Introduction: Air pollutants levels have been monitored closely for environmental and research issues in industrialized countries. We aimed to investigate the association between air pollutants levels and semen parameters in a cohort of white-European men seeking medical attention for primary couple’s infertility in Italy.
Methods: Complete demographic and laboratory data from 1152 infertile men consecutively assessed between 01/2015 and 12/2019 were analysed. Semen analyses were based on the 2010 WHO reference criteria. Health-significant comorbidities were scored with the Charlson Comorbidity Index (CCI). We analyzed the annual average level of the three main markers of air pollution (Pm10, Pm2.5, and NO2) between 2014-2018 (Legambiente, 2020, Annual dossier series on air quality in Italy, referring the European Environmental Agency) relative to patients’ addresses over the last 5 years. Descriptive statistics and linear regression analyses were used to test the association between air pollutants levels and semen parameters.
Results: Overall, median (IQR) age and BMI were 37 (33-41) years and 24.3 (22.7-26.5) kg/m2, respectively. A CCI score = 1 was found in 98 (8.5%) men, and 318 (27.6%) participants were active smokers. Of 1152 men, 87 (7.6%) had normal sperm parameters. Of 1065 patients with abnormal semen analyses, 237 (22.3%), 324 (30.4%), and 287 (27.0%) patients presented 1, 2 or 3 abnormalities, respectively; 217 (20.38%) patients were azoospermic. At linear regression analysis, Pm10, Pm2.5, and NO2 were negatively associated with sperm morphology (Pm10: ß: -0.5288 µg/m3, p=0.001; Pm2.5: ß: -0.5240 µg/m3, p=0.019; NO2: ß: -0.4396 µg/m3, p<0.0001). Furthermore, the adjusted odds of sperm normal morphology <4% were 1.06 (95% CI 1.03-1.09; p=0.007) for Pm10, 1.07 (95% CI 1.03-1.11; p=0.007) for Pm 2.5, and 1.03 (95% CI 1.02-1.05; p=0.001) for NO2, respectively (Fig.1).
Conclusions: Findings of this cross-sectional study showed that Pm10, Pm 2.5, and NO2 levels were negatively associated with sperm morphology; conversely, they were not consistently associated with an increased risk of other abnormal sperm parameters in infertile men. Further studies are needed to better characterize air pollution effects on sperm parameters.