Association between female infertility and agricultural work history

Killing two birds with one stone: Pregnancy is a sensitive window for endocrine effects on both the mother and the fetus

Pregnancy is a complex process requiring tremendous physiological changes in the mother in order to fulfill the needs of the growing fetus, and to give birth, expel the placenta and nurse the newborn. These physiological modifications are accompanied with psychological changes, as well as with variations in habits and behaviors. As a result, this period of life is considered as a sensitive window as impaired functional and physiological changes in the mother can have short- and long-term impacts on her health. In addition, dysregulation of the placenta and of mechanisms governing placentation have been linked to chronic diseases later-on in life for the fetus, in a concept known as the Developmental Origin of Health and Diseases (DOHaD). This concept stipulates that any change in the environment during the pre-conception and perinatal (in utero life and neonatal) period to puberty, can be "imprinted" in the organism, thereby impacting the health and risk of chronic diseases later in life. Pregnancy is a succession of events that is regulated, in large part, by hormones and growth factors. Therefore, small changes in hormonal balance can have important effects on both the mother and the developing fetus. An increasing number of studies demonstrate that exposure to endocrine disrupting compounds (EDCs) affect both the mother and the fetus giving rise to growing concerns surrounding these exposures. This review will give an overview of changes that happen during pregnancy with respect to the mother, the placenta, and the fetus, and of the current literature regarding the effects of EDCs during this specific sensitive window of exposure.

Flufenoxuron disturbs early pregnancy in pigs via induction of cell death with ER-mitochondrial dysfunction

The use of pesticides can result in unintended side effects, such as environmental pollution and animal diseases; in serious cases, it may cause abortion. Flufenoxuron is an inhibitor of chitin synthesis that is used widely as a pesticide on farmland. It is difficult to break down and therefore accumulates in the body, and has also been detected in breast milk. Moreover, the effects of flufenoxuron in pregnancy remain elusive. Therefore, we investigated the effects of flufenoxuron on early pregnancy. Our results suggested that flufenoxuron inhibits cell development and cell cycle progression in porcine trophectoderm (pTr) cell and porcine endometrial luminal epithelial (pLE) cell lines through the repression of signal transduction pathways. Flufenoxuron induced programmed cell death through DNA fragmentation and apoptotic signals. In addition, flufenoxuron induced ROS production, ER stress, and mitochondrial malfunction; consequently, the cytosolic and mitochondrial calcium levels were increased. Expression of proteins on the ER-mitochondrial axis was increased by flufenoxuron. Cell migration was decreased by flufenoxuron treatment between pLE and pTr cells. In addition, the expression of pregnancy-related genes was decreased flufenoxuron. Collectively, our results indicated that flufenoxuron may be harmful to livestock and women in the early stages of pregnancy.

Pyridaben leads to inhibition of cell growth and induction of cell death through intracellular mechanisms in early pregnancy

Recently, infertility has become a major global issue. It is crucial to identify environmental factors that lead to infertility. The prevalent use of pesticides in agriculture results in the exposure of livestock and humans to these pesticides. Studies have reported the harmful effects of pesticides on pregnancy. Pyridaben, a pesticide that inhibits mitochondrial complex 1, has been reported to have detrimental effects on neurons, spermatogenesis, hormonal balance, and embryonic development. However, the effect of pyridaben on the female reproductive system has not yet been studied. Therefore, in this study, we evaluated the effects of pyridaben on early pregnancy in porcine reproductive cell lines, which are known to mimic the female reproductive system. Results demonstrated that pyridaben decreased cell growth in porcine endometrial luminal epithelial and porcine trophectoderm cell lines through inhibition of cell signal transduction. Further, pyridaben increased subG1 phase and late apoptosis through the induction of reactive oxygen species production, mitochondrial dysfunction, calcium unbalances, pro-apoptotic signals, and endoplasmic reticulum (ER) stress. Moreover, we found that pyridaben induced autophagy and inhibition of placentation through the regulation of ER-mitochondria axis proteins. Overall, pyridaben was found to be harmful in early pregnancy in pigs and may have similar effects in human pregnancy.

Pesticide residues in honey and their potential reproductive toxicity

Honey is the sweet natural substance produced by honeybees. It may be contaminated with pesticide residues due to its intensive use. Almost no reviews have addressed pesticide residues in honey, calculated a hazard index or discussed their potential reproductive toxicity. The focus of this article is primarily to summarize advances in research related to pesticide residues, estimate daily intake of pesticide residues from consuming honey only and discuss the potential reproductive toxicity associated with those residues. The results showed that 92 pesticide residues were found in honey samples from 27 countries. Six residues belong to class IA toxicity, eight residues belong to class IB toxicity, 42 residues belong to class II, 35 residues belong to class III and one residue belong to class IV toxicity. The calculated hazard indices (HIs) suggest high potential health risk by consuming honey. In addition, residues found in honey are known to impair semen quality among exposed individuals and experimental animal models. In conclusion, consumption of honey as one of many food items contaminated with pesticide residues may induce male and female reproductive toxicity in consumers.

General and reproductive health outcomes among female greenhouse workers: a comparative study

Background

Agricultural activities as well as exposure to pesticides could have many adverse effects on health status and reproductive outcomes especially in reproductive aged greenhouse workers. The present study aimed to compare the general and reproductive health outcomes between female greenhouse workers and housewives.

Methods

This cross-sectional study was conducted on 645 females of reproductive age. They were categorized into two groups according to occupation in greenhouse (308 female greenhouse workers as exposed group and 337 housewives as control group). Participants were interviewed using a questionnaire about reproductive outcomes and occupational status. Clinical measures include blood pressure (BP), pulse and respiratory rate (PR and RR), body mass index (BMI) and hematological parameters. Mann-Whitney U test was used to assess differences between two groups in quantitative variables. Chi-square or Fisher’s exact tests was used to determine the differences in the distribution of categorical variables. Data was analyzed using SPSS software version 16.

Results

The average daily working hours of the greenhouse workers were 6.94 ± 1.99 h. Only 44.3% of them used personal protective equipment. Data revealed that the rate of spontaneous abortion, infertility, low birth weight (LBW), abnormal births and preterm birth were significantly higher among the greenhouse workers compared to the control group (p ≤ 0.05). The average number of female infants in greenhouse workers was significantly higher than the control group (p ≤ 0.05). Clinical measurements indicated an increase in RR of greenhouse workers and mean of BMI was decreased in them. Hematological parameters demonstrated that there was a significant increase in white blood cells (WBC) and significant decrease in hemoglobin (Hb), hematocrit (HCT), mean corpuscular volume (MCV) and mean corpuscular hemoglobin concentration (MCHC) among the female greenhouse workers compared to the control (p ≤ 0.05).

Conclusion

Local government efforts is needed to address associated issues including acute effects on health and long-term health risks, resulting from pesticide exposure to greenhouse workers, and gender differences should be considered. Also, occupational health and safety training is necessary and can be helpful in reducing adverse reproductive outcomes.

Low dose of flurochloridone affected reproductive system of male rats but not fertility and early embryonic development

BACKGROUND

Fluorochloridone (FLC) is a widely used herbicide, and its target organs are testes and epididymides. The Globally Harmonized System of Classification and Labelling of Chemicals classified FLC as Level 2-possibly cause fertility or fetal damage (no relevant data support). The maximum residue levels of FLC in processed crops have been reviewed in the latest European Food Safety Authority (EFSA) report in 2018. However, the toxic effect of FLC on fertility and early embryonic development is limited, and the health risk assessment of FLC needs further consideration. This study investigated the potential effects of FLC on fertility and early embryonic development in rats.

METHODS

One hundred rats of each sex were divided into four groups including three FLC-treated groups at doses of 2 mg/kg, 5 mg/kg and 15 mg/kg, and a vehicle control group (0.5% (w/v) sodium carboxymethyl cellulose). Male and female rats were dosed for 9 and 2 consecutive weeks, intragastrically, prior to cohabitation and lasted throughout the mating period for males and continued until Gestation Day 7 (GD7) for females. Parameters such as weights and coefficients of reproductive organs, epididymal sperm number and motility, indexes of copulation, fecundity and fertility indexes, mating period, estrous cycle, corporalutea number, implantations, live, dead and resorbed fetuses, preimplantation loss rate, and postimplantation loss rate were observed in this study.

RESULTS

Obvious toxicity of male reproductive system was found at the dose of 15 mg/kg including decreases in testicular and epididymal weight, also in sperm motility rate. Whereas the increase in sperm abnormality rate was observed. However, no significant effects of FLC were found on lutea count, implantations count, fetuses count and weight, live fetuses count (rate), dead fetuses count (rate), resorbed fetuses count (rate), placentas weight, fetuses gender, preimplantation loss (rate) and postimplantation loss (rate). Furthermore, FLC had no adverse effects on fertility and early embryonic development in rats.

CONCLUSION

The no-observable-adverse-effect level (NOAEL) of FLC on fertility and early embryonic development in rats was considered to be 5 mg/kg/day.

Effects of environmental contaminants on fertility and reproductive health

Recent research indicates that the human infertility rate is increasing. Although various reasons have been hypothesized for the growing infertility rate, environmental contaminants are potentially important causal agents associated with this change. Chemical contaminants are widespread throughout our environment and human exposure is virtually unavoidable. The overall contribution of environmental exposure to infertility is unknown, but studies involving occupational exposure, together with results from animal experiments, suggest that environmental contaminants may adversely affect fertility. We reviewed the adverse effects of environmental exposure on fertility and related reproductive outcomes. Environmental contaminants covered in this review include heavy metals, organic solvents, pesticides and endocrine disrupting chemicals. It is hoped that this review will highlight the need for further research in this area.

"When This Breaks Down, It's Black Gold": Race and Gender in Agricultural Health and Safety

Farmers are growing older, and fewer new agriculturists are rising to take their place. Concurrently, women and minorities are entering agriculture at an increasing rate. These rates are particularly curious viewed in light of the racialized and gendered nature of agriculture. Slavery and agriculture share strong historical roots, with many male slaves performing agricultural labor. So then, why would African American women choose to engage in agriculture in any form? Participant observation and in-depth interviews with a group of African American women urban farmers in the southeastern United States were asked this question. Interviews with seven such women revealed their perception of self-sustainable small-scale agriculture as a departure from, not return to, slavery. The women drew metaphors between the Earth and femininity, believing their work to be uniquely feminine. Production of food for consumption and trade provides a source for community and healthy food amid urban poverty and the plight of food deserts. These data encourage agricultural health and safety professionals and researchers to tackle the health-promoting nature of such work, with the entrée of anthropology and other social sciences into the field. In many ways, these women portrayed small-scale food cultivation as an important component of, rather than a threat to, health and safety. Indeed, they viewed such labor as wholly health promoting. Their strong social connections provide a potential means for community-led dissemination of any relevant health and safety information.

Fallopian damage induced by organophosphate insecticide methyl parathion, and protective effect of vitamins E and C on ultrastructural changes in rats

The aim of the present study was to examine the effects of subchronic methyl parathion (MP) administration on lipid peroxidation and fallopian tube damage, and to evaluate the preventive effects of the use of vitamins E and C against toxicity. The experimental groups were: rats treated with corn oil (control group), with 5 mg/kg MP and with 5 mg/kg body weight MP plus vitamins E and C (MP + Vit). The groups were given MP by oral gavage for five days a week for four weeks at a daily dose of 5 mg/kg (MP and MP + Vit) using corn oil as a vehicle. Vitamins E and C were injected at doses of 50 mg/kg intramuscularly and 20 mg/kg intraperitoneally, respectively, just after the treatment with MP in the MP + Vit group. The levels of malondialdehyde (MDA) were determined in rat plasma. Electron microscopic ultrastuructural and histopathological changes in the fallopian tissue were examined. MDA levels were higher in the MP group than in the control group, and lower in the MP + Vit group than in the MP group. MP led to deletions in microvilli and marked loss in kinocillia of surface epithelium. But these marked histopathological findings decreased in the MP + Vit group. Multiple doses of MP administration caused some damage in the fallopian tube, and treatment with vitamins E and C after MP could reduce this effect. Toxicology and Industrial Health 2007; 23: 429—438.

Effects of Endocrine-disrupting Chemicals on Female Reproductive Health

Endocrine-disrupting chemicals (EDCs) are increasingly prevalent in the environment and the evidence demonstrates that they affect reproductive health, has been accumulating for the last few decades. In this review of recent literature, we present evidence of the effects of estrogen-mimicking EDCs on female reproductive health especially the ovaries and uteri. As representative EDCs, data from studies with a pharmaceutical estrogen, diethylstilbestrol (DES), an organochlorine pesticide methoxychlor (MXC), a phytoestrogen (genistein), and a chemical used in plastics, bisphenol a (BPA) have been presented. We also discuss the effects of a commonly found plasticizer in the environment, a phthalate (DEHP), even though it is not a typical estrogenic EDC. Collectively, these studies show that exposures during fetal and neonatal periods cause developmental reprogramming leading to adult reproductive disease. Puberty, estrous cyclicity, ovarian follicular development, and uterine functions are all affected by exposure to these EDCs. Evidence that epigenetic modifications are involved in the progression to adult disease is also presented.

Persistent organochlorine pesticides residues in cow and goat milks collected from different regions of Ethiopia

The present study investigated the bioaccumulation of organochlorines in two milk-producing animals (goats and cows) grazed on the same feed to explore the extent of organochlorines availability in milk and any species effect on the bioaccumulation pattern. Six organochlorine pesticides: aldrin, α-endosulfan, β-endosulfan, p,p'-DDE, o,p'-DDT and p,p'-DDT were determined in samples collected from four regions in Ethiopia. Aldrin (11.6μgkg(-1)) was detected only in one cow milk sample and α-endosulfan was detected in one goat milk sample at a level of 142.1μgkg(-1), and in one cow milk sample (47.8μgkg(-1)) from the same region. p,p'-DDE was detected in 40% of the milk samples analyzed while o,p'-DDT and p,p'-DDT were found in high amounts in almost all samples. The average total DDT (excluding DDD) in the samples was 328.5μgkg(-1). Regions known for their malaria epidemics were the most contaminated with DDT residue. The accumulation pattern in both species was not clear under natural sampling.

Estrogenic endocrine-disrupting chemicals: molecular mechanisms of actions on putative human diseases

Endocrine-disrupting chemicals (EDC), including phthalates, bisphenol A (BPA), phytoestrogens such as genistein and daidzein, dichlorodiphenyltrichloroethane (DDT), and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), are associated with a variety of adverse health effects in organisms or progeny by altering the endocrine system. Environmental estrogens, including BPA, phthalates, and phytoestrogens, are the most extensively studied and are considered to mimic the actions of endogenous estrogen, 17β-estradiol (E2). Diverse modes of action of estrogen and estrogen receptors (ERα and ERβ) have been described, but the mode of action of estrogenic EDC is postulated to be more complex and needs to be more clearly elucidated. This review examines the adverse effects of estrogenic EDC on male or female reproductive systems and molecular mechanisms underlying EDC effects that modulate ER-mediated signaling. Mechanisms of action for estrogenic EDC may involve both ER-dependent and ER-independent pathways. Recent findings from systems toxicology of examining estrogenic EDC are also discussed.

Interactions between urinary 4-tert-octylphenol levels and metabolism enzyme gene variants on idiopathic male infertility

Octylphenol (OP) and Trichlorophenol (TCP) act as endocrine disruptors and have effects on male reproductive function. We studied the interactions between 4-tert-Octylphenol (4-t-OP), 4-n- Octylphenol (4-n-OP), 2,3,4-Trichlorophenol (2,3,4-TCP), 2,4,5-Trichlorophenol (2,4,5-TCP) urinary exposure levels and polymorphisms in selected xenobiotic metabolism enzyme genes among 589 idiopathic male infertile patients and 396 controls in a Han-Chinese population. Ultra high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used to measure alkylphenols and chlorophenols in urine. Polymorphisms were genotyped using the SNPstream platform and the Taqman method. Among four phenols that were detected, we found that only exposure to 4-t-OP increased the risk of male infertility (P(trend) = 1.70×10(-7)). The strongest interaction was between 4-t-OP and rs4918758 in CYP2C9 (P(inter) = 6.05×10(-7)). It presented a significant monotonic increase in risk estimates for male infertility with increasing 4-t-OP exposure levels among men with TC/CC genotype (low level compared with non-exposed, odds ratio (OR) = 2.26, 95% confidence intervals (CI) = 1.06, 4.83; high level compared with non-exposed, OR = 9.22, 95% CI = 2.78, 30.59), but no associations observed among men with TT genotype. We also found interactions between 4-t-OP and rs4986894 in CYP2C19, and between rs1048943 in CYP1A1, on male infertile risk (P(inter) = 8.09×10(-7), P(inter) = 3.73×10(-4), respectively).We observed notable interactions between 4-t-OP exposure and metabolism enzyme gene polymorphisms on idiopathic infertility in Han-Chinese men.

Targeted genome-wide methylation and gene expression analyses reveal signaling pathways involved in ovarian dysfunction after developmental EDC exposure in rats

Transient exposure to methoxychlor (MXC), an environmental endocrine-disrupting chemical, during fetal and neonatal stages causes ovarian dysfunction in pubertal, adult, and aging animals. Adult animals have reduced number of ovulations and abnormal follicular composition associated with altered gene expression and DNA methylation patterns. To test the hypothesis that the ovarian epigenomic changes induced by MXC are detectable following the exposure period, leading to altered gene expression by adulthood, we conducted a targeted genome-wide methylation study using Nimblegen 3x720K CpG Island Plus RefSeq Promoter Arrays. Control (vehicle), low-dose MXC (20 μg/kg/day), or high-dose MXC (100 mg/kg/day) treatments were administered between Embryonic Day 19 and Postnatal Day (PND) 7. Ovaries were collected at PND 7 immediately after exposure or at adulthood, PND 60. Array hybridizations were conducted with genomic DNA after methylated DNA immunoprecipitation and the array data were analyzed. DNA methylation events were functionally annotated, and candidate loci common to all the treatments or unique to some treatments were identified. Specific loci encoding signaling molecules such as the regulatory subunit p85 of phosphoinositide-3-kinase, insulin-like growth factor-1 receptor, Harvey rat sarcoma viral oncogene, insulin receptor, and forkhead box protein O3 were identified to be hypermethylated in MXC-treated ovaries at PND 7 and/or PND 60. Examination of gene expression changes with TaqMan low-density arrays revealed that nearly 25% of the genes that were assayed were downregulated. These data demonstrate that key molecules in specific signaling pathways such as PTEN signaling, IGF-1 signaling, or rapid estrogen signaling are epigenetically altered in MXC-exposed ovaries, which is associated with ovarian dysfunction and female infertility.

Genetic variants in epoxide hydrolases modify the risk of oligozoospermia and asthenospermia in Han-Chinese population

OBJECTIVES

Epoxide hydrolases are involved in detoxifying and excreting the environmental chemicals, which are associated with decreased semen quality and male infertility. We hypothesized that polymorphisms in epoxide hydrolases may be associated with risk of oligozoospermia and asthenospermia.

DESIGN AND METHODS

In this study, 468 fertile controls and 672 idiopathic male infertile patients were recruited. SNPstream and TaqMan assay were used to genotype four single nucleotide polymorphisms in EPHX1 and EPHX2. The semen analysis was performed by computer-assisted semen analysis system.

RESULTS

Our results demonstrated that rs1042064 of EPHX2 was significantly associated with decreased risk of oligozoospermia (OR=0.65, 95% CI: 0.44-0.98) and asthenospermia (OR=0.66, 95% CI: 0.46-0.94).

CONCLUSIONS

Our results provided evidence that genetic variants in epoxide hydrolases may modify the risk of oligozoospermia and asthenospermia in Han-Chinese population.

Social Justice

Nurse scholars with expertise in global health and culturally competent care recently proposed standards of practice for culturally competent nursing care that are founded on social justice as a broad framework. The purpose of this article is to respond to invited dialogue about the standards and to offer commentary on social justice and its relationship with context, advocacy, leadership, and culturally competent care. A model of culturally competent care for vulnerable groups informs this discussion. The context and culture that surround migrant and seasonal farmworkers illustrate how social justice illuminates their health inequities and necessitates their need for culturally competent care. The article concludes with recommendations for culturally competent education, practice, and research and offers suggestions for developing culturally competent interventions for migrant and seasonal farmworkers.

Polymorphisms in CYP1B1 modify the risk of idiopathic male infertility with abnormal semen quality

BACKGROUND

It is acknowledged that Cytochrome P450 1B1 (CYP1B1) plays a crucial role in metabolism and is involved in lots of diseases. We carried out this study to evaluate the association between CYP1B1 single nucleotide polymorphisms (SNPs) and male infertility in the Han-Chinese population with abnormal semen parameters.

METHODS

We genotyped five CYP1B1 polymorphisms by using TaqMan allelic discrimination assay and Genome Lab SNP-stream. A total of 591 idiopathic infertile men and 419 fertile controls were comprised in the research. Semen quality analysis was performed using computer assisted sperm analysis. According to semen parameters, we divided cases into 3 subgroups in the stratified analysis.

RESULTS

In our study, we only found genetic variant rs1056836 is correlated with idiopathic male infertility (P=0.012). Additionally, in strategy analysis, rs1056836 may decrease the risk of abnormal sperm motility (OR=0.11, 95% CI=0.01, 0.86). While other four variants showed no significant association with male infertility.

CONCLUSIONS

Our results suggested that polymorphism of CYP1B1 modified the risk of male infertility, and men harboring this polymorphism had lower risk of abnormal sperm parameters. These findings should be validated by more epidemiological and functional studies.

Epigenetic effects of endocrine-disrupting chemicals on female reproduction: an ovarian perspective

The link between in utero and neonatal exposure to environmental toxicants, such as endocrine-disrupting chemicals (EDCs) and adult female reproductive disorders is well established in both epidemiological and animal studies. Recent studies examining the epigenetic mechanisms involved in mediating the effects of EDCs on female reproduction are gathering momentum. In this review, we describe the developmental processes that are susceptible to EDC exposures in female reproductive system, with a special emphasis on the ovary. We discuss studies with select EDCs that have been shown to have physiological and correlated epigenetic effects in the ovary, neuroendocrine system, and uterus. Importantly, EDCs that can directly target the ovary can alter epigenetic mechanisms in the oocyte, leading to transgenerational epigenetic effects. The potential mechanisms involved in such effects are also discussed.

Alcohol, drugs, caffeine, tobacco, and environmental contaminant exposure: reproductive health consequences and clinical implications

Reproductive function and fertility are thought to be compromised by behaviors such as cigarette smoking, substance abuse, and alcohol consumption; however, the strength of these associations are uncertain. Furthermore, the reproductive system is thought to be under attack from exposure to environmental contaminants, particularly those chemicals shown to affect endocrine homeostasis. The relationship between exposure to environmental contaminants and adverse effects on human reproductive health are frequently debated in the scientific literature and these controversies have spread into the lay press drawing increased public and regulatory attention. Therefore, the objective of the present review was to critically evaluate the literature concerning the relationship between lifestyle exposures and adverse effects on fertility as well as examining the evidence for a role of environmental contaminants in the purported decline of semen quality and the pathophysiology of subfertility, polycystic ovarian syndrome, and endometriosis. The authors conclude that whereas cigarette smoking is strongly associated with adverse reproductive outcomes, high-level exposures to other lifestyle factors are only weakly linked with negative fertility impacts. Finally, there is no compelling evidence that environmental contaminants, at concentrations representative of the levels measured in contemporary biomonitoring studies, have any effect, positive or negative, on reproductive health in the general population. Further research using prospective study designs with robust sample sizes are needed to evaluate testable hypotheses that address the relationship between exposure and adverse reproductive health effects.

Fetal and neonatal exposure to the endocrine disruptor methoxychlor causes epigenetic alterations in adult ovarian genes

Exposure to endocrine-disrupting chemicals during development could alter the epigenetic programming of the genome and result in adult-onset disease. Methoxychlor (MXC) and its metabolites possess estrogenic, antiestrogenic, and antiandrogenic activities. Previous studies showed that fetal/neonatal exposure to MXC caused adult ovarian dysfunction due to altered expression of key ovarian genes including estrogen receptor (ER)-beta, which was down-regulated, whereas ERalpha was unaffected. The objective of the current study was to evaluate changes in global and gene-specific methylation patterns in adult ovaries associated with the observed defects. Rats were exposed to MXC (20 microg/kgxd or 100 mg/kg.d) between embryonic d 19 and postnatal d 7. We performed DNA methylation analysis of the known promoters of ERalpha and ERbeta genes in postnatal d 50-60 ovaries using bisulfite sequencing and methylation-specific PCRs. Developmental exposure to MXC led to significant hypermethylation in the ERbeta promoter regions (P < 0.05), whereas the ERalpha promoter was unaffected. We assessed global DNA methylation changes using methylation-sensitive arbitrarily primed PCR and identified 10 genes that were hypermethylated in ovaries from exposed rats. To determine whether the MXC-induced methylation changes were associated with increased DNA methyltransferase (DNMT) levels, we measured the expression levels of Dnmt3a, Dnmt3b, and Dnmt3l using semiquantitative RT-PCR. Whereas Dnmt3a and Dnmt3l were unchanged, Dnmt3b expression was stimulated in ovaries of the 100 mg/kg MXC group (P < 0.05), suggesting that increased DNMT3B may cause DNA hypermethylation in the ovary. Overall, these data suggest that transient exposure to MXC during fetal and neonatal development affects adult ovarian function via altered methylation patterns.

Lifetime occupational history and risk of endometriosis

OBJECTIVES

Endometriosis is the presence of functioning endometrial glands and stroma outside the uterine cavity, most often in the pelvic peritoneal cavity. Women with endometriosis commonly have dysmenorrhea, dyspareunia, pain, menorrhagia, and/or metrorrhagia. Disease complications can include adhesions, chronic pain, and infertility. In this exploratory case-control study, we investigated the relationship between lifetime occupational history and surgically confirmed endometriosis in a population-based sample.

METHODS

We conducted interviews with participants, all reproductive-aged female members of a large health-maintenance organization who were first diagnosed with surgically confirmed endometriosis between April 1, 1996 and March 31, 2001. Interviews were also conducted with randomly selected controls, reproductive-aged female enrollees of the same organization from the same time period. Each reported job was coded using US Census Occupations and Industries codes, and classified into categories. We used unconditional logistic regression to compare having worked in a given job class with never having done so.

RESULTS

Our study found that an increased risk of endometriosis was associated with having worked as a flight attendant, service station attendant, or health worker, particularly as a nurse or health aide (flight attendant: odds ratio (OR) 9.80, 95% CI 1.08-89.02; service station attendant: OR 5.77, 95% CI 1.03-32.43; health worker: OR 1.49, 95% CI 1.03-2.15). Income and education did not make a difference in the OR estimates for the occupations examined.

CONCLUSIONS

This exploratory study suggested that there might be an associated risk of endometriosis for those women who have worked as a flight attendant, service station attendant, or health worker, particularly a nurse.

Proceedings of the Summit on Environmental Challenges to Reproductive Health and Fertility: executive summary

The 2007 Summit on Environmental Challenges to Reproductive Health and Fertility convened scientists, health care professionals, community groups, political representatives, and the media to hear presentations on the impact of environmental contaminants on reproductive health and fertility, and to discuss opportunities to improve health through research, education, communication, and policy. Environmental reproductive health focuses on exposures to environmental contaminants, particularly during critical periods of development, and their potential effects on future reproductive health, including conception, fertility, pregnancy, adolescent development, and adult health. Approximately 87,000 chemical substances are registered for commercial use in the United States, with ubiquitous human exposures to environmental contaminants in air, water, food, and consumer products. Exposures during critical windows of susceptibility may result in adverse effects with lifelong and even intergenerational health impacts. Effects can include impaired development and function of the reproductive tract and permanently altered gene expression, leading to metabolic and hormonal disorders, reduced fertility and fecundity, and illnesses such as testicular, prostate, uterine, and cervical cancers later in life. This executive summary reviews effects of pre- and postnatal exposures on male and female reproductive health, and provides a series of recommendations for advancing the field in the areas of research, policy, health care, and community action.

Environmental contaminants and human infertility: hypothesis or cause for concern?

Throughout the 1980s and 1990s the crude human birth rate (live births per 1000 population) declined, indicating reduced fertility and suggesting a potential decline in fecundity (the potential to conceive). Detection of environmental contaminants in human tissues, together with reports of a global decline in semen quality, further fueled speculation that human infertility rates are increasing and environmental toxicants are potentially important causal agents associated with this change. However, there is little compelling evidence to suggest that infertility rates amongst the general population have changed over time. Moreover, recent studies suggest a rise in the fertility rates. While several studies documented increased time to pregnancy (TTP) in exposed study populations, other investigators were not able to replicate these findings. Nevertheless, studies involving occupational exposure together with results from animal experiments lend support to the conclusion that environmental contaminants potentially adversely affect fertility. Consequently, the impact of exposure to environmental contaminants on human fertility remains controversial. To test the hypothesis that environmental contaminant exposure was associated with enhanced risk of infertility, data concerning trends in fertility and infertility rates were examined to assess the impact of exposure of developing gametes to environmental contaminants. The relationship between exposure and reproductive outcomes was then examined to illustrate the range of adverse effects for reproductive toxicants with data sets of divergent depth and reliability. Data showed that only a weak association between exposure to environmental contaminants and adverse effects on human fertility exists. However, it is postulated that evidence of chemical exposure and potential health consequences of these exposures highlight the need for further research in this area.

Proceedings of the Summit on Environmental Challenges to Reproductive Health and Fertility: executive summary

The 2007 Summit on Environmental Challenges to Reproductive Health and Fertility convened scientists, health care professionals, community groups, political representatives, and the media to hear presentations on the impact of environmental contaminants on reproductive health and fertility, and to discuss opportunities to improve health through research, education, communication, and policy. Environmental reproductive health focuses on exposures to environmental contaminants, particularly during critical periods of development, and their potential effects on future reproductive health, including conception, fertility, pregnancy, adolescent development, and adult health. Approximately 87,000 chemical substances are registered for commercial use in the United States, with ubiquitous human exposures to environmental contaminants in air, water, food, and consumer products. Exposures during critical windows of susceptibility may result in adverse effects with lifelong and even intergenerational health impacts. Effects can include impaired development and function of the reproductive tract and permanently altered gene expression, leading to metabolic and hormonal disorders, reduced fertility and fecundity, and illnesses such as testicular, prostate, uterine, and cervical cancers later in life. This executive summary reviews effects of pre- and postnatal exposures on male and female reproductive health, and provides a series of recommendations for advancing the field in the areas of research, policy, health care, and community action.

Pesticide exposure, risk factors and health problems among cutflower farmers: a cross sectional study

This was a cross-sectional study which aimed to determine associations between hematologic indices such as red blood cell cholinesterase (RBC) and mean corpuscular volume (MCV), with illnesses related to pesticide exposure among cutflower farmers in La Trinidad, Benguet. One hundred two (102) randomly selected cutflower farmers underwent comprehensive, personal physical health and laboratory examinations and answered a questionnaire on work practices and illness. Majority were males (52%) and most belonged to the 20–35 age group (45%). Majority of exposed farmers were symptomatic, with most common complaints being headache (48%), easy fatigability (46.1%) and cough (40.2%). Analysis showed that RBC cholinesterase levels were positively associated with age (p = 0.02), and selling pesticide containers (p = 0.008). number of years of using pesticides (p = 0.022), use of contaminated cloth (p = 0.033), incorrect mixing of pesticides (p = 0.041), sex (p = 0.002) and illness due to pesticides (p = 0.005) were correlated with abnormal MCV. Significant associations were also found for hemoglobin, hematocrit, RBC, white blood cell (WBC) and platelet count. Predictors of RBC cholinesterase were years of pesticide use (p = 0.037) and abnormalities on health (p = 0.029). The findings of the study can be used for information dissemination and pesticide reduction programs for the cutflower farmers.

Adverse health effects of children's exposure to pesticides: what do we really know and what can be done about it

Children may be exposed to pesticides in several ways, such as by transplacental transfer during foetal life, by intake of contaminated breast milk and other nutrients, or by contact with contaminated subjects and areas in the environment such as pets treated with insecticides, house dust, carpets and chemically treated lawns and gardens. Exposure early in life, and particularly during periods of rapid development, such as during foetal life and infancy, may have severe effects on child health and development by elevating the risk of congenital malformations, cancer, malabsorption, immunological dysfunction, endocrine disease, and neurobehavioural deficiencies. As pesticides can also interfere with parental reproductive health, exposure of parents may have consequences for the offspring leading to reduced chance of male birth and increased risk of childhood cancer.

CONCLUSIONS

Current knowledge about tolerable levels and consequences of toxic exposure to pesticides during human development is rather scarce. Owing to the high risk of exposure to pesticides, particularly in less developed countries, further elucidation by well-controlled epidemiological studies in this field it is urgently needed. The Policy Interpretation Network on Children's Health and Environment (PINCHE), which is financed by the EU DG research has suggested actions against pesticide exposure. They have been presented and discussed in this paper. Several suggestions of PINCHE concerning action needed regarding pesticides were presented in the paper.

Pesticide exposure: the hormonal function of the female reproductive system disrupted?

Some pesticides may interfere with the female hormonal function, which may lead to negative effects on the reproductive system through disruption of the hormonal balance necessary for proper functioning. Previous studies primarily focused on interference with the estrogen and/or androgen receptor, but the hormonal function may be disrupted in many more ways through pesticide exposure. The aim of this review is to give an overview of the various ways in which pesticides may disrupt the hormonal function of the female reproductive system and in particular the ovarian cycle. Disruption can occur in all stages of hormonal regulation: 1. hormone synthesis; 2. hormone release and storage; 3. hormone transport and clearance; 4. hormone receptor recognition and binding; 5. hormone postreceptor activation; 6. the thyroid function; and 7. the central nervous system. These mechanisms are described for effects of pesticide exposure in vitro and on experimental animals in vivo. For the latter, potential effects of endocrine disrupting pesticides on the female reproductive system, i.e. modulation of hormone concentrations, ovarian cycle irregularities, and impaired fertility, are also reviewed. In epidemiological studies, exposure to pesticides has been associated with menstrual cycle disturbances, reduced fertility, prolonged time-to-pregnancy, spontaneous abortion, stillbirths, and developmental defects, which may or may not be due to disruption of the female hormonal function. Because pesticides comprise a large number of distinct substances with dissimilar structures and diverse toxicity, it is most likely that several of the above-mentioned mechanisms are involved in the pathophysiological pathways explaining the role of pesticide exposure in ovarian cycle disturbances, ultimately leading to fertility problems and other reproductive effects. In future research, information on the ways in which pesticides may disrupt the hormonal function as described in this review, can be used to generate specific hypotheses for studies on the effects of pesticides on the ovarian cycle, both in toxicological and epidemiological settings.

Exposure to pesticides and time to pregnancy among female greenhouse workers

The aim of the study was to evaluate the possible effect of maternal work in greenhouses, as characterised by potentially high exposure to pesticides, on female fertility. Nine hundred and ten women active in 34 greenhouse flower growing enterprises in 1998-2000, with at least one pregnancy, and aged less than 50 years were identified. Seven hundred and seventeen (79%) agreed to be interviewed and reported 1699 pregnancies, of which 713 had complete information on time to pregnancy and occupation. These pregnancies were classified as exposed or non-exposed according to the maternal occupation in greenhouses at the moment of conception and analysed using logistic regression and survival analysis methods. We found a slightly higher proportion of pregnancies with delayed conception (more than 6 months) in the exposed group. However, after adjustment for confounding variables, the estimated hazard ratio for reduced fertility among the exposed was not significantly different to that of the non-exposed pregnancies (HR=0.96, 95%CI: 0.81, 1.13). A significant reduction in fecundability was observed in older women and with a daily consumption of one or more alcoholic beverages or cups of tea.

In Utero and Lactational Exposure to an Environmentally Relevant Organochlorine Mixture Disrupts Reproductive Development and Function in Male Rats1

We hypothesized that in utero and lactational exposure of male rats to a mixture of more than 15 organochlorines, resembling that found in blubber from northern Quebec seals, alters reproductive development and function. Female rats were gavaged with either corn oil (controls) or the organochlorine mixture in increasing doses (low, medium, and high) for 5 wk before mating and through gestation. Developmental effects were monitored in the male offspring from Postnatal Day (PND) 2 until PND 90. The high-dose mixture reduced the number of pups per litter, percentage of live offspring, and pup weights (P < 0.05). Because only three rats from the high-dose treatment survived, data from this group beyond PND 2 were not included in the statistical analyses. As assessed by the time of preputial separation, puberty was delayed in the pups from treated dams (P < 0.05). Testes weights in the medium-dose group were greater than those in controls on PND 21 (P < 0.05). Ventral prostate weights were lower for the medium-dose group on PND 60 (P < 0.05). On PND 90, weights of the epididymis, ventral prostate, and seminal vesicle of the medium-dose rats were reduced compared to those of controls (P < 0.05). On PND 90, sperm motility parameters assessed by computer-assisted sperm analysis were altered in the low- and medium-dose groups (P < 0.05). Testicular and epididymal morphology was severely affected in rats exposed to the high dose of the mixture. Serum testosterone, LH, FSH, prolactin, and total thyroxine levels did not differ because of organochlorine treatment. Therefore, in utero and lactational exposure to an environmentally relevant organochlorine mixture adversely affects the reproductive system of male rats, perhaps via antiandrogenic effects during testis development, suggesting a possible reproductive health hazard for humans and other species.

Environmental and occupational factors affecting fertility and IVF success

Reproductive function has been shown to be sensitive to changes in the physical, psychosocial and chemical environments. Although reproductive effects of occupational exposure to hazardous chemicals have been well documented in the literature, the potential effects of chemical contaminants at levels representative of contemporary exposures in the general population are much less certain. Evidence for adverse effects of exposure to environmental contaminants is more conclusive among the lower animals than for humans where considerable controversy remains. In addition to potential reproductive hazards of exposure to environmental contaminants, there is also evidence for adverse reproductive effects of the physical and psychosocial environments. In this review we focus on the difficulties involved in linking exposure to putative hazardous substances in environmental and occupational settings to adverse reproductive outcomes, especially success of IVF procedures. We highlight the plausibility of adverse events through animal and cell studies and the application of these results to the interpretation of human data. We consider both the male and female partners since it is essentially their combined contributions of gametes which may be affected by chemicals, which lead to successful outcomes.

The use of pesticides in a Polish rural population and its effect on birth weight

INTRODUCTION

The risk of adverse reproductive outcomes related to pesticide exposure has been investigated in few studies; however, the results have not been consistent. The goal of the present study was to evaluate the influence of maternal residual exposure to pesticides on birth weight among women in an agricultural district in Central Poland.

METHOD

Subjects included 104 women who delivered a single, live infant between 1 January 1994 and 31 December 2000. Based on maternal reports, the type of farming (crops, orchards, non-farming jobs), involvement in field work and the trade names of pesticides used within last pregnancy were established. Birth weight for the most recent pregnancy was abstracted from the medical data of the local maternity unit.

RESULTS

Mothers who reported involvement in field work had a similar pregnancy duration but delivered infants with a significantly higher birth weight than mothers not reporting such activities in the first or second trimester of pregnancy (P=0.04). However, after controlling for pregnancy duration and other factors affecting birth weight, we found that maternal exposure to synthetic pyrethroids in the first or second trimester was associated with a small but statistically significant decrease in birth weight (P=0.02).

CONCLUSIONS

We postulate that the observed effect of pyrethroids exposure was related to a slower pace of foetal development corresponding to the small-for-gestational-age (SGA) birth.

Risk factors for female infertility in an agricultural region

BACKGROUND

Recent studies have suggested that agricultural occupations or exposure to pesticides may impair female fertility.

METHODS

The Fertility Risk Factor Study retrospectively examined agricultural and residential exposures and the risk of female infertility. Cases and controls (N = 322 each) came from women who sought treatment at a large group medical clinic in Wisconsin. Women and their male partners provided information on health, occupational and lifestyle exposures in response to a telephone interview during 1997-2001.

RESULTS

Mixing and applying herbicides 2 years before attempting conception was more common among infertile women (odds ratio [OR] = 27; 95% confidence interval [CI] = 1.9-380), as was the use of fungicides (OR = 3.3; CI = 0.8-13). Residing on a farm, ranch or in a rural area during this time period was protective of female fertility. Households supplied with central Wisconsin groundwater were at less risk for infertility than households using municipal sources (OR = 0.6; CI = 0.4-0.9). Behavioral risk factors included alcohol consumption (OR = 1.8; 1.2-2.5), smoking (1.6; 0.9-2.9), passive smoke exposure (1.8; 1.2-2.5), steady weight gain in adult life (3.5; 2.0-6.1), and having a male partner over the age of 40 (4.5; 1.2-16.3). Drinking 3 or more glasses of milk per day was protective of female fertility (0.3; 0.1-0.7).

CONCLUSION

These results suggest that certain agricultural, residential and lifestyle choices may modify the risk of female infertility.

Do environmental contaminants adversely affect human reproductive physiology?

There is increasing concern among Canadian women that unwitting and unwanted exposures to environmental contaminants are adversely affecting their health, particularly their ability to become pregnant and have a healthy baby. Evidence of adverse reproductive outcomes among populations exposed to environmental contaminants in the workplace via accidental poisoning, together with detection of environmental contaminant residues in serum and ovarian follicular fluid, has led to the hypothesis that chemical contaminants may be contributing to adverse reproductive outcomes such as infertility, endometriosis, polycystic ovary syndrome, spontaneous abortion, preterm labour, intrauterine growth restriction, and pregnancy-induced hypertension in the general population. The lack of clear evidence concerning the association between exposure to environmental contaminants and adverse reproductive outcomes hampers the clinician's ability to counsel women who are trying to conceive or who have concerns about their pregnancy. This review summarizes the evidence linking environmental contaminant exposure to selected adverse health outcomes by examining the changes in health-outcome trends, the consistency of the epidemiological evidence of an association between the health outcome of concern and exposure to environmental contaminants, and the biological plausibility for environmental contaminant mediated effects on human reproductive health. At best, only a moderate association can be found linking exposure to environmental contaminants with evidence of deleterious reproductive effects in women. Lack of disease trend data, weak exposure assessments, and limited mechanistic data supporting the biological plausibility of potential effects are the primary limitations to the hypothesis that exposure to environmental contaminants adversely affects human reproductive physiology.