Paraoxonase polymorphism and its effect on male reproductive outcomes among Chinese pesticide factory workers.

BACKGROUND: Serum paraoxonase has been associated with the metabolism of organophosphate pesticides in humans. Molecular analysis of the human paraoxonase gene (PON1) has revealed that Arg192 homozygotes have a greater detoxifying capability than Gln192 homozygotes. We examined the effects of PON1 genotypes on male reproductive outcomes and its interaction with exposure to organophosphate pesticides. METHODS: We studied 60 Chinese pesticide-factory workers and 89 textile-factory workers who were unexposed to pesticides. The respective allele frequencies of Arg192 and Gln192 were 0.62 and 0.38. Pesticide exposure among 36 exposed subjects and 12 unexposed subjects, regardless of gender, was assessed by personal measurement of pesticide residues over an entire 8-hr shift and measurement of urinary p-nitrophenol level over a 24-hr period. We analyzed semen and hormone data collected from male subjects. RESULTS: When the three PON1 genotypes were analyzed separately, a gene dose effect was not detected. We used the unexposed Arg192 homo/heterozygotes as the reference group, and re-analyzed the data. Exposed Arg192 homo/heterozygotes had significantly lower sperm count (chi 2 = 9.01, P < 0.01) and lower percentage of sperm with normal morphology (chi 2 = 4.18, P < 0.05) than the reference group. Both unexposed Gln192 homozygotes (chi 2 = 4.90, P < 0.05) and exposed Arg192 homo/heterozygotes (chi 2 = 10.00, P < 0.01) showed significantly lower sperm concentrations than the reference group. In addition, exposed Arg192 homo/heterozygotes had significantly higher serum LH levels (chi 2 = 7.94, P < 0.01) than the reference group. CONCLUSIONS: Because of a small sample size, our findings are highly preliminary. Nevertheless, it calls for further investigation of the interaction between the PON1 genotype and organophosphate pesticide exposure on male reproductive outcomes.     

Semen quality in workers exposed to 2-ethoxyethanol.

To evaluate whether long term exposure to 2-ethoxyethanol (2EE) may affect semen quality, a cross sectional study was conducted among men exposed to 2EE used as a binder slurry in a metal castings process. Full shift breathing zone exposures to 2EE ranged from non-detectable to 24 ppm (geometric mean 6.6 ppm). Because of the potential for substantial absorption of 2EE through skin exposure, urine measurements of the metabolite of 2EE, 2-ethoxyacetic acid (2EAA) were conducted, showing levels of 2EAA ranging from non-detectable to 163 mg 2EAA/g creatinine. Only 37 exposed men (50% participation) and 39 non-exposed comparison (26% participation) from elsewhere in the plant provided a sperm sample. A questionnaire to determine personal habits, and medical and work histories, and a physical examination of the urogenital tract were also administered. The average sperm count per ejaculate among the workers exposed to 2EE was significantly lower than that of the unexposed group (113 v 154 million sperm per ejaculate respectively; p = 0.05) after consideration of abstinence, sample age, subjects' age, tobacco, alcohol and caffeine use, urogenital disorders, fever, and other illnesses. The mean sperm concentrations of the exposed and unexposed groups did not significantly differ from each other (44 and 53 million/ml respectively). No effect of exposure to 2EE on semen volume, sperm viability, motility, velocity, and normal morphology or testicular volume was detected, although some differences in the proportion of abnormal sperm shapes were observed. These data suggest that there may be an effect of 2EE on sperm count among these workers, although the possibility that other factors may be affecting the semen quality in both exposed and unexposed men in this population or that the results reflect bias introduced by the low participation rates cannot be excluded.     

Semen quality in workers exposed to 2-ethoxyethanol

To evaluate whether long term exposure to 2-ethoxyethanol (2EE) may affect semen quality, a cross sectional study was conducted among men exposed to 2EE used as a binder slurry in a metal castings process. Full shift breathing zone exposures to 2EE ranged from non-detectable to 24 ppm (geometric mean 6.6 ppm). Because of the potential for substantial absorption of 2EE through skin exposure, urine measurements of the metabolite of 2EE, 2-ethoxyacetic acid (2EAA) were conducted, showing levels of 2EAA ranging from non-detectable to 163 mg 2EAA/g creatinine. Only 37 exposed men (50% participation) and 39 non-exposed comparison (26% participation) from elsewhere in the plant provided a sperm sample. A questionnaire to determine personal habits, and medical and work histories, and a physical examination of the urogenital tract were also administered. The average sperm count per ejaculate among the workers exposed to 2EE was significantly lower than that of the unexposed group (113 v 154 million sperm per ejaculate respectively; p = 0.05) after consideration of abstinence, sample age, subjects' age, tobacco, alcohol and caffeine use, urogenital disorders, fever, and other illnesses. The mean sperm concentrations of the exposed and unexposed groups did not significantly differ from each other (44 and 53 million/ml respectively). No effect of exposure to 2EE on semen volume, sperm viability, motility, velocity, and normal morphology or testicular volume was detected, although some differences in the proportion of abnormal sperm shapes were observed. These data suggest that there may be an effect of 2EE on sperm count among these workers, although the possibility that other factors may be affecting the semen quality in both exposed and unexposed men in this population or that the results reflect bias introduced by the low participation rates cannot be excluded.     

Occupational pesticide exposure and semen quality among Chinese workers

This study investigated the association between occupational pesticide exposure and semen quality among Chinese workers. Male workers, 32 who were exposed to organophosphate pesticides and 43 who were not exposed were recruited from two nearby factories and interviewed. Following a work shift, semen and urine samples were collected for pesticide metabolite analysis. Semen samples were analyzed for sperm concentration, percentage of motility, and percentage of normal structure. Within the exposed group, the mean end-of-shift urinary p-nitrophenol levels were 0.22 and 0.15 mg/L for the high- and low-exposure subgroups, respectively. Linear regression analysis of individual semen parameters revealed a significant reduction of sperm concentration (35.9 x 10(6) vs 62.8 x 10(6), p < 0.01) and percentage of motility (47% vs 57%, p = 0.03) but not percentage of sperm with normal structure (57% vs 61%, p = 0.13). Multivariate modeling showed a significant overall shift in the mean semen parameter. Occupational exposure to ethylparathion and methamidophos seems to have a moderately adverse effect on semen quality.     

Numerical chromosome anomalies in human sperm at low sperm concentration

INTRODUCTION: With the assisted reproduction techniques the natural selection of sperm is bypassed on different levels. AIM: The aim of the present work is to determine the frequencies of sperm numerical chromosome aberrations in infertile men with low sperm count and to examine the relationship between the spermatogram parameters (sperm count and motility) and the aneuploidy and diploidy frequencies. METHODS: 32 men with low sperm count were investigated. Semen analysis was performed according to the WHO criteria. Disomy and diploidy frequencies were detected with fluorescence in situ hibridization using 17, X and Y centromeric probes. 200,969 sperm were scored, with the mean of 6272 cells in each subjects. The rate of numerical chromosome anomalies were also estimated using the detected disomy and the diploidy frequencies. RESULTS: Mean sperm concentration of the 32 men was 18.2 million/ml (SD: +/- 8.43, range: 8.0-45.5), mean motility 49.4% (+/- 9.32, 30-69.2). The X/Y ratio was 1.07. The mean frequencies of sex chromosome disomy, chromosome 17 disomy and diploidy were 0.36%, 0.16% and 0.56%, respectively. The most frequent disomy was XY disomy (0.14). Sex chromosome disomy frequencies were higher in oligospermic samples (0.37% vs. 0.32%, OR = 1.18, 95% CI = 1.01-1.39, p < 0.001). With special regard to XY disomy (0.08% vs. 0.17%, OR = 1.99, 95% CI = 1.48-2.67, p < 0.001). In subjects with oligoasthenozoospermia the diploidy frequency increased (0.96%, OR = 2.39, 95% CI = 2.13-2.69, p < 0.001), mostly due to the elevated rate of diploid sperm of meiosis II. origin (XX or YY diploids). Estimated frequency of the numerical chromosome anomalies was 8.3 +/- 5.3 in the study population. Neither the sperm count, nor the sperm motility showed correlation with the detected frequency of the chromosome aberrations. CONCLUSIONS: In oligospermic patients there is a risk for elevated frequency of sperm with sex chromosome aneuploidy, especially the XY disomy. Furthermore, the diploidy frequency is increased in oligozooastenospermic samples. Nevertheless, classical parameters of semen analysis (sperm count and motility) do not correlate with the frequency of numerical chromosomal anomalies. The risk can be determined using fluorescens in situ hybridization on sperm.     

Is prenatal exposure to tobacco smoking a cause of poor semen quality? A follow-up study

A few studies indicate that exposure to maternal smoking during fetal life decreases semen quality in adult life, but the results are inconsistent and retrospectively collected smoking data were used in most studies. From a Danish pregnancy cohort established in 1984-1987, 347 of 5,109 sons were selected according to their exposure to tobacco smoke in fetal life. From February 2005 to January 2006, a semen sample from the 347 men was analyzed for conventional semen characteristics according to standardized criteria by using a mobile laboratory. The authors found an inverse association between maternal smoking during pregnancy and total sperm count (p = 0.002). Men exposed to more than 19 cigarettes daily during pregnancy had approximately 19% lower semen volume (p = 0.04), 38% lower total sperm count (p = 0.11), and 17% lower sperm concentration (p = 0.47) compared with unexposed men. The odds ratio for oligospermia was 2.16 (95% confidence interval: 0.68, 6.87) among exposed men compared with the unexposed. No associations were found for sperm motility or morphology. These results indicate that prenatal exposure to tobacco smoke may have an adverse effect on semen quality and, if these associations are causal, they could explain some of the reported differences between populations and secular changes in semen quality.     

Organophosphorous pesticide exposure increases the frequency of sperm sex null aneuploidy.

It has been estimated that 4 of 1,000 live births and 35% of spontaneous abortions are aneuploid and that an important proportion of embryo and newborn aneuploidy is of paternal origin. Exposure to organophosphorous pesticides (OP) has been associated with sperm hyperploidy/polyploidy. Therefore, we aimed to assess the frequency of sperm aneuploidy (X, Y, and 18) and its relationship with urinary OP metabolites in agricultural workers. We performed multicolor fluorescence in situ hybridization on samples from nine men obtained before and during the pesticide spraying season to assess sperm aneuploidy. We measured urinary OP metabolite levels by gas-liquid chromatography. Aneuploidies were found in 0.67% of total sperm nuclei. The most frequent aneuploidy was the lack of a sexual chromosome or sex null (0.19%), followed by XY18 (0.15%) and XY18-18 (0.06%). OP metabolites detected at higher concentrations were dimethylthiophosphate, dimethyldithiophosphate, and diethylphosphate (DEP). There were no differences in average aneuploidy frequency or urinary metabolite levels between samples collected before and after exposure. However, Poisson regression analysis adjusted for age, alcohol intake, and sperm concentration showed significant associations between OP metabolite concentrations and increased frequency of sperm aneuploidies. The association was more evident between DEP and sex null, and the risk increased further during the spraying season. Thus, OP exposure could interfere with sperm chromosome segregation and increase the risk for genetic syndromes, such as Turner's. Further studies are required to assess the prevalence of spontaneous abortions, birth defects, and genetic syndromes in agricultural communities.     

Benzene Exposure Near the U.S. Permissible Limit Is Associated with Sperm Aneuploidy

Background

Benzene is a common industrial chemical known to induce leukemia and other blood disorders, as well as aneuploidy, in both human blood cells and sperm at exposures > 10 ppm. Recent reports have identified health effects at exposure levels < 1 ppm, the permissible exposure limit (PEL; 8 hr) set by the U.S. Occupational Safety and Health Administration.

Objective

We investigated whether occupational exposures to benzene near 1 ppm induce aneuploidy in sperm.

Methods

We used multicolor fluorescence in situ hybridization to measure the incidence of sperm with numerical abnormalities of chromosomes X, Y, and 21 among 33 benzene-exposed men and 33 unexposed men from Chinese factories. Individual exposures were assessed using personal air monitoring and urinary concentrations of benzene and trans,trans-muconic acid (E,E-MA). Air benzene concentrations were not detectable in unexposed men; in exposed men, concentrations ranged from below the detection limit to 24 ppm (median, 2.9 ppm), with 27% of exposed men (n = 9) having concentrations of ≤ 1 ppm. Exposed men were categorized into low and high groups based on urinary E,E-MA (median concentrations of 1.9 and 14.4 mg/L, respectively; median air benzene of 1 and 7.7 ppm, respectively), and aneuploidy frequencies were compared with those of unexposed men.

Results

Sperm aneuploidy increased across low- and high-exposed groups for disomy X [incidence rate ratio (IRR) = 2.0; 95% confidence interval (CI), 1.1–3.4; and IRR = 2.8; 95% CI, 1.5–4.9, respectively], and for overall hyperhaploidy for the three chromosomes investigated (IRR = 1.6; 95% CI, 1.0–2.4; and IRR = 2.3; 95% CI, 1.5–3.6, respectively). We also found elevated disomy X and hyperhaploidy in the nine men exposed to ≤ 1 ppm benzene compared with unexposed men (IRR = 1.8; 95% CI, 1.1–3.0; and IRR = 2.0; 95% CI, 1.1–3.9, respectively).

Conclusions

Benzene appeared to increase the frequencies of aneuploid sperm for chromosomes associated with chromosomal abnormality syndromes in human offspring, even in men whose air benzene exposure was at or below the U.S. permissible exposure limit.     

Semen quality in papaya workers with long term exposure to ethylene dibromide

To examine whether long term occupational exposure to ethylene dibromide (EDB) affects semen quality a cross sectional study of semen quality was conducted among 46 men employed in the papaya fumigation industry in Hawaii, with an average duration of exposure of five years and a geometric mean breathing zone exposure to airborne EDB of 88 ppb (eight hour time weighted average) and peak exposures of up to 262 ppb. The comparison group consisted of 43 unexposed men from a nearby sugar refinery. Statistically significant decreases in sperm count per ejaculate, the percentage of viable and motile sperm, and increases in the proportion of sperm with specific morphological abnormalities (tapered heads, absent heads, and abnormal tails) were observed among exposed men by comparison with controls after consideration of smoking, caffeine and alcohol consumption, subject's age, abstinence, history of urogenital disorders, and other potentially confounding variables. No effect of exposure to EDB on sperm velocity, the overall proportion of sperm with normal morphology, or YFF bodies was observed. These data strongly suggest that EDB may increase the risk of reproductive impairment in workers at exposure levels near the National Institute for Occupational Safety and Health recommended limit of 45 ppb (as an eight hour time weighted average) and far below the current standard of the Occupational Safety and Health Administration of 20 ppm.     

Semen quality in papaya workers with long term exposure to ethylene dibromide.

To examine whether long term occupational exposure to ethylene dibromide (EDB) affects semen quality a cross sectional study of semen quality was conducted among 46 men employed in the papaya fumigation industry in Hawaii, with an average duration of exposure of five years and a geometric mean breathing zone exposure to airborne EDB of 88 ppb (eight hour time weighted average) and peak exposures of up to 262 ppb. The comparison group consisted of 43 unexposed men from a nearby sugar refinery. Statistically significant decreases in sperm count per ejaculate, the percentage of viable and motile sperm, and increases in the proportion of sperm with specific morphological abnormalities (tapered heads, absent heads, and abnormal tails) were observed among exposed men by comparison with controls after consideration of smoking, caffeine and alcohol consumption, subject's age, abstinence, history of urogenital disorders, and other potentially confounding variables. No effect of exposure to EDB on sperm velocity, the overall proportion of sperm with normal morphology, or YFF bodies was observed. These data strongly suggest that EDB may increase the risk of reproductive impairment in workers at exposure levels near the National Institute for Occupational Safety and Health recommended limit of 45 ppb (as an eight hour time weighted average) and far below the current standard of the Occupational Safety and Health Administration of 20 ppm.     

用双色荧光原位杂交法检测苯系物接触工人精子染色体数目 …

目的　探讨苯系物对男工精子性染色体数目畸变的影响。方法　用X、Yα 卫星染色体特异DNA探针与苯系物接触男工间期精子核进行双色荧光原位杂交 ,同时测定X和Y精子染色体非整倍体率。结果　车间空气中苯浓度几何均数 83 95mg m3 高于国家最高容许浓度 1倍。对 13位苯系物作业工人共计数 74 5 17条精子 ,X、Y和XY精子双体率分别为 ( 0 15± 0 0 5 ) %、( 0 13± 0 0 5 ) %和( 0 2 0± 0 11) % ;13位正常对照工人共计数 89662条精子中X、Y及XY精子双体率分别为 ( 0 10±0 0 4 ) %、( 0 10± 0 0 4 ) %和 ( 0 13± 0 0 6) %。接触组精子X双体率及总双体精子率高于对照组。结论　高浓度苯接触可以诱导接触工人精子性染色体非整倍体率增加。     

Semen quality and reproductive sex hormone levels in Peruvian pesticide sprayers

To determine the association between occupational pesticide exposure and semen quality among sprayers using organophosphate (OPs) pesticides, 31 pesticide sprayers and 80 men who were not exposed were studied. Semen and blood samples were obtained one day after last pesticide application. Semen samples were analyzed for sperm concentration, percentage of sperm motility, percentage of normal morphology, and fructose and zinc concentrations. Blood samples were analyzed for sex hormones. Pesticide sprayers had significantly reduced age-adjusted seminal volume, percentage of motility, percentage of sperm with normal morphology, serum luteinizing hormone, serum testosterone levels, and seminal zinc concentration (a marker of prostate function), as well as significantly increased time of liquefaction, seminal pH, percentage of immature sperm morphology, and leukocyte concentration. These findings provide further evidence that occupational exposures to OP pesticides adversely affect semen quality and sex hormones.     

Impact of PCB and p,p'-DDE contaminants on human sperm Y:X chromosome ratio: studies in three European populations and the Inuit population in Greenland

OBJECTIVE: Recent studies indicate that persistent organohalogen pollutants (POPs) may contribute to sex ratio changes in offspring of exposed populations. Our aim in the present study was to investigate whether exposure to 2,2 ,4,4 ,5,5 -hexachlorobiphenyl (PCB-153) and dichlorodiphenyldichloroethene (p,p -DDE) affects sperm Y:X chromosome distribution. SUBJECTS AND METHODS: We obtained semen and blood for analysis of PCB-153 and p,p -DDE levels from 547 men from Sweden, Greenland, Poland (Warsaw), and Ukraine (Kharkiv), with regionally different levels of POP exposure. The proportion of Y- and X-chromosome-bearing sperm in the semen samples was determined by two-color fluorescence in situ hybridization analysis. RESULTS: Swedish and Greenlandic men had on average significantly higher proportions of Y sperm (in both cohorts, 51.2%) and correspondingly higher lipid-adjusted concentrations of PCB-153 (260 ng/g and 350 ng/g, respectively) compared with men from Warsaw (50.3% and 22 ng/g) and Kharkiv (50.7% and 54 ng/g). In the Swedish cohort, log-transformed PCB-153 and log-transformed p,p -DDE variables were significantly positively associated with Y-chromosome fractions (p-values 0.04 and <0.001, respectively). On the contrary, in the Polish cohort PCB-153 correlated negatively with the proportion of Y-bearing fraction of spermatozoa (p=0.008). CONCLUSIONS: The present study indicates that POP exposure might be involved in changing the proportion of ejaculated Y-bearing spermatozoa in human populations. Intercountry differences, with different exposure situations and doses, may contribute to varying Y:X chromosome ratios.     

低浓度混苯暴露与精液质量下降及早早孕丢失的关系

目的：研究低浓度混苯暴露对职业人群精液质量和早早孕丢的伯影响。方法：选择混苯作业工人１２６人、无混苯作业对照６０人,进行生产环境监测和生物学监测;按混苯接地情况,选择暴露组男工７０人,内对照组男工９０人,外对照组男工１３２人,进行精液质量分析;选择暴露组女工４２人,内对照组女工４９人,外对照组女工１１８人,进行尿液人绒毛膜促性腺激素的检测。结果 石化企业混苯暴露以低浓度苯（０．７￣２７．０ｍｇ／     

农村男性接触有机磷农药对精液质量影响的研究

目的:研究慢性低剂量接触有机磷农药对男性生殖机能影响。方法:筛选161名男性为有机磷农药暴露组,161名为非暴露组,进行流行病学问卷调查、外生殖器检查和精液样本的采集和测定。结果:发现长期接触小剂量有机磷使精子密度明显下降,精子密度暴露组为76·0±84·8×106/ml,非暴露组为100·0±56·4×106/ml(P=0·0059);农药与精子质量Logistic回归分析发现,暴露组精子质量明显下降,两组相比较其差异有显著统计学意义;暴露组的性欲降低,性交次数减少。结论:本研究发现农民因防护不当、长期小剂量接触有机磷农药可导致生殖机能下降,因此要加强农村农药中毒的防治工作,杜绝慢性中毒事件发生,保护农民身体健康,促进农业生产发展。     

SPERM CHROMOSOME ANEUPLOIDY AS RELATED TO MALE FACTOR INFERTILITY AND SOME ULTRASTRUCTURE DEFECTS

Some men have elevated levels of sperm chromosome aneuploidy. In this study, we have evaluated and summarized sperm aneuploidy rates in male infertility patients and control groups. The mean aneuploidy rate for five chromosomes (X, Y, 13, 18, 21) was 1.2 ± 0.1 for fertile controls, 1.4 ± 0.1 for a general population control group, and 5.8 ± 1.14 for the patients. When the patients were classified by the type of male factor infertility, the total aneuploidy rate was 2.6 ± 0.3 in men with moderately diminished semen quality (n = 7), 4.0 ± 0.3 patients with severe teratoasthenooligozoospermia, and 15.9 ± 3.8 for men with rare ultrastructure defects such as round head only syndrome or severe tail agenesis. Some infertility patients have a severely elevated level of sperm chromosome aneuploidy, which may contribute to infertility or diminish the likelihood of a successful outcome from IVF/ICSI. The severity of sperm chromosome aneuploidy appears to be proportional to the severity of abnormal semen quality: in particular, abnormal morphology. The high rates of aneuploidy in patients with severe ultrastructure defects suggest that caution should be employed in counseling those patients prior to IVF/ICSI.     

Occupational exposure to benzene and chromosomal structural aberrations in the sperm of Chinese men

Background: Benzene is an industrial chemical that causes blood disorders, including acute myeloid leukemia. We previously reported that occupational exposures near the U.S. Occupational Safety and Health Administration permissible exposure limit (8 hr) of 1 ppm was associated with sperm aneuploidy.Objective: We investigated whether occupational exposures near 1 ppm increase the incidence of sperm carrying structural chromosomal aberrations.Methods: We applied a sperm fluorescence in situ hybridization assay to measure frequencies of sperm carrying partial chromosomal duplications or deletions of 1cen or 1p36.3 or breaks within 1cen-1q12 among 30 benzene-exposed and 11 unexposed workers in Tianjin, China, as part of the China Benzene and Sperm Study (C-BASS). Exposed workers were categorized into low-, moderate-, and high-exposure groups based on urinary benzene (medians: 2.9, 11.0, and 110.6 µg/L, respectively). Median air benzene concentrations in the three exposure groups were 1.2, 3.7, and 8.4 ppm, respectively.Results: Adjusted incidence rate ratios (IRRs) and 95% confidence intervals (CIs) for all structural aberrations combined were 1.42 (95% CI: 1.10, 1.83), 1.44 (95% CI: 1.12, 1.85), and 1.75 (95% CI: 1.36, 2.24) and for deletion of 1p36.3 alone were 4.31 (95% CI: 1.18, 15.78), 6.02 (95% CI: 1.69, 21.39), and 7.88 (95% CI: 2.21, 28.05) for men with low, moderate, and high exposure, respectively, compared with unexposed men. Chromosome breaks were significantly increased in the high-exposure group [IRR 1.49 (95% CI: 1.10, 2.02)].Conclusions: Occupational exposures to benzene were associated with increased incidence of chromosomally defective sperm, raising concerns for worker infertility and spontaneous abortions as well as mental retardation and inherited defects in their children. Our sperm findings point to benzene as a possible risk factor for de novo 1p36 deletion syndrome. Because chromosomal aberrations in sperm can arise from defective stem cells/spermatogonia, our findings raise concerns that occupational exposure to benzene may have persistent reproductive effects in formerly exposed workers.     

Testicular function among epichlorohydrin workers.

Epichlorohydrin (1,2-epoxy-3-chloropropane) (ECH) is a colourless liquid used in the production of insecticides, agricultural chemicals, epoxy resins, and many other productions. It is highly reactive and an alkylating agent suspected of possessing carcinogenic properties in man. The results of a clinical-epidemiological investigation to ascertain whether exposure to ECH may be associated with sperm count suppression among ECH production workers at two chemical plants are presented. Medical histories and physical examinations with special emphasis on the genitourinary tract were completed on each participant. Blood samples and three semen specimens were also obtained. Since no internal control group were available, the data arising from this effort were analysed for each plant (plant A, 44 men; plant B, 84 men) using a control group of 90 chemical plants workers unexposed to any agents known to be toxic to the tests who were included in previous studies. This study provides no evidence that exposure to ECH at the concentrations existing at the two plants studied is responsible for sperm count suppression.     

Semen quality and sexual hormones in greenhouse workers

OBJECTIVES: This study focused on determining the testicular function of greenhouse workers exposed to pesticides. METHODS: Semen was examined for 122 of 199 eligible men (61%) from 30 ornamental flower greenhouses. Sperm concentration, morphology, and viability were measured according to World Health Organization guidelines, and the curvilinear sperm velocity was determined by a computer-assisted analysis of video recordings. Three groups were formed according to expert judgment of current exposure to pesticides from cultures, pesticide formulations, and the transfer of pesticide residues from leaves to hands, and also ranked according to years of work in a greenhouse. The risk estimates were adjusted for the effects of sexual abstinence and other potentially confounding factors. RESULTS: According to current exposure the median values of sperm concentration and the proportion of normal spermatozoa were 60% and 14% lower, respectively, in the high-level exposure group (N=13) than in the low-level group (N=44), and the values of the intermediate group fell in between. The adjusted differences between the high-level and low-level exposure groups were statistically significant, while no differences were observed for the viability and velocity of sperm and sexual hormones. The median sperm concentration was 40% lower for the men with > 10 years' experience in a greenhouse than for those with < 5 years' experience. The age-adjusted testosterone/sex-hormone-binding globulin ratio declined 1.9% (95% confidence interval 0.4-3.4%) per year of work. CONCLUSIONS: The results are compatible with the hypothesis that male fecundity may be at risk from exposure to pesticides in the manual handling of cultures in greenhouses.     

Dioxin exposure, from infancy through puberty, produces endocrine disruption and affects human semen quality

BACKGROUND: Environmental toxicants are allegedly involved in decreasing semen quality in recent decades; however, definitive proof is not yet available. In 1976 an accident exposed residents in Seveso, Italy, to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). OBJECTIVE: The purpose of this study was to investigate reproductive hormones and sperm quality in exposed males. METHODS: We studied 135 males exposed to TCDD at three age groups, infancy/prepuberty (1-9 years), puberty (10-17 years), and adulthood (18-26 years), and 184 healthy male comparisons using 1976 serum TCDD levels and semen quality and reproductive hormones from samples collected 22 years later. RESULTS: Relative to comparisons, 71 men (mean age at exposure, 6.2 years; median serum TCDD, 210 ppt) at 22-31 years of age showed reductions in sperm concentration (53.6 vs. 72.5 million/mL; p = 0.025); percent progressive motility (33.2% vs. 40.8%; p < 0.001); total motile sperm count (44.2 vs. 77.5 x 10(6); p = 0.018); estradiol (76.2 vs. 95.9 pmol/L; p = 0.001); and an increase in follicle-stimulating hormone (FSH; 3.58 vs. 2.98 IU/L; p = 0.055). Forty-four men (mean age at exposure, 13.2 years; median serum TCDD, 164 ppt) at 32-39 years of age showed increased total sperm count (272 vs. 191.9 x 10(6); p = 0.042), total motile sperm count (105 vs. 64.9 x10(6); p = 0.036), FSH (4.1 vs. 3.2 UI/L; p = 0.038), and reduced estradiol (74.4 vs. 92.9 pmol/L; p < 0.001). No effects were observed in 20 men, 40-47 years of age, who were exposed to TCDD (median, 123 ppt) as adults (mean age at exposure, 21.5 years). CONCLUSIONS: Exposure to TCDD in infancy reduces sperm concentration and motility, and an opposite effect is seen with exposure during puberty. Exposure in either period leads to permanent reduction of estradiol and increased FSH. These effects are permanent and occur at TCDD concentrations < 68 ppt, which is within one order of magnitude of those in the industrialized world in the 1970s and 1980s and may be responsible at least in part for the reported decrease in sperm quality, especially in younger men.