Table 1.

Types of biochemical, cytological, genetic, and epigenetic disorders in male infertility after occupational and environmental exposure to stressors

Disorder	Occupational exposure	References	Environmental exposure	References
Hormonal	Testosterone ↓	(24, 33, 35)	Testosterone ↓ Oestradiol↓ Aromatase ↓ Gonadotropins↑ Aromatase↑ Leptin↑	(38, 39, 42, 43, 46, 47, 58, 115, 116, 119, 120)
Sperm	Sperm motility ↓ Apoptosis ↑ ROS generation Sperm count ↓ Asthenozoospermia Necrozoospermia Oligozoospermia Sperm immaturity↑	(14, 17, 18, 19, 20, 21, 22, 23, 24, 25, 34, 35)	Sperm count ↓ Sperm motility ↓ Abnormal morphology ↑ Oligozoospermia Asthenozoospermia Azoospermia Apoptosis↑	(6, 7, 25, 26, 27, 28, 36, 46, 47, 55, 56, 58, 59, 63, 64, 107, 108, 117, 118, 119, 120, 122, 124)
Mitochondrial	–	–	mitochondria Disturbances functionality in	(121, 125, 126)
DNA	DNA fragmentation Genome damage Disomy X ↑ Disomy Y ↑ Hyperhaploidy	(14, 15, 23, 35)	XY18 disomy Disomy of chromosome 13 Disrupted DNA integrity Sex chromosome aneuploidy Deletions in AZF region Sex chromosome disomy DNA damage DNA fragmentation	(11, 24, 48, 49, 50, 55, 56, 58, 59, 119, 120, 121)
DNA methylation	Sperm LINE-1 hydroxymethylation DNA hydroxymethylation partially dependent on trimethylation of H3 in human spermatogenesis	(36, 37, 38)	Hypermethylation of LINE-1 and hypomethylation of P16 gene	(10)