Testicular cancer and occupational exposures with a focus on xenoestrogens in polyvinyl chloride plastics

Design of a multi-electrode dielectric barrier discharge reactor and experimental study on the degradation of atrazine in water

Atrazine (ATZ) is widely used in agriculture as a triazine herbicide, and its long-term use can cause serious environmental pollution. This paper independently designed a multi-electrode reactor, explored the output power and energy utilization efficiency of the dielectric barrier discharge reactor, and used the dielectric barrier discharge reactor to treat ATZ solution. The results showed that the degradation efficiency of ATZ was 96.39% at 30 min at an initial ATZ concentration of 14 mg/L, an input voltage of 34 kV, an input current of 1.38 mA, an aeration rate of 100 L/h, and a treatment water volume of 150 mL. The degradation of ATZ was significantly increased by the addition of persulfate (PS), Fe2+, and H2O2. After adding radical quenchers (EtOH, p-BQ, and FFA), the degradation efficiency of ATZ decreased, indicating that free radicals (•OH, •O2-, and 1O2) played a key role in the degradation process of ATZ.

Microplastics in water: types, detection, and removal strategies

Microplastics are one of the most concerning groups of contaminants that pollute most of the surroundings of the Earth. The abundance of plastic materials available in the environment moved the scientific community in defining a new historical era known as Plasticene. Regardless of their minuscule size, microplastics have posed severe threats to the life forms like animals, plants, and other species present in the ecosystem. Ingestion of microplastics could lead to harmful health effects like teratogenic and mutagenic abnormalities. The source of microplastics could be either primary or secondary in which the components of microplastics are directly released into the atmosphere and the breakdown of larger units to generate the smaller molecules. Though numerous physical and chemical techniques are reported for the removal of microplastics, their increased cost prevents the large-scale applicability of the process. Coagulation, flocculation, sedimentation, and ultrafiltration are some of the methods used for the removal of microplastics. Certain species of microalgae are known to remove microplastics by their inherent nature. One of the biological treatment strategies for microplastic removal is the activated sludge strategy that is used for the separation of microplastic. The overall microplastic removal efficiency is significantly high compared to conventional techniques. Thus, the reported biological avenues like the bio-flocculant for microplastic removal are discussed in this review article.

Risk Factors for Testicular Cancer: Environment, Genes and Infections-Is It All?

The incidence of testicular cancer is steadily increasing over the past several decades in different developed countries. If on one side better diagnosis and treatment have shone a light on this disease, on the other side, differently from other malignant diseases, few risk factors have been identified. The reasons for the increase in testicular cancer are however unknown while risk factors are still poorly understood. Several studies have suggested that exposure to various factors in adolescence as well as in adulthood could be linked to the development of testicular cancer. Nevertheless, the role of environment, infections, and occupational exposure are undoubtedly associated with an increase or a decrease in this risk. The aim of this narrative review is to summarize the most recent evidence regarding the risk factors associated with testicular cancer, starting from the most commonly evaluated (cryptorchidism, family history, infections) to the newer identified and hypothesized risk factors.

Effects of endocrine disruptors on fetal testis development, male puberty, and transition age

PURPOSE

Endocrine disruptors (EDs) are exogenous substances able to impair endocrine system; consequently, they may cause numerous adverse effects. Over the last years, particular focus has been given to their harmful effects on reproductive system, but very little is known, especially in males. The aim of this review is to discuss the detrimental effects of EDs exposure on fetal testis development, male puberty, and transition age.

METHODS

A search for the existing literature focusing on the impact of EDs on fetal testis development, male puberty, andrological parameters (anogenital distance, penile length, and testicular volume), and testicular cancer with particular regard to pubertal age provided the most current information available for this review. Human evidence-based reports were given priority over animal and in vitro experimental results. Given the paucity of available articles on this subject, all resources were given careful consideration.

RESULTS

Information about the consequences associated with EDs exposure in the current literature is limited and often conflicting, due to the scarcity of human studies and their heterogeneity.

CONCLUSIONS

We conclude that current evidence does not clarify the impact of EDs on human male reproductive health, although severe harmful effects had been reported in animals. Despite controversial results, overall conclusion points toward a positive association between exposure to EDs and reproductive system damage. Further long-term studies performed on wide number of subjects are necessary in order to identify damaging compounds and remove them from the environment.

Atrazine in fish feed and african catfish (Clarias gariepinus) from aquaculture farms in Southwestern Nigeria

Extensive use of atrazine as herbicide in crop farming in Nigeria may lead to its accumulation in fish feed ingredients or aquatic ecosystem from aerosol or by runoff resulting in its residue in aquatic animals. Atrazine residues were determined in fish feed and catfish (Clarias gariepinus) fillets from commercial aquaculture farms in Southwestern Nigeria by matrix solvent particle dispersion and quantification using an ELISA kit. The mean atrazine concentrations in feed and fish were about 1.3–1.5 μg/kg and 1.4–1.8 μg/kg respectively. Atrazine was mostly detected in catfish from Ogun State (91.3%) and feed from Lagos State (80.0%) with mean concentrations of 1.4 ± 0.4 μg/kg and 1.5 ± 0.5 μg/kg, respectively. Mean atrazine concentration in catfish samples from Lagos State was significantly higher (P < 0.05) than the mean concentration in catfish samples from Ogun State. This study showed that the Estimated Average Daily Intake (EADI) of atrazine in fish samples from the selected states were below the Acceptable Daily Intake (ADI) value of 6 μg/kg for herbicide residues and thus within safe limit but their presence in fish is a cause for concern.

Effects and Mechanisms of Phthalates' Action on Reproductive Processes and Reproductive Health: A Literature Review

The production of plastic products, which requires phthalate plasticizers, has resulted in the problems for human health, especially that of reproductive health. Phthalate exposure can induce reproductive disorders at various regulatory levels. The aim of this review was to compile the evidence concerning the association between phthalates and reproductive diseases, phthalates-induced reproductive disorders, and their possible endocrine and intracellular mechanisms. Phthalates may induce alterations in puberty, the development of testicular dysgenesis syndrome, cancer, and fertility disorders in both males and females. At the hormonal level, phthalates can modify the release of hypothalamic, pituitary, and peripheral hormones. At the intracellular level, phthalates can interfere with nuclear receptors, membrane receptors, intracellular signaling pathways, and modulate gene expression associated with reproduction. To understand and to treat the adverse effects of phthalates on human health, it is essential to expand the current knowledge concerning their mechanism of action in the organism.

Potential Health Risk of Endocrine Disruptors in Construction Sector and Plastics Industry: A New Paradigm in Occupational Health

Endocrine disruptors (EDs) belong to large and diverse groups of agents that may cause multiple biological effects associated with, for example, hormone imbalance and infertility, chronic diseases such as diabetes, genome damage and cancer. The health risks related with the exposure to EDs are typically underestimated, less well characterized, and not regulated to the same extent as, for example, carcinogens. The increased production and utilization of identified or suspected EDs in many different technological processes raises new challenges with respect to occupational exposure settings and associated health risks. Due to the specific profile of health risk, occupational exposure to EDs demands a new paradigm in health risk assessment, redefinition of exposure assessment, new effects biomarkers for occupational health surveillance and definition of limit values. The construction and plastics industries are among the strongest economic sectors, employing millions of workers globally. They also use large quantities of chemicals that are known or suspected EDs. Focusing on these two industries, this short communication discusses: (a) why occupational exposure to EDs needs a more specific approach to occupational health risk assessments, (b) identifies the current knowledge gaps, and (c) identifies and gives a rationale for a future occupational health paradigm, which will include ED biomarkers as a relevant parameter in occupational health risk assessment, surveillance and exposure prevention.

Elucidating human male germ cell development by studying germ cell cancer

Human germ cell development is regulated in a spatio-temporal manner by complex regulatory networks. Here, we summarize results obtained in germ cell tumors and respective cell lines and try to pinpoint similarities to normal germ cell development. This comparison allows speculating about the critical and error-prone mechanisms, which when disturbed, lead to the development of germ cell tumors. Short after specification, primordial germ cells express markers of pluripotency, which, in humans, persists up to the stage of fetal/infantile spermatogonia. Aside from the rare spermatocytic tumors, virtually all seminomas and embryonal carcinomas express markers of pluripotency and show signs of pluripotency or totipotency. Therefore, it appears that proper handling of the pluripotency program appears to be the most critical step in germ cell development in terms of tumor biology. Furthermore, data from mice reveal that germline cells display an epigenetic signature, which is highly similar to pluripotent cells. This signature (poised histone code, DNA hypomethylation) is required for the rapid induction of toti- and pluripotency upon fertilization. We propose that adult spermatogonial cells, when exposed to endocrine disruptors or epigenetic active substances, are prone to reinitiate the pluripotency program, giving rise to a germ cell tumor. The fact that pluripotent cells can be derived from adult murine and human testicular cells further corroborates this idea.

Lifetime cancer risk assessment for inhalation exposure to di(2-ethylhexyl) phthalate (DEHP)

The plasticizer di(2-ethylhexyl) phthalate (DEHP) is ubiquitous in the environment and considered as carcinogen; however, the carcinogenic risk of human exposure to DEHP in the air via inhalation is lacking. A probabilistic incremental lifetime cancer risk (ILCR) model was implemented to quantitatively estimate the potential cancer risk of DEHP via human inhalation by using Monte Carlo simulation. We assessed the cancer risk in different age groups (children, adolescents, and adults) exposed to different DEHP concentrations (background low, indoor moderate, and occupational high) for different durations (2, 8, and 20 years). Results showed that the cancer risk of exposure to DEHP was below the acceptable limit (10^-6) in the ambient air but was serious in indoor and occupational environments even at short exposure duration (2 years). The cancer risk of DEHP via inhalation in children was lower than that in adolescents and adults, but the risk in children via dermal and oral exposure to indoor dust and soft PVC toys should be considered. Sensitivity analysis indicated that the exposure concentration of DEHP was the strongest factor that influenced ILCR. Our work provides the evidence of cancer risk of DEHP via inhalation and highlights the risk in indoor and occupational environments.

Etiology and early pathogenesis of malignant testicular germ cell tumors: towards possibilities for preinvasive diagnosis

Malignant testicular germ cell tumors (TGCT) are the most frequent cancers in Caucasian males (20-40 years) with an 70% increasing incidence the last 20 years, probably due to combined action of (epi)genetic and (micro)environmental factors. It is expected that TGCT have carcinoma in situ(CIS) as their common precursor, originating from an embryonic germ cell blocked in its maturation process. The overall cure rate of TGCT is more than 90%, however, men surviving TGCT can present long-term side effects of systemic cancer treatment. In contrast, men diagnosed and treated for CIS only continue to live without these long-term side effects. Therefore, early detection of CIS has great health benefits, which will require an informative screening method. This review described the etiology and early pathogenesis of TGCT, as well as the possibilities of early detection and future potential of screening men at risk for TGCT. For screening, a well-defined risk profile based on both genetic and environmental risk factors is needed. Since 2009, several genome wide association studies (GWAS) have been published, reporting on single-nucleotide polymorphisms (SNPs) with significant associations in or near the genes KITLG, SPRY4, BAK1, DMRT1, TERT, ATF7IP, HPGDS, MAD1L1, RFWD3, TEX14, and PPM1E, likely to be related to TGCT development. Prenatal, perinatal, and postnatal environmental factors also influence the onset of CIS. A noninvasive early detection method for CIS would be highly beneficial in a clinical setting, for which specific miRNA detection in semen seems to be very promising. Further research is needed to develop a well-defined TGCT risk profile, based on gene-environment interactions, combined with noninvasive detection method for CIS.

Socioeconomic patterning in the incidence and survival of teenage and young adult men aged between 15 and 24 years diagnosed with non-seminoma testicular cancer in northern england

PURPOSE

Previous research from developed countries has shown a marked increase in the incidence of testicular cancer in the past 50 years. This has also been demonstrated in northern England, along with improving 5-year survival. The present study aims to determine if socioeconomic factors may play a role in both etiology and survival from non-seminoma testicular cancer.

MATERIALS AND METHODS

We extracted all 214 cases of non-seminoma testicular cancer diagnosed in teenage and young adult men aged between 15 and 24 years during 1968 to 2006 from the Northern Region Young Persons' Malignant Disease Registry, which is a population-based specialist regional registry. Negative binomial regression was used to examine the relationship between incidence and both the Townsend deprivation score (and component variables) and small-area population density. Cox regression was used to analyze the relationship between survival and both deprivation and population density.

RESULTS

Decreased incidence was associated with living in areas of higher household overcrowding for young adults aged between 20 and 24 years (relative risk per 1% increase in household overcrowding = 0.79; 95% CI: 0.66-0.94) but no association was detected for young people aged between 15 and 19 years. Community-level household unemployment was associated with worse survival (hazard ratio per 1% increase in household unemployment = 1.04; 95% CI: 1.00-1.08).

CONCLUSIONS

This study has shown that increased risk of non-seminoma testicular cancer in teenage and young adult men may be associated with some aspect of more advantaged living. In contrast, greater deprivation is linked with worse survival prospects. The study was ecological by design and so these area-based results may not necessarily apply to individuals.

Occupational and environmental exposures associated with testicular germ cell tumours: systematic review of prenatal and life-long exposures

Background

Testicular germ cell tumours (TGCT) are the most common cancers in men aged between 15 and 44 years and the incidence has increased steeply over the past 30 years. The rapid increase in the incidence, the spatial variation and the evolution of incidence in migrants suggest that environmental risk factors play a role in TGCT aetiology. The purpose of our review is to summarise the current state of knowledge on occupational and environmental factors thought to be associated with TGCT.

Methods

A systematic literature search of PubMed. All selected articles were quality appraised by two independent researchers using the ‘Newcastle-Ottawa Quality Assessment Scale’.

Results

After exclusion of duplicate reports, 72 relevant articles were selected; 65 assessed exposure in adulthood, 7 assessed parental exposures and 2 assessed both. Associations with occupation was reported for agricultural workers, construction workers, firemen, policemen, military personnel, as well as workers in paper, plastic or metal industries. Electromagnetic fields, PCBs and pesticides were also suggested. However, results were inconsistent and studies showing positive associations tended to had lower quality ranking using the assessment scale (p=0.02).

Discussion

Current evidence does not allow concluding on existence of any clear association between TGCT and adulthood occupational or environmental exposure. The limitations of the studies may partly explain the inconsistencies observed. The lack of association with adulthood exposure is in line with current hypotheses supporting the prenatal origin of TGCT. Future research should focus on prenatal or early life exposure, as well as combined effect of prenatal and later life exposure. National and international collaborative studies should allow for more adequately powered epidemiological studies. More sophisticated methods for assessing exposure as well as evaluating gene–environment interactions will be necessary to establish clear conclusion.

[First French national survey on lifestyle and toxic factors in infertile couples]

OBJECTIVES

The purpose of our study is to assess, prior to any treatment for infertility, the environment and quality of life of candidate couples for medically assisted procreation (MAP) and the toxic factors which may be related to their difficulty in conceiving.

PATIENTS AND METHODS

A screening questionnaire aimed at 796 patients (348 couples) has been collected by 43 assisted reproductive techniques (ART) centers in France. Stress factors, anxiety, toxic and environmental factors have been recorded and analysed.

RESULTS

Women were on average younger than men (34.9 y ± 5.3 vs. 37.5 y ± 7.5), with a normal BMI, and 78% of them had no children. Sexual relations are regular: 2.14 per week. However, 1 in 8 women reports having sexual problems as opposed to 2 in 100 men (P < 0.0001), the most common problems being painful intercourse, insensitivity and bleeding. Fifty percent of the surveyed women say they have painful periods. Smoking and cannabis use were significantly higher in the men (32% vs. 20% and 6,4% vs. 1,2%). Alcohol consumption is more common in men (32 vs. 23%, P < 0.01). Stress related to infertility was significantly higher in the women (54% vs. 23%; P < 0.001).

DISCUSSION AND CONCLUSION

This first prospective French survey has revealed an increased incidence of smoking and an escalation of sexual problems (decrease in sexual relations, dyspareunia) and dysmenorrhea in women. It has also revealed stress at work in couples, and increased stress levels due to infertility in the female partners participating in this study. Our study suggests that there are numerous toxic and environmental factors which are potentially harmful for a couple's fertility and which should be corrected before any MAP treatment is attempted in order to optimise the results in ART and to increase natural fertility.

Environmental toxicology of testicular cancer

OBJECTIVE

Testicular cancer incidence appears to be increasing. In many regions, industrialization results in the production of potentially carcinogenic environmental toxins. We review the available data linking environmental toxins to testicular germ cell tumors (TGCT).

METHODS

A PubMed review of the English literature was performed to identify studies evaluating the relationship between environmental toxins and TGCT.

RESULTS

Many environmental toxins have been implicated in the development of TGCT, including organochlorines, polychlorinated biphenyls, polyvinyl chlorides, phthalates, marijuana, and tobacco. Variable levels of evidence exist and significant study design limitations preclude a definitive etiologic role for individual environmental toxins.

CONCLUSION

Environmental toxins may play an important but undetermined role in the development of TGCT. Further work is needed to evaluate specific toxins and TGCT carcinogenesis.

Adolescent and adult risk factors for testicular cancer

The incidence of testicular cancer has been increasing over the past several decades in many developed countries. The reasons for the increases are unknown because the risk factors for the disease are poorly understood. Some research suggests that in utero exposures, or those in early childhood, are likely to be important in determining an individual's level of risk. However, other research suggests that exposure to various factors in adolescence and adulthood is also linked to the development of testicular cancer. Of these, two adult occupational exposures-fire fighting and aircraft maintenance--and one environmental exposure (to organochlorine pesticides) are likely to be associated with increased risk of developing testicular cancer. By contrast, seven of the identified factors--diet, types of physical activity, military service, police work as well as exposure to ionizing radiation, electricity and acrylamide--are unlikely to increase the risk of developing testicular cancer. Finally, seven further exposures--to heat, polyvinyl chloride, nonionizing radiation, heavy metals, agricultural work, pesticides and polychlorinated biphenyls as well as marijuana use--require further study to determine their association with testicular cancer.

Epigenetic: a molecular link between testicular cancer and environmental exposures

In the last decades, studies in rodents have highlighted links between in utero and/or neonatal exposures to molecules that alter endocrine functions and the development of genital tract abnormalities, such as cryptorchidism, hypospadias, and impaired spermatogenesis. Most of these molecules, called endocrine disrupters exert estrogenic and/or antiandrogenic activities. These data led to the hypothesis of the testicular dysgenesis syndrome which postulates that these disorders are one clinical entity and are linked by epidemiological and pathophysiological relations. Furthermore, infertility has been stated as a risk factor for testicular cancer (TC). The incidence of TC has been increasing over the past decade. Most of testicular germ cell cancers develop through a pre-invasive carcinoma in situ from fetal germ cells (primordial germ cell or gonocyte). During their development, fetal germ cells undergo epigenetic modifications. Interestingly, several lines of evidence have shown that gene regulation through epigenetic mechanisms (DNA and histone modifications) plays an important role in normal development as well as in various diseases, including TC. Here we will review chromatin modifications which can affect testicular physiology leading to the development of TC; and highlight potential molecular pathways involved in these alterations in the context of environmental exposures.

BPA and environmental estrogen in potable water sources in Enugu municipality, South-East, Nigeria

BPA and environmental estrogen levels were assayed in potable water samples (38 tap water, 36 well water, 18 river water and 24 rain water samples) that were randomly collected from the different parts of Enugu metropolis, south-east Nigeria. The mean ± SD estrogen levels in tap, well, river and rain water samples were 0.10 ± 0.09, 0.05 ± 0.02, 0.05 ± 0.02 and 0.05 ± 0.02 μg/L respectively. Also, the mean BPA levels (μg/L) in the different water sources were 0.20 ± 0.07, 0.21 ± 0.07, 0.18 ± 0.04, and 0.40 ± 0.16, respectively. There was statistically significant difference (p = 0.0227) in BPA levels between the harvested rain water and the drinking tap water.

Detection of potential (anti)progestagenic endocrine disruptors using a recombinant human progesterone receptor binding and transactivation assay

The present work describes the identification of (anti)progestin endocrine disrupting chemicals (EDC) using a two step screening system. In the first step a competitive binding assay was developed using recombinant human progesterone receptor (hPR). The tested chemicals were of various classes like insecticides, their metabolites, industrial chemicals and waste water treatment plant (WWTP) effluents. All the tested chemicals demonstrated a high affinity binding for hPR. The average IC50 values of the test chemicals were within the range of 1-25microM. In the second step of screening, a mammalian cell-based hPR transactivation assay was developed where HEK 293 cells were co-transfected with hPR and luciferase reporter gene under the control of progesterone-response element. Stimulation of the cells with progesterone resulted in about 25-fold up regulation of luciferase activity, with EC50 value of 4nM. Potent anti-progesterone, RU486, significantly inhibited progesterone-induced transactivation and non-progestagenic steroids failed to transactivate hPR till 1microM concentrations. The chemicals showing high binding affinities in competitive binding assays were then tested in transactivation assay and all of them were found to be anti-progestative except WWTP effluents. Transactivation assays using extracted water samples from five different WWTP effluents showed that it was rich in progestative compounds. The levels of induction caused by these effluents were in the range of 15-25% of induction by progesterone and they represented about 6ng/l equivalent progesterone activities. In conclusion, we demonstrated that this two step assay provides an efficient screening tool for the detection of (anti)progestative EDC in various samples.

PPARα Agonist-Induced Rodent Tumors: Modes of Action and Human Relevance

Widely varied chemicals--including certain herbicides, plasticizers, drugs, and natural products--induce peroxisome proliferation in rodent liver and other tissues. This phenomenon is characterized by increases in the volume density and fatty acid oxidation of these organelles, which contain hydrogen peroxide and fatty acid oxidation systems important in lipid metabolism. Research showing that some peroxisome proliferating chemicals are nongenotoxic animal carcinogens stimulated interest in developing mode of action (MOA) information to understand and explain the human relevance of animal tumors associated with these chemicals. Studies have demonstrated that a nuclear hormone receptor implicated in energy homeostasis, designated peroxisome proliferator-activated receptor alpha (PPARalpha), is an obligatory factor in peroxisome proliferation in rodent hepatocytes. This report provides an in-depth analysis of the state of the science on several topics critical to evaluating the relationship between the MOA for PPARalpha agonists and the human relevance of related animal tumors. Topics include a review of existing tumor bioassay data, data from animal and human sources relating to the MOA for PPARalpha agonists in several different tissues, and case studies on the potential human relevance of the animal MOA data. The summary of existing bioassay data discloses substantial species differences in response to peroxisome proliferators in vivo, with rodents more responsive than primates. Among the rat and mouse strains tested, both males and females develop tumors in response to exposure to a wide range of chemicals including DEHP and other phthalates, chlorinated paraffins, chlorinated solvents such as trichloroethylene and perchloroethylene, and certain pesticides and hypolipidemic pharmaceuticals. MOA data from three different rodent tissues--rat and mouse liver, rat pancreas, and rat testis--lead to several different postulated MOAs, some beginning with PPARalpha activation as a causal first step. For example, studies in rodent liver identified seven "key events," including three "causal events"--activation of PPARalpha, perturbation of cell proliferation and apoptosis, and selective clonal expansion--and a series of associative events involving peroxisome proliferation, hepatocyte oxidative stress, and Kupffer-cell-mediated events. Similar in-depth analysis for rat Leydig-cell tumors (LCTs) posits one MOA that begins with PPARalpha activation in the liver, but two possible pathways, one secondary to liver induction and the other direct inhibition of testicular testosterone biosynthesis. For this tumor, both proposed pathways involve changes in the metabolism and quantity of related hormones and hormone precursors. Key events in the postulated MOA for the third tumor type, pancreatic acinar-cell tumors (PACTs) in rats, also begin with PPARalpha activation in the liver, followed by changes in bile synthesis and composition. Using the new human relevance framework (HRF) (see companion article), case studies involving PPARalpha-related tumors in each of these three tissues produced a range of outcomes, depending partly on the quality and quantity of MOA data available from laboratory animals and related information from human data sources.

The aryl hydrocarbon receptor complex and the control of gene expression

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that controls the expression of a diverse set of genes. The toxicity of the potent AhR ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin is almost exclusively mediated through this receptor. However, the key alterations in gene expression that mediate toxicity are poorly understood. It has been established through characterization of AhR-null mice that the AhR has a required physiological function, yet how endogenous mediators regulate this orphan receptor remains to be established. A picture as to how the AhR/ARNT heterodimer actually mediates gene transcription is starting to emerge. The AhR/ARNT complex can alter transcription both by binding to its cognate response element and through tethering to other transcription factors. In addition, many of the coregulatory proteins necessary for AhR-mediated transcription have been identified. Cross talk between the estrogen receptor and the AhR at the promoter of target genes appears to be an important mode of regulation. Inflammatory signaling pathways and the AhR also appear to be another important site of cross talk at the level of transcription. A major focus of this review is to highlight experimental efforts to characterize nonclassical mechanisms of AhR-mediated modulation of gene transcription.

Detection of aromatase and estrogen receptors (ERalpha, ERbeta1, ERbeta2) in human Leydig cell tumor

A Leydig cell tumor is a rare neoplasm, deriving from the interstitial cells, whose pathogenesis has not been still defined. Leydig cells of normal adult testis are known as physiological targets for estrogens. However, some studies on transgenic rodents suggest a role of estrogens in the development of Leydig cell hyperplasia and Leydig cell tumor. Therefore, with the aim to evaluate a possible link between estrogens and testicular tumorigenesis, this study investigated the expression of aromatase and estrogen receptors (ERalpha, ERbeta(1), ERbeta(2)) in testes from two patients with Leydig cell tumor. A strong immunoreactivity for aromatase, ERbeta(1), and ERbeta(2), together with a detectable ERalpha immunostaining, was revealed in tumoral tissues. These findings were confirmed by western blot analysis of tumor extracts detecting a 55 kDa P450arom, a 67 kDa ERalpha band, a 59 kDa ERbeta(1) band, and a 53 kDa ERbeta(2) band. The pattern of ER expression in neoplastic cells appears different from that of control Leydig cells exhibiting only ERbeta(1) and ERbeta(2) isoforms. The authors hypothesize how the high estrogen production could play a role in the neoplastic transformation of Leydig cells, while the exclusive presence of ERalpha in tumoral cells could amplify estradiol-17beta signaling contributing to the tumor cell growth and progression.

Use of cellular and cordless telephones and risk of testicular cancer

A case-control study on testicular cancer included use of cellular and cordless telephones. The results were based on answers from 542 (92%) cases with seminoma, 346 (89%) with non-seminoma, and 870 (89%) controls. Regarding seminoma the use of analog cellular phones gave odds ratio (OR) = 1.2, 95% confidence interval (CI) = 0.9-1.6, digital phones OR = 1.3, CI = 0.9-1.8, and cordless phones OR = 1.1, CI = 0.8-1.5. The corresponding results for non-seminoma were OR = 0.7, CI = 0.5-1.1, OR = 0.9, CI = 0.6-1.4, and OR = 1.0, CI = 0.7-1.4, respectively. There was no dose-response effect and OR did not increase with latency time. No association was found with place of keeping the mobile phone during standby, such as trousers pocket. Cryptorchidism was associated both with seminoma (OR = 4.2, CI = 2.7-6.5) and non-seminoma (OR = 3.3, CI = 2.0-5.6), but no interaction was found with the use of cellular or cordless telephones.

Space-time clustering analyses of testicular cancer amongst 15-24-year-olds in Northern England

There has been speculation that environmental exposures may be involved in the aetiology of testicular cancer in adolescent boys and young men. Indirect evidence for this hypothesis would be provided by the finding of space-time clustering. To examine this we have looked for evidence of space-time clustering using data from a population-based cancer registry from Northern England. All cases of testicular cancer diagnosed in males aged 15-24 years during the period 1968-2002 were included in the study. Tests for space-time interactions between cases were applied with fixed thresholds of close in space and close in time. Addresses at birth and diagnosis were used in the analyses. To adjust for the effect of varying population density tests were repeated replacing fixed geographical distances with nearest neighbour thresholds. A total of 257 cases of testicular cancer were identified for analysis. Overall there was no evidence for space-time clustering. However, there was statistically significant space-time clustering for 15-19-year-old based on time of birth and place of diagnosis (p<0.001). The very limited finding of space-time clustering may provide tentative evidence for an environmental, or infectious component to aetiology. However, it may well be a chance finding. A larger study based on national data is required.

Endocrine-disrupting chemicals and testicular cancer: a case-control study

Environmental factors appear to be important in the etiology of testicular cancer. In this study, the authors identified some risk factors for testicular cancer, paying particular attention to prenatal and early life exposure to endocrine-disrupting chemicals (EDCs). Using a questionnaire, the authors obtained information on male participants' environmental and occupational exposures during adolescence and adulthood. A multivariate logistic regression analysis of 103 cases and 215 controls showed an association between seminoma and nonseminoma and hobby activities that potentially involved the use of EDCs (eg, paints, glues, or solvents). Rural residence during adolescence was associated with all histological types of testicular cancer and with seminoma. No association was found with occupational exposures of the subjects. This study's findings also confirm previously identified risk factors, such as history of cryptorchidism and undescended testicle, high educational level, and low birth weight, and it gives some support to the hypothesis of a possible association between EDC exposures and testicular cancer.

ERα-AHR-ARNT Protein-Protein Interactions Mediate Estradiol-dependent Transrepression of Dioxin-inducible Gene Transcription

The aryl hydrocarbon receptor (AHR) and the aryl hydrocarbon receptor nuclear translocator (ARNT) form a heterodimeric transcription factor upon binding a wide variety of environmental pollutants, including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). AHR target gene activation can be repressed by estrogen and estrogen-like compounds. In this study, we demonstrate that a significant component of TCDD-inducible Cyp1a1 transcription is the result of recruitment of estrogen receptor (ER)-alpha by AHR/ARNT as a transcriptional co-repressor. Both AHR and ARNT were capable of interacting directly with ER alpha, as ascertained by glutathione S-transferase pull-down. 17Beta-estradiol repressed TCDD-activated Cyp1a1 and Cyp1b1 gene transcription in MCF-7 cells in the presence of cycloheximide, as determined by reverse transcription/real-time PCR. Furthermore, chromatin immunoprecipitation (ChIP) assays have shown that ER alpha is present at the Cyp1a1 enhancer only after co-treatment with E2 and TCDD, in MCF-7 cells. Sequential two-step ChIP assays were performed which demonstrate that AHR and ER alpha are present together at the same time on the Cyp1a1 enhancer during transrepression. Taken together these data support a role for ER-mediated transrepression of AHR-dependent gene regulation.

Mono(2-ethylhexyl)phthalate exhibits genotoxic effects in human lymphocytes and mucosal cells of the upper aerodigestive tract in the comet assay

Phthalic acid esters such as di(2-ethylhexyl)phthalate (DEHP) are widely used as plasticizers in PVC products manufactured for commercial, medical, and consumer purposes. Humans are exposed to phthalates originating, e.g., from blood storage bags, tubing materials, and from food-wrapping. While xenoestrogenic and chronic toxic effects of phthalates have been extensively discussed, there is little data on genotoxic effects in human cells. The alkaline comet assay was used to detect single-strand breaks and alkali labile sites of DNA after incubation of human nasal mucosal cells (n = 11) and peripheral lymphocytes (n = 11) with mono(2-ethylhexyl)phthalate (MEHP), the principal hydrolysis product of DEHP. MEHP showed a dose-dependent enhancement of DNA migration both in human mucosal cells and in lymphocytes. This effect indicates a genotoxic potential of MEHP in human mucosal cells. It confirms previous data obtained on the effect of MEHP on lymphocytes.

Testicular cancer and occupational exposure to polyvinyl chloride plastics: a case-control study

Exposure to polyvinyl chloride (PVC) plastics as a risk factor for testicular cancer was investigated. In total, 981 cases who were 20-75 years old and had reported to the Swedish Cancer Registry during 1993-1997 were included. One matched control from the population registry was used. Exposure was assessed by a questionnaire that was supplemented over the phone. Furthermore, an occupational hygienist qualified all exposures. In all, 791 matched pairs completed the questionnaire. Overall exposure to PVC plastics gave the odds ratio (OR)=1.35, 95% confidence interval (CI)=1.06-1.71, increasing with >10 year latency period to OR=1.45, 95% CI=1.06-1.98. No dose-response relationships were found but rather an inverse relationship with the highest odds ratios in the lowest exposure category. In conclusion, no clear association with testicular cancer and exposure to PVC could be found in our study in contrast to a previous observation.

Toxicological characteristics of endocrine-disrupting chemicals: developmental toxicity, carcinogenicity, and mutagenicity

It is generally accepted that endocrine-disrupting chemicals (EDCs) play a role in a variety of adverse health effects in an intact organism or its progeny as a consequence of changes in the endocrine system. Primary toxic effects of EDCs were reported to be related to infertility, reduction in sperm count, and teratogenicity, but other important toxic effects of EDCs such as carcinogenicity and mutagenicity have also been demonstrated. The aim of the present study was to systematically analyze the toxicological characteristics of EDCs in pesticides, industrial chemicals, and metals. A comprehensive literature survey on the 48 EDCs classified by the Centers for Disease Control and Prevention (CDC) was conducted using a number of databases which included Medline, Toxline, and Toxnet. The survey results revealed that toxicological characteristics of EDCs were shown to produce developmental toxicity (81%), carcinogenicity (79%, when positive in at least one animal species; 48%, when classified based on IARC evaluation), mutagenicity (79%), immunotoxicity (52%), and neurotoxicity (50%). Regarding the hormone-modulating effects of the 48 EDCs, estrogenic effects were the most predominant in pesticides, while effects on thyroid hormone were found for heavy metals. EDCs showing estrogen-modulating effects were closely related to carcinogenicity or mutagenicity with a high degree of sensitivity. Systematic information on the toxicological characteristics of the EDCs will be useful for future research directions on EDCs, the development of new screening methods, legal regulation, and for investigations of their mechanism of action.

Endocrine disruptors: effects on male fertility and screening tools for their assessment

During the recent decades, a lot of research has been performed concerning the so-called "endocrine disruptors", which are widespread in the environment. These compounds of anthropogenic or natural origin mimic the action of sex hormones and can interfere with the endocrine system. The largest body of evidence exists for those compounds that are estrogenic in nature, but the amount of experimental data on other types of interactions, especially anti-androgenic, steadily increases. Because of the growing public and scientific concern, epidemiological studies have been initiated to analyse the short and long-term effects of endocrine disruptors. In addition, a number of assays have been developed and are undergoing validation, aiming at high throughput screening of chemical agents with suspected endocrine disrupting properties. In the present review, we briefly describe the results of epidemiological studies dealing with observed time trends in male fertility disorders. In the second part of the article, an overview is given of the different classes of endocrine disruptors, followed by a description of the most important in vitro and in vivo bioassays, used to screen for the possible endocrine disruptive capacity of chemicals, together with future research needs for in vitro test development.

Pediatric exposure and potential toxicity of phthalate plasticizers

Phthalates are plasticizers that are added to polyvinyl chloride (PVC) products to impart flexibility and durability. They are produced in high volume and generate extensive though poorly defined human exposures and unique childhood exposures. Phthalates are animal carcinogens and can cause fetal death, malformations, and reproductive toxicity in laboratory animals. Toxicity profiles and potency vary by specific phthalate. The extent of these toxicities and their applicability to humans remains incompletely characterized and controversial. Two phthalates, diethylhexyl phthalate (DEHP) and diisononyl phthalate (DINP), have received considerable attention recently because of specific concerns about pediatric exposures. Like all phthalates, DEHP and DINP are ubiquitous contaminants in food, indoor air, soils, and sediments. DEHP is used in toys and medical devices. DINP is a major plasticizer used in children's toys. Scientific panels, advocacy groups, and industry groups have analyzed the literature on DEHP and DINP and have come to different conclusions about their safety. The controversy exists because risk to humans must be extrapolated from animal data that demonstrate differences in toxicity by species, route of exposure, and age at exposure and because of persistent uncertainties in human exposure data. This report addresses sensitive endpoints of reproductive and developmental toxicity and the unique aspects of pediatric exposures to phthalates that generate concern. DEHP and DINP are used as specific examples to illustrate the controversy.

Testicular cancer

A report of a 5-year survival rate of 39% for all patients with testis cancer in Kenya contrasts sharply with the 62% 5-year survival rate after tandem high-dose chemotherapy in first-line salvage of metastatic nonseminoma, and this figure provides a stark reminder of the differences in level of health care in the world. Nothing matches, however, the international significance of the success of Lance Armstrong in winning the Tour de France for the second time. It brings home the message of how complete the cure of this disease is and the need for more to be done to educate people about this success and encourage us to seek to discover the scientific basis for why this cancer is so different from all other cancers. The discovery that Lance Armstrong's brain metastases were totally necrotic at day 21 after the first treatment, taken with a report on the use of day 21 computed tomograph response to predict outcome, reinforces that message. With a second report suggesting that there are regions of the world that may have escaped the environmental damage to fertility that is now increasingly accepted as the most significant risk factor for development of this disease, we also need to remember the importance of germ cells as a weather vane of the environment. The first breakthrough in identifying a specific genetic region on the X chromosome with susceptibility to germ cell cancer of the testis by its association with development of undescended testis was one of the scientific landmarks of this past year. Clinically, with such high cure rates after salvage treatments, most of the controversy focuses now on early management of this disease. Debate continues regarding the need for orchidectomy or node dissection before chemotherapy in patients with metastases. There is also considerable debate concerning the need for any adjuvant treatment in stage 1 disease, whether surgical, chemotherapeutic, or radiotherapeutic. With reviews on late events highlighting the possibility that cisplatin dosage may be critical in synergizing with etoposide in causing leukemia and late cardiovascular events and reports suggesting that circulating cisplatin can be detected in the plasma as long as 20 years after treatment, the message of the year is clearly how to safely minimize the amount of treatment.