Dioxins, PCBs, chlorinated pesticides and brominated flame retardants in free-range chicken eggs from peri-urban areas in Arusha, Tanzania: Levels and implications for human health.

The environment in the northern part of Tanzania is influenced by rapid population growth, and increased urbanization. Urban agriculture is common and of economic value for low income families. In Arusha, many households sell eggs from free-ranging backyard chicken. In 2011, 159 eggs from different households in five different locations in Arusha were collected, homogenized, pooled into 28 composite samples and analyzed for a wide selection of POPs. Levels of POPs varied widely within and between the locations. The levels of dieldrin and ΣDDT ranged between 2 and 98,791 and 2 and 324ng/g lipid weight (lw), respectively. EU MRLs of 0.02mg/kg dieldrin for eggs were exceeded in 4/28 samples. PCBs, HCHs, chlordanes, toxaphenes and endosulfanes were found at lower frequency and levels. Brominated flame retardants (BFRs), e.g polybrominated diphenylethers (PBDEs), hexabromocyclododecane (HBCD) and 1,2-bis(2,4,6-tribromphenoxy)ethane (BTBPE) were present in 100%, 60% and 46% of the composite samples, respectively. Octa-and deca-BDEs were the dominating PBDEs and BDE 209 levels ranged between

Compound- and sex-specific effects on programming of energy and immune homeostasis in adult C57BL/6JxFVB mice after perinatal TCDD and PCB 153.

Early life exposure to endocrine disrupting compounds has been linked to chronic diseases later in life, like obesity and related metabolic disorders. We exposed C57BL/6JxFVB hybrid mice to the aryl hydrocarbon receptor agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and the constitutive androstane receptor/pregnane X receptor agonist polychlorinated biphenyl 153 (PCB 153) in an experimental design relevant for human exposure. Exposure occurred during gestation and lactation via maternal feed to a wide dose range (TCDD: 10-10,000 pg/kg body weight/day; PCB 153: 0.09-1406 µg/kg body weight/d). Then exposure was ceased and offspring were followed up to 1 year of age. Metabolic parameters like body weight, fat pad weights, glucose tolerance, endocrine serum profile, and neurobehavioral and immunological parameters were determined. Body weight was transiently affected by both compounds throughout the follow-up. TCDD-exposed males showed decreased fat pad and spleen weights and an increase in IL-4 production of splenic immune cells. In contrast, females showed increased fat pad weights and production of IFNγ. PCB 153-exposed males showed an increase in glucose, whereas females showed an increase in glucagon, a decrease in pancreas weight, and an increase in thymus weight. In conclusion, early life exposure to TCDD appears to affect programming of energy and immune homeostasis in offspring, whereas the effects of perinatal PCB 153 were mainly on programming of glucose homeostasis. Both compounds act sex-specifically. Lowest derived BMDLs (lower bounds of the (two sided) 90%-confidence interval for the benchmark dose) for both compounds are not lower than current tolerable daily intakes.

Liver DNA methylation analysis in adult female C57BL/6JxFVB mice following perinatal exposure to bisphenol A.

Bisphenol A (BPA) is a compound released from plastics and other consumer products used in everyday life. BPA exposure early in fetal development is proposed to contribute to programming of chronic diseases like obesity and diabetes, by affecting DNA methylation levels. Previously, we showed that in utero and lactational exposure of C57BL/6JxFVB hybrid mice via maternal feed using a dose range of 0-3000µg/kg body weight/day resulted in a sex-dependent altered metabolic phenotype in offspring at 23 weeks of age. The most univocal effects were observed in females, with reduced body weights and related metabolic effects associated with perinatal BPA exposure. To identify whether the effects of BPA in females are associated with changes in DNA methylation, this was analyzed in liver, which is important in energy homeostasis. Measurement of global DNA methylation did not show any changes. Genome-wide DNA methylation analysis at specific CpG sites in control and 3000µg/kg body weight/day females with the digital restriction enzyme analysis of methylation (DREAM) assay revealed potential differences, that could, however, not be confirmed by bisulfite pyrosequencing. Overall, we demonstrated that the observed altered metabolic phenotype in female offspring after maternal exposure to BPA was not detectably associated with liver DNA methylation changes. Still, other tissues may be more informative.

Effects of endocrine disrupting chemicals on in vitro global DNA methylation and adipocyte differentiation.

Recent studies suggest that endocrine disrupting chemicals (EDCs) may form a risk factor for obesity by altering energy metabolism through epigenetic gene regulation. The goal of this study is to investigate the effects of a range of EDCs with putative obesogenic properties on global DNA methylation and adipocyte differentiation in vitro. Murine N2A and human SK-N-AS neuroblastoma cells and murine preadipocyte fibroblasts (3T3-L1) were exposed to tributyltin (TBT), diethylstilbestrol (DES), bisphenol A (BPA), 2,3,7,8-tetrachlorodibenzo-[p]-dioxin (TCDD), 2,2',4,4',5,5'-hexachlorobiphenyl (PCB-153), hexachlorobenzene (HCB), hexabromocyclododecane (HBCD), 2,2',4,4'-tetrabrominated diphenyl ether (BDE-47) , perfluorinated octyl acid (PFOA) and perfluorinated octyl sulfonate (PFOS). A modest decrease in global DNA methylation was observed in N2A cells exposed to 10 µM DES, BPA, TCDD, BDE-47, PCB-153 and 1 µM HCB, but no changes were found in the human SK-N-AS cells. We reveal for the first time that BDE-47 increases adipocyte differentiation in a dose-dependent manner (2.5-25 µM). Adipocyte differentiation was also enhanced by TBT (≥ 10 nM) and BPA (>10 µM) and inhibited by TCDD (≥ 0.1 nM). The other chemicals showed either modest or no effects on adipocyte differentiation at the concentrations tested (PFOA, PFOS and HBCD at 10 µM; PCB-153, 3.4 µM and HCB, 1 µM). This study demonstrates that selected EDCs can induce functional changes in murine adipocyte differentiation in vitro which are accompanied by decreased global DNA methylation.

Integrated chemical and biological analysis to explain estrogenic potency in bile extracts of red mullet (Mullus barbatus).

A biological screening was performed to establish the total exposure to estrogenic compounds of red mullet (Mullus barbatus) collected at several sites along the Spanish Mediterranean coast by testing male fish bile extracts using the in vitro ER-LUC reporter gene assay. In addition, major metabolites were identified and measurements of OH-PAHs (1-naphthol, 9-phenantrol, 9-fluorenol, 1-pyrenol, 1OH-BaP and 3OH-BaP) and alkylphenols (4-n-nonylphenol (4-n-NP) and 4-tertoctylphenol (4-tert-OP)) in the same fish bile extracts were taken by gas chromatography-mass spectrometry in electron ionization mode (GC-EI-MS). Relative in vitro estrogenic potencies of the chemically quantified compounds were also tested. The highest biliary concentrations of 1-pyrenol, 9-fluorenol and 4-n-NP were found in fish from Barcelona and from the Mar Menor coastal lagoon. However, these concentrations can be considered relatively low compared to values reported in red mullet from other polluted waters in the Mediterranean Sea. The contribution of 1-pyrenol, 4-n-NP and 4-tert-OP to the total estrogenic potency measured in male fish bile was found to be negligible, indicating the presence of other estrogenic compounds in red mullet bile. Estrogenic potency in bile from male fish was markedly elevated in Mar Menor lagoon (234.8±5.7 pg E2EQ/µl), and further research will be necessary to explain whether the presence of natural and synthetic-hormones in the lagoon contributed to this finding. Values of approximately 15-16E2EQ pg/mg bile can be regarded as preliminary baseline levels of bile estrogenicity in male red mullet from the western Mediterranean Sea.