Sperm quality and environment: A retrospective, cohort study in a Northern province of Italy

Background: Several studies proposed a relationship between environmental factors and semen quality, as well as the negative effect of air pollution on spermatogenesis and gonadal function. No specific studies evaluated the environmental influence on semen quality in a specific geographical area.

Aim: to evaluate the environmental influence on male sperm parameters in a Northern Italian population referred for semen analysis in the National Health System. The objective of the study is the assessment of the relationship of both air pollution and environmental parameters with quality-related sperm variables, during the coldest months of the year when air is usually most polluted, due to low ventilation and poor rainfall.

Study design: A retrospective, observational, cohort study was carried out in the province of Modena, located in the Emilia-Romagna region of Northern Italy.

Methods: Semen analyses (n=406), environmental temperature, air humidity and air particulate matter (PM) measurements from the 1st of November 2014 to the 19th of February 2015 were acquired to the first database. Since spermatogenesis lasts over two months, a second, wider database was arranged, evaluating environmental exposure in the 3 months before semen collection (from August 1st 2014). All data included in the database were registered by geo-coding the residential address of the patients and the site of registration of environmental factors. The geo-codification of parameters was performed using Fusion Tables of Google available at https://www.google.com/fusiontables/data? dsrcid=implicit, considering the exact time of measurement.

Results: Average air temperature was inversely related to sperm concentration and to total sperm number (p<0.001). Semen volume was inversely related only to the minimum (p<0.001) and not to maximum recorded temperature (p=0.110). Air humidity was not related to sperm quantity and quality. PM2.5 was directly related to total sperm number (p<0.001). PM10 was directly related to both semen volume (0<0.001), and typical forms (p<0.001), inversely related to atypical forms (p<0.001), but related neither to sperm concentration (p=0.430) nor to sperm motility. The extended analyses considering environmental parameters in the 3 months before semen collection, confirmed the relationship between air temperature and sperm quantity, whereas no influence was found between PM and sperm quality.

Conclusion: An influence of environmental temperature on semen quantity is suggested, without a clear effect of air pollution, as assessed through PM10 levels, on sperm parameter variations.