Table 4 Effect of pollutants on spermatogenesis in humans

Selevan et al., 2000 [59]

272

PM10, SO₂, CO and NOx

Cross-sectional study: Compared sperm parameters of healthy 18-year-old men living in Teplice (industrialized area in Czech Republic) and those of healthy 18-year old men living in Prachatice (rural area in Czech Republic). Exposure data for PM10, SO₂, CO and NOx gathered for 90 days before sperm sample taken and categorized in low, medium and high levels.

Men living in Teplice had significant decreased sperm mobility (mean ± SD: 31.6 ± 16.3 vs 36.1 ± 17.9), normal sperm morphology (16.6 ± 7.3 vs 19.3 ± 8.6). No effects seen on sperm count or sperm chromatin quality. Whatever the district, compared to low exposure level, medium exposure level was associated with decreased sperm motility (adjusted regression analysis: β (95CI): −8.03 (−13.57;-2.49)) and sperm morphology.(OR (95CI): −0.54 (−0.86;–0.22)

High exposure level was associated with decreased normal sperm morphology (β(95CI): −0.84 (−1.15;–0.53)) and increased proportion of sperm with abnormal chromatin (β(95CI): 0.30 (0.08–0.52).

De Rosa et al., 2003 [54]

170

Multiple pollutants from automobile traffic

Cross sectional study: Compared exposed men (n = 85, working at an expressway toll plaza) to age-match control group (n = 85) from same area and employed as clerks, drivers, students or doctors.

In the exposed group compared to control group, Decreased sperm motility: 34.7 ± 2.2%vs 56.8 ± 0.8 (p < 0.0001) Decreased vitality: 51.7 ± 2.5% vs 80.7 ± 0.6 (p < 0.0001) Decreased sperm nuclear DNA integrity: 48.5 ± 2.2% vs 75.7 ± 0.6 (p< 0.0001) Decreased cervical mucus penetration: 15.9 ± 1.2 mm vs 30.3 ± 0.2 (p < 0.0001) No effect on sperm count and semen volume

Gaspari et al., 2003 [21]

182

PAH

Prospective cohort study: Study of sperm parameters in infertile Italian men with abnormal sperm morphologies who were partners of women without known causes of infertility. Measured sperm PAH-DNA adducts.

Positive correlation between level of sperm PAH-DNA adducts and abnormal morphology of sperm heads (r = 0.3; p = 0.0001).

Rubes et al., 2005 [68]

36

SO₂, NOx and PM10

Prospective cohort study: young healthy men living in Teplice (industrialized area) who gave 3 to 7 sperm samples during winter (highly polluted air) and summer (less polluted air). Average concentrations of SO₂, NOx and PM10 gathered in 90 days before each sampling.

Positive association between percentage of spermatozoa with abnormal chromatin and level of air pollution: β = 0.19 (95% CI: 0.02, 0.36) No association between exposure to air pollution and routine semen measures or sperm aneuploidy.

Hsu et al., 2006 [65]

48

PAHs

Cross sectional study: Semen evaluation among coke-oven workers at steel company in Taiwan. Compared “topside-oven” (TO, n = 16) most exposed group and “side-oven” least exposed group (SO, n = 32) group. PAH exposure measured in ambient air and urine.

Significantly higher rates of oligospermia (18.8 vs. 0%) and abnormal sperm morphology (32.3 vs. 14.6%) in TO vs. SO workers. No difference in semen volume, sperm count, motility, and frequency of asthenospermia. Positive correlations between urinary PAH level and percentage of abnormal sperm shapes (β (SE β): 0.107 (0.040); p = 0.012) and decondensed sperm chromatin (β (SE β): 0.235 (0.073); p = 0.003).

Sokol et al., 2006 [67]

48

O₃, NO₂, CO and PM10

Retrospective cohort study: Evaluated sperm count and motility from sperm donors (n = 48) who provided 5134 sperm donations over 2 year period. Exposure data for O₃, NO₂, CO and PM10 from donor’s place of residence over 3 periods: 0–9, 10–14, and 70–90 days before each donation.

Negative association between the level of O₃ exposure and total sperm count: For 0–9 day lag: 4.22% decrease per interquartile range (IQR) of 14.3 ppb increase in O₃, p = 0.01 For 10–14 day lag: 2.92% decrease per IQR of 14.3 ppb increase in O₃, p = 0.05) For 70–90 day lag: 3.90% decrease per IQR of 14.3 ppb increase in O₃, p = 0.05) No association between the level of O₃ exposure and total motile sperm count. No association with other pollutants studied.

Guven et al., 2008 [57]

73

Multiple pollutants from diesel exhaust

Cross sectional study: Compared semen parameters of men exposed to diesel vehicle exhaust (n = 38 men working as toll collectors at motorways) to men working as office personnel in same company (n = 35). No monitoring of exposure levels.

Significant decrease in sperm concentration (mean ± SD: 44.64 ± 36.26 vs 70.85 ± 50.0), mobility (54.76 ± 23.64 vs 70.25 ± 15.5) and sperm with normal morphology (p = 0.001) in exposed group compared to unexposed group.

Hammoud et al., 2010 [58]

2576 samples

PM2.5

Retrospective study of 2 populations over 5 years: Population 1: men attending a semen analysis (n = 1699 samples, 1.16 ± 0.46 (mean ± SD) semen samples per patient, number of patient not stated) Population 2: men presenting for artificial intrauterine insemination on at least four occasions (n = 169 patients, 877 samples). Local average monthly concentrations of PM2.5 in each of 4 months preceding sampling, based on national data.

Population 1: Contemporaneous PM 2.5 correlated negatively with current sperm morphology (r = −0.076;p = 0.018) Negative correlation between PM 2.5 recorded 2 months (β = − 0.510; p = 0.01) and 3 months (β = − 0.411; p = 0.04) previously andsperm motility. Population 2: Sperm motility correlated negatively with PM 2.5 values recorded 3 months previously (β = − 0.407; p = 0.04) No correlation between semen parameters and PM 2.5 values recorded 1, 3, and 4 months previously in both populations.

Jurewicz et al., 2015 [70]

212

O_3, CO, SO₂, NOx, PM2.5 and PM10

Prospective cohort study: Measured level of sperm aneuploidy in Polish men consulting for infertility with normal sperm counts. Exposure data for average CO, SO₂, NOx, PM2.5 and PM10 over 90 days before sampling at closest station to place of residence.

Positive association between PM2.5 exposure and disomy Y (β = 0.68 (95%CI: 0.55–0.85); p = 0.001), sex chromosome disomy (β = 0.78 (95%CI: 0.59–0.99; p = 0.05), disomy of chromosome 21 (β = 0.78 (95%CI: 0.62–0.97; p = 0.03). Positive association between PM10 exposure and disomy 21 (β = 0.58 (95%CI: 0.46–0.72; p = 0.02) No association between sperm aneuploidy and O₃, CO, SO₂ and NOx exposures.

Wijesekara et al., 2015 [62]

300

Multiple pollutants from environmental and occupational exposures

Cross-sectional study: Male partners from infertile couples with no known male cause, divided into exposed and unexposed groups according to environmental and occupational exposure to pollutants based on interviewer- administered questionnaire.

Among normozoospermic patients (n = 201), exposed men (n = 115) showed, compared to non-exposed men (n = 86), significant decreases in (mean (95%CI): Normal morphology (%): 39.03 (36.25–41.81) vs 43.89 (40.54–47.24) Sperm mobility (%): 48.42 (46.57–50.27) vs 52.48 (50.2–54.76) Sperm vitality(%): 56.67 (54.48–58.86) vs 64.71 (62.03–67.39) Among pathozoospermic men (n = 99), only sperm concentration (16.89 million/ml (12.25–21.53) vs 31.94 (23.45–40.43)) and sperm morphology (normal forms: 21.46% (17.2–25.72) vs 28.00% (23.35–32.65)) were affected in exposed vs non-exposed men.

Radwan et al., 2016 [66]

327

PM10, PM2.5, SO2, NOX, CO

Retrospective cohort study: Polish men with normal sperm counts treated for infertility. Obtained exposure data for average CO, SO₂, NOx, PM2.5 and PM10 over 90 days before sperm sampling at closest station to place of residence. Conducted multiple linear regression after adjusting for age, smoking, mean air temperature (over 90 days before sperm sampling), past diseases, duration of sexual abstinence and season.

Statistically significant associations between sperm morphology and exposure to each pollutant.: PM10: β =32.60; p = 0.0002 PM2.5: β =40.53; p = 0.0001 SO2: β =6.60; p = 0.0001 NOx: β =6.19; p = 0.01 CO: β =24.86; p = 0.0001. Statistically significant associations between the percentage of spermatozoa with immature chromatin and levels of PM2.5 (β =0.31; p = 0.0001) and PM10 (β =0.22; p = 0.02).