Comparison between active miners with high and low dust concentrations in 1994 (n=131)
| High for ⩾14 years (n=48) | Low for ⩾4 years (n=83) | p Value | |
| Age (y, mean (SD)) | 45.7 (3.4) | 45.5 (3.1) | 0.7 |
| Estimated cumulative exposure to dust (mg/m3.y, mean (SD)) | 71.8 (35.8) | 39.3 (39.9) | 0.0001 |
| Smoking (%): | |||
| Non-smokers | 12 | 29 | |
| Ex-smokers | 25 | 20 | 0.09 |
| Current smokers | 63 | 51 | |
| Selenium concentration (ng/ml, mean (SD)) | 59.5 (18.6) | 65.9 (19.1) | 0.06 |
| Plasma GSH-Px (U/l, mean (SD)) | 686 (203) | 698 (251) | 0.7 |
| Erythrocyte GSH-Px (U/g Hb, mean (SD)) | 37.9 (13.6) | 39.3 (11.6) | 0.5 |
| Adjusted means: | |||
| Age and smoking adjusted Se concentration (ng/ml) | 59.4 | 65.8 | 0.06 |
| Age and smoking adjusted plasma GSH-Px (U/l) | 682 | 689 | 0.9 |
| Age and smoking adjusted erythrocyte GSH-Px (U/g Hb) | 38.6 | 39.1 | 0.8 |