Frequencies Of MNed BNC Among Residents Exposed To Heavy Metals From E-waste And Its Inference Factors

Heavy metals including lead, cadmium, copper and nickel, are widely used in various electronic products. Numerous obsolesced electronic products, so-called electronic-waste can cause serious environment problem. When primary dismantling and recycle methods were used in a few plants, certain pollutants such as PBDE, PHA and heavy metals in e-waste can enter environmental media atmosphere, water body and soil, and threaten human health.It is well known that, heavy metals (such as lead, cadmium, copper and nickel) exists in the environment and can invade into human body, through many ways, resulting the damages of multiple systems in the organisms. For instance, lead had a stronger toxicity in the nervous system, the hematopoietic system, the digestive system, cardiovascular system and immunologic system. Cadmium is a proved carcinogen. Its adverse effects include damages in not only the kidney function and but also the function of the reproductive system in organisms, when they were exposed to Cadmium. Nickel associates with cancer of the respiratory system. Although copper is an essential element in human body, however, excessive level of Cu can cause disorder in the metabolism of the body.Recent years, widely concern on environment pollution relating to e-waste has been attracted. However, limited data reported that the adverse effects of pollutants from e-waste on the populations. In the present study, we recruited 58 subjects (as the exposure group) from a decade-long e-waste recycling site in southeast China. Another 80 subjects from an agricultural area that was similar to the exposure site in environment and custom, but without known pollution resources were recruited to be control. To evaluate the biological effects of pollutants from the e-waste on the population, levels of heavy metals, the oxidative stress indicators and the urinary 8-Hydroxy-desoxyguanosine (8-OHdG) were analyzed. In addition, frequencies of the micronucleated binucleated cells (MNed BNC) in the studied subjects were determined as well.Levels of heavy metals and oxidative stress indicators among the populaitonlevels of the lead, cadmium and nickel in the whole blood samples, and levels lead, cadmium, copper and nickel levels in the urine samples were detected using the graphite furnace atomic absorption spectroscopy method. Serum copper level was determined using the flame atomic absorption spectroscopy method. Levels of glutathione S-transferases (GST) and superoxide dismutase (SOD) and glutathione (GSH) activity were anayzed using the commercial kits. Levels of 8-OHdG were determined by high performance liquid chromatograph-electrochemistry method.The results showed that in the exposed levels of blood Pb (115.78μg/L) and urinary copper (0.03μg/mgCr) were significantly higher than those of the control (blood Pb: 87.25μg/L, P<0.01; urinary Cu: 0.02μg/mgCr, P<0.05); In exposed levels of blood copper and blodd nickel (0.80μg/L, 7.58μg/L) and urinary cadmium (0.001μg/mgCr) were significantly lower, compared to the control (blood Cu: 0.88μg/L, P<0.01; blood Ni: 13.55μg/L, P<0.01; urinary Cd: 0.002μg/mgCr, P<0.05). Levels of serum GST (median: 19.52 U/ml) and GSH (mean±SD: 205.39±31.21mg/L) in the exposed were significantly higher than those in the control (median: 14.47U/ml, P<0.01; mean±SD: 193.32±37.62mg/L, P<0.05). But no significantly difference were observed between the groups in levels of urinary 8-OHdG and serum SOD (P>0.05).Our findings suggest that the residents who lived in the E-waste recycling site had higher exposure of Cu but an accumulation of only lead in their body was found. In the control there are some unknown factors may cause oxidative stress reactions. Frequencies of micronucleated binucleated cells in the peripheral lymphocytes and its correlative factorsThe frequencies of micronucleated binucleated cells (MNed BNC) in the peripheral lymphocytes among the studies subjects were determined using Cytokinesis-Block Micronucleus assay (CBMN). The results showed that the median frequency of MNed BNC in the exposed is 4‰, which was significantly higher than that (median: 1‰) of the control (P<0.01). A positive correlation between the blood lead level and the frequency of MNed BNC was found (r=0.204, P<0.05). We also found that the history of occupational exposure of dismantling E-waste was a risk factor for the elevated frequency of MNed BNC, because the frequencies of MNed BNC in the workers were 6.7 times that of the control (P<0.01)The findings indicated that the detected DNA damage in the workers may associate with their exposure of higher level of Pb in their bodies, which need to be validated in the larger populations.