An exploration of biomarkers for noise exposure: mitochondrial DNA copy number and micronucleus frequencies in Chinese workers.

Few studies have been conducted that use biomarkers as early warning signals for noise-associated health hazards. To explore potentially effective biomarkers for noise-exposed populations, we recruited 218 noise-exposed male workers in China. We calculated cumulative noise exposure (CNE) through noise intensity and noise-exposed duration. When the model was fully adjusted, ln-transformed relative mitochondrial DNA copy number (mtDNAcn) decreased by 0.014 (95% confidence interval (CI): -0.026, -0.003) units with each 1 dB(A)∙year increase in CNE levels. CNE was further included in the model as a grouping variable, and the results showed a negative dose-effect relationship between relative mtDNAcn and CNE (P-trend = 0.045). However, we did not find a correlation between CNE and micronucleus (MN) frequencies. Our findings suggest that CNE in workers was associated with a decrease in relative mtDNAcn which may provide a potential biomarker for noise and for certain health risk but not with MN frequencies.

[Oral exposure of fluorochloridone caused testes damage of Sparague-Dawley rats].

OBJECTIVE: To investigate the effects of fluorochloridone (FLC) exposure on the testes of adult Sprague-Dawley (SD) rats. METHODS: Forty male SD rats were randomly divided into four groups. These groups, each of 10 male rats, were separately given FLC by gavage at a dose of 0 (control), 30, 150, or 750 mg/kg once daily for 28 d. The oxidative stress biomarkers in the testes were measured by spectrophotometry. The pathological changes in testicular tissues were evaluated under the light and electric microscopes. The cauda epididymal sperm count was determined. The testicular toxicity of FLC was assessed accordingly. RESULTS: Compared with the control group, the 750 mg/kg FLC group had significantly lower testicular weight and organ coefficient, epididymal weight, and cauda epididymal sperm count (P < 0.05 or P < 0.01), the 150 and 750 mg/kg FLC groups had significantly increased malonaldehyde content (P < 0.05 or P < 0.01), each exposed group had a significantly reduced glutathione (GSH) level (P < 0.05 or P < 0.01), the 750 mg/kg FLC group had significantly reduced activities of superoxide dismutase (SOD), catalase (CAT), GSH peroxidase, GSH S-transferase (GSH-ST), and GSH reductase (GSH-GR) (P < 0.05 or P < 0.01), the 150 mg/kg FLC group showed significant decreases in the activities of all antioxidant enzymes except GSH-GR (P < 0.05 or P < 0.01), and the 30 mg/kg FLC group showed significant decreases in the activities of SOD and CAT (P < 0.05 or P < 0.01). Furthermore, seminiferous epithelial degeneration, Sertoli cell vacuolization, spermatogenic cell loss, and nuclear damage were observed under the light and electronic microscopes in the 150 and 750 mg/kg FLC groups. CONCLUSION: FLC could damage the testes of adult rats by inducting oxidative stress. This research provided clues and directions for further exploration of the mechanism of FLC testicular toxicity.