Occupational hazards for the male reproductive system

Effects and possible mechanisms of combined exposure to noise and carbon monoxide on male reproductive system in rats

Environmental hazards are an increasing concern due to the rapid pace of industrialization. Among these hazards, noise and carbon monoxide (CO) are common risk factors and have been shown to cause serious health problems. However, existing studies focused on the individual effects of noise and CO exposure and the combined effects of these two factors remain poorly understood. Our study aimed to examine the combined effects of noise and CO exposure on testicular function by constructing individual and combined exposure models. Our findings indicated that combined exposure to noise and CO was associated with a higher risk of testicular damage and male reproductive damage when compared to exposure alone. This was evidenced by poorer semen quality and more severe pathological damage to the testis. This combined exposure led to higher levels of oxidative stress and apoptosis in the testes, with bioinformatics analyses suggesting the signaling pathways involved in these responses. Specifically, activation of the P53 signaling pathway was found to contribute to the testicular damage caused by the combined exposure. Encouragingly, pterostilbene (PTE), a novel phytochemical, alleviated combined exposure-induced testicular damage by reducing oxidative stress and germ cell apoptosis. Overall, we identified joint reproductive toxicity resulting from the exposure to noise and CO, and found that PTE is a promising potential treatment for injuries caused by these factors. The cover image is based on the Research Article Effects and possible mechanisms of combined exposure to noise and carbon monoxide on male reproductive system in rats by Yingqing Li et al., https://doi.org/10.1002/tox.23927.

[Impact of lifestyle and environmental factors on male reproductive health]

The identification of potential environmental hazards is of clinical relevance for the diagnosis of male infertility. Knowledge about these factors will improve prevention of fertility disorders. Apart from drugs or factors related to lifestyle such as alcohol and tobacco smoke, various environmental and occupational agents, both chemical and physical, may impair male reproduction. Reproductive toxicity may evolve at the hypothalamic-pituitary, testicular, or posttesticular level; endpoints comprise deterioration of spermatogenesis and sperm function as well as endocrine disorders and sexual dysfunction. However, due to the complex regulation of the male reproductive system, information regarding single exogenous factors and their mechanisms of action in humans is limited. This is also due to the fact that extrapolation of results obtained from experimental animal or in vitro studies remains difficult. Nevertheless, the assessment of relevant exposures to reproductive toxicants should be carefully evaluated during diagnostic procedures of andrological patients.

Immunotoxicity of radiofrequency radiation

Growing evidence recommends that radiofrequency radiations might be a new type of environmental pollutant. The consequences of RFR on the human immune system have gained considerable interest in recent years, not only to examine probable negative effects on health but also to understand if RFR can modulate the immune response positively. Although several studies have been published on the immune effects of RFR but no satisfactory agreement has been reached. Hence this review aims to evaluate the RFR modulating impacts on particular immune cells contributing to various innate or adaptive immune responses. In view of existing pieces of evidence, we have suggested an intracellular signaling cascade responsible for RFR action. The bio-effects of RFR on immune cell morphology, viability, proliferation, genome integrity, and immune functions such as ROS, cytokine secretion, phagocytosis, apoptosis, etc. are discussed. The majority of existing evidence point toward the possible shifts in the activity, number, and/or function of immunocompetent cells, but the outcome of several studies is still contradictory and needs further studies to reach a conclusion. Also, the direct association of experimental studies to human risks might not be helpful as exposure parameters vary in real life. On the basis of recent available literature, we suggest that special experiments should be designed to test each particular signal utilized in communication technologies to rule out the hypothesis that longer exposure to RFR emitting devices would affect the immunity by inducing genotoxic effects in human immune cells.

Assessment of semen quality of taxi drivers exposed to whole body vibration

Whole body vibration (WBV) is a recognized occupational hazard for many workers such as drivers and operators of heavy and light machinery and exposure to it is accompanied by physical and mental repercussions. Only the limited studies have been done on the effects of vibration exposure on reproductive indices, however vibration exposure has been indicated as being a hazardous agents with the potential of being able to directly affect the reproductive system. Considering the importance of infertility, the present study was conducted with the aim of investigating semen quality among taxi drivers in Tehran and determine the effect of exposure to WBV on sperm parameters. The study population consisted of 70 taxi drivers and 70 office employee who attended infertility clinics for diagnostic purposes in the past year. The participants had to meet the entry criteria of the study while also being willing to recruit. Data was collected in the form of demographic questionnaires and general health questionnaires as well as sperm analysis conducted in an infertility clinic according to standard laboratory guidelines. The 8-hour time-weighted average (TWA) exposure to of WBV in automobile was measured as per ISO 2631-1. The TWA exposure to WBV among the taxi drivers and office employees were 0.697 ± 0.13 m/s² and 0.068 ± 0.09 m/s² respectively (P < 0.05). A statistically significant difference in total sperm count, progressive motility, non-progressive motility and total motility was observed between the taxi drivers and the office employees (P < 0.05). According to the univariate analysis of variance, exposure to WBV had negative effect on sperm concentration, progressive motility and normal morphology (P > 0.05); moreover exposure to WBV resulted in the larger effect size (B) on sperm parameters than the demographic variables (P > 0.05). Being taxi drivers increase the chance of the decreased semen quality (P > 0.05). It is difficult to draw definitive conclusions regarding the effects of WBV while intervening factors exist, such as psychological stressors, quality of sleep, background issues as well as environmental factors such as chemical pollutants (heavy metals) or ergonomic factors (body posture and working while sitting down).

Relationship between occupational exposure to whole-body vibration and noise with sex hormone levels: An empirical assessment in an automobile parts manufacturing plant

The present study investigated the relationship between occupational exposure to noise and whole-body vibration (WBV) with the levels of sex hormones in an automobile parts manufacturing plant. The level of workers' exposure (n = 162) to each of the mentioned stressors was measured through standard methods, and the time-weighted average of exposure was calculated for each person. In order to determine serum sex hormones (free testosterone, luteinizing hormone, and follicle-stimulating hormone), blood samples were taken from all participants after 8-10 h of fasting between 7 and 9 am and then the blood samples were analyzed by an enzyme-linked immunosorbent assay method. In general, regarding testosterone as the main male sex hormone, only 49% of the participants were in the normal range. In a total of three sections, the lowest mean testosterone levels were observed in the third exposure group (WBV > 1.93 m/s²; noise >92.69 dB) of the studied stressor; however, only the difference in testosterone levels between the three different groups of exposure to noise was statistically significant (p = 0.001). The relationship between demographic variables and levels of noise and WBV exposure with sex hormones was not linear and only the relationship between noise exposure and testosterone levels was statistically significant (R = -0.201, p = 0.013). According to the results of logistic regression, the WBV had the greatest effect on testosterone levels. However, according to the results of the correlation test, only the relationship between noise exposure and testosterone levels was statistically significant.

[Impact of lifestyle and environmental factors on male reproductive health]

The identification of potential environmental hazards may be clinically relevant in the diagnosis of male infertility. Knowledge about these factors will improve prevention of fertility disorders. Apart from drugs or factors related to lifestyle such as alcohol and tobacco smoke, various environmental and occupational agents, both chemical and physical, may impair male reproductive function. Reproductive toxicity may evolve at the hypothalamic-pituitary, testicular, or post-testicular level; endpoints comprise deterioration of spermatogenesis and sperm function as well as endocrine disorders and sexual dysfunction. With regard to the complex regulation of the male reproductive system, the available information concerning single exogenous factors and their mechanisms of action in humans is limited. This is also due to the fact that extrapolation of results obtained from experimental animal or in vitro studies remains difficult. Nevertheless, the assessment of relevant exposure to reproductive toxicants should be carefully evaluated during diagnostic procedures of andrological patients.

Offspring gender rates in active duty fighter pilots and flight officers

INTRODUCTION

It has been reported in small studies that fighter pilots have a higher likelihood of producing female offspring secondary to job-related exposures. No large-scale study has investigated this potential gender disparity.

METHODS

This retrospective study utilized electronic medical record systems to identify men with flight-related occupations within the U.S. military from September 2012 to January 2018. The gender of offspring born to those men at least one year after entry into the flight community were compared to gender rates of children born to the U.S. general population during the same time period.

RESULTS

10,879 and 62,624 children born to fighter pilots and pilots of non-fighter type aircraft respectively were compared. The gender distribution of children born to both communities was similar to U.S. general population trends.

CONCLUSIONS

This large-scale study provides social reassurances that the degree of risk imposed on our nation's air defense force does not influence the gender balance of the subsequent generation.

Associations of C677T polymorphism in methylenetetrahydrofolate reductase (MTHFR) gene with male infertility risk: A meta-analysis

PURPOSE

Methylenetetrahydrofolate reductase is one of the key enzymes in folate metabolism. But the association between polymorphism and the risk of male infertility is still controversial. Therefore, this study used a meta-analysis on the collection of data to analyze MTHFR gene C677T polymorphism (known as c.665 C>T, rs1801133, p.Ala222Val).

METHODS

PubMed, EMBASE, China National Knowledge Infrastructure (CNKI), and Wan fang. Data were searched to identify eligible studies. We sifted the data collection by Hardy-Weinberg equilibrium calculator and used odds ratios (ORs) and 95% confidence intervals (95% CIs) to conduct data through RevMan5.0 and StataSE12.0 software.

RESULTS

A total of 15 studies have 3853 patients with infertility and 3613 healthy controls in this meta-analysis. Our results showed that T variant of MTHFR C677T gene polymorphism was significantly associated with an increased risk of male infertility (forT vs. C: OR=1.38, 95% CI=1.18-1.63; for TT vs. CC: OR=1.86, 95% CI=1.36-2.54; for CT vs. CC: OR=1.34, 95% CI=1.03-1.74; for TT vs. CT: OR=1.52, 95% CI=1.26-1.84; for TT vs. CT+CC: OR=1.42, 95% CI=1.19-1.70; for TT+CT versus CC: OR=1.46, 95%CI=1.05-2.04). In addition, the results indicated that T allele had the positive association which was driven by East-asian populations (random: OR=1.44, 95% CI=1.2-1.74; fixed: OR=1.39, 95% CI=1.20-1.61), Middle-eastern populations (random: OR=1.30, 95% CI=1.05-1.63; fixed: OR=1.30, 95% CI=1.05-1.63) and Mixed-race (random: OR=1.96, 95% CI=1.35-2.85; fixed: OR=1.31, 95% CI=1.20-1.43).

CONCLUSION

This meta-analysis suggests that MTHFR C677T polymorphism is associated with male infertility.

Toxicology Study of Single-walled Carbon Nanotubes and Reduced Graphene Oxide in Human Sperm

Carbon-based nanomaterials such as single-walled carbon nanotubes and reduced graphene oxide are currently being evaluated for biomedical applications including in vivo drug delivery and tumor imaging. Several reports have studied the toxicity of carbon nanomaterials, but their effects on human male reproduction have not been fully examined. Additionally, it is not clear whether the nanomaterial exposure has any effect on sperm sorting procedures used in clinical settings. Here, we show that the presence of functionalized single walled carbon nanotubes (SWCNT-COOH) and reduced graphene oxide at concentrations of 1-25 μg/mL do not affect sperm viability. However, SWCNT-COOH generate significant reactive superoxide species at a higher concentration (25 μg/mL), while reduced graphene oxide does not initiate reactive species in human sperm. Further, we demonstrate that exposure to these nanomaterials does not hinder the sperm sorting process, and microfluidic sorting systems can select the sperm that show low oxidative stress post-exposure.

Potential confounding factors in measurement of specific cell-free seminal mRNAs and microRNAs derived from human reproductive organs

Cell-free seminal RNA (cfs-RNA) is mixed transcripts derived from male reproductive organs, and is potential biomarker for the research and diagnosis of male reproductive-related diseases. However, some clinical factors, including age, asymptomatic Ureaplasma urealyticum (UU) infection, scrotal heat stress, abstinence period, and the storage condition of semen samples, may interfere with sperm parameters and the measurement of seminal biomarkers. Accordingly, this study was designed to evaluate the effect of above clinical factors on the measurement of cfs-RNA, aiming to lay a foundation for its research use and potential clinical application. Semen samples were collected according to the selected clinical factors. Cell-free seminal plasma was obtained by centrifugation and total RNA was extracted with TRIzol LS. Selective male reproductive organ-specific cfs-mRNAs and cfs-miRNAs were quantified by quantitative real-time PCR. The concentration and total amount of cfs-mRNAs and cfs-miRNAs in one ejaculate were calculated and compared. ACTB, DDX4 (testis-specific), WFDC9 (epididymis-specific), and miR-514a-3p (testis-specific) significantly increased after scrotal heat stress. SEMG1 (seminal vesicle-specific) showed declining tendency with the prolonged abstinence period. Age, asymptomatic UU infection, and the storage condition showed no significant impact on the measurement of cfs-RNA. These results indicate that scrotal heat stress significantly interfere with the selected cfs-RNA derived from the testis and epididymis, and abstinence period may affect the yield of cfs-mRNA from seminal vesicle, while other clinical factors has no significant impact on the measurement. Thus, heat exposure and abstinence period should be considered for the cfs-RNA measurement in its research or clinical application.

Blood Cadmium Level Associates with Lower Testosterone and Sex Hormone-Binding Globulin in Chinese men: from SPECT-China Study, 2014

Cadmium is a widespread environmental pollutant. We aimed to determine whether blood cadmium level (BCL) associates with reproductive hormones in a cross-sectional study. Our data were from SPECT-China. We selected 5690 participants (2286 men and 3404 women), aged 18 years and older, among whom 1589 were postmenopausal women. BCL, blood lead level, total testosterone (TT), estradiol (E2), sex hormone-binding globulin (SHBG), luteinizing hormone, and follicle-stimulating hormone were measured. Results showed that BCL was significantly higher in men (median 1.90 μg/L) than that in women (median 1.56 μg/L). The median level of cadmium in postmenopausal women was 1.40 μg/L. In men, BCL was negatively correlated with TT (Spearmen coefficient = -0.057, P < 0.01) and SHBG (Spearmen coefficient = -0.098, P < 0.01), but in postmenopausal women, this correlation was not observed. In linear regression, after full adjustment for blood lead level, age, body mass index, residence area, economic status, and smoking, TT and SHBG were still negatively associated with BCL in men. Additionally, the association between BCL and TT levels was modified by BMI group (P for interaction = 0.041). However, from base model to fully adjusted model, BCL was not associated with TT and E2 in postmenopausal women. In conclusion, men had higher BCL than women in China, and BCL was associated with TT and SHBG in Chinese men, which may have important implications for male reproductive health. Concerted efforts are warranted to reduce adult cadmium exposure.

Biomonitoring of agricultural workers exposed to pesticide mixtures in Guerrero state, Mexico, with comet assay and micronucleus test

The aim of this study was to evaluate the genotoxic effect of pesticides in exfoliated buccal cells of workers occupationally exposed in Guerrero, Mexico, using the comet assay and the micronucleus test. The study compared 111 agricultural workers in three rural communities (Arcelia 62, Ajuchitlan 13, and Tlapehuala 36), with 60 non-exposed individuals. All the participants were males. The presence of DNA damage was investigated in the exfoliated buccal cells of study participants with the comet assay and the micronucleus (MN) test; comet tail length was evaluated in 100 nuclei and 3000 epithelial cells of each individual, respectively; other nuclear anomalies such as nuclear buds, karyolysis, karyorrhexis, and binucleate cells were also evaluated. Study results revealed that the tail migration of DNA and the frequency of MN increased significantly in the exposed group, which also showed nuclear anomalies associated with cytotoxic or genotoxic effect. No positive correlation was noted between exposure time and tail length and micronuclei frequencies. No significant effect on genetic damage was observed as a result of age, smoking, and alcohol consumption. The MN and comet assay in exfoliated buccal cells are useful and minimally invasive methods for monitoring genetic damage in individuals exposed to pesticides. This study provided valuable data for establishing the possible risk to human health associated with pesticide exposure.

Associations of variants in MTHFR and MTRR genes with male infertility in the Jordanian population

Folate pathway is expected to play an important role in spermatogenesis since it is involved in DNA synthesis, repair and methylation. The purpose of this study was to examine the association between male infertility and the MTHFR (C677T and A1298C) and MTRR (A66G) polymorphisms. A group of 300 males was recruited in this study from different Jordanian infertility clinics. Of these, 150 cases of infertile men that included oligozoospermia cases (n=45), severe oligozoospermia (n=71) and azoospermia (n=34) were studied. The other 150 males were age matched fertile controls. Genotyping of MTHFR and MTRR polymorphisms was performed using PCR-RFLP technique. The results showed an association between MTHFR 677TT genotype and male infertility (P<0.05). However, the distribution of MTHFR A1298C and MTRR A66G genotypes were not different between the fertile and infertile groups (P>0.05). In addition, none of the examined polymorphisms was related to any of the semen parameters in the infertile group. In conclusion, this study showed that MTHFR C677T polymorphism is associated with male infertility in Jordanians.

What should it take to describe a substance or product as 'sperm-safe'

BACKGROUND

Male reproductive potential continues to be adversely affected by many environmental, industrial and pharmaceutical toxins. Pre-emptive testing for reproductive toxicological (side-)effects remains limited, or even non-existent. Many products that come into direct contact with spermatozoa lack adequate testing for the absence of adverse effects, and numerous products that are intended for exposure to spermatozoa have only a general assumption of safety based on the absence of evidence of actual harm. Such assumptions can have unfortunate adverse impacts on at-risk individuals (e.g. couples who are trying to conceive), illustrating a clear need for appropriate up-front testing to establish actual 'sperm safety'.

METHODS

After compiling a list of general areas within the review's scope, relevant literature and other information was obtained from the authors' personal professional libraries and archives, and supplemented as necessary using PubMed and Google searches. Review by co-authors identified and eliminated errors of omission or bias.

RESULTS

This review provides an overview of the broad range of substances, materials and products that can affect male fertility, especially through sperm fertilizing ability, along with a discussion of practical methods and bioassays for their evaluation. It is concluded that products can only be claimed to be 'sperm-safe' after performing objective, properly designed experimental studies; extrapolation from supposed predicate products or other assumptions cannot be trusted.

CONCLUSIONS

We call for adopting the precautionary principle, especially when exposure to a product might affect not only a couple's fertility potential but also the health of resulting offspring and perhaps future generations.

A qualitative study of Ottawa university students' awareness, knowledge and perceptions of infertility, infertility risk factors and assisted reproductive technologies (ART)

BACKGROUND

Awareness of infertility risk factors is an essential first step to safeguard future fertility. Whereas several studies have examined university students' awareness of female fertility and related risk factors, the topic of male infertility has not been well examined. The objective of this study was to assess young men and women's awareness, knowledge and perceptions of infertility, male and female infertility risk factors and assisted reproductive technologies (ART).

METHODS

Semi-structured interviews were conducted in 2008 with a multi-ethnic sample of sixteen male and twenty-three female Ottawa university students, followed by qualitative data analysis to identify major themes. Interview topics included awareness of male and female infertility risk factors, infertility diagnosis/treatments and personal options in the event of future infertility.

RESULTS

Participants were generally familiar with infertility as a biomedical health problem, could identify sex-specific risk factors but overestimated fertility of women in their thirties and ART success rates. Reproductive health knowledge gaps and confusion of the physiological life-stage of menopause with infertility were apparent. Most participants would pursue in vitro fertilization or international adoption in the event of personal infertility. Some participants wished to use a 'natural' approach and were concerned with potential side effects of ART-related medications.

CONCLUSIONS

The general awareness of infertility in young adults is promising and supports the potential uptake for health promotion of fertility preservation. This study underscores the continued need for comprehensive sexual and reproductive health education and promotion for adolescents and young adults.

The effects of chronic ingestion of mercuric chloride on fertility and testosterone levels in male Sprague Dawley rats

Although male infertility is well researched, the effects of inorganic mercury on male reproduction and fertility are less well known. Studies pertaining to mercury and male fertility identified reduced concentration of testosterone in the serum of male workers, a toxic influence on fertility of organic mercury compounds within concentrations at the workplace, and increased days to pregnancy. We evaluated the effect of chronic mercuric chloride (HgCl₂) exposure in male rats on reproductive endpoints. Thirty-day old male Sprague Dawley rats (n = 31) were exposed to 0.0, 1.0, or 2.0 mg/kg/day of HgCl₂ via gavage. After 60 days exposure, they were housed with nonexposed females for 21 days. A survivor analysis revealed the exposed animals took longer to impregnate the females and had a lower rate of impregnation. Further statistical analysis revealed a lower correlation between testicular testosterone levels and days to impregnate, and also lower sperm counts in the epididymis head and body of the exposed males. The results indicate that HgCl₂ exposure had significant adverse effects on male rat reproduction endpoints including fertility at a dose that was not clinically toxic.

Determination of DNA damage after exposure to inhalation anesthetics in human peripheral lymphocytes and sperm cells in vitro by comet assay

In this study, genotoxic activities of four halogenated anesthetics (halothane, isoflurane, sevoflurane and desflurane) were investigated in human peripheral blood lymphocytes (PBLs) and sperm cells in vitro by alkaline comet assay. For this purpose, sperm or lymphocyte suspension was exposed to different concentrations (0.1 mM, 1 mM, 10 mM and 100 mM) of anesthetic agents and 1% dimethyl sulfoxide (DMSO) or phosphate-buffered saline (PBS) as controls. The DNA strand breaks as well as alkali-labile sites were measured as percentage tail intensity with comet assay. The results of this study demonstrate that all analyzed drugs were capable of inducing DNA damage on PBLs in a dose-dependent manner in vitro. However, the results in sperm cells were slightly different since we did not observe any genotoxic effect for desflurane in any of the exposure doses, and the genotoxic effect of halothane was not dose dependent. This experimental study points out to the presence of DNA damage after exposure to halogenated anesthetics in both PBLs and sperm cells, although this effect seems to be higher in PBLs.

Establishment of cell-cell cross talk in the epididymis: control of luminal acidification

Male infertility is often caused by sperm that have low motility and interact poorly with the oocyte. Spermatozoa acquire these crucial functions in the epididymis. A low luminal bicarbonate (HCO(3)(-)) concentration and low pH keep sperm quiescent during their maturation and storage in this organ. This review describes how epididymal epithelial cells work in a concerted manner, together with spermatozoa, to establish and maintain this acidic luminal environment. Clear cells express the proton-pumping ATPase (V-ATPase) in their apical membrane and actively secrete protons. HCO(3)(-) induces V-ATPase accumulation in apical microvilli in clear cells via HCO(3)(-)-sensitive adenylyl cyclase-dependent cAMP production. HCO(3)(-) is secreted from principal cells following basolateral stimulation, to transiently "prime" spermatozoa before ejaculation. Luminal ATP and adenosine also induce V-ATPase apical accumulation in clear cells via activation of P2 and P1 receptors, respectively. ATP is released into the lumen from sperm and principal cells and is then metabolized into adenosine by local nucleotidases. In addition, the V-ATPase is regulated by luminal angiotensin II via activation of basal cells, which can extend narrow body projections that cross the tight junction barrier. Basal cells then secrete nitric oxide, which diffuses out to stimulate proton secretion in clear cells via activation of the cGMP pathway. Thus, an elaborate communication network is present between principal cells and clear cells, and between basal cells and clear cells, to control luminal acidification. Monitoring and decoding these "intercellular conversations" will help define pathophysiologic mechanisms underlying male infertility.

Environmental/lifestyle effects on spermatogenesis

The high incidence of low sperm counts in young (European) men and evidence for declining sperm counts in recent decades mean that the environmental/lifestyle impact on spermatogenesis is an important health issue. This review assesses potential causes involving adverse effects on testis development in perinatal life (primarily effects on Sertoli cell number), which are probably irreversible, or effects on the process of spermatogenesis in adulthood, which are probably mainly reversible. Several lifestyle-related (obesity, smoking) and environmental (exposure to traffic exhaust fumes, dioxins, combustion products) factors appear to negatively affect both the perinatal and adult testes, emphasizing the importance of environmental/lifestyle impacts throughout the life course. Apart from this, public concern about adverse effects of environmental chemicals (ECs) (pesticides, food additives, persistent pollutants such as DDT, polychlorinated biphenyls) on spermatogenesis in adult men are, in general, not supported by the available data for humans. Where adverse effects of ECs have been shown, they are usually in an occupational setting rather than applying to the general population. In contrast, a modern Western lifestyle (sedentary work/lifestyle, obesity) is potentially damaging to sperm production. Spermatogenesis in normal men is poorly organized and inefficient so that men are poorly placed to cope with environmental/lifestyle insults.

Human exposure to endocrine disrupters and semen quality

Reproductive pathology in the male represents about 20% of infertility cases. Male infertility may be attributed to a number of causes, including genetic and congenital abnormalities, infection, multisystemic diseases, varicocele, and others; however, a significant number of cases are idiopathic. Global declines in semen quality were suggested to be associated with enhanced exposure to environmental chemicals that act as endocrine disrupters as a result of our increased use of pesticides, plastics, and other anthropogenic materials. A significant body of toxicology data based upon laboratory and wildlife animals studies suggests that exposure to certain endocrine disrupters is associated with reproductive toxicity, including (1) abnormalities of the male reproductive tract (cryptorchidism, hypospadias), (2) reduced semen quality, and (3) impaired fertility in the adult. There is, however, a relative paucity of studies designed to measure exposure to endocrine disrupters on semen quality parameters (sperm concentration, motility, morphology). An overview of the human semen quality literature is presented that examines the role of endocrine disrupters including organochlorines (OC), dioxins, phthalates, phytoestrogens, and chemical mixtures (pesticides and tobacco smoke).

Paternal occupational exposure to radiofrequency electromagnetic fields and risk of adverse pregnancy outcome

BACKGROUND

During the last decades, public concern that radiofrequency radiation (RFR) may be related to adverse reproductive outcomes has been emerging. Our objective was to assess associations between paternal occupational exposure to RFR and adverse pregnancy outcomes including birth defects using population-based data from Norway.

METHODS

Data on reproductive outcomes derived from the Medical Birth Registry of Norway were linked with data on paternal occupation derived from the general population censuses. An expert panel categorized occupations according to exposure. Using logistic regression, we analyzed 24 categories of birth defects as well as other adverse outcomes.

RESULTS

In the offspring of fathers most likely to have been exposed, increased risk was observed for preterm birth (odds ratio (OR): 1.08, 95% confidence interval (CI): 1.03, 1.15). In this group we also observed a decreased risk of cleft lip (OR: 0.63, 95% CI: 0.41, 0.97). In the medium exposed group, we observed increased risk for a category of "other defects" (OR: 2.40, 95% CI: 1.22, 4.70), and a decreased risk for a category of "other syndromes" (OR: 0.75, 95% CI: 0.56, 0.99) and upper gastrointestinal defects (OR: 0.61, 95% CI: 0.40, 0.93).

CONCLUSION

The study is partly reassuring for occupationally exposed fathers.

Low blood lead concentration in association with infertility in women

This study investigated the relationship between low-level lead exposure and risk of infertility in women. Study participants consisted of 64 cases recruited at a private infertility clinic and 83 control women from the postpartum clinic unit at a medical center in Kaohsiung, Taiwan. With informed consent, venous blood samples were obtained from subjects, during their early follicular phases (the 1st to 5th days of the menstrual cycle), for measuring concentrations of lead and hormones. Information on other potential risk factors associated with infertility, including reproductive history, Chinese herbal Medicine use, dairy product consumption, residential environment, and sociodemographic status, was obtained during an in-person interview. The mean blood lead level (BLL) in infertile women was significantly higher than that in controls (3.55 vs 2.78 microg/dL, P=0.007). Compared to women with BLL < or = 2.5 microg/dL, women with BLL>2.5 microg/dL were associated with a threefold increased risk for infertility (adjusted odds ratio=2.94, 95% confidence interval 1.18-7.34), after controlling for age, body mass index, smoking, Chinese herbal Medicine use, and irregular menstruation. Women's BLL was a significant predictor of the serum estradiol concentration also. These findings suggest an important role of very low BLL in the risk of infertility in women.

Adverse reproductive outcomes among male painters with occupational exposure to organic solvents

OBJECTIVES

To assess the risks of reproductive disorders and birth defects in offspring of male painters with exposure to organic solvents, and to determine the shape of the dose-response relationship.

METHODS

Random samples of painters and carpenters were drawn from workers affiliated with the Dutch Trade Union for Construction Workers, the Netherlands, 2001. Information on reproductive outcomes, occupational exposures, and lifestyle habits was retrospectively obtained through self-administered questionnaires filled in by 398 painters exposed to organic solvents in paints, thinners, and cleansers in the period of three months before the last pregnancy, and 302 carpenters with little or no exposure to solvents. A statistical model was used to estimate quantitative exposure measures.

RESULTS

Workers employed as painters at three months before pregnancy had an increased risk (odds ratio 6.2, 95% CI 1.4 to 27.9) of congenital malformations in offspring compared to carpenters. There was a positive exposure-response trend with increasing exposure to organic solvents based on quantitative model predicted exposure estimates using toluene as a marker. There was some indication of an increased risk of functional developmental disorders in offspring among painters with intermediate and high model predicted exposure. The risk of low birth weight children seemed to be slightly increased among painters as well. Results for other reproductive outcomes (time to pregnancy, spontaneous abortion, and preterm birth) did not show increased risks.

CONCLUSION

This study showed a positive association between paternal occupational exposure to organic solvents and congenital malformations in offspring. However, the small numbers of cases, especially when examining different exposure levels, as well as the self-reported nature of exposure and outcome variables, may hamper interpretation of the results.

Adverse pregnancy outcomes in offspring of fathers working in biomedical research laboratories

BACKGROUND

Laboratory work may constitute a possible health hazard for workers as well as for their offspring, and involves a wide range of exposures, such as organic solvents, carcinogenic agents, ionizing radiation, and/or microbiological agents. Adverse pregnancy outcomes in the offspring of male employees in biomedical research laboratories are examined.

METHODS

Offspring to males employed 1970-1989 at four Swedish universities were identified via the Medical Birth Register (MBR), along with other pregnancy parameters. Offspring of fathers with laboratory work (n = 2,281) is considered exposed, and of non-laboratory employees unexposed (n = 1,909). Exposure data were obtained by questionnaires to research group leaders. Logistic regression analysis estimated odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Paternal laboratory work in general showed no statistically significant increased ORs concerning birth weight and/or gestational age, but work specifically with radioactive isotopes gave OR 1.8 (CI 1.0-3.2) for high birth weight and a relative risk of 1.2 (CI 1.0-1.4) for sex ratio (male/female).

CONCLUSIONS

There was no clear association between periconceptional paternal laboratory work and adverse reproductive outcomes, but use of radioactive isotopes showed increased OR for high birth weight in offspring.

Role of acid/base transporters in the male reproductive tract and potential consequences of their malfunction

Acid/base transporters play a key role in establishing an acidic luminal environment for sperm maturation and storage in the male reproductive tract. Impairment of the acidification capacity of the epididymis, via either genetic mutations or exposure to environmental factors, may have profound consequences on male fertility.

Sperm DNA damage correlates with polycyclic aromatic hydrocarbons biomarker in coke-oven workers

OBJECTIVES

The aim was to determine whether occupational exposure to polycyclic aromatic hydrocarbons (PAHs) in men has adverse effect on semen quality.

METHODS

Forty-eight coke-oven workers, including 16 topside-oven (TO) workers and 32 sideoven (SO) workers, were studied. Ambient PAHs exposure, urinary 1-hydroxypyrene (1-OHP) levels, and parameters of semen quality were determined.

RESULTS

TO workers had significantly higher ambient PAHs exposure (3,436.1+/-3,411.0 vs. 1,123.1+/-1,829.3 ng/m3, P < 0.01), urinary 1-OHP levels (207.8+/-176.4 vs. 54.0+/-44.8 microg/g, P < 0.001), frequency of oligospermia (18.8 vs. 0%, P < 0.05), and morphological abnormality in sperm (32.3 vs. 14.6%, P < 0.01) than SO workers. Among cigarette smokers, TO workers had significantly higher rates of DNA denaturation in spermatozoa (alphaT) and percentage of sperm with increased DNA denaturation (COMP alphaT) levels than SO workers (246.2+/-49.5 vs. 198.1+/-30.3 for alphaT; 34.8+/-14.4 vs. 19.3+/-13.9% for COMP alphaT, P < 0.05). There was a positive correlation between urinary 1-OHP and alphaT, COMP alphaT, and abnormal sperm morphology and a tenfold increase in urinary 1-OHP associated with a 2.35-fold increase in alphaT, as well as a 1.07-fold increase in percentage of sperm with abnormal morphology.

CONCLUSIONS

A potential risk of sperm dysfunction should be considered for workers occupationally exposed to high levels of PAHs. Cigarette smoking may aggravate this risk. Urinary 1-OHP can be used as a biomarker predicting sperm dysfunction.

Reproductive toxicology in occupational settings: an update

OBJECTIVE

This article mainly attempts to review the recent human literature on the adverse effects of occupational factors on fertility, developmental effects and genetic changes in the germ line, which lead to genetic malformations or to genetic disease. The secondary study aim is to answer whether occupational exposures are quantitative momentously for 15% involuntarily childless couples, 10-20% spontaneous abortions and 3% birth defects.

METHODS

A literature survey was conducted for publications on these subjects focusing on the latest publications. PubMed (Medline. 2005) was used for this literature search.

RESULTS

Publication bias and a large amount of confounding factors, which have to be controlled, make the design of human fertility studies difficult. Epidemiologic studies using time to conception techniques have been useful in identifying substances and exposure scenarios with proven toxic effect on fertility. The collected studies suggest that the exposure to the following substances or occupational settings may affect fertility function: lead, organic mercury compounds, manganese, carbon disulfide, 2-bromopropane and dibromochloropropane, welding, professional driving and working with heat. Concerning developmental effects even for methyl mercury, which was in group A of the German MAK list, to date no reliable evidence of the damaging effect on the human fetus under actual work conditions has been obtained. It is also difficult to classify substances according to their mutagenic potential for the germ cell, since no direct evidence of an association between exposure against a physical or chemical pollutant and the occurrence of a hereditary disorder has been found yet.

CONCLUSION

In conclusion there are only a few substances which may affect reproductive function in the workplace without a doubt. The decreasing fertility of women in Western countries can be explained by the increasing female reproduction age, rather than by occupational exposures. Also the rates for spontaneous abortions and birth defects cannot be explained by industrial exposures at the workplace.

Semen quality and reproductive endocrine function with regard to blood cadmium in Croatian male subjects

In 123 Croatian men with no occupational exposure to metals, the influence of cadmium on reproductive parameters was examined after adjusting for age, smoking, alcohol, and biomarkers of lead, copper, zinc, and selenium. The following variables were measured: blood cadmium (BCd), blood lead (BPb), activity of delta-aminolevulinic acid dehydratase (ALAD), erythrocyte protoporphyrin, serum copper (SCu), serum zinc (SZn), serum selenium (SSe), activity of glutathione peroxidase (GPx) in blood, testis size, semen quality (including sperm concentration, motility, viability, and morphology), indicators in seminal fluid (the lactate dehydrogenase isoenzyme LDH-C4, fructose, zinc, acid phosphatase, and citric acid), and hormones in serum (follicle-stimulating hormone--FSH, luteinizing hormone, prolactin, testosterone, and estradiol). The median and range BCd values were 2.94 (0.49-11.93) microg/L in 61 smokers and 0.59 (0.20-3.71) microg/L in 62 nonsmokers (p < 0.0001). Smoking habits (cigarettes/day) highly significantly correlated with BCd (p < 0.0001). After adjusting for potential confounding variables by multiple regression, BCd was significantly associated with a decrease in testis size (p < 0.03) and an increase in serum estradiol (p < 0.005), FSH (p < 0.03), and testosterone (p < 0.04). Smoking was significantly associated with a decrease in serum prolactin (p < 0.006) and LDH-C4 in seminal fluid (p < 0.03). Several reproductive parameters were significantly associated with BPb and ALAD, biomarkers of lead, and/or with SCu, SZn, SSe, and GPx. The necessity of controlling for various metals, and other potential confounders when assessing the influence of a particular metal on reproductive function in men, is emphasized.

A survey of semen indices in insecticide sprayers

This study aims at clarifying the semen indices of insecticide sprayers who are exposed mainly to organophosphorus and pyrethroid insecticides. Eighteen male sprayers out of 54 working for 9 companies in central Japan and 18 age-matched students or medical doctors as unexposed controls participated in detailed reproductive check-ups conducted in summer and the following winter. The sprayers were exposed to insecticides more in summer, the busiest season, than winter, the off-season (p<0.05). Erythrocyte true cholinesterase activities in the sprayers were lower than in the controls in summer (p<0.05), and decreased in significant association with the increase in exposure frequency. Testicular volumes in the sprayers tended to be smaller than in the controls (p=0.06). The serum testosterone concentration in winter in the sprayers was higher than in the controls (p<0.05), though luteinizing hormone and follicle stimulating hormone concentrations were not significantly different. The sperm counts and vitality were comparable between the groups, but detailed sperm motility analysis in summer revealed that the percentages of slow progressive and nonprogressive motile sperm were twice as high in the sprayers (p<0.05), and that of rapid progressive sperm tended to be lower (p=0.06). Such differences were not observed in winter. Differential sperm morphology counts showed that interaction of group and abstinence effects were significant in sperm with normal morphology and with head deformity only in the summer check-up. Despite possible inherent differences between the groups, the above season-dependent differences suggested that the observed lower semen quality in the sprayers was associated with pesticide spraying work.

Occupational Exposure Associated with Reproductive Dysfunction

Evidence suggestive of harmful effects of occupational exposure on the reproductive system and related outcomes has gradually accumulated in recent decades, and is further compounded by persistent environmental endocrine disruptive chemicals. These chemicals have been found to interfere with the function of the endocrine system, which is responsible for growth, sexual development and many other essential physiological functions. A number of occupations are being reported to be associated with reproductive dysfunction in males as well as in females. Generally, occupations involving the manufacture/or application of some of the persistent chemicals that are not easily degradable as well as bio-accumulative chemicals, occupations involving intensive exposure to heat and radiation, occupations involving the use of toxic solvents as well as toxic fumes are reported to be associated with reproductive dysfunction. Occupational exposure of males to various persistent chemicals have been reported to have male mediated adverse reproductive outcomes in the form of abortion, reduction in fertility etc. with inconclusive or limited evidence. Nevertheless, there is a need for more well designed studies in order to implicate any individual chemical having such effects as in most occupations workers are exposed to raw, intermediate and finished products and there are also several confounding factors associated with lifestyles responsible for reproductive dysfunction. There is an urgent need to look at indiscriminate use of persistent chemicals especially pesticides and persistent organic pollutants (POP's) as these chemicals enter the food chain also and could be potential for exposure during the critical period of development. It is also necessary to impart information, and to educate about the safe use of these chemicals, as a very sensitive reproduction issue is involved with exposure to these chemicals. Occupational exposures often are higher than environmental exposures, so that epidemiological studies should be conducted on these chemicals, on a priority basis, which are reported to have adverse effects on reproduction in the experimental system.

Spermatogenic arrest in men with testicular hyperthermia

Sperm is produced by a highly complex and poorly understood differentiation process known as spermatogenesis. Occupational exposure to high temperatures adversely affect testicular function, causing partial or complete spermatogenic arrest. Dyers, cooks, blast furnace workers, and men with varicocele are known to develop testicular hyperthermia, which leads to oligoasthenoteratozoospermia (OAT) and azoospermia. Semen analysis of 122 infertile men (and 25 fertile controls), following the WHO guidelines, 1999, showed azoospermia in 106 men and oligozoospermia in 16 men. Twenty azoospermic and fourteen oligozoospermic men had high testiculoepididymal temperatures, either due to occupational exposure to high temperature or varicocele. All the 14 oligozoospermic men showed a very high percentage of sperm with abnormal morphology, impaired motility and they were subclassified as OAT group. Observations made in this study reiterates that high intratesticular temperature causes partial or complete spermatogenic arrest and may lead to increased production of morphologically abnormal sperm with impaired motility. This inverse relationship of sperm function with elevated temperature has implications in clinical medicine both in understanding pathological states and for therapeutic measures.

New evidence of the influence of exogenous and endogenous factors on sperm count in man

OBJECTIVE

To examine the association between individual exposures due to occupation, environment and lifestyle on sperm count, we conducted a case-control study among 92 fertile and 73 sub-fertile Caucasian males.

STUDY DESIGN

Data from questionnaires were analysed using simple univariate and multivariate logistic regression models.

RESULTS

At risk for oligozoospermia are men exposed to pesticides (odds ratio (OR) 8.4; 95% confidence interval (CI) 1.3-52.1), welding (OR 2.8; CI 0.9-8.7), antibiotic use (OR 15.4; CI 1.4-163), a history of mumps (OR 2.9; CI 1.3-6.7), gastrointestinal complaints (OR 6.2; CI 1.4-26.8), decreased intake of fruits (OR 2.3; CI 1.0-5.1), vegetables (OR 1.9; CI 0.7-5.0), or with female fertility disorders in their families (OR 8.4; CI 1.7-41.9). Unlike other studies, no associations were observed between oligozoospermia and exposure to paint or heat.

CONCLUSION

This study suggests new risk factors oligozoospermia in man and confirms previously reported results from others.

Health effects of welding

Many of the epidemiology studies performed are difficult to compare because of differences in worker populations, industrial settings, welding techniques, duration of exposure, and other occupational exposures besides welding fumes. Some studies were conducted in carefully controlled work environments, others during actual workplace conditions, and some in laboratories. Epidemiology studies have shown that a large number of welders experience some type of respiratory illness. Respiratory effects seen in full-time welders have included bronchitis, airway irritation, lung function changes, and a possible increase in the incidence of lung cancer. Pulmonary infections are increased in terms of severity, duration, and frequency among welders. Although epidemiological studies have demonstrated an increase in pulmonary illness after exposure to welding fumes, little information of the causality, dose-response, and possible underlying mechanisms regarding the inhalation of welding fumes exists. Even less information is available about the neurological, reproductive, and dermal effects after welding fume exposure. Moreover, carcinogenicity and short-term and long-term toxicology studies of welding fumes in animals are lacing or incomplete. Therefore, an understanding of possible adverse health effects of exposure to welding fumes is essential to risk assessment and the development of prevention strategies and will impact a large population of workers.

Semen quality of Indian welders occupationally exposed to nickel and chromium

The semen quality of 57 workers from a welding plant in South India and 57 controls was monitored. Blood nickel and chromium concentrations were determined by ICP-MS. Analysis of semen samples was performed in accordance with World Health Organization criteria. The blood level of nickel and chromium for the 28 exposed workers was 123.3 +/- 35.2 and 131.0 +/- 52.6 microg/l, resepctively, which was significantly higher than the 16.7 +/- 5.8 and 17.4 +/- 8.9 microg/l for the control group (n=27). Sperm concentrations of exposed workers were 14.5 +/- 24.0 millions/ml and those of the control group were 62.8 +/- 43.7 millions/ml. Rapid linear sperm motility was decreased in exposed workers compared to controls. There was a significant positive correlation between the percentage of tail defects and blood nickel concentration in exposed workers. The sperm concentration showed a negative correlation with blood chromium content in workers. More abnormal characteristics were found in the semen of exposed workers. Semen abnormalities correlated with the number of years of exposure to welding fumes containing nickel and chromium.

Bulky DNA adducts in human sperm: relationship with fertility, semen quality, smoking, and environmental factors

The integrity of DNA of spermatogenic cells can be affected by endogenous and exogenous genotoxic factors. Resulting DNA damage in spermatozoa may significantly contribute to impaired fertility. Here, the 32P-postlabeling method was used to analyze the levels of bulky DNA adducts in sperm cells in a group of 179 males, either healthy donors or patients with an impaired fertility. When all donors were analyzed, the levels of bulky DNA adducts was 1.2-fold higher in smokers than in non-smokers, but the difference was not statistically significant (P=0.054). However, a statistically significant difference existed between current smokers and never smokers among the healthy individuals (1.7-fold increase, P=0.008). No correlation between alcohol or coffee consumption and sperm DNA adducts was found. The levels of DNA adducts in sperm seemed to be unaffected by environmental and occupational factors. On the other hand, groups of healthy persons and patients with male-factor infertility differed significantly with respect to the level of bulky DNA adducts (P=0.012). A significant negative correlation between DNA adducts and sperm concentration or sperm motility existed among patients with an impaired fertility (n=93; P<0.029, r(S)=-0.225). These results suggest that DNA adducts in sperm cells can be applied as potential biomarkers in studies of human infertility.

Effects of Genistein Isoflavone (4',5',7-Trihydroxyisoflavone) and Dexamethasone on Functional Characteristics of Spermatozoa

Caudal epididymal spermatozoa were used to study the influence of genistein isoflavone and dexamethasone (dxm) on the functional characteristics of spermatozoa. The effects of genistein alone and in combination with dxm on sperm motility, sperm morphology, spontaneous acrosome reaction (AcR), and ionophore A23187-induced AcR were investigated. The FITC-PSA/Hoechst 33258 staining procedure was used to assess sperm cell viability and AcR status and thus to differentiate between true AcR and acrosome degeneration. The overall results indicated that (1) lower doses of genistein alone, or in combination with dxm, did not significantly influence sperm motility or sperm morphology; (2) ionophore A23187 induced AcR in rat spermatozoa; (3) there appeared to be no direct correlation between sperm motility and AcR, (4) higher doses of genistein, alone or in combination with dxm, significantly interfered with percentage sperm motility and caused significant detachment of sperm heads but did not cause morphological defects; and (5) higher doses of genistein caused significant decrease in sperm acrosome reactivity with long duration of exposure. In view of the fact that sperm capacitation and AcR are physiological prerequisites for successful fertilization of oocytes, the findings suggest that chronic exposure of spermatozoa to high doses of genistein could be associated with infertility problems through suppression/inhibition of AcR and sperm motility. Dexamethasone did not appear to influence the effect of genistein on the functionality of postspermatogenic spermatozoa.

Polycyclic aromatic hydrocarbon-DNA adducts in human sperm as a marker of DNA damage and infertility

Severe DNA damage, which might prevent egg fertilization or the development of the embryo, could be a cause of infertility. In order to assess whether polycyclic aromatic hydrocarbon (PAH)-DNA adducts are an early marker of sperm genotoxicity and infertility, we studied 205 men consecutively recruited from 1 January to 30 May 2001 through the Infertility Clinic of the University of Milan (Italy), with morphological abnormalities in the sperm. No known causes of infertility were present in their female partners. Sperm were collected after 3-5 days of abstinence, fixed on polylysine slides, and frozen at -20 degrees C. PAH-DNA adducts were measured by immunofluorescence using a polyclonal antiserum. A questionnaire was filled out at the time of the visit, with demographic information, smoking and drinking habits, and occupational history. Data on PAH-DNA adducts were available for 182 men. The mean age of the subjects was 35.5+/-5.0 years; 38.6% of them were current smokers. PAH-DNA adducts were negatively correlated with the percentage of physiologic forms (r=-0.18; P=0.016) and with abnormalities of the neck of the sperm cell (r=-0.21; P>/=0.009), while they were positively correlated with morphological abnormalities of the head (r=0.30; P>0.0001). Occupational exposure to PAH, but not smoking, was significantly associated with higher levels of PAH-DNA adducts. A significant negative association was observed between daily alcohol consumption and PAH-DNA adducts in sperm (P=0.01). PAH-DNA adducts levels were significantly higher in infertile versus fertile men (P=0.04). These results suggest a role for DNA damage in infertility.

Changes in semen quality in Jerusalem between 1990 and 2000: a cross-sectional and longitudinal study

The aim of the present study was to investigate whether sperm quality has changed during the years 1990-1999 among men residing in Jerusalem, Israel, who were involved in treatment by intrauterine insemination (IUI). Both cross-sectional and longitudinal analyses were performed. A total of 2638 male partners in couples that underwent treatment by IUI participated in the cross-sectional investigation. Of them, 417 men (16%) were included in the longitudinal study. Total sperm counts and percent motility were evaluated on an annual basis to assess changes over 10 years from 1990 through 1999. A significant downward trend in sperm count and motility was demonstrated in the cross-sectional study. Sperm count decreased by 5.2 x 10(6)+/-0.9 x 10(6) (p<.0001) each year and percent motility declined by 0.50+/-0.14% (p=.0003). Similar changes were found in the longitudinal evaluation, but they were not statistically significant. These data suggest that during the last decade in Jerusalem, sperm count and motility declined significantly among men involved in infertile relationships and treated by IUI.

Comprehensive office evaluation in the new millennium

The success of a comprehensive office-based evaluation of male-factor infertility depends on the physician's thorough understanding of risk assessment in the history, identification of pertinent physical examination findings, and correct assessment of laboratory data. Office-based ultrasonographic techniques have already increased the urologist's ability to visualize suspected anatomic abnormalities, and the use of functional tests of sperm has given greater depth to the limited, but essential, prognostic capabilities of the routine semen analysis.

Male employment in some printing trades is associated with prolonged time to conception

We investigated whether male employment in defined occupational groups was associated with decreased fecundity as revealed by prolonged time to conception. The analysis was carried out on data from questionnaires completed over a period of 21 months by 4808 couples with a planned pregnancy and collected as part of the Avon Longitudinal Study of Pregnancy and Childhood. Previously logistic regression had identified nine non-occupational factors associated with taking >6 or >12 months to conceive and this model was used to analyse the association of the fathers ever having worked in defined occupational groups with delayed conception. If the man had worked in 'Printing and related trades' (OPCS code 56), couples had a statistically significantly increased odds ratio (OR) of taking >6 [1.86 (1.21, 2.94)] or >12 months [1.96 (1.13, 3.39)] to conceive [OR (95% confidence intervals)] after adjustment for non-occupational factors. The association with time to conception was stronger in the subgroup 'Other printing related trades' (OPCS code 569) but no statistically significant associations after adjustment for other factors were found for other printing jobs.

Diagnostics in assisted human reproduction

The World Health Organization (WHO) estimates that 50-80 x 10(6) couples in the world are infertile, i.e. 7-15% of all couples of reproductive age (15-45 years old). The term infertility refers to couples who have been unable to conceive children for at least 1 year of regular unprotected intercourse. Although the frequency and origin of infertility varies, approximately 40-60% of the aetiology of infertility in the population studied is due to female causes. The introduction of assisted reproduction techniques, which offer couples the best opportunities for pregnancy, has opened a vast field of knowledge in reproductive biology. The medical history must be taken meticulously, with enough time to obtain the largest possible amount of relevant information. It is recommended that both partners be included in the initial work-up. In recent decades, technological progress has been favoured with the development of a great variety of diagnostic tests. Moreover, a very valuable tool helping to solve this problem has gained strength and is available to everybody - so-called 'evidence-based medicine'. There are three categories in infertility diagnostic tests. The first category includes tests showing a well-established correlation with pregnancy, e.g. semen analysis, tubal patency with hysterosalpingography or laparoscopy, and ovulation detection. The second category includes patients whose results are not consistently related to pregnancy. Here, these tests include sperm penetration assay in the zona-free hamster oocyte, post-coital tests, sperm penetration into cervical mucus, and tests to detect anti-sperm antibodies. The third group includes patients whose tests are not correlated with pregnancy. The relevant tests include endometrial biopsy, the presence of varicocele, and Chlamydia detection tests. Tests for infertility are often expensive. Since these patients are usually anxious and eager and will do almost anything to have a child, care must be taken to avoid exploitation of their hopes with unnecessary procedures. This text now reviews and updates the procedures used to investigate infertility.

The "Christmas Effect" and other biometeorologic influences on childbearing and the health of women

OBJECTIVE

To review the body of literature addressing biometeorologic and chronobiologic effects on conception, pregnancy, parturition, and other health conditions.

DATA SOURCES

Computerized searches of MEDLINE, PUBMED, CINAHL, and the World Wide Web.

STUDY SELECTION

Studies, including international research, dating from 1938 to 2001.

DATA EXTRACTION

Data were extracted and information organized under the following categories: influence of leisure time and seasonality on the rate of conception and birth, the relationship of meteorologic changes and lunar cycles to childbearing, the "Christmas Effect" and its impact on other health outcomes, and nursing implications.

DATA SYNTHESIS

Research from the disciplines of biometeorology and chronobiology indicates that there are patterns in the occurrence of conception, pregnancy, and onset of labor that vary in timing and amplitude in different populations and geographic regions. Consideration of these factors should be included in the analysis of birth data when planning and providing maternity care. The Christmas Effect is one of the most predominant seasonal patterns that can be seen in birth data throughout the world.

CONCLUSIONS

Biometeorologic and other cyclic phenomena are underused in the United States in planning and providing maternity care. These phenomena warrant consideration when planning holistic health care.

Concurrent analysis of nucleoside reverse transcriptase inhibitors in a pool of endogenous nucleosides by short-end injection-capillary electrochromatography on a beta-cyclodextrin-bonded stationary phase

As part of our on-going study of the analysis of anti-human immunodeficiency virus (HIV) nucleosides, a capillary electrochromatography (CEC) method has been developed for the concurrent analysis of nucleoside HIV reverse transcriptase inhibitors (NRTIs) in a pool of endogenous nucleosides. Up to now, beta-cyclodextrin-bonded silica stationary phases have mainly been dedicated to the separation of enantiomers; however, these polysaccharides can be also be used in achiral way. This work aims at showing how CEC performed on a beta-cyclodextrin-bonded silica stationary phase can be used to concurrently resolve zidovudine (AZT), lamivudine (3TC), didanosine (ddA) and its administrated form (ddI), stavudine (d4T) and hivid (ddC) in a mixture of adenosine (A), cytidine (C), guanosine (G), thymidine (T) and uridine (U). The influence of several parameters (pH buffer, ionic strength, acetonitrile content, temperature and voltage) on both the retention times and the retention factors has been investigated using the short-end injection technique to achieve baseline separation in a short-time analysis before quantitation. Moreover, the retention factors of the charged solutes in short-end injection-CEC were calculated using theoretically derived equations, allowing for the actual voltage drop in the packed section of the semipacked CEC capillary.

A case of reversible azoospermia following withdrawal from alcohol consumption

Chronic alcohol intake is associated with male reproductive function impairment. However, no longitudinal studies have been carried out to determine the recovery of alcohol-related spermatogenetic failure subsequent to moderate periods of abstinence. The present report describes the achievement of a pregnancy 3 months after withdrawal from alcohol consumption in the partner of a patient with azoospermia secondary to heavy alcoholic intake (mean daily alcohol consumption: 90 g). Alcoholism was the putative cause of the infertile condition of this patient because, during alcohol consumption, he first had teratozoospermia characterized by a never reported high percentage of spermatozoa with large heads (associated with a nonmegaloblastic macrocytic anaemia in the blood smear), and subsequently azoospermia.

Alterations of serum hormone levels in male workers occupationally exposed to cadmium

In order to investigate the influence of occupational exposure to cadmium (Cd) on the levels of serum hormone, a cross-sectional study was undertaken in male workers. Creatinine-adjusted urinary cadmium (UCd) was used as the indicator of cadmium body burden in workers. The levels of serum testosterone (T), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) were determined by radioimmunoassay and enzyme immunoassay, respectively. The results showed that with cadmium exposure, the levels of serum testosterone and LH were significantly increased after controlling for confounding factors such as age, smoking habits, and alcohol consumption. However, no significant cadmium-associated changes in the levels of serum FSH were found. At the same time, a significant negative correlation of serum testosterone levels with age was detected. In contrast, the levels of serum FSH and LH were significantly elevated with increasing age. When taking the marital status into consideration, only significantly elevated FSH levels were noted in married workers after controlling for confounding factors. These results indicate that occupational cadmium exposure and other factors such as age and marital status may independently contribute to alterations in the levels of serum sex hormones in males.