Dynamics of Organohalogenated Contaminants in Human Serum from Obese Individuals during One Year of Weight Loss Treatment

We investigated the dynamics of several organohalogenated contaminants (OHCs) and their metabolites in an obese population during weight loss. Serum samples from obese individuals were taken before patients lost weight and after three, six, and twelve months. Samples were also collected from a matched lean control population. Analyzed OHCs were polychlorinated biphenyls (PCBs) and their hydroxylated metabolites (HO-PCBs), pentachlorophenol (PCP), polybrominated diphenyl ethers, and organochlorine pesticides (OCPs). Significantly lower concentrations of major PCBs, their metabolites, and PCP were measured in obese individuals at the initial moment of their enrolling in the project. While dilution differences might be responsible for the lower concentrations in the neutral OHCs, we suggest that a lower CYP-mediated metabolic activity can partially explain the data for the HO-PCBs. Additionally, lower chlorinated substituted PCBs had a higher percentage contribution to the sum PCBs in obese individuals, while higher chlorinated PCBs had a higher contribution for the controls. Increasing serum levels for all OHCs were observed during weight loss. The release from adipose tissue seemed dependent on the octanol–water partition coefficient, since OHCs with higher log <i>K</i>_ow values displayed a higher release in serum. This also influenced the HO-PCBs profile after weight loss with lower chlorinated HO-PCBs increasingly gaining importance. Although weight loss is beneficial, it also influences the release of OHCs from adipose tissue and their metabolism. Therefore, the increase in the levels of compounds with endocrine effects might be of concern

Characteristics of the study population.

<p>Ethnicity, gender and diabetic status of the subjects are represented as well as clinical and anthropometric characteristics which are represented as median values (minimum–maximum). All included subjects were citizens of Belgium. <i>T2D = Type 2 diabetes; BMI = body mass index; VAT/SAT = ratio visceral/subcutaneous adipose tissue; CT = Computed tomography</i>.</p

Overview of the major findings of this manuscript.

<p>A. Levels of obesity markers in VAT, SAT and serum of the obese population depending on gender and diabetic status. B. Associations between obesity markers and POP levels.</p

Overview of standard linear regression analyses with obesity marker levels as dependent variables and POP levels in VAT/SAT, BMI and gender or diabetes as independent variables.

<p>Only significant models are shown, and the adjusted R² and p-value (n = 50) of each model are shown in the table. Standardized coefficients are reported (β), with their p-value. Significant variables in a model are shown in bold. No significant model was obtained by including diabetic status as independent variable.</p

Serum concentrations and gene expression levels of obesity markers in relation to gender and diabetes.

<p>Data represent mean (±SE) of the serum concentrations of leptin and adiponectin (A) and gene expression of leptin, adiponectin, TNFα and PPARγ normalised to the gene expression of TBP gene*1000 of AT samples (B, C, D, E). Significant differences between men (n = 17) and women (n = 33) (B, C), diabetic (n = 8) and non diabetic patients (n = 42) (D, E) are indicated with asterisks (Mann Whitney U-test; *p≤0.05; **p≤0.01).</p

Correlations between obesity marker genes and POP concentrations in AT.

<p>Scatterplots are representing gene expression values of obesity maker genes (X-axis) in relation to the POP concentrations (Y-axis). Only highly significant spearman correlations (p≤0.007) are shown, ρ-values and p-values of the Spearman correlations are indicated on the scatterplot.</p

Spearman correlation coefficients (ρ) of total CT, VAT/SAT ratio and BMI with obesity marker expression levels in fat tissue (gene expression values) and serum (adipokine concentrations) related to gender and diabetic status.

<p>Data represent ρ values and significance level (p-value). Significant values (p-value≤0.05) are indicated in bold. <i>T2D = Type 2 diabetes; VAT/SAT = ratio visceral/subcutaneous adipose tissue; SAT = Subcutaneous adipose tissue; VAT = Visceral adipose tissue.</i></p

Spearman correlation coefficients (ρ) of total CT, VAT/SAT ratio and BMI with obesity marker expression levels in fat tissue (gene expression values) and serum (adipokine concentrations) in the overall population (n = 50).

<p>Data represent ρ values and significance level (p-value). Significant values (p-value≤0.05) are indicated in bold. <i>T2D = Type 2 diabetes; VAT/SAT = ratio visceral/subcutaneous adipose tissue; SAT = Subcutaneous adipose tissue; VAT = Visceral adipose tissue.</i></p

Expression levels of obesity marker genes.

<p>Data represent the median gene expression levels of the marker genes normalized to the household gene TATA box binding Protein (<i>TBP</i>) expression in SAT and VAT and the median values of the serum concentration levels of adiponectin and leptin. Minimum and maximum expression ratios are represented between brackets. Differences between VAT an SAT gene expression levels were examined with a Mann Whitney U-test, significant differences (p≤0.05; n = 50) are shown in bold. <i>SAT = Subcutaneous adipose tissue; VAT = Visceral adipose tissue</i>.</p

Flame Retardant Chemicals in College Dormitories: Flammability Standards Influence Dust Concentrations

Furniture flammability standards are typically met with chemical flame retardants (FRs). FRs can migrate out of products into dust and are linked to cancer, neurological impairment, and endocrine disruption. We collected 95 dust samples from dormitory common areas and student rooms on two U.S. college campuses adhering to two different furniture flammability standards: Technical Bulletin 117 (TB117) and Technical Bulletin 133 (TB133). Because TB133 requires furniture to withstand a much-more-demanding test flame than TB117, we hypothesized that spaces with TB133 furniture would have higher levels of FRs in dust. We found all 47 targeted FRs, including 12 polybrominated diphenyl ether (PBDE) congeners, 19 other brominated FRs, 11 phosphorus FRs (PFRs), 2 Dechlorane-Plus (DP) isomers, and 3 hexabromocyclododecane (HBCDD) isomers in the 95 dust samples. We measured the highest reported U.S. concentrations for a number of FRs, including BDE 209 (up to 990 000 ng/g), which may be used to meet the TB133 standard. We prioritized 16 FRs and analyzed levels in relation to flammability standard as well as presence and age of furniture and electronics. Adherence to TB133 was associated with higher concentrations of BDE 209, decabromodiphenylethane (DBDPE), DPs, and HBCDD compared to adherence to TB117 in univariate models (<i>p</i> < 0.05). Student dormitory rooms tended to have higher levels of some FRs compared to common rooms, likely a result of the density of furniture and electronics. As flammability standards are updated, it is critical to understand their impact on exposure and health risks