Semen Quality in a Large Cohort of Males Living in Highly Polluted Areas of Campania Region in Southern Italy with a Focus on the Role of Cadmium Exposure

Background/Objectives: The “Land of Fires” (LF) in the Campania Region has attracted considerable attention due to massive environmental contamination deriving from decades of illegal disposal, burial, and burning of urban, industrial, and toxic waste. Cadmium (Cd) has been repeatedly proven to affect male reproductive function by a plethora of endocrine and non-endocrine mechanisms. The scientific literature is almost devoid of large studies addressing semen quality in this area, particularly by directly correlating seminal parameters to objectively measured pollutant burden in biological samples. Therefore, the aim of the current study was to comprehensively evaluate semen quality of males of reproductive age living in the LF, by correlating seminal parameters to cumulative local male reproductive tract Cd burden objectively quantified in whole semen samples. Methods: The current single-center, observational, cross-sectional study evaluated semen quality in 493 males aged 14–50 (29.07 ± 7.17) years living in three LF municipalities. Moreover, the association of semen quality with whole semen Cd (sCd) levels measured by inductively coupled plasma mass spectrometry (ICP-MS) was addressed in a subgroup of participants; semen samples suitable for semen Cd measurements were available from 383/493 (77.7%) participants of the total cohort, and all analyses involving semen Cd were performed within the measured subset. Results: In the total cohort, seminal parameters were as follows: semen pH 8.32 ± 0.3, semen volume 3.13 ± 1.67 mL, sperm concentration 37.58 ± 30.18 × 106/mL, total count 111.2 ± 104 × 106/ejaculate, total motility 56.83 ± 16.09%, progressive motility 50.22 ± 16.63%, in situ motility 6.72 ± 3.43%, immotile spermatozoa 43.07 ± 15.88%, normal morphology 7.97 ± 4.02%, and viability 64.75 ± 15.34%. Prevalence of normozoospermia and pathological seminal parameters was as follows: normozoospermia 66.5% (328/493), pathological seminal parameters 33.5% (165/493), specifically, oligozoospermia 14% (69/493), cryptozoospermia 0.8% (4/493), azoospermia 2.2% (11/493), asthenozoospermia 3% (15/493), teratozoospermia 0.6% (3/493), oligo-astheno-teratozoospermia 6.1% (30/493), necrozoospermia 5.7% (28/493), and different combined seminal parameters alterations 7.1% (35/493). Whole semen Cd was below (undetectable) or above (detectable) the limit of detection (LoD) (0.2 μg/L) in 66.6% (255/383) and 33.4% (128/383) whole semen samples, respectively. In samples with detectable sCd, sCd level was below or above the median value (0.76 μg/L; min–max 0.1–5.95 μg/L) in 23.4% (30/128) and 76.6% (98/128) whole semen samples, respectively. Participants with detectable sCd levels had a significantly reduced sperm total count (93.28 ± 84.88 × 106/ejaculate vs. 113.2 ± 101.5 × 106/ejaculate; p = 0.037), and normal morphology (7.29 ± 3.71% vs. 8.23 ± 3.91%; p = 0.034), and a significantly lower prevalence of normozoospermia (60.2% vs. 72.2%; p = 0.02) and significantly higher prevalence of pathological seminal parameters (39.8% vs. 27.8%; p = 0.02), specifically, a significantly higher prevalence of oligozoospermia (21.1% vs. 12.6%; p = 0.036) than those with undetectable sCd levels. Whole semen Cd levels were significantly higher in participants with pathological seminal parameters (1.08 ± 0.84 μg/L vs. 0.93 ± 0.74 μg/L; p = 0.037) than those with normozoospermia. Participants with sCd levels above the median value (N = 98) had a significantly reduced sperm concentration (29.12 ± 24.84 × 106/mL vs. 43.62 ± 29.55 × 106/mL; p = 0.015) and displayed a trend towards reduced sperm normal morphology (6.92 ± 3.38% vs. 8.55 ± 4.49%; p = 0.057) than those with sCd levels below the median value (N = 30). Moreover, participants with sCd levels above the median value (N = 98) had a significantly reduced sperm concentration (29.12 ± 24.84 × 106/mL vs. 35.3 ± 26.29 × 106/mL; p = 0.03), total count (85.77 ± 80.52 × 106/ejaculate vs. 113.2 ± 101.5 × 106/ejaculate; p = 0.008) and normal morphology (6.92 ± 3.38% vs. 8.23 ± 3.91%; p = 0.006), and a significantly lower prevalence of normozoospermia (57.1% vs. 72.2%; p = 0.008) and significantly higher prevalence of pathological seminal (42.9% vs. 27.8%; p = 0.008), specifically, a significantly higher prevalence of oligozoospermia (23.5% vs. 12.6%; p = 0.014) than those with undetectable sCd levels. Conclusions: The results of the current study demonstrate an association between the environmental Cd exposure and the impairment of seminal parameters, with a significantly poorer semen quality in participants with detectable sCd, and, more markedly, in those with sCd level above the median value, compared to participants with undetectable sCd, although subgroups comparisons highlighted a homogeneous profile in major confounders including age, BMI, and smoking habits among subgroups of participants with different sCd burden.