Region-specific growth effects in the developing rat prostate following fetal exposure to estrogenic ultraviolet filters

Embryonal exposure to 4-methylbenzylidene camphor induces reproduction impairment in adult zebrafish (Danio rerio)

This study investigated how early exposure to xenobiotics can lead to disease in adulthood, which is challenging for toxicologists. We employed a 'cradle to grave' approach using zebrafish (Danio rerio) embryos exposed to 4-methylbenzylidene camphor (4-MBC), a commonly used organic UV filter. Molecular docking and simulation studies confirmed the predictive toxicity and stable interaction of 4-MBC with androgen and estrogen receptors, with binding energies of -9.28 and -9.01 kcal/mol, respectively. Exposure to 4-MBC at 5, 50, and 500 μg/L concentrations resulted in significantly altered transcriptional and translational responses of ar, esr1, and vtg1 genes in embryos at 120 h post-fertilization (hpf). The exposure induced a non-monotonic dose-response pattern (NMDR), a characteristic feature of endocrine-disrupting chemicals. Additionally, a significant decrease in fertilization was observed in adults. Although fecundity was not affected in inter- and intra-breeding performances, developmental deformities were observed in F1 progenies with impaired survival at 10 days post-fertilization. The findings of this study show that embryonic exposure to 4-MBC is likely to induce reproductive and transgenerational toxicity in D. rerio and exhibit endocrine disruption in aquatic non-target organisms. This work is the first to elucidate the low-level long-term effects of 4-MBC from the embryonic stage to adulthood.

Development and application of diffusive gradients in thin films for in situ sampling of the organic UV filter 4-methylbenzylidene camphor (4-MBC) in waters

4-Methylbenzylidene camphor (4-MBC), a typical organic UV filter (OUVF) in personal care products, is considered to be a potential endocrine disruptor due to its estrogenic activity and bioaccumulation. Although 4-MBC residues have been extensively identified in aquatic waters, little is known about their occurrence, levels, and potential risk in coastal waters. This study developed a reliable sampling approach, based on diffusive gradients in thin films (DGT) with XAD-2 as the binding agent, for monitoring 4-MBC in coastal waters. The diffusion coefficients of 4-MBC in freshwater and artificial seawater were 3.65 × 10-6 cm2/s and 3.83 × 10-6 cm2/s, respectively. XAD-2 binding gel showed rapid adsorption to 4-MBC. The accumulated masses of 4-MBC in XAD-2 DGT increased linearly with deployed time for 7 days in freshwater and seawater, which agreed well with theoretical predictions. The sampling performance was independent of ionic strength (0.0001-0.5 M), pH (4.0-8.5), and dissolved organic matter (0-20 mg/L). Field deployment in the river estuary and bathing beach showed that DGT-measured 4-MBC concentrations were consistent in comparison with grab sampling. Environmental risk assessment showed that 4-MBC may pose a medium risk to aquatic organisms based on computed risk quotient (RQ) values. Sewage discharge is the main source of 4-MBC risk, while the residue in recreation beaches contributes more significantly in summer. The established DGT sampling is suitable for seasonal monitoring, source identification, and risk assessment of 4-MBC in coastal waters.

Developmental estrogenization: Prostate gland reprogramming leads to increased disease risk with aging

While estrogens are involved in normal prostate morphogenesis and function, inappropriate early-life estrogenic exposures, either in type, dose or timing, can reprogram the prostate gland and lead to increased disease risk with aging. This process is referred to as estrogen imprinting or developmental estrogenization of the prostate gland. The present review discusses published and new evidence for prostatic developmental estrogenization that includes extensive research in rodent models combined with epidemiology findings that together have helped to uncover the architectural and molecular underpinnings that promote this phenotype. Complex interactions between steroid receptors, developmental morphoregulatory factors, epigenetic machinery and stem-progenitor cell targets coalesce to hard wire structural, cellular and epigenomic reorganization of the tissue which retains a life-long memory of early-life estrogens, ultimately predisposing the gland to prostatitis, hyperplasia and carcinogenesis with aging.

Gene expression profiling in dorsolateral prostates of prepubertal and adult Sprague-Dawley rats dosed with estradiol benzoate, estradiol, and testosterone

The imbalance of testosterone to estradiol ratio has been related to the development of prostate diseases. Although rat models of prostate diseases induced by endocrine-disrupting chemicals (EDCs) and/or hormone exposure are commonly used to analyze gene expression profiles in the prostate, most studies utilize a single endpoint. In this study, microarray analysis was used for gene expression profiling in rat prostate tissue after exposure to EDCs and sex hormones over multiple time points (prepubertal through adulthood). We used dorsolateral prostate tissues from Sprague-Dawley rats (male offspring) and postnatally administered estradiol benzoate (EB) on postnatal days (PNDs) 1, 3, and 5, followed by treatment with additional hormones [estradiol (E) and testosterone (T)] on PNDs 90-200, as described by Ho et al. Microarray analysis was performed for gene expression profiling in the dorsolateral prostate, and the results were validated via qRT-PCR. The genes in cytokine-cytokine receptor interaction, cell adhesion molecules, and chemokines were upregulated in the EB+T+E group on PNDs 145 and 200. Moreover, early-stage downregulation of anti-inflammatory gene: bone morphogenetic protein 7 gene was observed. These findings suggest that exposure to EB, T, and E activates multiple pathways and simultaneously downregulates anti-inflammatory genes. Interestingly, these genes are reportedly expressed in prostate cancer tissues/cell lines. Further studies are required to elucidate the mechanism, including analyses using human prostate tissues.

In vitro metabolism of sunscreen compounds by liquid chromatography/high-resolution tandem mass spectrometry

RATIONALE

Exposure to UV light can induce adverse effects on human health, such as photo-aging, immunosuppression, and cancer. Sunscreens are used to prevent the absorption of UV rays, but certain UV-filtering compounds have been shown to disrupt endocrine systems or act as carcinogens. To assess the effects of the exposure to such compounds, it is important to study the pathways by which they are biotransformed in the body.

METHODS

Liquid chromatography coupled to high-resolution tandem mass spectrometry (LC/HRMS/MS) was employed to evaluate the oxidative metabolism and, specifically, the formation of reactive metabolites of six active ingredients commonly used in sunscreen formulations: oxybenzone, avobenzone, homosalate, octisalate, octocrylene, and octinoxate. In vitro incubations were performed with human and rat liver microsomes in the presence of β-nicotinamide adenine dinucleotide phosphate and glutathione. An LC/HRMS/MS method was developed to identify metabolites employing a biphenyl reversed-phase column for separating parent molecules, metabolites, and glutathione (GSH) adducts.

RESULTS

Each tested compound resulted in the formation of several metabolites, including at least one GSH adduct. Compounds containing ester groups were hydrolyzed, and some metabolites of the free acid forms were also detected. High-resolution MS/MS data was crucial for the structural elucidation of metabolites and GSH adducts. Fragmentation pathways were proposed for all parent compounds, as well as each described metabolite and adduct.

CONCLUSIONS

The results of this study will help better understand the metabolism and detoxification pathways of these xenobiotics.

Homosalate aggravates the invasion of human trophoblast cells as well as regulates intracellular signaling pathways including PI3K/AKT and MAPK pathways

Homosalate is an organic ultraviolet filter used in most sunscreens but has been reported to be toxic to marine organisms. The estrogenic activity of homosalate has also been reported, but its endocrine-disrupting effect remains unclear. Although homosalate has been detected in human placental tissues, its effect on the survival of human trophoblast cells needs to be investigated. Therefore, in this study, we evaluated if HTR8/SVneo, a human trophoblast cell line, treated with homosalate showed decreasing proliferative activity in a dose-dependent manner. Homosalate promoted the death of HTR8/SVneo cells with elevated lipid peroxidation and intracellular Ca²⁺ concentration. It also induced endoplasmic reticulum stress and mitochondrial morphological disturbances associated with the differentiation of human trophoblast cells. However, when the intracellular Ca²⁺ or reactive oxygen species were removed using BAPTA-AM or N-acetyl-L-cysteine (NAC), the cell proliferation suppressed by homosalate was restored. Homosalate also significantly inhibited the invasion of HTR8/SVneo cells. Furthermore, it modulated phosphoinositide 3-kinase (PI3K)/AKT and mitogen-activated protein kinase (MAPK) signaling pathways, which were involved in the cross-talk between both signaling pathways in HTR8/SVneo cells. Thus, homosalate adversely affects the survival, proliferation, and invasiveness of human trophoblast cells and therefore pregnant women should practice caution while using personal care products containing homosalate.

Evaluation of the endocrine-disrupting effects of homosalate (HMS) and 2-ethylhexyl 4-dimethylaminobenzoate (OD-PABA) in rat pups during the prenatal, lactation, and early postnatal periods

Homosalate (HMS) and 2-ethylhexyl 4-dimethylaminobenzoate (OD-PABA) are ultraviolet filters. We aimed to investigate the effects of dermal exposure to HMS and OD-PABA during the prenatal, lactation, and early infancy periods on pubertal development and thyroid function in male and female rats. The thyroid glands, uteri, testes, prostate glands, and seminal vesicles were excised and weighed, the reproductive organs were analyzed histologically, and the serum hormone levels were measured. In the prenatal period, the thyroxine (T4) levels increased in the female rats in the exposed groups ( p < 0.05); the thyroid weights, reproductive organ weights, and gonadal hormone levels were not altered. In males, the testosterone levels decreased ( p < 0.05), but the thyroid weights, T4 levels, prostate, and testis weights were not changed. In the lactation period, the weights of the thyroid glands increased in the exposed female groups ( p < 0.05), but the T4, gonadal hormone levels, and reproductive organ weights were not changed. In the males, the thyroid gland weights, T4 levels, reproductive organ weights, and gonadal hormone levels were not changed. During infancy, the thyroid gland weights increased in the female rats in the exposed groups ( p < 0.05), but the T4 levels, gonadal hormone levels, and reproductive organ weights were not affected. In the male rats in the exposed groups, the T4 levels were increased ( p < 0.05), but the thyroid and reproductive organ weights, gonadal hormone levels were not affected. Organ histopathology was not affected in all groups. HMS and OD-PABA do not have endocrine disruptor effects on thyroid function and the pubertal development of female and male rats.

Stereoselective metabolism of the UV-filter 2-ethylhexyl 4-dimethylaminobenzoate and its metabolites in rabbits in vivo and vitro

.The stereoselective metabolism of the enantiomers of the UV-filter 2-ethylhexyl 4-dimethylaminobenzoate (EDP) and its two major metabolites were studied in rabbits in vivo and in vitro. Cytotoxicity of EDP and its two metabolites was also investigated in hepatocytes.

Recent Advances on Endocrine Disrupting Effects of UV Filters

Ultraviolet (UV) filters are used widely in cosmetics, plastics, adhesives and other industrial products to protect human skin or products against direct exposure to deleterious UV radiation. With growing usage and mis-disposition of UV filters, they currently represent a new class of contaminants of emerging concern with increasingly reported adverse effects to humans and other organisms. Exposure to UV filters induce various endocrine disrupting effects, as revealed by increasing number of toxicological studies performed in recent years. It is necessary to compile a systematic review on the current research status on endocrine disrupting effects of UV filters toward different organisms. We therefore summarized the recent advances on the evaluation of the potential endocrine disruptors and the mechanism of toxicity for many kinds of UV filters such as benzophenones, camphor derivatives and cinnamate derivatives.

Effects of 4-methylbenzylidene camphor (4-MBC) on neuronal and muscular development in zebrafish (Danio rerio) embryos

The negative effects of overexposure to ultraviolet (UV) radiation in humans, including sunburn and light-induced cellular injury, are of increasing public concern. 4-Methylbenzylidene camphor (4-MBC), an organic chemical UV filter, is an active ingredient in sunscreen products. To date, little information is available about its neurotoxicity during early vertebrate development. Zebrafish embryos were exposed to various concentrations of 4-MBC in embryo medium for 3 days. In this study, a high concentration of 4-MBC, which is not being expected at the current environmental concentrations in the environment, was used for the purpose of phenotypic screening. Embryos exposed to 15 μM of 4-MBC displayed abnormal axial curvature and exhibited impaired motility. Exposure effects were found to be greatest during the segmentation period, when somite formation and innervation occur. Immunostaining of the muscle and axon markers F59, znp1, and zn5 revealed that 4-MBC exposure leads to a disorganized pattern of slow muscle fibers and axon pathfinding errors during the innervation of both primary and secondary motor neurons. Our results also showed reduction in AChE activity upon 4-MBC exposure both in vivo in the embryos (15 μM) and in vitro in mammalian Neuro-2A cells (0.1 μM), providing a possible mechanism for 4-MBC-induced muscular and neuronal defects. Taken together, our results have shown that 4-MBC is a teratogen and influences muscular and neuronal development, which may result in developmental defects.

Acute toxicity of benzophenone-type UV filters for Photobacterium phosphoreum and Daphnia magna: QSAR analysis, interspecies relationship and integrated assessment

The hazardous potential of benzophenone (BP)-type UV filters is becoming an issue of great concern due to the wide application of these compounds in many personal care products. In the present study, the toxicities of BPs to Photobacterium phosphoreum and Daphnia magna were determined. Next, density functional theory (DFT) and comparative molecular field analysis (CoMFA) descriptors were used to obtain more detailed insight into the structure - activity relationships and to preliminarily discuss the toxicity mechanism. Additionally, the sensitivities of the two organisms to BPs and the interspecies toxicity relationship were compared. Moreover, an approach for providing a global index of the environmental risk of BPs to aquatic organisms is proposed. The results demonstrated that the mechanism underlying the toxicity of BPs to P. phosphoreum is primarily related to their electronic properties, and the mechanism of toxicity to D. magna is hydrophobicity. Additionally, D. magna was more sensitive than P. phosphoreum to most of the BPs, with the exceptions of the polyhydric BPs. Moreover, comparisons with published data revealed a high interspecies correlation coefficient among the experimental toxicity values for D. magna and Dugesia japonica. Furthermore, hydrophobicity was also found to be the most important descriptor of integrated toxicity. This investigation will provide insight into the toxicity mechanisms and useful information for assessing the potential ecological risk of BP-type UV filters.

Computational study of binding affinity to nuclear receptors for some cosmetic ingredients

We studied the ingredients of cosmetic products as potential endocrine disruptors (ED) by in silico methods (docking). The structures of 14 human nuclear receptors have been retrieved from the protein data bank (PDB). We only considered the mechanism linked with direct binding to nuclear receptors with well-defined crystal structures. Predictions were performed using the Endocrine Disruptome docking program http://endocrinedisruptome.ki.si/ (Kolšek et al., 2013). 122 compounds were estimated to be possible endocrine disruptors bind to at least one of the receptors, 21 of them which are predicted to be probable toxicants for endocrine disruption as they bind to more than five receptors simultaneously. According to the literature survey and lack of experimental data it remains a challenge to prove or disprove the in silico results experimentally also for other potential endocrine disruptors.

Hepatic oxidative stress biomarker responses in freshwater fish Carassius auratus exposed to four benzophenone UV filters

Benzophenone (BP) type UV filters are widely used in many personal care products to protect human from UV irradiation. Despite the estrogenic potencies to fish and the environmental occurrences of BP derivatives in aquatic systems, little information is available regarding their effects on the antioxidant defense system in fish. In this work, the oxidative stress induced in livers of Carassius auratus was assessed using four biomarkers. The integrated biomarker response (IBR) was applied to assess the overall antioxidant status in fish. Moreover, liver tissues were also studied histologically. The changes in the activities of antioxidant enzymes and glutathione levels suggested that BPs generates oxidative stress in fish. The IBR index revealed that the hepatic oxidative toxicity followed the order BP-1>BP-2>BP-4>BP-3. The histopathological analysis revealed lesions caused by BPs. This investigation provides essential information for assessing the potential ecological risk of BP-type UV filters.

Sunscreens: are they beneficial for health? An overview of endocrine disrupting properties of UV-filters

Today, topical application of sunscreens, containing ultraviolet-filters (UV-filters), is preferred protection against adverse effects of ultraviolet radiation. Evidently, use of sunscreens is effective in prevention of sunburns in various models. However, evidence for their protective effects against melanoma skin cancer is less conclusive. Three important observations prompted us to review the animal data and human studies on possible side effects of selected chemical UV-filters in cosmetics. (1) the utilization of sunscreens with UV-filters is increasing worldwide; (2) the incidence of the malignant disorder for which sunscreens should protect, malignant melanoma, is rapidly increasing and (3) an increasing number of experimental studies indicating that several UV-filters might have endocrine disruptive effects. The selected UV-filters we review in this article are benzophenone-3 (BP-3), 3-benzylidene camphor (3-BC), 3-(4-methyl-benzylidene) camphor (4-MBC), 2-ethylhexyl 4-methoxy cinnamate (OMC), Homosalate (HMS), 2-ethylhexyl 4-dimethylaminobenzoate (OD-PABA) and 4-aminobenzoic acid (PABA). The potential adverse effects induced by UV-filters in experimental animals include reproductive/developmental toxicity and disturbance of hypothalamic-pituitary-thyroid axis (HPT). Few human studies have investigated potential side effects of UV-filters, although human exposure is high as UV-filters in sunscreens are rapidly absorbed from the skin. One of the UV-filters, BP-3, has been found in 96% of urine samples in the US and several UV-filters in 85% of Swiss breast milk samples. It seems pertinent to evaluate whether exposure to UV-filters contribute to possible adverse effects on the developing organs of foetuses and children.

Endocrine-disrupting chemicals: associated disorders and mechanisms of action

The incidence and/or prevalence of health problems associated with endocrine-disruption have increased. Many chemicals have endocrine-disrupting properties, including bisphenol A, some organochlorines, polybrominated flame retardants, perfluorinated substances, alkylphenols, phthalates, pesticides, polycyclic aromatic hydrocarbons, alkylphenols, solvents, and some household products including some cleaning products, air fresheners, hair dyes, cosmetics, and sunscreens. Even some metals were shown to have endocrine-disrupting properties. Many observations suggesting that endocrine disruptors do contribute to cancer, diabetes, obesity, the metabolic syndrome, and infertility are listed in this paper. An overview is presented of mechanisms contributing to endocrine disruption. Endocrine disruptors can act through classical nuclear receptors, but also through estrogen-related receptors, membrane-bound estrogen-receptors, and interaction with targets in the cytosol resulting in activation of the Src/Ras/Erk pathway or modulation of nitric oxide. In addition, changes in metabolism of endogenous hormones, cross-talk between genomic and nongenomic pathways, cross talk with estrogen receptors after binding on other receptors, interference with feedback regulation and neuroendocrine cells, changes in DNA methylation or histone modifications, and genomic instability by interference with the spindle figure can play a role. Also it was found that effects of receptor activation can differ in function of the ligand.

[Solar protection products: efficacy and risks]

Solar protection products (SPP) containing chemical filters and/or mineral filters are extensively used today in photoprotection; however, concerns continue to be voiced about their efficacy and about their possible dangers. A rapid review of photoprotection strategies shows that SPP owe their photoprotective effect to the absence of other photoprotection methods having clearly established efficacy in healthy subjects; in addition, they exhibit real protective efficacy against the majority of harmful effects of solar radiation, provided they have been devised in keeping with the specifications clearly set out in the recommendations of the French Medicines Agency (Afssaps). Such efficacy is dependent on their correct usage, recently reiterated by Afssaps in its recommendations to end-users concerning the good use of solar products: application of adequate quantities of such products, selection of the appropriate photoprotection class based on phototype and conditions of exposure, and regular renewal of applications in the event of prolonged exposure and after bathing or profuse sweating. Solar filters have long been known to cause contact allergic dermatitis, irritative dermatitis and photosensitisation, and a particular risk has appeared with the use of octocrylene. However, debate has centred primarily on the risk of endocrine disturbance potentially induced by chemical filters, certain of which exhibit established transcutaneous penetration. The risk of mimicry of an effect of oestradiol has been raised on the basis of a series of studies, almost all of which were carried out by the same team, and which mainly concerned 4-methylbenzylidene-camphor (4-MBC) following oral absorption in the rat. The risk of this type of effect with SPPs under normal conditions of use seems fairly remote according to the current state of knowledge; in any event, within the context of the "National Fertility Action Plan", Afssaps has been formally requested to analyse the risk associated with cosmetic substances that are "reprotoxic" and/or affect endocrine function, as a result of which various filters are currently being reassessed for such risk. The greater alleged safety of mineral filters, based on the absence of introduction of risk of photosensitisation (as a result of which they are preferred for use in young children), no longer seems so clear since the introduction of titanium dioxide (TiO2) and zinc oxide (ZnO) in the form of nanoparticles. Afssaps drew up a risk assessment report concerning cutaneous penetration, genotoxicity and oncogenesis for TiO(2) and ZnO in nanoparticle form; further studies are needed before any general conclusions may be drawn. The European Scientific Committee on Consumer Safety (SCCS) is also carrying out an evaluation of the use of TiO(2) and of ZnO as UV filters. Finally, current data do not suggest that SPPs exert any harmful effects by inhibiting the beneficial effects of the sun, in particular, vitamin D synthesis.

Atypical fetal prostate development is associated with ipsilateral hypoplasia of the wolffian ducts in the ACI rat

For over a half century, the ACI (August x Copenhagen) rat has been a primary model for studying renal agenesis and ipsilateral hypoplasia (IHP) of the Wolffian-derived structures (WDS). Because the ACI rat is also used as a model for prostate research, it is important to examine the relationship of IHP and urogenital sinus (UGS) development. The prostate is dependent on androgens for proper growth and differentiation. Alteration in androgen production and/or delivery to the UGS has the potential to perturbate normal development. In this study, we investigate whether the ipsilateral loss of the WDS is associated with altered prostate development. Digital images of serial-sectioned fetal ACI rat UGS were used to create three-dimensional (3-D) surface-rendered models of the developing prostate, seminal vesicle, vas deferens, and utricle on gestational day 21. The number and volume of prostate ducts developing from the UGS were calculated from the 3-D model data. Animals exhibiting IHP had a significant decrease in total fetal prostate volume (40%; P < 0.005) with significant regional specific differences when compared with normal male ACI rats. Anatomical and histological differences in the utricle, abnormal histology of the ipsilateral testes, and a truncation of the ipsilateral Wolffian ductal mesenchyme were also seen in the animals with IHP. Additional research is needed to further understand the mechanisms and consequences of IHP on prostate growth and development. Alterations to normal prenatal development of the male accessory sex organs can have important consequences for the growth and morphology of the adult gland.

Androgenic regulation of ventral epithelial bud number and pattern in mouse urogenital sinus

The ventral urogenital sinus (UGS) of control male mice has two rows of 3-4 prostatic buds at birth, but how androgens regulate ventral bud (VB) number and patterning is unclear. VBs in both sexes appeared to be a mixture of prostatic and urethral buds. UGSs from Tfm male and antiandrogen (flutamide)-exposed mice had small VBs, suggesting that initiation of some VBs is androgen independent. Tfm male mice are widely considered completely androgen insensitive yet their UGSs were 5alpha-dihydrotestosterone (DHT)- responsive. VBs (6-8) were generally distributed bimodally on the left-right axis at both minimal and normal male androgen signaling. Yet control females and DHT-exposed Tfm males had 13-14 VBs, whose left-right distribution was fairly uniform. These results suggest that VB number and distribution respond biphasically as androgen signaling increases from minimal, and that androgens regulate bud specification. Complete VB agenesis by the selective budding inhibitor 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) required high androgen signaling.

Estrogen signaling is not required for prostatic bud patterning or for its disruption by 2,3,7,8-tetrachlorodibenzo-p-dioxin

Estrogens play an important role in prostatic development, health, and disease. While estrogen signaling is essential for normal postnatal prostate development, little is known about its prenatal role in control animals. We tested the hypothesis that estrogen signaling is needed for normal male prostatic bud patterning. Budding patterns were examined by scanning electron microscopy of urogenital sinus epithelium from wild-type mice, mice lacking estrogen receptor (ER)alpha, ERbeta, or both, and wild-type mice exposed to the antiestrogen ICI 182,780. Budding phenotypes did not detectably differ among any of these groups, strongly suggesting that estrogen signaling is not needed to establish the prototypical prostatic budding pattern seen in control males. This finding contributes to our understanding of the effects of low-level estrogen exposure on early prostate development. In utero exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) can greatly alter the pattern in which prostatic buds form and reduce their number. For several reasons, including a prior observation that inhibitory effects of TCDD on prostatic budding in rats depend heavily on the sex of adjacent fetuses, we tested the hypothesis that estrogen signaling is needed for TCDD to disrupt prostatic budding. However, budding did not detectably differ among wild-type mice, or mice lacking ERalpha, ERbeta, or both, that were exposed prenatally to TCDD (5 microg/kg on embryonic day 13.5). Nor did ICI 182,780 detectably affect the response to TCDD. These results strongly suggest that estrogen signaling is not needed for TCDD to inhibit prostatic epithelial budding.

Endocrine-disrupting chemicals: an Endocrine Society scientific statement

There is growing interest in the possible health threat posed by endocrine-disrupting chemicals (EDCs), which are substances in our environment, food, and consumer products that interfere with hormone biosynthesis, metabolism, or action resulting in a deviation from normal homeostatic control or reproduction. In this first Scientific Statement of The Endocrine Society, we present the evidence that endocrine disruptors have effects on male and female reproduction, breast development and cancer, prostate cancer, neuroendocrinology, thyroid, metabolism and obesity, and cardiovascular endocrinology. Results from animal models, human clinical observations, and epidemiological studies converge to implicate EDCs as a significant concern to public health. The mechanisms of EDCs involve divergent pathways including (but not limited to) estrogenic, antiandrogenic, thyroid, peroxisome proliferator-activated receptor gamma, retinoid, and actions through other nuclear receptors; steroidogenic enzymes; neurotransmitter receptors and systems; and many other pathways that are highly conserved in wildlife and humans, and which can be modeled in laboratory in vitro and in vivo models. Furthermore, EDCs represent a broad class of molecules such as organochlorinated pesticides and industrial chemicals, plastics and plasticizers, fuels, and many other chemicals that are present in the environment or are in widespread use. We make a number of recommendations to increase understanding of effects of EDCs, including enhancing increased basic and clinical research, invoking the precautionary principle, and advocating involvement of individual and scientific society stakeholders in communicating and implementing changes in public policy and awareness.

Endocrine disruptors and prostate cancer risk

There is increasing evidence both from epidemiology studies and animal models that specific endocrine-disrupting compounds may influence the development or progression of prostate cancer. In large part, these effects appear to be linked to interference with estrogen signaling, either through interacting with ERs or by influencing steroid metabolism and altering estrogen levels within the body. In humans, epidemiologic evidence links specific pesticides, PCBs and inorganic arsenic exposures to elevated prostate cancer risk. Studies in animal models also show augmentation of prostate carcinogenesis with several other environmental estrogenic compounds including cadmium, UV filters and BPA. Importantly, there appears to be heightened sensitivity of the prostate to these endocrine disruptors during the critical developmental windows including in utero and neonatal time points as well as during puberty. Thus infants and children may be considered a highly susceptible population for ED exposures and increased risk of prostate cancers with aging.

Prostate development: a historical perspective

The regional anatomy of the human prostate has been debated periodically over the last century with various levels of controversy and agreement, beginning with the concept of lobes and replaced by the current model of zones. During this period a variety of classifications have been proposed, based upon the studies of glandular morphogenesis, responses to hormones or histopathology. The current paradigm suggests that the regional differences seen in the prostate of both animal models and the human are a consequence of specific epithelial-mesenchymal interactions along the cranial-caudal axis of the urogenital sinus. The distinctive regional patterns seen in the rodent prostate and the histological heterogeneity of the human adult gland all point to the modification of the distal portion of the ducts, while the proximal segments retain their spatial relationship to the urethra that was formed during fetal development. This suggests that the early epithelial budding that occurs in utero represents a common, fairly symmetrical pattern of growth in many species, while the regional differences in branching morphogenesis and cytodifferentiation are controlled by the instructional influences of mesenchyme and temporal expression of growth factors. Perturbation of the normal processes involved during critical periods of fetal development during reproductive organ development may also play a role in the susceptibility of the prostate to disease in adulthood. Past descriptions of detailed anatomical studies, which span over a century, have provided much insight into the architecture and processes that form a complex tubulo-alveolar gland. New insights into the ductal detail and the advent of sophisticated analyses of cell-cell interactions and molecular mechanisms controlling pathways of cellular growth, differentiation, and apoptosis will likely lead to new approaches for prevention and therapy of prostatic diseases.