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This paper presents a study of the counts of lymphocytes, (CD3+)T-cells, (CD4+)T-helper and (CD8+)T-suppressor and (CD16+)NK-cells in the peripheral blood of 101 males with a history of occupational exposure to metallic mercury vapours (Hg0) and in 36 males without this exposure. These workers were divided depending on the duration of exposure: 37 males with a short-term history of exposure to Hg0 (up to 10 years) and 64 males with a history of long-term exposure (10 to 37 years). For the determination of T-cell populations monoclonal antibodies were used in indirect immunofluorescence tests. The time weighted average of mercury concentrations in air was 0.028 mg m-3. Mercury concentration in the urine of the exposed subjects ranged from 20-260 micrograms dm-3, and in blood it was from 4 to 72 micrograms dm-3. Stimulation of the T-cell line was noted as evidenced by increased numbers of (CD3+)T-cells, (CD4+)T-helper and (CD8+)T-suppressor cells in the workers with < 10 or > 10 years' exposure to Hg0. Lower increase count of (CD3+)T-cells and (CD4+)T-helper cells than (CD8+)T-suppressor cells was the cause of decreased values in the (CD3+)T/(CD8+)T-suppressor ratio and (CD4+)T-helper/(CD8+)T-suppressor ratio in the workers with < 10 or > 10 years' of exposure. Moreover, no changes were observed in the T-cell populations between workers with < 10 and those with > 10 years' exposure. In addition, statistical analysis of the effects of age and duration of exposure to Hg0 on the studied immunological parameters indicates that exposure duration may affect some of the values. These quantitative changes of T-cell population as well as changes of the (CD3+)T/(CD8+)T-suppressor and (CD4+)T-helper/(CD8+)T-suppressor ratio have been proposed as immunological indicators of exposure to Hg0, which can be used for monitoring and to explain the origin of autoimmunity disorders induced by metallic mercury.

The influence of occupational exposure to mercury vapours on the activity of the red cell enzymes [glucose-6-phosphate dehydrogenase (G-6PD), acetylcholinesterase (AChE), glutathione reductase (GR) and superoxide dismutase (SOD)], as well as on peripheral blood indices [erythrocyte number (RBC), HCT, Hb, MCHC] and on serum concentrations of iron, ferritin, transferrin and total iron binding capacity (TIBC), was assessed. Studies were carried out on 46 men aged between 21 and 56 years (X = 39 +/- 10.4) exposed to mercury vapours during their work from 7 months to 32 years (= 14.7 +/- 10.8). The control group consisted of 35 healthy workers aged between 20 and 54 years (X = 33.6 +/- 9.8) not exposed to chemical nor physical agents. In both groups studied, there were 50% and 34.3% smokers, respectively. The activity of studied red cell enzymes--G-6PD, AChE, GR and SOD--was estimated according to the colorimetric methods described by Beutler and expressed as international units per gram of hemoglobin (IU g Hb(-1)). Peripheral blood cell parameters were determined using an automatic cell counter. The concentration of serum iron and TIBC was determined using colorimetric methods (Beckman), while that of ferritin and transferrin by nephelometric methods. The time-weighted average (TWA) of mercury concentration in the air determined before the study was 0.0028 mg m(-3). Statistical analysis of the data was performed using either the Cochran and Cox C-test or the Student's t-test. The medium mercury concentration in the urine was 77.44 +/- 48.15 microg l(-1). In the group exposed to mercury vapours, a significant decrease was found in G-6PD activity (23.9%, P<0.001), GR (18.8%, P<0.001), and SOD (5%, P<0.001) with a concomitant increase in AChE activity (35.9%, P<0.001) was found. Moreover, a statistically significant increase occurred in HCT and RBC, and a decrease in MCV and MCHC as well as increases of ferritin (130.9%, P<0.001), transferrin (118.4%, P<0.001) and TIBC (11.2%, P<0.05). Our results indicate that long-term exposure to mercury vapours induces changes in the activity of red cell enzymes--G-6PD, AChE, GR and SOD--and may also influence other important hematological parameters of the peripheral blood.