Evidence of reproductive endocrine effects in women with occupational fuel and solvent exposures

Impact of xylene exposure during organogenesis on foeto-placental efficiency and foetal viability: Exploring its association with oxidative stress-induced inflammation and apoptosis in utero

The potential maternal and foetal toxicity resulting from exposure to xylene at or below the allowable limit of 100 ppm during gestation is not thoroughly studied. The aim of this study was to investigate maternal and foetal outcomes following prenatal exposure to xylene during organogenesis. Pregnant Sprague Dawley (SD) rats were administered intraperitoneal (IP) corn oil (vehicle), 100, 500, and 1000 parts per million (ppm) of xylene from gestational day (GD) 6 until GD17. Clinical signs, maternal weight gain, and food consumption were recorded daily. A caesarean hysterectomy was performed on GD21 to assess the reproductive and foetal outcomes. Exposure to 1000 ppm of xylene caused a significant decrease in the maternal body weight and food consumption, and an increase in intrauterine foetal deaths. Foetal assessment revealed a significant decrease in foetal weight in both male and female foetuses of female rats treated with 500 and 1000 ppm. Male placental weight was significantly decreased in all xylene-treated groups, while 1000 ppm xylene significantly decreased female placental weight. Histologically, marked uterine inflammatory lesions, fibrosis of the liver and renal tissues, as well as increased placental glycogen content were observed. Immunohistochemistry revealed a significant increase in lipid peroxidation and apoptotic markers. Thus, the foeto-maternal toxicities of xylene have been shown to be mediated by a systemic inflammatory response that exacerbates intrauterine oxidative stress and impairs foeto-placental transfer, leading to an increase in foetal mortality.

The human health effects of unconventional oil and gas (UOG) chemical exposures: a scoping review of the toxicological literature

Many chemicals associated with unconventional oil and natural gas (UOG) are known toxicants, leading to health concerns about the effects of UOG. Our objective was to conduct a scoping review of the toxicological literature to assess the effects of UOG chemical exposures in models relevant to human health. We searched databases for primary research studies published in English or French between January 2000 and June 2023 on UOG-related toxicology studies. Two reviewers independently screened abstracts and full texts to determine inclusion. Seventeen studies met our study inclusion criteria. Nine studies used solely in vitro models, while six conducted their investigation solely in animal models. Two studies incorporated both types of models. Most studies used real water samples impacted by UOG or lab-made mixtures of UOG chemicals to expose their models. Most in vitro models used human cells in monocultures, while all animal studies were conducted in rodents. All studies detected significant deleterious effects associated with exposure to UOG chemicals or samples, including endocrine disruption, carcinogenicity, behavioral changes and metabolic alterations. Given the plausibility of causal relationships between UOG chemicals and adverse health outcomes highlighted in this review, future risk assessment studies should focus on measuring exposure to UOG chemicals in human populations.

Environmental Exposures and Anti-Müllerian Hormone: A Mixture Analysis in the Nurses' Health Study II

BACKGROUND

Previous studies have linked environmental exposures with anti-Müllerian hormone (AMH), a marker of ovarian reserve. However, associations with multiple environment factors has to our knowledge not been addressed.

METHODS

We included a total of 2,447 premenopausal women in the Nurses' Health Study II (NHSII) who provided blood samples during 1996-1999. We selected environmental exposures linked previously with reproductive outcomes that had measurement data available in NHSII, including greenness, particulate matter, noise, outdoor light at night, ultraviolet radiation, and six hazardous air pollutants (1,3-butadiene, benzene, diesel particulate matter, formaldehyde, methylene chloride, and tetrachloroethylene). For these, we calculated cumulative averages from enrollment (1989) to blood draw and estimated associations with AMH in adjusted single-exposure models, principal component analysis (PCA), and hierarchical Bayesian kernel machine regression (BKMR).

RESULTS

Single-exposure models showed negative associations of AMH with benzene (percentage reduction in AMH per interquartile range [IQR] increase = 5.5%, 95% confidence interval [CI] = 1.0, 9.8) and formaldehyde (6.1%, 95% CI = 1.6, 10). PCA identified four major exposure patterns but only one with high exposure to air pollutants and light at night was associated with lower AMH. Hierarchical BKMR pointed to benzene, formaldehyde, and greenness and suggested an inverse joint association with AMH (percentage reduction comparing all exposures at the 75th percentile to median = 8.2%, 95% CI = 0.7, 15.1). Observed associations were mainly among women above age 40.

CONCLUSIONS

We found exposure to benzene and formaldehyde to be consistently associated with lower AMH levels. The associations among older women are consistent with the hypothesis that environmental exposures accelerate reproductive aging.

Benzene exposure causes structural and functional damage in rat ovaries: occurrence of apoptosis and autophagy

Studies to date have provided evidence for damage that can occur from hydrocarbon benzene on different tissues/organs. However, little is known regarding the possible influence of this hydrocarbon on female reproduction. In this study, female Wistar rats were treated with low (2000 ppm), middle (4000 ppm), and high (8000 ppm) doses of benzene by inhalation for 30 min daily for 28 days. Benzene exposure adversely affected ovarian function and structure by inducing histopathological changes and altering reproductive steroid hormone release. In addition, benzene-exposed ovaries exhibited increased TMR red fluorescent signals at middle and high doses, revealing significant apoptosis. Interestingly, the investigation of the autophagic protein marker LC3 showed that this protein significantly increased in all benzene-treated ovaries, indicating the occurrence of autophagy. Moreover, ovaries from benzene-treated groups exhibited differential regulation of several specific genes involved in ovarian folliculogenesis and steroidogenesis, including the INSL3, CCND1, IGF-1, CYP17a, LHR, ATG5, and GDF9 genes.

Effect of Xylene Oral Exposure on the Mouse Uterus – A Preliminary Study

Xylene is one of the environmental pollutants with a negative impact mainly on several organ systems. The aim of this study was to determine the effect of xylene on the uterus of mice. The study was performed on 12 adult female mice. Control mice (n = 6) were fed shredded pellets at a dose of 4 g per day. Xylene mice (n = 6) were fed the same diet at the same dose and orally administered xylene at 10 μl per day for 14 days. The mice were synchronized using the Whit-ten effect and introduced to males before the end of the procedure. Mice of both groups with no copulation plug were euthanized by cervical dislocation. The uteri were collected for routine histological and immunohistochemical analysis. The endometrial epithelium demonstrated vacuolar degeneration, mitotic cell activity, and the presence of leukocytes typical of metoestrus. Reductions of the endometrium, stroma, and myometrium were observed in the xylene mice. The xylene application did not have a significant effect on the superficial epithelium, or the size and number of uterine tubular glands. The immunohistochemical analysis of a proliferation marker PCNA revealed that the xylene increased its expression in the stroma, endometrial and myometrial cells, but did not significantly affect the superficial epithelial cells. The expression of an anti-apoptotic marker Bcl-xl in the xylene mice was stronger in the superficial epithelial, stromal, and endometrial cells. The Bcl-xl expression in the myometrial cells was similar to the controls. The results showed that the application of xylene stimulated the proliferation and exerted an anti-apoptotic effect on the uterine cells. However, the increased proliferation can lead to the malignant transformation of cells, resulting in their uncontrollable division.

Dietary Supplementation of Flaxseed (Linum usitatissimum L.) Alters Ovarian Functions of Xylene-Exposed Mice

The aim of the performed study was to examine the ability of xylene, flaxseed, and their combinations to affect morphological and endocrine indexes of murine ovaries. The 72 indexes of secondary and tertiary follicular cells, oocytes, corpora lutea, and ovarian stroma have been quantified: diameter, markers of proliferation PCNA and apoptosis caspase 3, receptors to FSH, oxytocin, estrogen (alpha and beta), and progesterone. In addition, concentrations of the ovarian hormones progesterone, estradiol, and IGF-I in the blood, as well as their production by isolated ovaries cultured with and without gonadotropins (FSH + LH mixture), were determined using histological, immunohistochemical, and immunoassay analyses. The character of xylene and flaxseed effects on ovarian functions in mice depended on the stage of ovarian folliculogenesis. It was shown that flaxseed could mitigate and prevent the major (63%) effects of xylene on the ovary. In addition, the ability of gonadotropins to affect ovarian hormone release and prevent its response to xylene has been shown. The effects of these additives could be mediated by changes in the release and reception of hormones. These observations suggest that flaxseed and possibly gonadotropins could be natural protectors of a female reproductive system against the adverse effects of xylene.

Tribulus terrestris can suppress the adverse effect of toluene on bovine and equine ovarian granulosa cells

Influence of oil-related product toluene and herbal remedy puncturevine Tribulus terrestris L. (TT) on female reproduction is known. However, mechanisms of their action on ovaries in different species and potential protective effect of TT against adverse toluene action remain to be established. We studied effect of toluene, TT, and their combination on ovarian granulosa cells from two mammalian species (cows and horses). Viability, markers of proliferation (PCNA) and apoptosis (bax), steroid hormones, IGF-I, oxytocin, and prostaglandin F (PGF) release were analyzed by trypan blue exclusion test, quantitative immunocytochemistry, and EIA/ELISA. Toluene suppressed all analyzed parameters. In both species, TT stimulated proliferation and reduced progesterone, oxytocin, and PGF. In horses, TT inhibited testosterone and IGF-I. In both species, TT supported toluene effect on viability, steroids, IGF-I, and PGF, inverted its action on apoptosis. In cows, TT promoted toluene effect on proliferation. In horses, TT supported toluene effect on oxytocin but suppressed its influence on proliferation. In both species, toluene induced inhibitory action of TT on viability, steroids, IGF-I, and PGF, prevented its stimulatory action on proliferation. In cows, toluene supported inhibitory action of TT on oxytocin and prevented its stimulatory action on apoptosis. In horses, toluene induced stimulatory effect of TT on apoptosis. Our results indicate potential toxic toluene effect on farm animal ovaries, applicability of TT as a biostimulator of farm animal reproduction and as a protector against adverse influence of toluene on female reproduction.

Toxicological Effects of Technical Xylene Mixtures on the Female Reproductive System: A Systematic Review

Technical xylene is a compound of massive production that is used in applications such as petrochemical and healthcare laboratories. Exposure to xylene can cause acute and chronic effects in humans and animals. Currently available studies regarding xylene’s adverse effects with credible designs were dated almost twenty years ago. This systematic review summarizes the findings regarding the detrimental effects of technical xylene from human, animal, and in vitro studies. It recapitulated available studies with respect to the effects of xylene on the female reproductive system to stress the need for updating the current data and guidelines. Based on pre-specified criteria, 22 studies from journal databases exploring the toxic effects of xylene on menstruation, endocrine endpoints, fetal development, and reproductive functions were included for the review. It was found that related studies with a specific focus on the effects of technical xylene on the female reproductive system were insufficient. Therefore, further studies are necessary to update the existing data, thus improving the quality and reliability of risk assessment of exposure to xylene in pregnant women

Occupational health hazards and wide spectrum of genetic damage by the organic solvent fumes at the workplace: A critical appraisal

Long-term exposure to organic solvents is known to affect human health posing serious occupational hazards. Organic solvents are genotoxic, and they can cause genetic changes in the exposed employees' somatic or germ cells. Chemicals such as benzene, toluene, and gasoline induce an excessive amount of genotoxicity results either in genetic polymorphism or culminates in deleterious mutations when concentration crosses the threshold limits. The impact of genotoxicity is directly related to the time of exposure, types, and quantum of solvent. Genotoxicity affects almost all the physiological systems, but the most vulnerable ones are the nervous system, reproductive system, and blood circulatory system. Based on the available literature report, we propose to evaluate the outcomes of such chemicals on the exposed humans at the workplace. Attempts would be made to ascertain if the long-term exposure makes a person resistant to such chemicals. This may seem to be a far-fetched idea but has not been studied. The health prospect of this study is envisaged to complement the already existing data facilitating a deeper understanding of the genotoxicity across the population. This would also demonstrate if it correlates with the demographic profile of the population and contributes to comorbidity and epidemiology.

Blood absorption toxicokinetics of glycol ethers after inhalation: A human controlled study

Glycol ethers are organic solvents present in countless products for professional and domestic use. The main toxicological concerns are hematotoxicity, respiratory and reproductive toxicity. The general population can be exposed when using products containing one or several glycol ethers that evaporate or if sprayed, generate aerosols that can be inhaled. The rate at which glycol ethers enters blood following inhalation exposure are unknown in humans, and chemical risk assessors only rely on animal and in vitro toxicity studies. Propylene glycol monomethyl ether (PGME) and propylene glycol monobutyl ether (PGBE) are two examples of glycol ethers used worldwide. Our study aimed to provide human toxicokinetic data after inhalation exposure of low PGME and PGBE concentrations tested alone or in mixture. Healthy participants (n = 28) were exposed to 35 ppm (131 mg/m³) of PGME and 15 ppm (i.e., 83 mg/m³) of PGBE for 2 or 6 h. Blood was regularly collected during the exposure sessions. PGME and PGBE were immediately bioavailable in blood during exposure, and the mean absorption rates were up to 13 μg/L/min and 2.45 μg/L/min, respectively. Maximum mean blood concentration (Cmax) was 2.91 mg/L and 0.41 mg/L for PGME and PGBE. The cumulative internal doses over time (area under the curve, AUC) were 11 mg∗h/L and 1.81 mg∗h/L for PGME and PGBE. PGME and PGBE total blood uptake could possibly be higher in physically active individuals, such as workers. We recommend that glycol ethers present on the market undergo toxicological testing with the internal doses we found in our toxicokinetic study.

Investigating the Potential Toxicity of Hydraulic Fracturing Flowback and Produced Water Spills to Aquatic Animals in Freshwater Environments: A North American Perspective

Unconventional methods of oil and natural gas extraction have been a growing part of North America's energy sector for the past 20-30 years. Technologies such as horizontal hydraulic fracturing have facilitated the exploitation of geologic reserves that were previously resistant to standard drilling approaches. However, the environmental risks associated with hydraulic fracturing are relatively understudied. One such hazard is the wastewater by-product of hydraulic fracturing processes: flowback and produced water (FPW). During FPW production, transport, and storage, there are many potential pathways for environmental exposure. In the current review, toxicological hazards associated with FPW surface water contamination events and potential effects on freshwater biota are assessed. This review contains an extensive survey of chemicals commonly associated with FPW samples from shale formations across North America and median 50% lethal concentration values (LC₅₀) of corresponding chemicals for many freshwater organisms. We identify the characteristics of FPW which may have the greatest potential to be drivers of toxicity to freshwater organisms. Notably, components associated with salinity, the organic fraction, and metal species are reviewed. Additionally, we examine the current state of FPW production in North America and identify the most significant obstacles impeding proper risk assessment development when environmental contamination events of this wastewater occur. Findings within this study will serve to catalyze further work on areas currently lacking in FPW research, including expanded whole effluent testing, repeated and chronic FPW exposure studies, and toxicity identification evaluations.

Polybrominated Biphenyl Exposure and Menstrual Cycle Function

BACKGROUND

Brominated flame retardants, including polybrominated biphenyls (PBB), are persistent compounds reported to affect sex hormones in animals; less is known about potential effects in humans. An industrial accident in 1973-1974 exposed Michigan residents to PBB through contaminated food. We examined whether this exposure to PBB had long-term effects on menstrual cycle function.

METHODS

In 2004-2006, we recruited reproductive-aged women in the Michigan PBB Registry who were not pregnant, lactating, or taking hormonal medications. Participants kept daily diaries and provided daily urine samples for up to 6 months. We assayed the urine samples for estrone 3-glucuronide (E13G), pregnanediol 3-glucuronide (Pd3G), and follicle stimulating hormone (FSH). We fit linear mixed models among women aged 35-42 years to describe the relation between serum PBB levels and log-transformed, creatinine-adjusted daily endocrine levels among women who were premenarchal during the exposure incident in 1973-1974 (n = 70).

RESULTS

We observed that high (>3.0 parts per billion [ppb]) and medium (>1.0-3.0 ppb) PBB exposure were associated with lower E13G levels across the menstrual cycle and lower FSH levels during the follicular phase, compared with low PBB exposure (≤1.0 ppb). High PBB exposure was also associated with lower Pd3G levels across the cycle compared with low PBB exposure, whereas Pd3G levels were similar in women with medium and low PBB exposure.

CONCLUSION

Our results are consistent with a hypothesized effect of exposure to an exogenous estrogen agonist but the modest sample size of the study requires cautious interpretation.

Ayurvedic formulations containing benzoic and ascorbic acids as additives: benzene formation during storage and impact of additives on quality parameters

OBJECTIVES

Ayurvedic formulations are becoming the prior choice of people as health care supplements. The increasing demand for these formulations has led to extensive development of Ayurvedic pharmaceutical industries worldwide. The reaction between the preservatives (sodium benzoates and ascorbic acid) used in these formulations could generate benzene. Benzene is classified as class-1 human carcinogen and responsible for various short and long term health effects.

METHODS

In this study, 25 formulations (containing ascorbic acid and sodium benzoate) of various manufacturers available as over the counter products were obtained and their benzene content were determined using gas chromatograph with flame ionization detector.

RESULTS

The result showed that 64% of the formulations were free from benzene contamination whereas 36% of formulations were found to be contaminated with benzene. A simple, less time-consuming, economic, and validated gas chromatographic method for estimation of benzene in Ayurvedic formulations was also developed successfully in present study.

CONCLUSIONS

The data revealed that the level of benzene was within permissible limits, yet the presence of a carcinogen in the marketed formulations intended for internal use is an alarming situation.

Hormonal Profiles of Menstrual Bleeding Patterns During the Luteal-Follicular Transition

CONTEXT

Menstrual cycle function is determined by a complex endocrine axis that controls the ovaries and endometrium. While the late luteal phase is characterized by declining progesterone and estrogen, how these hormonal profiles relate to menstrual bleeding patterns is not well understood.

OBJECTIVE

Characterize associations between luteal phase hormonal profiles and subsequent menstrual bleeding patterns, specifically spotting before bleeding.

DESIGN, SETTING, AND PARTICIPANTS

We examined creatinine-adjusted urinary estrone 3-glucuronide (E13G) and pregnanediol 3-glucuronide (Pd3G) levels in relation to spotting in 116 premenopausal women (ages 20-47) who kept daily menstrual diaries and collected first morning urine samples for ≥ 2 consecutive cycles or 1 luteal-follicular transition (n = 283 transitions). We used linear mixed models to estimate associations between luteal phase hormone levels and spotting before bleeding.

MAIN OUTCOME MEASURE(S) AND RESULTS

Transitions with ≥ 1 days of spotting before menstrual bleeding (n = 118) had greater luteal phase Pd3G levels vs nonspotting transitions (n = 165). Differences in Pd3G between spotting and nonspotting transitions were largest at menses onset (34.8%, 95% confidence interval, 18.9%, 52.7%). Pd3G levels for spotting transitions dropped to similar levels as nonspotting transitions an average of 1 day later, which aligned with the first day of bleeding for transitions with contiguous spotting. Spotting transitions were preceded by slower rates of Pd3G decline than nonspotting transitions, whereas E13G declines were similar.

CONCLUSIONS

Self-reported bleeding patterns may provide insight into luteal phase Pd3G levels. First bleed appears to be the best choice for defining the end of the luteal phase and achieving hormonal consistency across transitions.

No Correlation between Blood Benzene Levels and Luteinizing Hormone Plasma Values in Outdoor Workers

OBJECTIVE

The purpose of the study is to evaluate whether low-dose exposure to benzene, an environmental pollutant to which male and female traffic policemen are daily exposed to could cause alterations in plasma luteinizing hormone (LH) levels.

METHODS

From an initial sample of 1594 workers, we only selected 95 workers of whom study we knew the values of late-shift benzene and LH hormone. All subjects underwent biological monitoring (final blood benzene evaluation) and luteinizing hormone dosing. Excluding subjects with the main confounding factors, the final sample included 76 workers. The normal distribution of the variables was evaluated using the Kolmogorov - Smirnov test, followed by the logarithmic transformation of the LH and benzene values. The comparison among means was performed by using the t-test for the independent samples. The ANOVA test was performed for variables with more than 2 modes (ages and seniority) and Pearson correlation index between variables in the total sample and after subdivision as to sex, job, sports activity and smoking. The results were considered significant when p values were less than 0.05.

RESULTS/CONCLUSION

The study did not show a correlation between benzene levels and LH plasma levels in outdoor workers.

Assessing effects of germline exposure to environmental toxicants by high-throughput screening in C. elegans

Chemicals that are highly prevalent in our environment, such as phthalates and pesticides, have been linked to problems associated with reproductive health. However, rapid assessment of their impact on reproductive health and understanding how they cause such deleterious effects, remain challenging due to their fast-growing numbers and the limitations of various current toxicity assessment model systems. Here, we performed a high-throughput screen in C. elegans to identify chemicals inducing aneuploidy as a result of impaired germline function. We screened 46 chemicals that are widely present in our environment, but for which effects in the germline remain poorly understood. These included pesticides, phthalates, and chemicals used in hydraulic fracturing and crude oil processing. Of the 46 chemicals tested, 41% exhibited levels of aneuploidy higher than those detected for bisphenol A (BPA), an endocrine disruptor shown to affect meiosis, at concentrations correlating well with mammalian reproductive endpoints. We further examined three candidates eliciting aneuploidy: dibutyl phthalate (DBP), a likely endocrine disruptor and frequently used plasticizer, and the pesticides 2-(thiocyanomethylthio) benzothiazole (TCMTB) and permethrin. Exposure to these chemicals resulted in increased embryonic lethality, elevated DNA double-strand break (DSB) formation, activation of p53/CEP-1-dependent germ cell apoptosis, chromosomal abnormalities in oocytes at diakinesis, impaired chromosome segregation during early embryogenesis, and germline-specific alterations in gene expression. This study indicates that this high-throughput screening system is highly reliable for the identification of environmental chemicals inducing aneuploidy, and provides new insights into the impact of exposure to three widely used chemicals on meiosis and germline function.

The ever-increasing number of new chemicals introduced into our environment poses a significant problem for risk assessment. In addition, assessing the direct impact of toxicants on human meiosis remains challenging. We successfully utilized a high-throughput platform in the nematode C. elegans, a genetically tractable model organism which shares a high degree of gene conservation with humans, to identify chemicals that affect the germline leading to aneuploidy. We assessed chemicals that are highly prevalent in the environment in worms carrying a fluorescent reporter construct allowing for the identification of X chromosome nondisjunction combined with a mutation increasing cuticle permeability for analysis of low doses of exposure. Follow up analysis of three chemicals: DBP, permethrin and TCMTB, further validated the use of this strategy. Exposure to these chemicals resulted in elevated levels of DNA double-strand breaks, activation of a DNA damage checkpoint, chromosome morphology defects in late meiotic prophase I as well as impaired early embryogenesis and germline-specific changes in gene expression. Our results support the use of this high-throughput screening system to identify environmental chemicals inducing aneuploidy, and provide new insights into the effects of exposure to DBP, permethrin, and TCMTB on meiosis and germline function.

Health Risk Associated with Exposure to PM10 and Benzene in Three Italian Towns

Air pollution in urban areas is a major concern as it negatively affects the health of a large number of people. The purpose of this study was to assess the inhalation health risk for exposure to PM10 and benzene of the populations living in three Italian cities. Data regarding PM10 and benzene daily measured by "traffic" stations and "background" stations in Torino, Perugia, and Lecce during 2014 and 2015 were compared to the limits indicated in the Directive 2008/50/EC. In addition, an inhalation risk analysis for exposure to benzene was performed for adults and children by applying the standard United States Environmental Protection Agency's (USEPA) methodology. The levels of PM10 detected in Torino exceeded the legal limits in both years with an increased mean concentration >10 µg/m³ comparing with background station. Benzene concentrations never exceeded the legislative target value. The increased cancer risk (ICR) for children exposed to benzene was greater than 1 × 10-6 only in the city of Torino, while for adults, the ICR was higher than 1 × 10-6 in all the cities. The results suggest the need for emission reduction policies to preserve human health from continuous and long exposure to air pollutants. A revision of legal limits would also be recommended.

Influence of oil-related environmental pollutants on female reproduction

The petroleum low-weight aromatic hydrocarbons benzene, toluene, ethylbenzene, m/p-xylene, and o-xylene, also known as BTEX, are among the most common hazardous sources of environmental contamination. This paper reviews the available data concerning the effects of BTEX on different aspects of female reproduction, including the fecundity, ovaries, central nervous system (CNS), oocytes, embryos, oviducts, cytogenetics of somatic and generative cells, intracellular signaling systems, and hypothalamic, pituitary and peripheral reproductive hormones. Analysis of the available literature demonstrates that BTEX can exert negative effects on various female reproductive sites, including the CNS-pituitary-ovarian axis, their signaling molecules and receptors, ovarian follicles, corpora lutea, oocytes, embryos, oviducts, ovarian cycles, fertility, and the viability of offspring. These effects could be due to the ability of BTEX to destroy chromosomes, to affect cell metabolism, including the accumulation of free radicals, and to affect the release of hormonal regulators of reproductive processes and intracellular protein kinases.

New insights on 'old' toxicants in occupational toxicology (Review)

In order to deliver the best possible working environment, it is essential to identify professional conditions that could be harmful for worker's health and prevent (or limit) the occurrence of such conditions. The appropriate use of personal protective equipment and the development of appropriate regulations allowed to reduce the prevalence of 'classic' occupational diseases, such as occupational hearing loss or asbestosis, just to name a few. Nowadays, environmental pollution seems to be one of the most relevant concerns for human and animal health, and toxicology is becoming one of the most prominent fields of interest in occupational settings. An increasing number of studies demonstrate that the presence of toxicants in the workplace could be responsible for the development of chronic diseases, even at doses that were considered 'safe'. The present review summarizes some of the most recent advancements in occupational toxicology, focusing on topics that have long been debated in the past and that have recently returned to the fore.

Towards sustainable and safe apparel cleaning methods: A review

Perchloroethylene (PERC) is a compound commonly used as a solvent in dry cleaning, despite its severe health and environmental impacts. In recent times chemicals such as hydrocarbons, GreenEarth(®), acetal and liquid carbon dioxide have emerged as less damaging substitutes for PERC, and an even more sustainable water-based wet cleaning process has been developed. We employed a systematic review approach to provide a comprehensive overview of the existing research evidence in the area of sustainable and safe apparel cleaning methods and care. Our review describes traditional professional dry cleaning methods, as well as those that utilise solvents other than PERC, and their ecological attributes. In addition, the new professional wet cleaning process is discussed. Finally, we address the health hazards of the various solvents used in dry cleaning and state-of-the-art solvent residue trace analysis techniques.

Occupational exposure to carcinogens: Benzene, pesticides and fibers (Review)

It is well known that the occupational exposure to contaminants and carcinogens leads to the development of cancer in exposed workers. In the 18th century, Percivall Pott was the first to hypothesize that chronic exposure to dust in the London chimney sweeps was associated with an increased risk of developing cancer. Subsequently a growing body of evidence indicated that other physical factors were also responsible for oncogenic mutations. Over the past decades, many carcinogens have been found in the occupational environment and their presence is often associated with an increased incidence of cancer. Occupational exposure involves several factors and the association between carcinogens, occupational exposure and cancer is still unclear. Only a fraction of factors is recognized as occupational carcinogens and for each factor, there is an increased risk of cancer development associated with a specific work activity. According to the International Agency for Research on Cancer (IARC), the majority of carcinogens are classified as 'probable' and 'possible' human carcinogens, while, direct evidence of carcinogenicity is provided in epidemiological and experimental studies. In the present review, exposures to benzene, pesticides and mineral fibers are discussed as the most important cancer risk factors during work activities.

Three components of cigarette smoke altered the growth and apoptosis of metastatic colon cancer cells via inducing the synthesis of reactive oxygen species and endoplasmic reticulum stress

Cigarette smoke (CS) is a well-known risk factor for carcinogenesis and has been found to be related to the occurrence and development of colon cancer. In this study, the effect of formaldehyde (FA), benzene (Bz), and isoprene (IP), which are included in main components of CS, on cell viability and apoptosis of SW620 colorectal cancer cells was examined to identify the connection between CS components and colon cancer. In cell viability assay, FA, Bz, and IP decreased cell viability of SW620 cells in a dose dependent manner. In Western blot assay, the protein expression of cell cycle related genes, cyclin D1 & E1, was decreased by FA, Bz, and IP, which corresponded to their inhibitory effect on cell viability. In addition, FA, Bz, and IP increased the protein expression of pro-apoptotic genes, C/EBP homologous protein (CHOP) and Bax, and reduced the protein expression of anti-apoptotic gene, Bcl-2. In reactive oxygen species (ROS) assay using dichlorofluorescin diacetate (DCFH-DA), FA, Bz, and IP increased the ROS production in SW620 cells. In the measurement of apoptotic cells, the numbers of apoptotic cells were increased by the treatment of FA, Bz, and IP. As CHOP is an endoplasmic reticulum (ER)-stress related apoptosis marker of which production is induced by ROS, it was considered that these CS components induce apoptosis of SW620 cells by increasing ROS synthesis and ER-stress. Taken together, these results showed that CS components, i.e., FA, Bz, and IP, inhibited the cell viability of SW620 cells by down-regulating the protein expression of cyclin D1 & E1 and induced apoptosis of SW620 cells by increasing ROS production and simultaneously activating ER-stress.

Menstrual cycle perturbation by organohalogens and elements in the Cree of James Bay, Canada

Persistent organohalogens (POHs) and metals have been linked to alterations in menstrual cycle function and fertility in humans. The Cree First Nations people living near James Bay in Ontario and Quebec, Canada, have elevated levels of POHs, mercury and lead compared to other Canadians. The present study examines the interrelationships between selected POHs and elements on menstrual cycle function in these Cree women. Menstrual cycle characteristics were derived from structured daily diaries and endocrine measurements from daily urine samples collected during one cycle for 42 women age 19-42. We measured 31 POHs in blood plasma and 18 elements in whole blood, for 31 of the participants. POHs and elements detected in ≥ 70% of the participants were transformed by principal component (PC) analysis to reduce the contaminant exposure data to fewer, uncorrelated PCA variables. Multiple regression analysis revealed that, after adjusting for confounders, PC-3 values showed significant negative association with cycle length, after adjusting for confounders (p = 0.002). PC-3 accounted for 9.2% of the variance and shows positive loadings for cadmium, selenium, and PBDE congeners 47 and 153, and a negative loading for copper. Sensitivity analysis of the model to quantify likely effect sizes showed a range of menstrual cycle length from 25.3 to 28.3 days using the lower and upper 95% confidence limits of mean measured contaminant concentrations to predict cycle length. Our observations support the hypothesis that the menstrual cycle function of these women may be altered by exposure to POHs and elements from their environment.

Benzene exposure is associated with epigenetic changes (Review)

Benzene is a volatile aromatic hydrocarbon solvent and is known as one of the predominant air pollutants in the environment. Chronic exposure to benzene is known to cause aplastic anemia and increased risk of acute myelogenous leukemia in humans. Although the mechanisms by which benzene causes toxicity remain to be fully elucidated, it is widely accepted that its metabolism is crucial to its toxicity, with involvement of one or more reactive metabolites. Novel approaches aimed at evaluating different mechanisms by which benzene can impact on human health by altering gene regulation have been developed. Among these novel approaches, epigenetics appears to be promising. The present review article summarizes the most important findings, reported from the literature, on epigenetic modifications correlated to benzene exposure. A computerized search in PubMed was performed in November 2014, using search terms, including 'benzene', 'epigenetic', 'histone modifications', 'DNA methylation' and 'microRNA'. Epidemiological and experimental studies have demonstrated the potential epigenetic effects of benzene exposure. Several of the epigenomic changes observed in response to environmental exposures may be mechanistically associated with susceptibility to diseases. However, further elucidation of the mechanisms by which benzene alters gene expression may improve prediction of the toxic potential of novel compounds introduced into the environment, and allow for more targeted and appropriate disease prevention strategies.

A review of environmental and occupational exposure to xylene and its health concerns

Xylene is a cyclic hydrocarbon, and an environmental pollutant. It is also used in dyes, paints, polishes, medical technology and different industries as a solvent. Xylene easily vaporizes and divides by sunlight into other harmless chemicals. The aim of the present review is to collect the evidence of the xylene toxicity, related to non-cancerous health hazards, as well as to provide possible effective measurement to minimize its risk ratio. For current study a bibliographic search of more than 250 peer-reviewed papers in scientific data including PubMed, and Google Scholar about xylene was done. But approximately 130 peer-reviewed papers relevant to xylene were included (Figure 1(Fig. 1)). All scientific data was reviewed with key words of "xylene toxicity", "xylene toxic health effects", "environmental volatile organic compounds", "human exposure to xylene", "xylene poisoning in laboratory workers", "effects of xylene along with other hydrocarbons", "neurotoxicity of selected hydrocarbons", and "toxic effects of particular xylene isomers in animals". According to these studies, xylene is released into the atmosphere as fugitive emissions from petrochemical industries, fire, cigarette, from different vehicles. Short term exposure to mixed xylene or their individual isomers result in irritation of the nose, eyes and throat subsequently leading toward neurological, gastrointestinal and reproductive harmful effects. In addition long term exposure to xylene may cause hazardous effects on respiratory system, central nervous system, cardiovascular system, and renal system. The health concerns of xylene are well documented in animals and human. It is important to improve health policies, launch xylene related health and toxicity awareness campaigns, to get rid of its dangerous outcomes. Chronic diseases have become a threat to human globally, with special prominence in regions, where xylene is used with other chemicals (benzene, toluene etc.) especially in petroleum and rubber industry. The mechanism of toxicity and interactions with endocrine system should be followed up which is the main threat to human health.

A review of environmental and occupational exposure to xylene and its health concerns

Xylene is a cyclic hydrocarbon, and an environmental pollutant. It is also used in dyes, paints, polishes, medical technology and different industries as a solvent. Xylene easily vaporizes and divides by sunlight into other harmless chemicals. The aim of the present review is to collect the evidence of the xylene toxicity, related to non-cancerous health hazards, as well as to provide possible effective measurement to minimize its risk ratio. For current study a bibliographic search of more than 250 peer-reviewed papers in scientific data including PubMed, and Google Scholar about xylene was done. But approximately 130 peer-reviewed papers relevant to xylene were included (Figure 1(Fig. 1)). All scientific data was reviewed with key words of "xylene toxicity", "xylene toxic health effects", "environmental volatile organic compounds", "human exposure to xylene", "xylene poisoning in laboratory workers", "effects of xylene along with other hydrocarbons", "neurotoxicity of selected hydrocarbons", and "toxic effects of particular xylene isomers in animals". According to these studies, xylene is released into the atmosphere as fugitive emissions from petrochemical industries, fire, cigarette, from different vehicles. Short term exposure to mixed xylene or their individual isomers result in irritation of the nose, eyes and throat subsequently leading toward neurological, gastrointestinal and reproductive harmful effects. In addition long term exposure to xylene may cause hazardous effects on respiratory system, central nervous system, cardiovascular system, and renal system. The health concerns of xylene are well documented in animals and human. It is important to improve health policies, launch xylene related health and toxicity awareness campaigns, to get rid of its dangerous outcomes. Chronic diseases have become a threat to human globally, with special prominence in regions, where xylene is used with other chemicals (benzene, toluene etc.) especially in petroleum and rubber industry. The mechanism of toxicity and interactions with endocrine system should be followed up which is the main threat to human health.

Breast cancer risk after occupational solvent exposure: the influence of timing and setting

Organic solvents are ubiquitous in occupational settings where they may contribute to risks for carcinogenesis. However, there is limited information on organic solvents as human breast carcinogens. We examined the relationship between occupational exposure to solvents and breast cancer in a prospective study of 47,661 women with an occupational history in the Sister Study cohort. Occupational solvent exposure was categorized using self-reported job-specific solvent use collected at baseline. Multivariable Cox regression analyses were used to assess breast cancer risk, adjusting for established breast cancer risk factors. A total of 1,798 women were diagnosed with breast cancer during follow-up, including 1,255 invasive cases. Overall the risk of invasive breast cancer was not associated with lifetime exposure to solvents [HR, 1.04; 95% confidence interval (CI), 0.88-1.24]. Parous women who worked with solvents before their first full-term birth had an increased risk of estrogen receptor-positive invasive breast cancer compared with women who never worked with solvents (HR, 1.39; 95% CI, 1.03-1.86). A significantly elevated risk for estrogen receptor-positive invasive breast cancer was associated with solvent exposure among clinical laboratory technologists and technicians (HR, 2.00; 95% CI, 1.07-3.73). Occupational exposure to solvents before first birth, a critical period of breast tissue differentiation, may result in increased vulnerability for breast cancer. Our findings suggest a need for future studies in this area to focus on exposure time windows and solvent types in different occupational settings.

Identification of genomic features in environmentally induced epigenetic transgenerational inherited sperm epimutations

A variety of environmental toxicants have been shown to induce the epigenetic transgenerational inheritance of disease and phenotypic variation. The process involves exposure of a gestating female and the developing fetus to environmental factors that promote permanent alterations in the epigenetic programming of the germline. The molecular aspects of the phenomenon involve epigenetic modifications (epimutations) in the germline (e.g. sperm) that are transmitted to subsequent generations. The current study integrates previously described experimental epigenomic transgenerational data and web-based bioinformatic analyses to identify genomic features associated with these transgenerationally transmitted epimutations. A previously identified genomic feature associated with these epimutations is a low CpG density (<12/100bp). The current observations suggest the transgenerational differential DNA methylation regions (DMR) in sperm contain unique consensus DNA sequence motifs, zinc finger motifs and G-quadruplex sequences. Interaction of molecular factors with these sequences could alter chromatin structure and accessibility of proteins with DNA methyltransferases to alter de novo DNA methylation patterns. G-quadruplex regions can promote the opening of the chromatin that may influence the action of DNA methyltransferases, or factors interacting with them, for the establishment of epigenetic marks. Zinc finger binding factors can also promote this chromatin remodeling and influence the expression of non-coding RNA. The current study identified genomic features associated with sperm epimutations that may explain in part how these sites become susceptible for transgenerational programming.

Current understandings and perspectives on non-cancer health effects of benzene: a global concern

OBJECTIVE

Benzene, as a volatile organic compound, is known as one of the main air pollutants in the environment. The aim of this review is to summarize all available evidences on non-cancerous health effects of benzene providing an overview of possible association of exposure to benzene with human chronic diseases, specially, in those regions of the world where benzene concentration is being poorly monitored.

METHODOLOGY

A bibliographic search of scientific databases including PubMed, Google Scholar, and Scirus was conducted with key words of "benzene toxic health effects", "environmental volatile organic compounds", "diabetes mellitus and environmental pollutants", "breast cancer and environmental pollution", "prevalence of lung cancer", and "diabetes prevalence". More than 300 peer reviewed papers were examined. Experimental and epidemiologic studies reporting health effects of benzene and volatile organic compounds were included in the study.

RESULTS

Epidemiologic and experimental studies suggest that benzene exposure can lead to numerous non-cancerous health effects associated with functional aberration of vital systems in the body like reproductive, immune, nervous, endocrine, cardiovascular, and respiratory.

CONCLUSION

Chronic diseases have become a health burden of global dimension with special emphasis in regions with poor monitoring over contents of benzene in petrochemicals. Benzene is a well known carcinogen of blood and its components, but the concern of benzene exposure is more than carcinogenicity of blood components and should be evaluated in both epidemiologic and experimental studies. Aspect of interactions and mechanism of toxicity in relation to human general health problems especially endocrine disturbances with particular reference to diabetes, breast and lung cancers should be followed up.

Evaluating the effects of maternal exposure to benzene, toluene, ethyl benzene, and xylene on oral clefts among offspring in Texas: 1999-2008

BACKGROUND

There is evidence from previous studies that maternal occupational exposure to hazardous air pollutants (HAPs) is positively associated with oral clefts; however, studies evaluating the association between residential exposure to these toxicants and oral clefts are lacking. Therefore, our goal was to conduct a case-control study examining the association between estimated maternal residential exposure to benzene, toluene, ethyl benzene, and xylene (BTEX) and the risk of oral clefts among offspring.

METHODS

Data on 6045 nonsyndromic isolated oral cleft cases (3915 cleft lip with or without cleft palate [CL ± P] and 2130 nonsyndromic isolated cleft palate [CP] cases) delivered between 1999 and 2008 were obtained from the Texas Birth Defects Registry. The control group was a sample of unaffected live births, frequency matched to cases on year of birth. Census tract-level estimates of annual average exposures were obtained from the U.S. Environmental Protection Agency 2005 Hazardous Air Pollutant Exposure Model (HAPEM5) for each pollutant and assigned to each subject based on maternal residence during pregnancy. Logistic regression was used to assess the relationship between estimated maternal exposure to each pollutant (BTEX) separately and the risk of oral clefts in offspring.

RESULTS

High estimated maternal exposure to benzene was not associated with oral clefts, compared with low estimated exposure (CL ± P adjusted OR = 0.95; 95% CI = 0.81 - 1.12; CP adjusted OR = 0.85; 95% CI = 0.67 - 1.09). Similar results were seen for the other pollutants.

CONCLUSION

In our study, there was no evidence that maternal exposure to environmental levels of BTEX was associated with oral clefts.

Antimüllerian hormone as a predictor of natural fecundability in women aged 30-42 years

OBJECTIVE

To generate estimates of the association between markers of ovarian aging and natural fertility in a community sample at risk for ovarian aging.

METHODS

Women aged 30-44 years with no history of infertility who had been trying to conceive for less than 3 months provided early-follicular phase serum and urine (N=100). Subsequently, these women kept a diary to record menstrual bleeding and intercourse and conducted standardized pregnancy testing for up to 6 months. Serum was analyzed for estradiol, follicle-stimulating hormone (FSH), antimüllerian hormone, and inhibin B. Urine was analyzed for FSH and estrone 3-glucuronide. Diary data on menstrual cycle day and patterns of intercourse were used to calculate day-specific fecundability ratios.

RESULTS

Sixty-three percent of participants conceived within 6 months. After adjusting for age, 18 women (18%) with serum antimüllerian hormone levels of 0.7 ng/mL or less had significantly reduced fecundability given intercourse on a fertile day compared with women with higher antimüllerian hormone levels (fecundability ratio 0.38; 95% confidence interval [CI] 0.08-0.91). The day-specific fecundability for women with early-follicular phase serum FSH values greater than 10 milli-international units/mL compared with women with lower FSH levels was also reduced, although nonsignificantly (11% of women affected; fecundability ratio 0.44; 95% CI 0.08-1.10). The association with urinary FSH was weaker (27% women affected; fecundability ratio 0.61; 95% CI 0.26-1.26), and the associations for the other markers were weaker still.

CONCLUSION

Early-follicular phase antimüllerian hormone appears to be associated with natural fertility in the general population.

LEVEL OF EVIDENCE

II.

Health outcomes among infants born to women deployed to United States military operations during pregnancy

BACKGROUND

Military professionals who deploy to combat operations may encounter hazards that could adversely affect reproductive health. Pregnant women are generally exempt from deployment to military operations; however, exposures to such environments may inadvertently occur. We investigated whether maternal deployment during pregnancy was associated with adverse health outcomes in infants.

METHODS

The United States Department of Defense Birth and Infant Health Registry identified infants born to military service women between 2002 and 2005, and defined their health outcomes at birth and in the first year of life. Multivariable modeling was applied to investigate preterm birth and birth defects among infants, based on maternal deployment experience during pregnancy.

RESULTS

Among 63,056 infants born to military women from 2002 to 2005, 22,596 were born to women with deployment experience in support of the current military operations before, during, or after their pregnancy. These included 2941 infants born to women who appeared to have been deployed some time during their first trimester of pregnancy. Compared to infants born to women who deployed at other times, or never deployed, exposed infants were not more likely to be born preterm, diagnosed with a major birth defect, or diagnosed with a malignancy.

CONCLUSIONS

In this exploratory analysis, infants born to women who inadvertently deployed to military operations during their pregnancy were not at increased risk of adverse birth or infant health outcomes. Future analyses should examine outcomes related to specific maternal exposures during deployment, and outcomes among the growing number of infants conceived after deployment.

Systemic molecular and cellular changes induced in rats upon inhalation of JP-8 petroleum fuel vapor

Limited information is available regarding systemic changes in mammals associated with exposures to petroleum/hydrocarbon fuels. In this study, systemic toxicity of JP-8 jet fuel was observed in a rat inhalation model at different JP-8 fuel vapor concentrations (250, 500, or 1000 mg/m(3), for 91 days). Gel electrophoresis and mass spectrometry sequencing identified the alpha-2 microglobulin protein to be elevated in rat kidney in a JP-8 dose-dependent manner. Western blot analysis of kidney and lung tissue extracts revealed JP-8 dependent elevation of inducible heat shock protein 70 (HSP70). Tissue changes were observed histologically (hematoxylin and eosin staining) in liver, kidney, lung, bone marrow, and heart, and more prevalently at medium or high JP-8 vapor phase exposures (500-1000 mg/m(3)) than at low vapor phase exposure (250 mg/m(3)) or non-JP-8 controls. JP-8 fuel-induced liver alterations included dilated sinusoids, cytoplasmic clumping, and fat cell deposition. Changes to the kidneys included reduced numbers of nuclei, and cytoplasmic dumping in the lumen of proximal convoluted tubules. JP-8 dependent lung alterations were edema and dilated alveolar capillaries, which allowed clumping of red blood cells (RBCs). Changes in the bone marrow in response to JP-8 included reduction of fat cells and fat globules, and cellular proliferation (RBCs, white blood cells-WBCs, and megakaryocytes). Heart tissue from JP-8 exposed animals contained increased numbers of inflammatory and fibroblast cells, as well as myofibril scarring. cDNA array analysis of heart tissue revealed a JP-8 dependent increase in atrial natriuretic peptide precursor mRNA and a decrease in voltage-gated potassium (K+) ion channel mRNA.

A literature review of air medical work hazards and pregnancy

An increased percentage of miscarriages among coworkers at one air medical transport company in 2008 prompted a literature review of selected hazards relevant to the profession of rotor wing air medical flight crew. Because of a lack of known research specific to this population, relevant studies from 1990 to 2008 were chosen to investigate pregnancy risks associated with exposure to vibration, jet fuel, noise, altitude, and fatigue in other occupations. Findings were summarized and recommendations made for future research.

Occupational risk factors for endometrial cancer among textile workers in Shanghai, China

OBJECTIVE

A case-cohort study was conducted to investigate associations between occupational exposures and endometrial cancer nested within a large cohort of textile workers in Shanghai, China.

METHODS

The study included 176 incident endometrial cancer cases diagnosed from 1989 to 1998 and a randomly-selected age-stratified reference subcohort (n = 3,061). Study subjects' complete work histories were linked to a job-exposure matrix developed specifically for the textile industry to assess occupational exposures. Hazard ratios (HR) and 95% confidence intervals were calculated using Cox proportional hazards modeling adapted for the case-cohort design, adjusting for age at menarche and a composite variable of gravidity and parity.

RESULTS

An increased risk of endometrial cancer was detected among women who had worked for > or =10 years in silk production (HR = 3.8, 95% CI 1.2-11.8) and had exposure to silk dust (HR = 1.7, 95% CI 0.9-3.4). Albeit with few exposed women (two cases and eight subcohort women), there was a 7.4-fold increased risk associated with > or =10 years of silica dust exposure (95% CI 1.4-39.7).

CONCLUSIONS

The findings suggest that some textile industry exposures might play a role in endometrial carcinoma and should be further replicated in other occupational settings.

The occupational role of women in military service: validation of occupation and prevalence of exposures in the Millennium Cohort Study

To better understand the US military's global peacekeeping and combat operations, which may expose a growing population of American service women to challenging occupations and environments. Concordance between self-reported and electronic occupation codes for female participants in the Millennium Cohort was measured using kappa statistics. Multivariable logistic regression modeling was used to assess the odds of five self-reported potentially toxic environmental exposures or disturbing experiences among different occupational categories, while adjusting for demographic and military characteristics, including deployment. Self-reported occupations were moderately to highly reliable when compared with electronic occupation data. Active-duty and Reserve/Guard females differentially reported witnessing death or trauma and exposure to chemical or biological warfare, depleted uranium, or pesticides. Findings suggest that self-reported occupation can be used with a high degree of confidence. Occupational groups with higher odds of reporting military exposures of concern will be followed longitudinally through 2022 and prospectively compared using baseline and follow-up evaluations.

Exposure to urban stressor and effects on luteinizing hormone (LH) in female outdoor workers

There are few studies in literature about exposure to urban pollutants and effects on female reproductive health. The aim of the study was to evaluate if the occupational exposure to chemical urban stressor could cause luteinizing hormone (LH) plasma levels alterations in female traffic police compared to a control group. One hundred and eighty subjects were included in the study, subdivided into three different groups according to the day of the menstrual cycle (7th, 14th, 21st) in which a blood sample was taken. In follicular and lutheal phase of ovarian cycle, the LH mean levels were significantly higher in traffic police vs. controls. The distribution of LH values in traffic police and controls was significant in follicular, and lutheal phase. In ovulatory phase, LH mean levels were lower but not significant in traffic police compared to controls. An increase was found concerning mental health disorders referred to the questionnaire items in traffic police vs. controls, although the difference was not significant. Our results suggest that occupational exposure to urban stressor in female traffic police, may alter LH plasma concentrations. LH may be used in occupational set as an early biomarker of exposure to urban stressor.

Biomedical Research on Health and Performance of Military Women: Accomplishments of the Defense Women's Health Research Program (DWHRP)

In 1994, Congress provided dollar 40 M for biomedical research on issues of importance for military women. This supported 104 intramural and 30 extramural studies and launched an era of research to narrow the knowledge gap on protection and enhancement of health and performance of military women. Projects addressed issues specific to female physiology (e.g., gynecological health in the field, maternal malaria), problems with higher prevalence for women (e.g., marginal iron deficiency, stress fracture), and issues of drug and materiel safety that had only been extrapolated from studies of men (e.g., chemical agent prophylaxis, fatigue countermeasures). Several important assumptions about female physiology and occupational risks were found to be astoundingly wrong. Hormonal changes through the menstrual cycle were less important to acute health risks and performance than predicted, exercise did not increase risk for amenorrhea and consequent bone mineral loss, and women tolerated G-forces and could be as safe as men in the cockpit if their equipment was designed for normal size and strength ranges. Data on personal readiness issues, such as body fat, physical fitness, nutrition, and postpartum return to duty, allowed reconsideration of standards that were gender appropriate and not simply disconnected adjustments to existing male standards. Other discoveries directly benefited men as well as women, including development of medical surveillance databases, identification of task strength demands jeopardizing safety and performance, and greater understanding of the effects of psychosocial stress on health and performance. This surge of research has translated into advances for the welfare of service women and the readiness of the entire force; relevant gender issues are now routine considerations for researchers and equipment developers, and some key remaining research gaps of special importance to military women continue to be investigated.

The Relation of Occupational Organic Solvent Exposure to Symptom Reporting in a Sample of White and Chinese Midlife Women

OBJECTIVE

This study examined the relation of occupational solvent exposure to menopausal and other symptoms in midlife women.

METHODS

We conducted a cross-sectional study of 480 Chinese and 494 white women, aged 40-55 years, in Northern California. Levels of exposure to organic solvents (none, low, medium, or high) were assigned to each current job using a job-exposure matrix.

RESULTS

A lower proportion of women with low occupational organic solvent exposure reported hot flashes or night sweats than working women with no solvent exposure (adjusted prevalence odds ratio [APOR] = 0.48, 95% confidence interval [CI] = 0.19-1.21). A greater proportion of women with high solvent exposure reported forgetfulness than women with no exposure (APOR = 2.51, 95% CI = 1.12-5.63).

CONCLUSIONS

Some symptom reporting in midlife women was related to their occupational organic solvent exposure.

Occupational exposure to metalworking fluids and risk of breast cancer among female autoworkers

BACKGROUND

Metalworking fluids (MWF) are used for lubrication during metal manufacturing. Previous studies have observed increased risks of several cancers among MWF-exposed workers. We hypothesized that MWF may be associated with risk of breast cancer because they can contain carcinogenic or endocrine-disrupting chemicals.

METHODS

We conducted a case-control study nested in a cohort of 4,680 female automobile workers employed for at least 3 years between 1/1/41 and 1/1/85, with follow-up through 1994. Cases were identified using the National Death Index (NDI), Michigan cancer registries, and company records. Detailed quantitative MWF exposure data were available for each subject, although data on known breast cancer risk factors were not.

RESULTS

Ninety-nine cases of breast cancer and 626 matched controls were identified. There was a weak positive association between lifetime cumulative exposure to soluble MWF and breast cancer risk, but no evidence of association with either straight or synthetic fluids. When exposure was divided into time-windows, the association was strongest for soluble MWF in the decade preceding diagnosis. Controlling for earlier exposures, there was an odds ratio of 1.18 (95% CI=1.02-1.35) per mg/m3-year of cumulative exposure to soluble MWF in this 10-year period.

CONCLUSION

This hypothesis-generating study provides some preliminary evidence for an association between exposure to soluble MWF and increased risk of breast cancer. Additional studies of MWF and breast cancer, with data on known breast cancer risk factors, are warranted.

The value of home-based collection of biospecimens in reproductive epidemiology

Detection, quantification, and prognosis of environmental exposures in humans has been vastly enhanced by the ability of epidemiologists to collect biospecimens for toxicologic or other laboratory evaluation. Ease of collection and level of invasiveness are commonly cited reasons why study participants fail to provide biospecimens for research purposes. The use of methodologies for the collection of biospecimens in the home offers promise for improving the validity of health effects linked to environmental exposures while maximizing the number and type of specimens capable of being collected in a timely and cost-effective manner. In this review we examine biospecimens (urine and blood) that have been successfully collected from the home environment. Related issues such as storage and transportation will also be examined as well as promising new approaches for collecting less frequently studied biospecimens (including hair follicles, breast milk, semen, and others). Such biospecimens are useful in the monitoring of reproductive development and function.

Increased synthesis of GFAP by TCDD in differentiation-disrupted SFME cells

The effects of 2,3,7,8-tetrachloro-dibenzo-p-dioxin (TCDD) on gene expression and synthesis of glial fibrillary acidic protein (GFAP) in differentiation-disrupted serum-free mouse embryo (SFME) cells were examined. SFME cells were exposed to fetal calf serum (FCS) and dimethyl sulfoxide (DMSO) to induce differentiation and increase GFAP synthesis. Disruption of differentiation was caused by low-level toluene, significantly inhibiting GFAP synthesis. TCDD at 0.01, 0.1 and 1 pg/ml in the presence of low-level toluene increased GFAP synthesis in the SFME cells, while expression of GFAP mRNA showed no significant change. The TCDD-treated SFME cells detached from the culture substratum, indicating an apparent change in cell adhesion. These results suggest that low-level TCDD further disrupts differentiation of SFME cells in the presence of low-level toluene by upregulating GFAP synthesis and by altering the ability in cell adhesion and that GFAP synthesis is not disrupted at transcription but at translation.

Biological and health effects of exposure to kerosene-based jet fuels and performance additives

Over 2 million military and civilian personnel per year (over 1 million in the United States) are occupationally exposed, respectively, to jet propulsion fuel-8 (JP-8), JP-8 +100 or JP-5, or to the civil aviation equivalents Jet A or Jet A-1. Approximately 60 billion gallon of these kerosene-based jet fuels are annually consumed worldwide (26 billion gallon in the United States), including over 5 billion gallon of JP-8 by the militaries of the United States and other NATO countries. JP-8, for example, represents the largest single chemical exposure in the U.S. military (2.53 billion gallon in 2000), while Jet A and A-1 are among the most common sources of nonmilitary occupational chemical exposure. Although more recent figures were not available, approximately 4.06 billion gallon of kerosene per se were consumed in the United States in 1990 (IARC, 1992). These exposures may occur repeatedly to raw fuel, vapor phase, aerosol phase, or fuel combustion exhaust by dermal absorption, pulmonary inhalation, or oral ingestion routes. Additionally, the public may be repeatedly exposed to lower levels of jet fuel vapor/aerosol or to fuel combustion products through atmospheric contamination, or to raw fuel constituents by contact with contaminated groundwater or soil. Kerosene-based hydrocarbon fuels are complex mixtures of up to 260+ aliphatic and aromatic hydrocarbon compounds (C(6) -C(17+); possibly 2000+ isomeric forms), including varying concentrations of potential toxicants such as benzene, n-hexane, toluene, xylenes, trimethylpentane, methoxyethanol, naphthalenes (including polycyclic aromatic hydrocarbons [PAHs], and certain other C(9)-C(12) fractions (i.e., n-propylbenzene, trimethylbenzene isomers). While hydrocarbon fuel exposures occur typically at concentrations below current permissible exposure limits (PELs) for the parent fuel or its constituent chemicals, it is unknown whether additive or synergistic interactions among hydrocarbon constituents, up to six performance additives, and other environmental exposure factors may result in unpredicted toxicity. While there is little epidemiological evidence for fuel-induced death, cancer, or other serious organic disease in fuel-exposed workers, large numbers of self-reported health complaints in this cohort appear to justify study of more subtle health consequences. A number of recently published studies reported acute or persisting biological or health effects from acute, subchronic, or chronic exposure of humans or animals to kerosene-based hydrocarbon fuels, to constituent chemicals of these fuels, or to fuel combustion products. This review provides an in-depth summary of human, animal, and in vitro studies of biological or health effects from exposure to JP-8, JP-8 +100, JP-5, Jet A, Jet A-1, or kerosene.

An occupational reproductive research agenda for the third millennium

There is a significant public health concern about the potential effects of occupational exposure to toxic substances on reproductive outcomes. Several toxicants with reported reproductive and developmental effects are still in regular commercial or therapeutic use and thus present potential exposure to workers. Examples of these include heavy metals, organic solvents, pesticides and herbicides, and sterilants, anesthetic gases, and anticancer drugs used in health care. Many other substances are suspected of producing reproductive or developmental toxicity but lack sufficient data. Progress has been limited in identifying hazards and quantifying their potencies and in separating the contribution of these hazards from other etiologic factors. Identifying the causative agents, mechanisms by which they act, and any potential target populations, present the opportunity to intervene and protect the reproductive health of workers. The pace of laboratory studies to identify hazards and to underpin the biologic plausibility of effects in humans has not matched the pace at which new chemicals are introduced into commerce. Though many research challenges exist today, recent technologic and methodologic advances have been made that allow researchers to overcome some of these obstacles. The objective of this article is to recommend future directions in occupational reproductive health research. By bridging interdisciplinary gaps, the scientific community can work together to improve health and reduce adverse outcomes.

The effects of jet fuel on immune cells of fuel system maintenance workers

Jet fuel is a common occupational exposure among commercial and military maintenance workers. JP-8 jet fuel, a military formulation, has shown immunotoxic effects in mice, but little data exist for humans. The aim of this cross-sectional study was to determine whether immune cell counts in the peripheral blood were altered among tank entry workers at three Air Force bases. After adjusting for covariates, fuel system maintenance personnel (n = 45) were found to have significantly higher counts of white blood cells (P = 0.01), neutrophils (P = 0.05), and monocytes (P = 0.02) when compared with a low-exposure group (n = 78), but no differences were noted in the numbers of total lymphocytes, T-cells, T-helper cells, T-suppressor cells, natural killer cells, and B-cells. Investigations are needed to evaluate the functional ability of these cells to produce lymphokines and cytokines and modulate the immune system.

Urinary reproductive hormone level differences between African American and Caucasian women of reproductive age

OBJECTIVE

To compare urinary levels of reproductive hormones in African American and Caucasian women.

DESIGN

Cross-sectional study.

SETTING

Ten United States Air Force (USAF) bases.

PATIENT(S)

African American (n = 33) and Caucasian (n = 65) women of reproductive age from a larger study of USAF women (n = 170).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Urinary endocrine end points: follicular luteinizing hormone (LH), preovulatory LH, level of LH surge peak, early follicular follicle stimulating hormone (FSH), follicular LH:FSH ratio, midluteal FSH, FSH rise before menses, early follicular estrone 3-glucuronide (E(1)3G), midfollicular E(1)3G, periovulatory E(1)3G peak, midluteal E(1)3G, early follicular pregnanediol 3-glucuronide (Pd3G), follicular Pd3G, rate of periovulatory Pd3G increase, E(1)3G:Pd3G on the day of luteal transition, slope of E(1)3G:Pd3G, and midluteal Pd3G.

RESULT(S)

Relative to Caucasians, African American women had significantly lower follicular phase LH:FSH ratios (mean +/- SD: 0.7 +/- 0.4 vs. 1.0 +/- 0.6), lower follicular phase Pd3G levels (1.0 +/- 0.5 vs. 1.2 +/- 0.8 microg/mg creatinine), and lower rates of periovulatory Pd3G increase (0.5 +/- 0.7 vs. 1.0 +/- 1.2 microg/mg creatinine).

CONCLUSION(S)

Findings of this analysis should be considered preliminary evidence of racial differences in hormone levels. Future studies are needed to determine whether these differences have clinical significance.