Elevated levels of urinary 8-hydroxy-2 -deoxyguanosine, lymphocytic micronuclei, and serum glutathione S-transferase in workers exposed to coke oven emissions

Abstract

To investigate associations among occupational exposure to coke oven emissions (COEs), oxidative stress, cytogenotoxic effects, change in the metabolizing enzyme glutathione S-transferase (GST), and internal levels of polycyclic aromatic hydrocarbons (PAHs) in coke oven workers, we recruited 47 male coke oven workers and 31 male control subjects from a coke oven plant in northern China. We measured the levels of 1-hydroxypyrene (1-OHP) and 8-hydroxy-2 -deoxyguanosine (8-OHdG) in urine, micronucleated binucleated cells (BNMNs) in peripheral blood lymphocyte, and GST in serum. Our results showed that the group exposed to COEs had significantly increased levels of 1-OHP [median 5.7; interquartile range (IQR), 1.4-12.0 micromol/mol creatinine] compared with the control group (3; 0.5-6.4 micromol/mol creatinine). In addition, the median levels (IQR) of 8-OHdG, BNMNs, and GST were markedly increased in the exposed [1.9 (1.4-15.4) micromol/mol creatinine; 6 (2-8) per thousand ; 22.1 (14.9-31.2) U/L, respectively] compared with controls [1.3 (1.0-4.0) micromol/mol creatinine, 2 (0-4) per thousand; and 13.1 (9.5-16.7) U/L, respectively]. These results appeared to be modified by smoking. However, multivariate logistic regression analysis revealed that exposure to COEs had the highest odds ratio among variables analyzed and that smoking was not a significant confounder of the levels of studied biomarkers. Overall, the present findings suggest that COE exposure led to increased internal PAH burden, genetic damage, oxidative stress, and GST activity. The consequences of the changes in these biomarkers, such as risk of cancer, warrant further investigations.

Figure 1

Scatter plot of correlation between log₁₀-transformed serum GST activities and log₁₀-transformed urinary 1-OHP levels in the exposed group (A; y = 0.1709x + 1.2198; Spearman rank correlation coefficient = 0.434; p = 0.002) and in the control group (B; y = −0.0569x + 1.1001; Spearman rank correlation coefficient = 0.076; p = 0.686).