Effect of Cr(VI) exposure on sperm quality: Human and animal studies

The semen status of male workers occupationally exposed to hexavalent chromium(VI) was investigated. Sperm counts from exposed workers were 47.05±2.13×10⁶/ml and those from control group 88.96±3.40×10⁶/ml. Sperm motility decreased from 81.92±0.41% for the control group to 69.71±0.93% for the exposed workers. The levels of zinc, lactate dehydrogenase (LDH), and lactate dehydrogenase C4 isoenzyme (LDH-x) in seminal plasma for the exposed workers were 1.48±0.07 μmol/ml, 1.05±0.02×10³ U, and 0.47±0.01×10³ U, respectively, which were significantly lower than those of 5.72±0.15 μmol/ml, 1.49±0.02×10³ U, and 0.78±0.15×10³ U for the control group, respectively. Follicle stimulating hormone (FSH) (7.34±0.34×10^-3 IU/ml) in serum from the exposed workers was significantly higher than that (2.41±0.08×10^-3 IU/ml) from the control group. On the other hand, there were no significant differences in semen volume, semen liquefaction time, luteinizing hormone (LH) level in serum, and Cr concentration in both serum and seminal plasma between the exposed workers and the control group. Feeding Cr(VI) to rats significantly reduced the epididymal sperm counts from 87.40±3.85×10⁶/g epididymis in control group to 21.40±1.20×10⁶/g epididymis at a CrO₃ dose of 10 mg/kg body weight and to 17.48±1.04×10⁶/g epididymis at a CrO₃ dose of 20 mg/kg body weight. Exposure of rats to Cr(VI) also significantly increased the sperm abnormality from 2.75±0.06% in the control group to 6.68±0.32% in the exposed group at a CrO₃ dose of 10 mg/kg body and to 7.6±0.15% at a CrO₃ dose of 20 mg/kg body weight. In exposed rats, there was visible disruption in germ cell arrangement near the walls of the seminiferous tubules. The diameters of seminiferous tubules in exposed rats were smaller. These results suggest that occupational exposure to chromium(VI) leads to alteration of semen status and may affect the reproductive success of exposed workers.