Objective To analyze the association of blood routine test indices with peripheral micronucleus (MN) frequencies in diagnosed chronic benzene poisoning patients who have been removed from benzene-exposed environment for 2 to 48 years.
Methods Thirty-six patients with chronic benzene poisoning diagnosed in a Shanghai hospital and then leaving benzeneexposed environment were selected as the case group, and another 36 sex-and-age-matched healthy participants elected from a community were grouped as the controls. All participants were subjected to routine blood tests, and cytokinesis-block micronucleus assay was used to detect peripheral MN frequencies. Paired t test and Poisson regression were used to analyze routine blood test results and MN frequencies between the case and control groups. Trend test was applied to analyze the relationship between routine blood test results and MN frequencies of the case group. Chi-square test was used to analyze abnormal MN frequencies. Logistic regression models were used to find out the factors relevant to MN abnormality.
Results Compared with the control group, white blood counts, neutrophil numbers, lymphocyte numbers, red blood counts, hemoglobin, and platelets were significantly decreased by 1.95×109/L, 0.85×109/L, 0.7×109/L, 0.39×1012/L, 9.21 g/L, and 50.17×1012/L in the case group, respectively (P < 0.01). The rates of abnormal white blood counts, abnormal neutrophil numbers, and abnormal hemoglobin in the case group were higher than those in the control group (χ2=20.67, P < 0.001; χ2=12.77, P < 0.001; χ2=11.61, P=0.001, respectively). The MN frequencies in the case group(7.22±2.87)‰ was 74% higher than that in the control group(4.14±1.66)‰ (FR=1.74, P < 0.001). White blood counts and neutrophil numbers were both negatively correlated to MN frequencies, and the Spearman correlation coefficients were -0.416 (P < 0.05) and -0.495 (P < 0.01), respectively. The patients with normal white blood counts (n=18, ≥ 4.0×109/L and ≤ 10.0×109/L) showed higher MN frequencies than those of the paired controls (FR=1.40, P < 0.05). The case group was further separated to three sub-groups according to the years following being removed from benzene exposure. The MN frequencies of the three sub-groups increased with the increasing years following being removed from benzene exposure (FR=1.46, P=0.025; FR=1.92, P < 0.001; FR=1.79, P < 0.001), and the odds ratio of abnormal MN frequencies also increased (OR=4.05, P=0.153; OR=27.33, P=0.001; OR=355.26, P=0.001).
Conclusion Hematotoxicity and genetic toxicity persist in patients with chronic benzene poisoning even after being removed from benzene exposure. MN frequency is more sensitive than white blood counts.
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