A 10-year cohort study conducted in Henan province of China, with 12,000 male coal miners as the research object, showed that the risk of hypertension in coal miners related with the level of coal dust exposure . Additionally, epidemiological study has found that the prevalence of cardiovascular diseases in coal miners is high and gradually increasing, in which obesity is the main risk factor . The present study showed no obesity and cardiovascular diseases in coal miners, even more coal miners’ diastolic pressure and heart rate were better than that of auxiliary workers, which suggested physical work benefiting cardiac function . Also, studies have shown that the poor living habits and stressful working environment of coal miners can easily lead to dyslipidemia [11, 12]. Additionally, excessive caloric intake and insufficient exercise result in abnormal blood lipid metabolism . The present study showed no abnormal lipid metabolism. Our results indicate that the coal mine environment selected in present study has no adverse effects on cardiovascular system and lipid metabolism.
Bhuiyan et al.  report that the water nearby the coal mine is polluted with heavy metals. Heavy metals mainly accumulate in the kidney of fish living in water polluted by copper, lead, chromium and cadmium . The results are confirmed with a population study, which shows that the risk of kidney disease is higher for people who living in coal mining areas . Additionally, studies have found that exposure to silica dust increases the risk of chronic kidney disease, and there is a direct relationship between air pollution and renal disease [15, 16]. BUN and BUN/CRE are effective biomarkers for renal function, and their increasing associated with renal impairment [17, 18]. BUN and BUN/CRE of coal miners increasing in present study, suggested that the coal mine environment induced adverse effects on renal function. Except causing renal function damage, air pollution also correlated with prevalence of anemia, characterized with a reduction of RBC and HGB [19, 20]. RBC and HGB are biomarkers of anemia, the present study showed lower RBC and HGB of coal miners, which indicated that the coal mine environment may enhance the risk of anemia.
As the main indicator of the immunity function, LYMPH reducing means immune functional impairment . In addition, EO and BASO are involved in innate and adaptive immune regulation, contributing to homeostasis in the body [22, 23]. In the present study, LYMPH, BASO and EO of coal miners decreased, which suggested that the coal mine environment may impair immune system. When immune function is weak, it is susceptible to infection. Epidemic study and animal experiment show that coal dusts can induce inflammatory response in lung and cardiovascular system [9, 24]. Except coal dusts, exhausted gas also induces inflammatory response . NEUT, as the main immune cells, increase significantly in inflammatory status . Higher NEUT of coal miners in the present study indicated that the coal mine environment induced inflammatory.
Oxidative stress induced by coal dusts shows time dependent increasing in coal miners, furthermore it can damage DNA [5, 27]. In addition to oxidative stress, DNA damage can also be induced by water-soluble heavy metals including copper, lead, chromium and cadmium [28, 29]. Studies have demonstrated that DNA damage results in karyocyte apoptosis [30, 31]. Besides DNA damage, many factors including inflammatory cytokines, coal dusts and high temperature also can induce apoptosis [32, 33, 34]. Additionally, karyocyte apoptosis contributes to a reduction of LYMPH in population . The present study showed that apoptotic cells elevated and LYMPH decreased in peripheral blood of coal miners, which indicates that LYMPH reducing may attribute to apoptosis.
In the present study, regression analysis reveals four effective biomarkers sequenced with karyocyte apoptosis, LYMPH, BUN/CRE and HGB that are sensitive to coal mine environment.