Exploring the relationship between ambient sulfur dioxide and semen quality parameters:A systematic review and meta-analysis

Objective:To investigate the relationship between ambient sulfur dioxide(SO2)exposure and semen quality parameters.Methods:A systematic literature search was conducted to identify relevant studies investigating the association between SO2 exposure and semen quality parameters.This search encompassed the timeframe from January 2000 to May 2023 and included electronic databases such as Web of Science,Google Scholar,PubMed,Cochrane,and Scopus.Pooled effect estimates with 95%confidence intervals(CI)were calculated using percent changes(PC).The meta-analysis included seven studies with 6711 participants and 15087 semen samples.Results:The results revealed a significant negative association between ambient SO2 exposure and certain semen quality parameters.In particular,SO2 exposure was associated with a significant decrease in progressive motility(PC=0.032;95%CI:-0.063 to-0.001;P=0.044)and sperm concentration(PC=-0.020;95%CI:-0.036 to-0.005;P=0.012).However,no statistically significant associations were observed for total sperm count(PC=-0.038;95%CI:-0.079 to 0.003;P=0.070),seminal fluid volume(PC=-0.009;95%CI:-0.048 to-0.030;P=0.662)and sperm motility(PC=-0.17;95%CI:-0.363 to 0.022;P=0.830).In addition,the results of the subgroup analysis revealed specific variables that were associated with the decrease in relevant sperm parameters.Conclusions:This systematic review and meta-analysis provides compelling evidence supporting a consistent negative association between exposure to ambient SO2 and semen quality parameters.

Patterns of alteration in boar semen quality from 9 to 37 months old and improvement by protocatechuic acid

Background Comprehending the patterns of alteration in boar semen quality and identifying effective nutritional interventions are crucial for enhancing the productivity of commercial pig systems.This study aimed to examine the alteration in semen quality in boars,and assess the impact of protocatechuic acid(PCA)on semen quality during the phase of declining semen quality.Methods In Exp.1,a total of 38 Pig Improvement Company(PIC)boars were selected and their semen quality data were recorded from the age of 9 to 37 months.In Exp.2,18 PIC boars(28 months old)were randomly assigned into three groups(n=6)and fed a basal diet,a basal diet containing 500 or 1,000 mg/kg PCA,respectively.The experiment lasted for 12 weeks.Results The semen volume,concentration,and total number of spermatozoa in boars exhibited an increase from 9 to 19 months old and showed a significant linear decreased trend in 28,24,and 22 months old.Sperm motility displayed an upward trajectory,reaching its peak at 20 months of age,and showed a significant linear decreased trend at 20 months old.Dietary supplementation of PCA demonstrated an effect to mitigate the decrease in semen volume,concentration of spermatozoa,total number of spermatozoa(P>0.05),and significantly increased the sperm motility(P<0.05).Moreover,supplementation of 1,000 mg/kg PCA significantly increased the sperm viability(P<0.05).Analysis on cellular signaling pathways revealed that PCA restored serum testosterone levels and alleviated oxidative damage by upregulating the expression of HO-1,SOD2,and NQO1 in testicular stromal cells.Notably,PCA can enhance phosphorylation by selectively binding to AMP-activated protein kinase(AMPK)protein,thereby improving sperm mitochondrial function and augmenting sperm motility via PGC-1/Nrf1.Conclusions These data elucidated the pattern of semen quality variation in boars within the age range of 9 to 37 months old,and PCA has the potential to be a natural antioxidant to enhance sperm quality through modulation of the AMPK/PGC-1/Nrf1 signaling pathway.

Source and level of dietary iron influence semen quality by affecting inflammation, oxidative stress and iron utilization levels in boars

Background Boars fed a mixed form of inorganic and organic iron in excess of the NRC recommended levels still develop anemia,which suggested that the current level and form of iron supplementation in boar diets may be inappropriate.Therefore,56 healthy Topeka E line boars aged 15–21 months were randomly divided into 5 groups:basal diet supplemented with 96 mg/kg ferrous sulfate(FeSO_(4))and 54 mg/kg glycine chelated iron(Gly-Fe,control);80 mg/kg or 115 mg/kg Gly-Fe;80 mg/kg or 115 mg/kg methionine hydroxyl analogue chelated iron(MHA-Fe,from CalimetFe)for 16 weeks.The effects of dietary iron supplementation with different sources and levels on semen quality in boars were investigated.Results 1)Serum Fe and hemoglobin concentrations were not affected by reduced dietary iron levels in the 80 mg/kg or 115 mg/kg Gly-Fe and MHA-Fe groups compared with the control group(P>0.05).2)Serum interleukin-6(IL-6)and sperm malondialdehyde(MDA)levels in the 80 mg/kg or 115 mg/kg MHA-Fe groups were lower than those in the control group(P<0.05),and higher serum superoxide dismutase levels and lower MDA levels in the 115 mg/kg MHA-Fe group(P<0.05).3)Boars in the 80 mg/kg or 115 mg/kg Gly-Fe and MHA-Fe groups had lower serum hepcidin(P<0.01),ferritin(P<0.05),and transferrin receptor(P<0.01)concentrations,and boars in the 115 mg/kg MHA-Fe group had higher seminal plasma Fe concentrations compared with the control group.4)Boars in the 80 mg/kg and 115 mg/kg MHA-Fe groups had lower abnormal sperm rate and in situ oscillating sperm ratio compared to the control group at weeks 12 and/or 16 of the trial.However,the effect of Gly-Fe on improving semen quality in boars was not evident.5)Serum IL-6 level was positively correlated with hepcidin concentration(P<0.05),which in turn was significantly positively correlated with abnormal sperm rate(P<0.05).Furthermore,significant correlations were also found between indicators of iron status and oxidative stress and semen quality parameters.Conclusions Dietary supplementation with 80 mg/kg or 115 mg/kg MHA-Fe did not induce iron deficiency,but rather reduced serum inflammatory levels and hepcidin concentration,alleviated oxidative stress,increased body iron utilization,and improved semen quality in adult boars.

The Effects of Age and Ejaculatory Abstinence on Semen Quality and Reproductive Hormones in Africa and the Middle East

The aim of this study was to retrospectively evaluate the effects of male age and ejaculatory abstinence on semen parameters and reproductive hormones among men residing in Africa and the Middle East. A total of 70,142 semen analysis results were analysed and grouped according to the age intervals (16 - 20, 21 - 30, 31 - 40, 41 - 50, 51 - 60, >60) and ejaculatory abstinence (<2 days, 2 - 5 days and >5 days). Semen parameters i.e. volume, concentration, progressive motility, total progressively motile count, morphology, total normal sperm count, DNA fragmentation, viability, sORP, normed sORP were specifically evaluated. Additionally, for each age interval, reproductive hormones i.e. estradiol, luteinizing hormone, follicle stimulating hormone, testosterone and prolactin were evaluated. Semen volume, total progressively motile count, sperm morphology and total normal sperm count constantly decrease significantly after the age of 30 years. Sperm concentration started declining significantly after the age of 50 years. There was a constant age- related increase in number of spermatozoa with damaged DNA. sORP constantly increased up to 60 years. Furthermore, constantage-related decreases in FSH, serum testosterone and prolact in were observed from patients aged between 16 years and 60 years. Semen volume, sperm concentration, progressive motility and normal morphology were significantly higher in patients having > 5 days of abstinence. Patients having > 5 days of abstinence had the lowest normed sORP. Male age significantly affects sperm parameters and reproductive hormones in fertile and infertile men residing in Africa and the Middle East. Prolonged abstinence days provides better semen quality.

Seasonal stress on semen quality profiles, seminal biochemical and oxidative stress attributes in endangered Teressa goat of Andaman and Nicobar Islands

Objective:To measure seasonal effects on semen quality profiles,seminal biochemical and oxidative stress attributes in fresh and liquid stored semen in monsoon and dry seasons.Methods:A total of 10 Teressa bucks(3-4 years)were selected from breeding farm,ICAR-Central Island Agricultural Research Institute,Port Blair,Andaman and Nicobar Islands,India.Semen samples(n=25 per season)were collected through artificial vagina method and preserved at refrigerated temperature(5℃)for 48 h using Tris citrate glucose based extender.We detected semen quality parameters[volume,mass activity,pH,sperm concentration,total motility,viability,total sperm abnormality,and plasma membrane,acrosomal and nuclear integrities],biochemical profiles[aspartate amino transferase(AST),alanine amino transferase(ALT)and total cholesterol],and oxidative stress markers[total antioxidant capacity(TAC)and malondialdehyde(MDA)]during monsoon and dry seasons.Results:Semen quality parameters significantly differed between seasons(P<0.05)and among storage periods(P<0.05).Volume,pH,mass activity,motility,viability,acrosomal,plasma membrane and nuclear integrities,and TAC were significantly higher(P<0.05).Sperm concentration,sperm abnormalities,MDA,AST,ALT and total cholesterol were significantly lower in fresh semen of monsoon than dry season(P<0.05).Motility,viability,acrosomal,plasma membrane and nuclear integrities,and TAC were significantly decreased(P<0.05)while sperm abnormality,AST,ALT,total cholesterol and MDA were significantly increased as liquid semen storage period advanced(P<0.05).Conclusions:Monsoon season has higher beneficial effects on semen quality profiles and liquid stored semen remained usable for upto 48 h.Good quality ejaculates with higher TAC and lower MDA can be cryopreserved and will be used for artificial insemination.

Lifestyle: an underrated but potentially important influencing factor on semen quality

Lifestyle factors play a crucial role in the influence of semen quality,and they are especially significant in the context of traditional Chinese medicine(TCM)clinical treatment for poor semen quality.TCM theory emphasizes the importance of healthy lifestyle habits for overall well-being.Therefore,it is essential to consider lifestyle factors in the clinical management of TCM and semen quality.Lifestyle can act as a bias factor that affects research quality,making it vital to pay special attention to its impact in clinical trial research on male semen quality.This article aims to improve the quality and design of clinical research on male sperm quality by examining the effects of various lifestyle factors on semen quality,including physical activities,dietary patterns,smoking,alcohol consumption,coffee intake,sleep,and psychological stress.Each lifestyle factor has its own distinct influence on semen quality,and there is a synergistic effect when multiple lifestyle factors are combined.These findings emphasize the need for careful consideration of lifestyle factors and their interactions in the design and implementation of TCM clinical trial research.

Do Ureaplasma urealyticum infections in the genital tract affect semen quality?

Aim： To investigate the relationship between Ureaplasma urealyticum （UU） infection and semen quality. Methods： From 2001 to 2003, 346 eligible patients aged 20-45 years were invited from two hospitals in Shanghai, China, to participate in an investigation which included questionnaires about general and reproductive health, an external genital tract examination, UU culture and semen analysis. Multiple linear regression models were used to examine whether UU had a significant effect on semen quality after adjustment for confounding factors. Results： Findings suggested that UU infection was associated with higher semen viscosity and lower semen pH value. Sperm concentration was lower in UU positive subjects than that in UU negative subjects （54.04 × 10^6/mL vs.70.58 × 10^6/mL）. However, UU did not significantly affect other semen quality indexes. Conclusion： UU infection of the male genital tract could negatively influence semen quality.

Normal reference ranges for semen quality and their relations to fecundity

Several recent studies have shown that the fecundity of a man decreases progressively with sperm concentrations below 40 million spermatozoa per mL. Therefore, it is unfortunate that the new World Health Organization guidelines for semen analysis recommend lowering the lower cutoff value for normal sperm concentration from 20 to 15 million spermatozoa per mL. As a result large groups of subfertile men across the world may not receive appropriate andrological help in the future.

Do reproductive hormones explain the association between body mass index and semen quality？

Aim： To examine whether reproductive hormones play a role in the association between body mass index （BMI） and semen quality. Methods： Semen quality and testosterone （T）, luteinizing hormone （LH）, follicle-stimulating hormone （FSH） and estradiol （E2） were evaluated in 990 fertile males with age 38.9 ± 9.7 （mean ＋ SD） years recruited from the Chinese general population in 2001 and 2002. Results： Semen quality was reduced among underweight （BMI 〈 18.5） compared with normal （BMI 18.5-24.9） and overweight （BMI 25.0-29.9）, but the associations were independent of reproductive hormones. After adjustment for the potential confounders, underweight men had reductions in sperm concentration （22.4 × 10^6/mL）, total sperm count （52.9× 10^6） and percentage of normal sperm forms （6.9%） compared with men with normal BMI. Being underweight may be a risk factor for low sperm concentration （OR： 4.68, 95% confidence intervals [CI]： 2.01-10.91）. Otherwise, being overweight may be a protected factor for low sperm concentration （OR： 0.25; 95% CI： 0.08-0.83） and low total sperm count （OR： 0.37, 95% CI： 0.15-0.87）. Conclusion： Low BMI was associated with reduced semen quality. The associations between BMI and semen quality were found statistically significant even after adjustment for reproductive hormones. Reproductive hormones cannot explain the association between BMI and semen quality.

Does exposure to computers affect the routine parameters of semen quality?

Aim： To assess whether exposure to computers harms the semen quality of healthy young men. Methods： A total of 178 subjects were recruited from two maternity and children healthcare centers in Shanghai, 91 with a history of exposure to computers （i.e., exposure for 20 h or more per week in the last 2 years） and 87 persons to act as control （no or little exposure to computers）. Data on the history of exposure to computers and other characteristics were obtained by means of a structured questionnaire interview. Semen samples were collected by masturbation in the place where the semen samples were analyzed. Results： No differences in the distribution of the semen parameters （semen volume, sperm density, percentage of progressive sperm, sperm viability and percentage of normal form sperm） were found between the exposed group and the control group. Exposure to computers was not found to be a risk factor for inferior semen quality after adjusting for potential confounders, including abstinence days, testicle size, occupation, history of exposure to toxic substances. Conclusion： The present study did not find that healthy： men exposed to computers had inferior semen quality. （Asian J Andro12005 Sep; 7： 263-266）

Decline of semen quality among 10 932 males consulting for couple infertility over a 20-year period in Marseille, France

Semen from 10 932 male partners of infertile couples was analysed and sperm parameter trends were evaluated at the Reproduction Biology Laboratory of the University Hospital of Marseille （France） between 1988 and 2007. After 3-6 days of abstinence, semen samples were collected. Measurements of seminal fluid volume, pH, sperm concentration, total sperm count, motility and detailed morphology of spermatozoa were performed. Sperm parameters were analysed on the entire population and in men with normal total numeration （ 〉~ 40 million per ejaculate）. The whole population demonstrated declining trends in sperm concentration （1.5% per year）, total sperm count （1.6% per year）, total motility （0.4% per year）, rapid motility （5.5% per year） and normal morphology （2.2% per year）. In the group of selected samples with total normal sperm count, the same trends of sperm quality deterioration with time were observed. Our results clearly indicate that the auality of semen decreased in this population over the study period.

Comparison of Semen Quality and Spermadhesins' m RNA Expression between Luchuan and Exotic Boars

Spermadhesins,as the most important components of boar semen seminoproteins,play a regulatory role in sperm motility,sperm capacitation and sperm-ovum fusion.In order to study the fertility differences among different boar breeds,the sperm motility,sperm viability and sperm deformity,as well as the spermadhesins＇ m RNA expression in fresh semen of Luchuan,Landrace and Duroc boars were compared.The results showed that the sperm motility and viability of Luchuan boar showed no significant differences with those of Landrace and Duroc boars（P〉 0.05）,but its sperm deformity was significantly lower than those of the other two exotic breeds（P〈0.01）;no significant differences were found in the m RNA expression levels of spermadhesins between Luchuan and Landrace,Duroc boars（P〉0.05）,excepting that the m RNA expression level of AQN1 in Luchuan boar semen was significantly lower than that in Duroc boar semen（P〈0.05）;the m RNA expression levels of AQN3,AWN and PSP-II in Landrace boar semen were significantly higher than those in Duroc boar semen（P〈0.05,P〈0.01）.In short,there were significant differences in the m RNA expression levels of spermadhesins among different pig breeds,which showed no significant correlations with the differences in sperm motility,viability and deformity.

Decline of semen quality during IVF is not associated with subjective male stress

The aim of the present study was to assess if semen quality declines during in vitro fertilization （IVF） and whether or not this phenomenon is triggered by chronic male stress. In order to test this hypothesis, we first investigated a retrospective cohort of 155 male IVF patients （testing cohort）. Subsequently, we started a prospective cohort study in men undergoing their first IVF and assessed semen quality and subjective male chronic stress using a validated tool, i.e. the Fertility Problem Inventory （FPI） questionnaire. The association between stress and sperm quality decline measured 4-6weeks before the start of IVF （T1） and at the day of oocyte retrieval （T2） was the primary outcome. Live birth rate, first trimester abortion and rate of poor responders were secondary outcomes. In the testing cohort, mean progressive motility, but not mean sperm density significantly declined. There were 78/154 （51%） men who showed a decline in semen density and 50/154 （32%） men who showed a decline in progressive motility. In the validation cohort, progressive motility declined, whereas, sperm density increased from T1 to T2. Of 78 men, 27 men had increased stress （FPI-score 〉 146）. Sperm density and progressive motility were not significantly different in men with and without stress. However, in the presence of male stress, couples had a higher rate of poor responders, miscarriages and a lower rate of live births. Subjective stress is not associated with a decline in semen quality observed during IVF but may be associated with adverse ore^nancv outcome.

Environmental mercury exposure, semen quality and reproductive hormones in Greenlandic Inuit and European men： a cross-sectional study

Several animal studies indicate that mercury is a male reproductive toxicant, but human studies are few and contradictory. We examined semen characteristics and serum levels of reproductive hormones in relation to environmental exposure to mercury. Blood and semen samples were collected from 529 male partners of pregnant women living in Greenland, Poland and Ukraine between May 2002 and February 2004. The median concentration of the total content of mercury in whole blood was 9.2 ng ml-1 in Greenland （0.2- 385.8 ng ml-1）, 1.0 ng m1-1 in Poland （0.2-6.4 ng ml-z） and 1.0 ng ml-I in Ukraine （0.2-4.9 ng ml-1）. We found a significantly positive association between the blood levels of mercury and serum concentration of inhibin B in men from Greenland （p=0.074, 95% confidence interval （CI）=0.021 to 0.126） and in an analysis including men from all three regions （p=0.067, 95% C1=0.024 to O. 110）. The association may be due to beneficial effects of polyunsaturated fatty acids （PUFAs）, which are contained in seafood and fish. No significant association （P〉O.05） was found between blood concentrations of mercury and any of the other measured semen characteristics （semen volume, total sperm count, sperm concentration, morphology and motility） and reproductive hormones （free androgen index {FAI）, follicle-stimulating hormone （FSH）, luteinizing hormone （LH）, testosterone and LH xtestosterone） in any region. In conclusion, the findings do not provide evidence that environmental mercury exposure in Greenlandic and European men with median whole blood concentration up to 10 ng m1^-1 has adverse effects on biomarkers of male reproductive health.

Natural astaxanthin enhanced antioxidant capacity and improved semen quality through the MAPK/Nrf2 pathway in aging layer breeder roosters

Background:Natural astaxanthin(ASTA)has strong antioxidant properties and has been widely used as a health product to improve human health.However,the effects of ASTA on the reproductive performance of aging roosters have been poorly studied.We aimed to investigate the effects of dietary ASTA on semen quality and antioxidant capacity in aging roosters and to explore the potential mechanism of semen quality change via antioxidation defense system.Methods:In the present study,9653-week-old Jinghong No.1 layer breeder roosters were fed a corn-soybean meal basal diet containing 0,25,50,or 100 mg/kg ASTA for 6 weeks.Results:Semen quality in the ASTA groups remarkably improved than that in the control group,and antioxidant activities,the abilities to scavenge hydroxyl radicals and superoxide anions,increased gradually with ASTA addition(P<0.05).In addition,the mRNA levels of antioxidant enzymes as well as the mRNA and protein levels of the mitogen-activated protein kinase(MAPK)and nuclear factor-erythroid 2-related factor 2(Nrf2)were markedly increased in the 50-100 mg/kg ASTA group(P<0.05).Conclusions:Collectively,these results demonstrate that dietary ASTA may improve semen quality by increasing antioxidant enzyme activities and the ability to scavenge hydroxyl radicals,which may be related to upregulation of the MAPK/Nrf2 pathway.

The Canonical Correlation Analysis on Semen Quality and Serum Heavy Metals in Chinese Young Men

Objective To explore the correlation between serum, heavy metal and semen quality in normal Chinese young menMethods This study was designed as a multi-center cross-sectional investigation. The subjects consisted of 562 male vomunteers who had undergone premarital physical examination in maternal and children health centers in 7 provinces in China. Results Results from Spearman rank correlation analysis (partial variable: region) show that serum lead and cadmium are negatively related to percentage of morphological normal sperm, but canonical correlation between semen quality and serum heavy metal are not significant. Canonical correlation analysis among the subjects from Guizhou shows cadmium is harmful to sperm morphology. In Henan, furthermore, results show lead and cadmium could negatively affect sperm viability and morphology. Conclusion Among all study subjects, canonical correlation between semen quality and serum heavy metal were not significant; however, results in some region showed serum cadmium and lead might be harmful to sperm quality.

Single semen analysis as a predictor of semen quality： clinical and epidemiological implications

It is generally thought that a single ejaculate is a bad predictor of semen quality of a subject, because of significant intra-individual variation. Therefore, we investigated the degree to which the results of a first semen analysis differ from that of a second analysis among men from a how the two different semen results mirrored the overall general population in Norway. In addition, we analysed semen quality assessment. A total of 199 volunteers participated in the study and delivered two semen samples with an interval of 6 months. The semen parameters were determined according to the World Health Organization （WHO） 1999 guidelines, which were also used to determine whether semen quality was normal or abnormal. In addition, the DNA fragmentation index （DFI） was determined using the Sperm Chromatin Structure Assay. The two samples from each individual were very similar with regard to standard semen parameters and DFI （rs： 0.67-0.72）, and there were no significant systematic differences between the two samples. The result of the first sample （normal/abnormal） was highly predictive of the overall conclusion based on the two samples （sperm concentration： in 93% of the cases （95% confidence interval [CI]： 89%-96%）; sperm motility： in 85% of the cases （95% CI： 79%-89%）; overall semen quality： in 85% of the cases （95% CI： 80%-90%）. In epidemiological studies, one ejaculate is a sufficient indicator of semen quality in a group of subjects. In a clinical situation, when the question is whether the semen quality is normal or not, the first ejaculate will, in at least 85% of cases, give a correct overall conclusion.

Correlation between sperm DNA 8-Hydroxy-2'-deoxyguanosine level and semen quality

8-hydroxy-2’-deoxyguanosine (8-OHdG), a typical form ofDNA adducts, is a key molecular biomarker for DNA oxidativedamage. The aim of the present study was to evaluote the correla-tion between the sperm DNA 8-OHdG level and the semen quality.In 52 male infertile patients, the sperm DNA 8-OHdG level wasdetermined by a high performance liquid chromatograph with elec-trochemical detector and the semen quality was examined according

Taurine in semen extender modulates post–thaw semen quality,sperm kinematics and oxidative stress status in mithun(Bos frontalis)spermatozoa

Objective:To assess the effect of taurine on post-thaw semen quality parameters,sperm kinematics,antioxidant and oxidative stress profiles and sperm cholesterol efflux in mithun(Bos frontalis).Methods:A total of 50 ejaculates(n=25 samples)were selected based on biophysical parameters.Each sample was split into four equal aliquots after dilution with the Tris-citrate-glycerol extender.GroupⅠ,Ⅱ,ⅢandⅣcontained 0 mM(the control),25 mM,50 mM and 100 mM of taurine,respectively.Frozen-thawed samples were analysed for motility parameters(progressive forward and in bovine cervical mucus penetration test),kinetic and velocity parameters by computer-assisted sperm analyzer,viability,sperm and nuclear abnormalities,acrosome integrity,plasma membrane and nuclear integrities,sperm enzymatic leakage and biochemical(sperm cholesterol and oxidative stress)profiles.Results:The extender containing 50 mM taurine led to a significant enhancement in viability,acrosomal integrity,plasma membrane integrity,motility(progressive and in cervical mucus),and sperm cholesterol content and notably reduced sperm morphological and nuclear abnormalities,and leakage of intracellular enzymes compared to other taurine treated and untreated control groups(P<0.05).Moreover,in addition to significant improvement in kinetic and velocity profiles,50 mM taurine protected the integrity of acrosome and biochemical membranes than in the untreated control and other taurine treated groups.Inclusion of 50 mM taurine held a clear advantage over the control or 25 mM or 100 mM taurine in cryopreservation of mithun semen.Conclusions:Taurine(50 mM)supplementation in semen extender can be effectively utilized to reduce oxidative stress and improve post-thaw semen quality in mithun.

Impact of organophosphorous pesticide exposure on semen quality of Chinese peasants

Aim: To investigate the impact of organophosphorous pesticide exposure and other risk factors on the semen quality of Chinese peasants. Method: Questionnaire investigation, external genital examination and laboratory examination were conducted on 322 male peasants, including the exposed and the control groups of 161 subjects each. Results: Multivariate analysis showed that the educational level and the years of alcohol drinking influenced the semen volume. Compared with subjects of primary school education or lower, those with junior high school education had a higher semen volume (OR=1.961). Proportion of subjects with higher semen volume decreased with increased years of alcohol drinking (OR=0.962). Organophosphorous pesticide exposure decreased the number of forward progression sperm (OR=0.528), the sperm density (OR=0.266), the sperm viability (OR=0.398) and the percentage of normal morphology sperm (OR=0.281). A possible relationship was present between the season of semen collection and the number of forward progression sperm, sperm viability and percentage of normal morphology sperm. Compared with the summer data, the above three indices were higher in winter (OR being 2. 272, 4.060 and 5.249, respectively). Conclusion: Exposure to organophosphorous pesticide could damage the semen quality of the peasants. Education and alcohol drinking also affect the semen quality.