the concentration of selenium and thiobarbituric acid reactive substances ( tbars ) and activity of glutathione peroxidase ( gsh - px ) were determined in blood of 34 workers of a tannery in gniezno , poland , who worked in an area containing chromium compounds . 
 fourteen workers were exposed to chromium compounds at concentrations of 0.11 + /- 
 0.07 mg cr / m3 ( mean + /- 
 sd ) and 20 at concentrations 5 - 10 times lower i.e. , 0.022 + /- 
 0.009 mg cr / m3 . 
 excretion of se in urine was measured in all of the investigated workers . 
 decreased se concentration in whole blood and blood plasma and elevated tbars concentration in blood plasma were found in the whole group of investigated tanners as compared to controls . 
 tanners working in areas with high chromium concentrations had a statistically significant decrease in se concentration in blood and plasma and decreased urinary excretion of the microelement as compared with other tanners . 
 tbars concentration was 2.5 times lower in workers exposed to higher chromium concentrations ( p < 0.005 ) than in other workers . 
 positive linear correlations were found between the concentration of se in blood and the amount of the element excreted in urine ( r = 0.48 ; p < 0.005 ) , the concentration of se in blood plasma and in urine ( r = 0.46 ; p < 0.01 ) , and the concentration of se in blood and erythrocyte gsh - px activity ( r = 0.42 ; p < 0.02 ) . 
 the observed differences between se concentration in blood and urine of tannery workers and people who are not employed in the industry may indicate a kind of specific adaptation of the body to the working environment containing chromium compounds.imagesfigure 1.figure 2 .