Table 4.

Articles studying the relationship between heavy metals and reproductive parameters in occupationally or environmentally exposed study subjects.

Ref.	Exposure	Study Groups	Biological Matrix	Detection Method	Metal Profile	Main Findings
[83]	E	Infertile men (n = 117) and fertile men as control group (n = 67)	H	ICP-MS	Hg	-A daily Hg intake of 0.3–0.7 mg per kg of body weight may be sufficient to inhibit the spermatogenesis process. -There was a significant correlation between male subfertility and the level of Hg in the hair of males between the ages of 25 and 75.
[84]	E	Infertile men (n = 117) and fertile men as control group (n = 49)	H	ICP-MS	Mn, Fe, Zn, Cu, Cd, Pb, Ni, Hg and Cr	-Compared to fertile males, subfertile males had up to a 40% of Hg in hair.
[85]	E	Infertile men (n = 150) and fertile men as control group (n = 60)	S	AAS	Pb and Cd	-Inverse correlation of both toxicants with sperm motility.
[86]	E	Men recruited from a reproductive medicine center (n = 746)	SP	ICP-MS	Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Sn, Sb, W, Tl, Pb and U	-SPAs was negatively associated with total and progressive sperm motility. -Inverse correlations between Cd quartiles and progressive and total sperm motility. -Positive correlations between Zn quartiles and sperm concentration, between Cu and As quartiles and the percentage of tail DNA, between As and Se quartiles and tail extent and tail distributed moment, and between Sn and the percentage of necrotic spermatozoa.
[87]	E	Men from the general population (n = 587)	SE	ICP-MS	Cd	-A higher Cd concentration may reduce semen volume, progressive motility and morphology among men without occupational exposure to Cd.
[88]	E	Normozoospermic men from general population (n = 62)	SP and U	F-AAS, ETA-AAS and HG-AAS	Zn, Cu, Cd, As, Se and Pb	-Urinary Cd concentrations were negatively associated with sperm viability. -The normozoospermic group had significantly lower seminal plasma Cu concentrations than the abnormal group.
[89]	O	Exposed men (n = 5) and fertile and unexposed men as control group (n = 8)	B and S	AAS	Pb	-In the exposed group, the Pb concentration in blood and semen were significantly higher. -BPb and SPb concentrations were negatively associated with motility.
[90]	E	Exposed group (n = 20) and non-exposed group (n = 27) as control group	B and S	GFAAS	Pb	-The PbB concentration was significantly greater in the exposed group, as well as the PbS. -In the exposed group, there was a significant correlation between PbS and PbB. -Overall, the sperm quality was lower in the exposed group than in the non-exposed group. There were significant differences in motility, concentration, viability and abnormal morphology.
[91]	O	Low occupationally exposed group (n = 30) with 7–10 years exposure for 8 hours per day and high exposed group (n = 50), with more than 10–15 years of lead exposure.; non-occupationally exposed as control group (n = 50)	B and S	AAS	Pb	-After exposure, there was evidence of diminution in sperm cell production. -Low sperm vitality and hypoosmotic swelling percentage with high malondialdehyde content and altered seminal plasma ascorbate level indicated damage of sperm cell surface. -Altered sperm membrane surface. -Lower sperm velocity, gross and forward progressive motility. -High BPb and SPb levels were associated with teratozoospermia.
[92]	O	Low exposed group with 7–10 years exposure (n = 30) and high exposed group with exposure period of more than 10–15 years (n = 50); 40 non-occupationally exposed as control group	B and S	GFAAS	Pb	-Exposure lead to a lower sperm count and density, motility and volume along with an increased incidence of spermatic abnormalities and prolonged liquefaction time. -Also, exposure showed structural alteration of sperm cells, significantly low sperm viability, high sperm membrane lipid peroxidation rate, altered dehydroascorbate levels and low hypoosmotic swelling test (HOST) percentage. -Both BPb and SPb were significantly higher among the factory workers.
[93]	O	Husbands of women going though infertility treatment (n = 80) and workers from a thermometer manufacturing plant as exposed control group (n = 7)	S and U	CV-AAS	Hg	-The urinary concentration of Hg in exposed subjects was similar to non-exposed subjects. -Workers occupationally exposed to Hg showed elevated levels in semen.
[94]	O	Men with proven fertility (n = 12), normozoospermic patients (n = 44), unselected patients of an infertility clinic (n = 118) and industrial workers with occupational exposure to cadmium (n = 2)	SP	ETA-ASS	Cd	-No significant correlation was found between SPCd levels and traditional semen parameters. -Mean Cd concentration in seminal plasma of normozoospermic patients was higher in the group of smokers.
[95]	O	Male tea garden workers (n = 200) and samples from age-matched donors as control group (n = 200)	S	F-AAS	Pb and Cd	-In the high-concentration groups, Pb and Cd concentrations showed positive associations with a higher number of defects in sperm and with the level of markers of seminal oxidative stress.
[96]	E and O	Male partners (n = 300) of couples investigated for infertility	SP	GFAAS	Pb and Cd	-In SP, the levels of PB and Cd were associated with reduced sperm viability, count, motility and normal forms.
[97]	E	Infertile men with intramedullary nailing prosthesis (IMN) (n = 60) and age-matched healthy men as control group (n = 30)	SP	ICP-MS	Co, Cr and Mo	-Individuals with IMN had high concentrations of Co, Cr and Mo in SP. This led to a greater spermatozoal apoptotic activity.
[98]	E	Male partners in couples from a reproductive medicine center (n = 1247)	U	ICP-MS	As, Cd and Pb	-Urinary As, Cd and Pb were associated with oxidative stress markers (8-OHdG, HNE-MA and 8-isoPGF2α), which were also associated with impaired semen quality.
[99]	E and O	Infertile men (n = 74) and fertile men as control group (n = 76)	B, SP and U	ICP-MS	As, Mn, Co, Cd, Pb, Zn and Se	-Heavy metals levels in blood were not related to a lower fertility in Lebanese men.
[100]	E	Exposed men (n = 30) and control groups: men from towns 100 km away (n = 32, control group one) and 200 km away (n = 33, control group two)	SP	GFAAS	Cd, Cr and Cu	-SP Cr values displayed a significant negative correlation with normal morphology sperm rate, motility and rapid progressive sperm motility. -SP Cu values also displayed a negative correlation with normal morphology sperm rate.
[101]	E	Non-smoking males visiting infertility clinics (n = 333)	U	ICP-MS	Cd, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Mo, Sn, Sb, Ba, W, Tl, Pb and U	-Cd modified the association between polycyclic aromatic hydrocarbons (PAH) and pyrene with seminal quality parameters.
[102]	O	Workers from plants with a range of exposure to Pb (from no exposure to moderate Pb exposure) (n = 98) and no likely exposure (n = 51)	SP, B and SE	AAS	BCd, SZn, SfZn, Scu	-BPb was significatively associated with a decrease in sperm density, viability and progressive motility. It was also associated with an increase in abnormal sperm head morphology, an impaired prostate secretory function and a decreased serum testosterone and estradiol levels. -BCd was associated with a decrease in sperm motility. It also was associated with an increase in abnormal sperm morphology and with increased levels of serum testosterone. -Moderate exposures to Pb and Cd could significantly diminish human semen quality without impairing the reproductive endocrine function.
[103]	O	Welders workers (n = 57) and 57 controls (n = 57)	B	ICP-MS	Ni and Cr	-Ni was associated with a higher percentage of sperm with tail defects. -Cr was negatively correlated with the spermatic concentration.

E, environmental; O, occupational; B, blood; H, hair; S, semen; SE, serum; SP, seminal plasma; U, urine; AAS, atomic absorption spectroscopy; CV-AAS, cold vapor-atomic absorption spectroscopy; ETA-AAS, electrothermal-atomic absorption spectroscopy; F-AAS, flame-atomic absorption spectroscopy; GFAAS, graphite furnace atomic absorption spectroscopy; HG-AAS, hydride generation-atomic absorption spectroscopy; ICP-MS, inductively coupled plasma-mass spectrometry; Al, Aluminum; As, Arsenic; Ba, Barium; Cd, Cadmium; Cr, Chromium; Cu, Copper; Co, Cobalt; Fe, Iron; Hg, Mercury; Mn, Manganese; Mo, Molybdenum; Ni, Nickel; Sb, Antimony; Se, Selenium; Sn, Tin; Sr, Strontium; Tl, Thallium; U, Uranium; W, Tungsten; Zn, Zinc.