Effects of low level manganese exposure on the serum neuroendocrine hormones in the welders / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To study the effects of low level manganese (Mn) exposure on the serum neuroendocrine hormones levels of the welders.</p><p><b>METHODS</b>The exposure group consisted of 41 male welders, 40 male workers without exposing to harmful agents served as controls. The serum contents of prolactin (PRL), luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone (TST) and thyroid stimulating hormone (TSH) of 81 subjects were detected by chemiluminescence immunoassay.</p><p><b>RESULTS</b>The geometric mean value of airborne Mn concentrations was 0.03 mg/m(3) (0.003 - 0.519 mg/m(3)) in the welding circumstances. The levels of Mn in red blood cells (RBCs) and urinary Mn of the exposure group were significantly higher than those of control group (P < 0.01). The contents of serum LH and TSH of the exposure group were 2.89 ± 0.69 mIU/ml and 1.45 ± 0.56 uIU/ml, which were significantly lower than those (3.82 ± 1.61 mIU/ml and 2.19 ± 1.28 µIU/ml) of control group (P < 0.01). The serum contents of LH, FSH and TSH of the group exposed to Mn for < 5 years were significantly lower than those of the control group, The serum TST level of the group exposed to Mn for < 5 years was significantly higher than those of the control group and group exposed to Mn for 5 ∼ years, the serum FSH level of the group exposed to Mn for < 5 years was significantly lower than that of the group exposed to Mn for 10 years (P < 0.05 or P < 0.01). The serum contents of LH and TSH of the group exposed to Mn for 5 ∼ years were significantly lower than those of the control group (P < 0.05 or P < 0.01). The serum contents of PRL, LH and TSH of the group exposed to Mn for 10 years were significantly lower than those of the control group (P < 0.05). There was negative correlation between blood (RBC) Mn and urinary Mn (r = -0.310, P < 0.05), also there was negative correlation between serum PRL and serum TST (r = -0.409, P < 0.01), the positive correlation between serum LH and serum FSH was observed (r = 0.361, P < 0.05).</p><p><b>CONCLUSION</b>The results of present study showed that the long exposure to low level of Mn may decrease the levels of serum PRL, LH and TSH in workers occupationally exposed to Mn, which can influence the metabolism of neuroendocrine hormones to certain extent.</p>

Variations of brain magnetic resonance imaging among manganese-exposed workers / 中华预防医学杂志

<p><b>OBJECTIVE</b>Variations of the signal intensities in the magnetic resonance (MR) T(1)-weighted image (T(1)WI) of globus pallidus among manganese(Mn)-exposed workers were explored to provide a scientific basis for exposed biomarker of manganese-injured central nervous system (CNS).</p><p><b>METHODS</b>The brain MR T(1) and T(2) WI in eighteen male asymptomatic Mn-exposed, eight manganism and nine healthy control workers were examined routinely by adopting a 1.5 Tesla signal superconducting system. The SIGP and the signal intensity in frontal white matter (SIFWM) in the same side were determined, then pallidal index (PI) was calculated. Concentration of MnO(2) in workplaces and content of manganese in red blood cell (MnRBC) among workers were respectively determined by flame atomic absorption spectrometer (AAS) and inductively coupled plasma-atomic emission spectrophotometry (ICP-AES). The follow-up investigation in the eight high Mn-exposed workers was made one year later.</p><p><b>RESULTS</b>The results showed that the median of air MnO(2) in smelting workplace was 0.64 mg/m(3)(0.07 - 5.40 mg/m(3)), which were respective 0.56 mg/m(3)(0.09 - 1.71 mg/m(3)) in power distribution room (low Mn-exposure) and 0.89 mg/m(3) (0.07 - 5.40 mg/m(3)) in furnace (high Mn-exposure). PI in the Mn-exposed and high Mn-exposed workers were both higher than those of the manganism and control workers(116.4 +/- 8.2, 119.0 +/- 7.9, 105.3 +/- 8.4 and 102.2 +/- 1.5, respectively. Mn vs control, t' = 7.146, P = 0.000; Mn vs manganism, t = 3.181, P = 0.004. High Mn-exposure vs control, t' = 7.446, P = 0.000; high Mn-exposure vs manganism, t = 3.763, P = 0.001). The increased signal in T(1)WI of globus pallidus was observed in Mn-exposed workers, especially in high Mn-exposed workers. The content of manganese in red blood cell of Mn-exposed and control workers was significantly higher than those of the manganism workers [(151.6 +/- 40.5) ng/ml, (149.2 +/- 21.3) ng/ml, (154.5 +/- 46.6) ng/ml, (144.4 +/- 14.2) ng/ml, (20.8 +/- 7.4) ng/ml respectively. The difference was significant in statistics. Manganism vs control, t = 20.206, P = 0.000; manganism vs Mn, t' = 13.144, P = 0.000; manganism vs low and high Mn, t' = 12.964, 9.957, respectively, P = 0.000]. Only a decreased median of air MnO(2) in furnace was found one year later (0.89, 0.31 mg/m(3), Z = -2.142, P = 0.032). The difference was significant in statistics.</p><p><b>CONCLUSION</b>Our data suggests that SIGP of MR T(1)WI among workers was obviously increased by manganese-exposure. PI may be taken as the signal of CNS injury which was induced by manganese-exposure.</p>