Exposure To Air Pollutants And Human Semen Quality In Nanjing,China

Present researches have found the association between ambient air pollution and a range of diseases including cardiovascular and respiratory diseases and cancers.Animal studies provide evidence that ambient air pollution exposure can adversely affect male germ cells.Particulate matter(PM)is a vital indicator of air pollution and it is associated with a series of diseases.Pires et al.showed that fine particulate matter(PM2.5)is detrimental to spermatogenesis in mice.Recently,there has been increasing interest in the effects of air pollution on male reproductive health.In humans,several studies reported changes of sperm parameters,such as sperm mobility and movement,after exposure to air pollution.However,the effects of PM exposure on the reproductive system have been inconsistent.Particularly,studies concerning PM exposure and semen parameters in men known to be fertile are limited.Male infertility is responsible for about 50% of infertile in couples and is a vital public health issue worldwide.A significant decline in human semen quality has been observed over the past 70 years,even in fertile men.The World Health Organization(WHO)reports that 1.4 billion urban residents live in areas with air quality that does not meet WHO air quality guideline.China has experienced deterioration of the air quality as its rapid socioeconomic development.The situation is especially notable in the Yangtze River Delta,one of the fastest areas in China undergoing most rapid urbanization.Because development of sperm takes approximately three months,most studies analyzed PM exposure in the 90 days before semen examination.Sperm development covers three key stages before semen ejaculation: 0-9(epididymal storage),10-14(development of sperm motility),and 70-90 days(spermatogenesis).However,few researchers have considered different exposure stages within the 90-day window,and the conclusions are inconsistent.We therefore investigated the effects of up to 90 days PM exposure(both PM2.5 and PM10)on semen quality in a fertile male population in Nanjing,China and we further attempted to clarify which stage of sperm development is most impacted by PM exposure.Only a few studies have examined the association of PM with semen quality,and this is the first to do so among a large population of fertile men and including 14 parameters of semen quality.Part ?Air pollution in NanjingObjective To study the effect of atmospheric particulate pollution in Nanjing on the semen quality among a fertile population,we analyzed the spatial and temporal distribution of atmospheric particulates in Nanjing during 2014 to 2016.Methods We obtained the daily air pollution(PM2.5 and PM10)data of nine ground monitoring stations in Nanjing from Nanjing Environmental Protection Bureau.The daily average temperature of the same period were obtained from Nanjing Meteorological Bureau.We used R software to perform basic statistical descriptions and correlation analyses.Results The daily average concentration of PM2.5 and PM10 has a significant seasonal variation,and the highest average PM2.5 concentration was 83.44 ?g/m3 in winter,and the lowest was 45.19 ?g/m3 in summer.During year of 2014 to 2016,the rate over Chinese 24-hour grade two standard of PM2.5 was 40.3%,21.1% and 17.5%,respectively.The daily average concentration of PM2.5 and PM10 has a significant seasonal variation,and the highest average PM2.5 concentration was 134.82 ?g/m3 in winter,and the lowest was 72.93 ?g/m3 in summer.For PM10,the rate was 24.6%,13.4% and 12%,respectively.The highest average temperature was 31.1 ? in summer,and the lowest concentration was-6.6 ? in winter.Pearson correlation analyses for average daily concentration of PM2.5,PM10 and temperature in Nanjing during 2014 to 2016 indicated that correlation coefficient between the PM2.5 concentration and PM10 concentration was 0.92.The correlation coefficient between the PM2.5,PM10 and temperature was both-0.27.Conclusion The atmospheric particulate pollution in Nanjing city during 2014 to 2016 was characterized by a seasonal variation.Compared with other seasons,the air pollution in winter was more serious and year of 2014 had a worse air condition.The concentrations of PM10 and PM2.5 had a significantly strong correlation,and the temperature was significantly related to particulate matters.Part ?Association between air pollution and semen quality in NanjingObjective We investigated the effects of PM exposure on semen quality among a population of fertile men in Nanjing,China.Methods We evaluated 14 parameters of semen quality in 1554 fertile men in Nanjing from2014 to 2016.Individual exposure to particular matter ? 10 ?m in diameter(PM10)and ? 2.5 ?m(PM2.5)during key periods of sperm development(0-90,0-9,10-14 and70-90 days before semen collection)were estimated by inverse distance weighting interpolation.Associations between PM exposure and semen quality were estimated using multivariable linear regression.Results Higher ninety-day average PM2.5 was associated with decreased sperm motility(2.14% for total motility,1.86% for progressive motility per 10 ?g/m3 increase,P <0.001)and four quantitative aspects of sperm motion(curvilinear velocity(VCL),straight line velocity(VSL),average path velocity(VAP),and amplitude of lateral head displacement(ALH),P < 0.001,P < 0.001,P < 0.00 and P = 0.009).Similar results were obtained in the 1019 men with normal values for all sperm parameters.For this 90 day exposure period,PM10 was associated only with decreased VCL and VAP.No significant association was observed between PM exposure and sperm concentration.Conclusion Exposure to PM2.5 adversely affects semen quality,specifically lower sperm motility,in fertile men.