Infertility is a prominent issue in reproductive health of both males and females worldwide. This study was aimed to investigate the impacts of physical condition, lifestyle and occupational factors for the development of poor semen parameters. The outcomes of the present study can be very important to diagnose and treat the male infertility in Sri Lanka.
Present study confirmed that cigarette smoking is a risk factor for decreasing sperm production and eventually leads to infertility. Individuals with heavy smoking showed a drastic decline of the sperm concentration, compared to the non-smoker. Smokers with a habit of using > 5 cigarettes per day is highly vulnerable to become oligospermic. Cigarette smoking causes elevated oxidative stress, and cell apoptosis, which lead to reduce semen quality, spermatogenesis and sperm maturation. In the present study identified that both the motility analyses (none or progressive) showed a risk of asthenospermia with increased smoking. Similarly, studies reported that smoking significant associated with low sperm concentration and mortality and semen quality [6, 17, 18]. Cigarette smoking causes DNA damage, aneuploidies, and mutations in sperm .
Alcohol interferes with the production of hormones associated with male reproductive system (GnRH, FSH, LH, and testosterone) and reduces the functions of Leydig and Sertoli cells (10). Therefore, development and maturation of spermatozoa gradually decline with increasing levels of alcohol intake [20, 21]. However, Alcohol consuming was not a significant factor for sperm concentration and mortality in the present study. In contrast to this study, Muthusami et al. 2005 revealed that alcohol consuming individuals had significantly decreased semen volume, sperm concentration, motility and percentage of normal sperm morphology .
Boxer briefs and tight underwear users showed significant relationships with low sperm concentration and motility and poor semen quality. Boxer brief and tight underwear users had significant relationships with low sperm volume, high percentage of abnormal forms, progressive motility and non-motility. Wang et al. 1997 reported that temperature increase in the scrotum in athletic supporters (0.8 °C to 1 °C) who wear tight underwear. When increasing 1 °C in testis, a total of 14% decline in the spermatogenesis . Therefore, genital heat stress is a risk factor for male infertility . Parazzini et al. 1995 reported that individuals wearing tight fitting underwear had a risk of 2.5 of having impaired semen quality . Therefore, it is suggested that loose fitting underwear is advantageable for high quality sperm parameters. Elevated temperatures in the scrotum lead to oxidative stress, and sperm DNA damage .
Males exposed to high temperature at their workplaces were more prone to infertility. Excess environmental heat increases the temperature of the scrotum, causing a negative effect on quantity of sperm production and decrease in motility and morphology of the sperms. High temperature stimulates more generation of reactive oxygen species (ROS) in cells . ROS negatively effect on cell metabolism by damaging sperm plasma membrane and fragmentation of both nuclear and mitochondrial DNA . Several studies reported that lower sperm production and motility and high rate of abnormal forms were significantly associated with increasing temperature of testis [26–28].
In the present study, chemical, agrochemical, heat and radiation were considered as occupational exposures. Individuals exposed to either chemical or heat exposed individuals have shown a significant association with low sperm concentration and low sperm motility. Similarly, a previous study in Sri Lanka, reported that a significant relationship between occupational exposure (Agrochemical or Industrial chemical and heavy metals) with sperm concentration and quality . Sperm motility and viability were not significant relationship with the exposed group.
Poor semen parameters increase with the advancement of male ages. In the present study, low sperm concentration and high rate of non-motility, abnormal forms and progressive motility observed in > 40 years of age category. Similarly, several studies reported that low sperm concentration, volume and progressive motility of sperm was significantly associated with increasing age after 40 years old [29, 30]. A total of 0.17–0.6% of motility rate decreased with per year of age and resulting 3–12% decline in motility over 20 years [31, 32]. Although the production of spermatozoa exists until death, the quality of male germ cells is negatively associated with advanced paternal age . After the age of 45, semen volume and the percentage of normal sperm morphology begins to decline [34, 35]. In addition, the age is directly related to elevation of oxidative stress and it is responsible for DNA fragmentations .
In the present study, no significant relationship was found between Mumps infection with semen parameters. However, a study performed by Povey et al. 2012 revealed individuals who exposed to mumps at ≥ 13 years of age have a risk of lower motile sperm concentration . Mumps infections are associated with the production of anti-sperm anti bodies and inflammation. Anti-sperm antibodies adversely affect sperm quality and production and finally cause infertility.
Distress at the workplace, will decreased motivation of workers and develops psychological and physiological dysfunctions . Psychological stress is associated with abnormal semen parameters affecting male infertility. Stress activates the hypothalamus–pituitary–adrenal (HPA) axis  and has an inhibitory effect on the hypothalamus–pituitary–gonandal (HPG) axis. The inhibition of the HPG axis reduces luteinizing hormone (LH) and testosterone pulsing, thus reducing spermatogenesis and sperm quality [39, 40]. Reduction of testosterone secretion negatively effects on spermatogenesis . In the present study, sperm concentration and mortality were negatively associated with occupation exposure. Similarly, several studies reported that negative associations between stress and sperm motility, sperm concentration, percentage of morphologically normal spermatozoa and low semen quality [42, 43].
Glucose metabolism is very important to produce sperms. The present study found that sperm motility and volumes are significantly lesser in individuals with diabetes compared to non-diabetics. Many studies have reported that diabetes associated with male infertility by reduced motility, structural defects in nuclear and mitochondrial DNA and decreased zona pellucida binding capacity of sperms [44–46].
Overweight and obese are well known characteristics with low sperm quality and a greater risk of infertility in males. The excess adipose tissue causes increased conversion of testosterone to oestrogen and affects the HPG axis to reduce the production of gonadotropin. It adversely effects on spermatogenesis . Obese men were prone to be oligozoospermic or azoospermic compared to men within a normal weight range . Present study did not find any significant difference between normal and high BMI group of individuals with sperm concentration. In contrast to this study, Hammoned et al. 2008 found the prevalence of oligozoospermia was increased with increasing BMI .