CASA-based sperm kinematics of environmental risk factor-exposed human semen samples designated as normozoospermic in conventional analysis

This study was conducted after an initial epidemiological survey of patients in and around Calcutta, India, concerning their lifestyle history, degree of risk exposure and semen analysis based on conventional WHO criteria. It was found that a large group of exposed patients were showing normozoospermic semen parameters in conventional semen analysis. Hence, a selected group of subjects, designated as normozoospermic in routine analysis, but under risk factor exposure, were selected for a repeat computer aided semen analysis (CASA) and were compared with a control group. The parameters considered among CASA results were: curvilinear velocity (VCL), straight-line velocity, average path velocity (VAP), straightness index (STR), lateral head displacement (ALH) and beat cross frequency. The results depict a significant decline in the mean values of VCL (P = 0.029) and STR (P = 0.007) in the tobacco-exposed group when compared with the unexposed group. On the other hand, there was a significant decline in the mean values of VCL (P = 0.014) and ALH (P = 0.040) in the heavy metal-exposed group when compared with the unexposed group. The other parameters did not show significant change in either group. Semen samples that had been designated normozoospermic in conventional analysis were seen to be influenced by risk factors at the level of sperm motion kinetics.