[Red cell system and selected red cell enzymes in men occupationally exposed to mercury vapours].

Determination of erythrocyte number and their indices and enzymatic activity of: glucose-6-phosphate dehydrogenase (G-6PD), superoxide dismutase (SOD), acetylcholinesterase (AchE), glutathione reductase (GR) and hexokinase (Hx) in peripheral blood erythrocytes of workers chronically exposed to mercury vapours during the production of chloride (the mercuric electrolysis method). The studied workers were equipment operators, electricians and electrolysis maintenance men at the chloride production department using the mercuric electrolysis method. The study involved 46 men, aged 21 to 56, (x = 39 +/- 10.4) exposed to mercury vapours for the period from 7 months to 32 years (x = 14.7+/-10.8), working in a three shift system, for 8 hours a day. Smokers constituted 50% of the studied group (23 men). Urine mercury concentrations of workers exposed to mercury vapours were in the range from 10 to 215 microg/dm3 (x = 81,4 +/- 72,9) and in blood in range 4 do 72 microg/dm3 (x=16.3 +/- 15,0). Controls were 46 men aged 20-54, (x=33.6 +/- 9.8), workers and voluntary blood donors, who never experienced occupational exposure to mercury vapours or other chemicals, and to physical agents. The percentage of smokers in the control group was 34.7% (16 men). Basic haematological determinations (hematocrit - Hct, Hb concentration, erythrocyte number in mm3 of blood, mean red cell hemoglobin concentration (MCHC), mean red cell volume (MCV) and enzymatic studies (activity of G-6PD, SOD, AchE, GR, Hx) in peripheral blood samples obtained from workers and controls were performed. Hematological parameters of the peripheral blood were determined using AVL 808 hematological counter, following the manufacturer's instructions. Activity of the studied enzymes was estimated by the spectrophotometric method described by Beutler, following the recommendations of the International Committee for Standardisation in Hematology. Values of Ht were higher in all the subgroups exposed to Hg workers (divided according to duration of exposure or urine mercury concentrations) in comparison to the control group. The erythrocyte number in mm3 of peripheral blood was also higher in the exposed workers group than in controls. MCHC in the total group exposed to mercury vapours was lower than in the controls. In the subgroup exposed to mercury vapours for < 10 years, the value of this parameter was lower than in the control group; whereas in the subgroups separated in respect to mercury concentration in the urine, it was lower only in workers showing the highest urine concentration of this metal. In workers exposed to mercury vapours, MCV index values were lower than in the controls. In the subgroups of workers who smoked and those who did not smoke, they were also lower than in the controls; whereas in the group of the longest exposed workers from 21 to 35 years, it was found to be higher than in controls. The activity of G6PD was lower in the group of subjects occupationally exposed to mercury vapours than in the control group - 5.60 +/- 1.60 and 7.41 +/- 0.43 IU/gHb respectively. When comparing the subgroups of smokers and non-smokers with the controls, workers showed lower G6PD activity than in the matching control subgroups - 6.24 +/- 1.97 and 7.44 +/-0.22 IU/gHb in the subgroups of smokers and 4.97 +/- 0.72 and 7.38 +/- 0.18 IU/gHb in non-smokers respectively. Erythrocyte G6PD activity was lower in all studied groups separated in respect to exposure time - 5.54 +/- 1.75, 6.02 +/- 2.05 and 5.54 +/- 1.05 IU/gHb respectively. The same pattern of changes was observed in the subgroups separated in respect to mercury concentration in the urine compared to the controls. The lowest enzyme activity was found in the subgroups showing the highest mercury concentration in the urine wnen compared with the subgroup with the lowest urine concentration of this metal - 5.19 +/- 1.50 and 6.00 +/- 1.84 IU/gHb respectively SOD activity in the group of workers exposed to mercury was lower compared to the controls - 2289.97 +/- 122.31 and 2418.03 +/- 60.28 IU/gHb respectively. The smoking and non-smoking workers showed respective SOD activities on - 2305.43 +/- 102.75 and 2274.50 +/- 124.5 IU/gHb; whereas in the matching subgroup of controls - 2452.11 +/- 88.72 and 2382.09 +/- 91.22 IU/gHb, respectively. The activity of this enzyme in all investigated groups selected in respect to length of employment, revealed lower values when compared with the controls - 2271.20 +/- 115.23 in the group with under 10 years of exposure, 2335.11 +/-167.71 IU/gHb in those exposed for 11-20 years, and 2290.40 +/- 26.12 IU/gHb in the subgroup exposed for the longest period of time. Similar changes were observed in the activity of this enzyme in the subgroups separated in respect to mercury concentration in the urine when SOD activity was compared with the controls. The AchE activity was higher in the group exposed to mercury vapours compared to the controls and the respective values were - 50.22 +/- 14.44 and 36.87 +/- 2.92 IU/gHb. In the subgroups separated in respect to length of exposure, the activity of this enzyme was statistically significantly higher than in the control group. The GR activity levels were lower in the exposed group - 8.01 +/-2.54 IU/gHb, compared to the controls - 10.24 +/- 1.24 IU/gHb. In the subgroups of smokers and non-smokers, GR activity was lower, 8.48 +/- 2.37 and 7.54 +/- 2.68 IU/gHb, compared to smokers and non-smokers in the control group, 10.26 +/- 1.01 and 10.16 +/- 1.03 IU/gHb, respectively. The GR activity was also statistically significantly lower in all groups separated in respect to duration of exposure, with the values of 8.56 +/-2.39, 8.26 +/- 2.38, 7.06 +/- 2.75 IU/gHb, respectively in subject groups and 10.24 +/- 1.35 in the control group. Similar changes were noticed in the subgroup separated in respect to mercury concentration in the urine. The Hx activity was lower in the group exposed to mercury vapours - 1.08 +/-0.11. compared with the controls - 1.21 +/- 0.16 IU/gHb. The enzyme activity showed a similar pattern in the subgroups separated in respect to duration of exposure when they were compared with the control group. Exposure to mercury vapours present changes in the red blood cells, manifested by increased (when compared with the control group), number of erythrocytes in peripheral and decreased mean cell volume and mean cell hemoglobin concentration values, as well as changes in the metabolic processes occurring in the erythrocytes. In subjects exposed to mercury vapours some metabolic processes may be additionally modified by addiction to cigarette smoking.