44 mercu ry-exposed workers were examined and compared with those of non-expose d, age- and sex-matched individuals. At the time of testing, the expos ed population had a mean (+/- S.D.) mercury urinary concentration of 2 4.7 +/- 19.1 and in 40 of them urinary mercury levels were below the c urrently accepted limit of 50 mu g/g creatinine. Increased IgG, IgA an d IgM levels were found in the mercury-exposed individuals and in 16, a second evaluation was performed six months later. During the interve ning six months, the level of hygiene was improved throughout the plan t, and urinary mercury concentrations were determined monthly in each worker. Despite a significant reduction in mercury urinary concentrati ons, serum immunoglobulin levels did not return to the normal range. T here was no correlation between the length or level of exposure and th e immunoglobulin levels. Liver protein synthesis, as studied by factor V, prothrombin time, prealbumin and transaminase activity, was normal and liver injury, as evaluated by serum aspartate and alanine aminotr ansferase activities (AST and ALT, respectively), was not observed. No haemotological abnormalities were noted. These results indicate that ''safe'' levels of mercury exposure may lead to humoral immunological stimulation.