**Acknowledgements**

between characteristics of cell phone usage and semen quality [50]. It showed that talking for ≥1 h/day and during device charging was associated with higher rate of abnormal semen concentration. Among men who reported holding their phones ≤50 cm from the groin, a nonsignificantly higher rate of abnormal sperm concentration was found. Multivariate analysis revealed that talking while charging the device and smoking were risk factors for abnormal sperm concentration. It suggests that certain aspects of cell phone usage may bear adverse

Concerning the usage of wireless internet, researchers have demonstrated that continuous Wi-Fi exposure with 2.45 GHz affected the testes of growing rats. Avendano et al. divided the motile spermatozoa, from 29 healthy donors, into two aliquots and one of them was exposed to a Wi-Fi computer but not the other. 4 h later, research findings showed that the sperm motility and the sperm DNA fragmentation in Wi-Fi group were significantly decreased and increased, respectively [51]. However, current studies are not able to reveal the relationship well enough, and, therefore, larger scales of studies concerned about this aspect are needed.

Accumulating evidence suggests that environmental factors are posing major threats to human reproductive health (**Figure 1**). Impaired spermatogenesis can be incurred by exposures in

**Figure 1.** Schematic representation of environmental risk factors of male infertility.

effects on sperm concentration.

166 Spermatozoa - Facts and Perspectives

**4. Conclusion**

This work was supported by National Natural Science Foundation of China (no. 81401213, 81673217), Jiangsu Overseas Visiting Scholar Program for University Prominent Young & Middle-aged Teachers and Presidents, National Key Research and Development Program (2016YFC1000207), and the Priority Academic Program for the Development of Jiangsu Higher Education Institutions (Public Health and Preventive Medicine).
