BLOOD ANTIOXIDANT STATUS IN COAL DUST-INDUCED RESPIRATORY DISORDERS -A LONGITUDINAL EVALUATION OF MULTIPLE BIOMARKERS

To investigate the involvement of oxidative stress in coal dust-induce d respiratory disorders, red brood cell and serum antioxidants in 66 c oal miners were related to 5-year changes in coal workers' pneumoconio sis (CWP), chronic bronchitis, and lung function decrease (n = 40). Re duced (GSH) and oxidized (GSSG) glutathione concentrations, glutathion e peroxidase (Gpx), glutathione-S-transferase (GST), superoxide dismut ase (SOD), and catalase activities were measured in erythrocytes and v itamin A, Vitamin E and iron were determined in serum. Changes in CWP were determined by chest radiography, chronic bronchitis was determine d from a validated questionnaire and lung function decline was calcula ted by linear regression for a 10 year interval before blood sampling. SOD activity was increased in miners with progression of CWP (2308 +/ - 156 vs 1703 +/- 155 U g(-1) Hb, p < 0.05), and GSH was reduced in th ose with chronic bronchitis at follow-up (3.53 +/- 0.16 vs 4.05 +/- 0. 09 mmol g(-1) Hb, p < 0.01). Stepwise discriminant analysis showed tha t for both pneumoconiotic and non-pneumoconiotic respiratory disease i n this cohort, increased enzymatic antioxidants (i.e. Gpx, Catalase, S OD) were high risk factors, while increased 'non-enzymatic' antioxidan ts (i.e. vitamin E, GSH) indicated reduced risk. GST activity showed d iscriminative power in two ways, i.e. decreased activity in those at r isk for CWP, but increased in those with rapid decline in FEV(1). We c onclude that the multiple marker approach applied here shows the relev ance of interpretation of total 'antioxidant status' versus single ant ioxidant measurements in health screening of individuals at risk for r espiratory impairments.