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The goal of this report is to evaluate brominated persistent organic pollutants (POPs) in the indoor air and dust to further assess their health effects on thyroid hormones and neurodevelopment in infants, toddlers, and young children. This category of brominated POPs includes polybrmonated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs), polybrominated biphenyls (PBBs), and polybrominated dibenzo-p-dioxins (PBDD/DFs). These organobromines are lipophilic compounds which resist physical and chemical degradation in the environment and biota, and so easily bioaccumulate in adipose tissue. Brominated POPs, particularly in brominated fire retardants (BFRs) such as PBDEs, HBCDs, and PBBs, are ubiquitous in indoor environments due to their inadvertent release from certain consumer products. Some of these organobromines have been recognized in some in-vitro and in-vivo studies to be neurotoxins and disrupt thyroid hormones, although the evidence from actual epidemiological studies is contradicted and inconsistent, especially for infants, toddlers, and young children, who are particularly vulnerable to these substances as they spend most of their time in the home. This report focuses on exposure to PBDEs, HBCDs, PBBs, and PBDD/DFs in the indoor dust and on the indoor aerosol, to explore their association with human health, particularly the disruption of thyroid hormones and neurodevelopment in early childhood.

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Our goal was to determine dioxin levels in 800 soil samples collected from Taiwan. An in vitro DR-CALUX® assay was carried out with the help of an automated Soxhlet system and fast cleanup column. The mean dioxin level of 800 soil samples was 36.0 pg-bioanalytical equivalents (BEQs)/g dry weight (d.w.). Soil dioxin-BEQs were higher in northern Taiwan (61.8 pg-BEQ/g d.w.) than in central, southern, and eastern Taiwan (22.2, 24.9, and 7.80 pg-BEQ/g d.w., respectively). Analysis of multiple linear regression models identified four major predictors of dioxin-BEQs including soil sampling location (β = 0.097, p < 0.001), land use (β = 0.065, p < 0.001), soil brightness (β = 0.170, p < 0.001), and soil moisture (β = 0.051, p = 0.020), with adjusted R2 = 0.947 (p < 0.001) (n = 662). An univariate logistic regression analysis with the cut-off point of 33.4 pg-BEQ/g d.w. showed significant odds ratios (ORs) for soil sampling location (OR = 2.43, p < 0.001), land use (OR = 1.47, p < 0.001), and soil brightness (OR = 2.83, p = 0.009). In conclusion, four variables, including soil sampling location, land use, soil brightness, and soil moisture, may be related to soil-dioxin contamination. Soil samples collected in northern Taiwan, and especially in Bade City, soils near industrial areas, and soils with darker color may contain higher dioxin-BEQ levels.