Toxic effects of the easily avoidable phthalates and parabens.

Abstract

"Some environmental toxins like DDT and other chlorinated compounds accumulate in the body because of their fat-soluble nature. Other compounds do not stay long in the body, but still cause toxic effects during the time they are present. For serious health problems to arise, exposure to these rapidly-clearing compounds must occur on a daily basis. Two such classes of compounds are the phthalate plasticizers and parabens, both of which are used in many personal care products, some medications, and even foods and food preservation. The phthalates are commonly found in foods and household dust. Even though they have relatively short half-lives in humans, phthalates have been associated with a number of serious health problems, including infertility, testicular dysgenesis, obesity, asthma, and allergies, as well as leiomyomas and breast cancer. Parabens, which can be dermally absorbed, are present in many cosmetic products, including antiperspirants. Their estrogenicity and tissue presence are a cause for concern regarding breast cancer. Fortunately, these compounds are relatively easy to avoid and such steps can result in dramatic reductions of urinary levels of these compounds."

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Evaluation of a Screening System for Obesogenic Compounds: Screening of Endocrine Disrupting Compounds and Evaluation of the PPAR Dependency of the Effect

Abstract

"Recently the environmental obesogen hypothesis has been formulated, proposing a role for endocrine disrupting compounds (EDCs) in the development of obesity. To evaluate this hypothesis, a screening system for obesogenic compounds is urgently needed. In this study, we suggest a standardised protocol for obesogen screening based on the 3T3-L1 cell line, a well-characterised adipogenesis model, and direct fluorescent measurement using Nile red lipid staining technique. In a first phase, we characterised the assay using the acknowledged obesogens rosiglitazone and tributyltin. Based on the obtained dose-response curves for these model compounds, a lipid accumulation threshold value was calculated to ensure the biological relevance and reliability of statistically significant effects. This threshold based method was combined with the well described strictly standardized mean difference (SSMD) method for classification of non-, weak- or strong obesogenic compounds. In the next step, a range of EDCs, used in personal and household care products (parabens, musks, phthalates and alkylphenol compounds), were tested to further evaluate the obesogenicity screening assay for its discriminative power and sensitivity. Additionally, the peroxisome proliferator activated receptor γ (PPARγ) dependency of the positive compounds was evaluated using PPARγ activation and antagonist experiments. Our results showed the adipogenic potential of all tested parabens, several musks and phthalate compounds and bisphenol A (BPA). PPARγ activation was associated with adipogenesis for parabens, phthalates and BPA, however not required for obesogenic effects induced by Tonalide, indicating the role of other obesogenic mechanisms for this compound."

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PPAR-mediated activity of phthalates: A link to the obesity epidemic?

Abstract

"The endocrine disruption hypothesis asserts that exposure to small amounts of some chemicals in the environment may interfere with the endocrine system and lead to harmful effects in wildlife and humans. Many of these chemicals may interact with members of the nuclear receptor superfamily. Peroxisome proliferator-activated receptors (PPARs) are such candidate members, which interact with many different endogenous and exogenous lipophilic compounds. More particularly, the roles of PPARs in lipid and carbohydrate metabolism raise the question of their activation by a sub-class of pollutants, tentatively named "metabolic disrupters". Phthalates are abundant environmental micro-pollutants in Europe and North America and may belong to this class. Mono-ethyl-hexyl-phthalate (MEHP), a metabolite of the widespread plasticizer di-ethyl-hexyl-phthalate (DEHP), has been found in exposed organisms and interacts with all three PPARs. A thorough analysis of its interactions with PPARgamma identified MEHP as a selective PPARgamma modulator, and thus a possible contributor to the obesity epidemic."

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Endocrine-Disrupting Chemicals: Associated Disorders and Mechanisms of Action

Abstract

"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."

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