| BackgroundWith the continuous improvement of the degree of industrialization and the continuous improvement of heavy metal mining and application,heavy metal pollution in China’s environment is becoming increasingly serious.At present,it is an indisputable fact that male semen quality decreases year by year.There is evidence that abnormal metal elements in the body play an important role in the decline of male semen quality,and reproductive system may be one of the target organs of heavy metals.In recent years,studies on the toxic effects of heavy metals on the reproductive system have mainly focused on animal experiments on the effects of exposure to high concentrations of heavy metals on the reproductive system.ObjectivesThe levels of common heavy metals in plasma and seminal plasma were determined to understand the exposure of heavy metals in fertile males in Puyang city,Henan Province,and to explore and analyze the correlation between seminal plasma and plasma heavy metals content.The levels of malondialdehyde,a biomarker of oxidative damage in seminal fluid,and the relationship between them and heavy metals were analyzed to study the effects of general exposure to heavy metals on semen quality.MethodsFrom December 2017 to August 2018,841 men of childbearing age who received medical treatment and physical examination in the Reproductive Health Center of Maternal and Child Health Care Hospital of Puyang City were selected according to the inclusion and exclusion criteria.Collect blood and semen,Using inductively coupled plasma mass spectrometer seminal plasma and plasma aluminum（Al）,chromium（Cr）,manganese（Mn）,copper（Cu）,zinc（Zn）,selenium（Se）,arsenic（As）,cadmium（Cd）,nickel（Ni）,lead（Pb）,cobalt（Co）,vanadium（V）,rubidium（Rb）,silver（Ag）,barium（Ba）,thallium（Tl）,iron（Fe）And lithium（Li）a total of 18 metals;Semen quality analysis and sperm morphology analysis were performed.The content of malondialdehyde（MDA）in seminal plasma was determined by thiobarbituric acid method.SPSS 21.0,SAS 9.1 and R software were used for statistical analysis.M（P25,P75）was used for statistical description of heavy metal exposure levels in blood and semen.Logistic regression analysis and linear regression analysis were used to adjust for confounding factors such as age,body mass index（BMI）,smoking and alcohol consumption to analyze the effects of various metals on semen quality.The dose-response relationship between heavy metal exposure and semen quality was explored and analyzed using restricted cubic spline function（RCS）.Cluster analysis was used to analyze the relationship between heavy metals and semen quality.Results1.Exposure to heavy metals in men of childbearing age in Puyang city,Henan ProvinceThe content of Zn in seminal plasma was significantly higher than that of other metals,with an average concentration of 181789.69 ppb.The concentration of Ag was the lowest,with an average concentration of 0.030 ppb.In plasma,Fe content was the highest,with an average concentration of 13871.19 ppb.The metal with the lowest concentration was Ag,with an average concentration of 0.025 ppb.The concentration of As,Rb,Cd,Tl and Pb in semen is higher than that in blood.Co,As,Se and Ba in seminal plasma were correlated with the corresponding metals in plasma,but no correlation of other metals in seminal plasma and plasma was found.2.Relationship between seminal plasma metal concentration and semen parametersLogistic regression analysis showed that seminal plasma V、Ni was associated with semen quality damage in single metal model and polymetal model.In the polymetallic model,Cr was associated with semen quality damage.The dose response relationship between V,Ni,Cr and main semen parameters was analyzed by using RCS curves.It was found that the exposure levels of V and Cr in seminal plasma had nonlinear relationship with sperm concentration,sperm total number,normal sperm morphology rate,forward movement percentage and so on.At high exposure（V > 0.58 ppb）,the concentration of V in the seminal plasma was associated with decreased sperm concentration,decreased sperm count,and increased risk of semen quality damage.When Cr > 5.05 ppb,the risk of semen quality damage increased with increased Cr exposure（OR=4.13（1.86,9.15））.When Cr≤5.54 ppb,sperm concentration increased with increasing Cr exposure（β=19.75（2.63,32.86）,P=0.024）.When 3.55ppb< Cr< 7.21 ppb,sperm count increased with increased Cr exposure（β=38.92（5.67,158.65）,P=0.035）.According to semen parameters,the subjects were divided into five groups by cluster analysis.The differences of Mn,Ni,As,Se,Ba,Tl,Fe and Pb among the five groups were statistically significant（P<0.05）,suggesting that these metals may also affect semen quality.3.Relationship of seminal plasma MDA concentration with heavy metals and semen parametersAfter adjusting for confounding factors（age,BMI,smoking,alcohol consumption）,MDA level in spermatoplasm was negatively correlated with sperm motor parameters such as sperm curve line velocity,straight line velocity,velocity of average path and lateral head movement.After adjusting for confounders（age,BMI,smoking,alcohol consumption）,MDA was negatively correlated with Al and Zn and positively correlated with Se.Conclusions1.The exposure level of heavy metals in male of childbearing age in Puyang city of Henan Province is similar to that in other areas of China.The concentration of As,Rb,Cd,Tl and Pb in semen is higher than that in blood,suggesting that semen has enrichment effect on these metals.2.Under general environmental exposure,heavy metals V and Cr affect semen quality,and there is non-linear relationship between seminal plasma V and Cr and semen quality.3.There was a negative correlation between plasma MDA level and sperm motility parameters,and the decreased motility of sperm might be related to oxidative damage. |
