Table 1.

Number of publications in each database according to the different keywords utilized after applying the inclusion criteria.

Keyword	Pubmed	Scopus	WOS
Male Fertility	38,256	186,504	52,261
Heavy metals	345,873	513,286	199,667
Human Spermatogenesis	9211	54,300	199,667
Human Sperm	35,460	133,717	46,870
Heavy metals and Human Spermatogenesis	101	1144	69
Heavy metals and Human Sperm	573	2972	222
Heavy metals and Male Fertility	428	2722	290