Size-resolved particle measurements of polybrominated diphenyl ethers indoors: Implications for sources and human exposure

Contamination levels, influencing factors, and risk assessment of polybrominated diphenyl ethers in house dust of northern Serbia

Polybrominated diphenyl ethers (PBDEs) are a group of compounds that, due to their applications, are considered mainly indoor contaminants. To obtain the first information about the presence of PBDEs in Serbia, dust samples (n = 50) were collected in settlements in the northern Serbian province of Vojvodina. The selected/target congeners (BDE-28, 47, 99, 100, 153, 154, and 183) were extracted from house dust by microwave-assisted extraction technique, and purified extracts were analyzed on a dual-column gas chromatograph with micro-electron capture detectors. A wide range of ΣPBDEs was detected (0.295 to 394 ng g-1 dust), which reflects large differences in contamination among the examined homes. For the majority of samples (72%), ΣPBDEs were lower than 5 ng g-1 indicating that people living in Vojvodina province are exposed to low concentrations of PBDEs present in their households. Based on principal component analysis (PCA), balcony areas and age of the house positively correlate with the PBDE congeners with higher detection frequencies (≥ 50%), namely, with BDE-99, BDE-153, and BDE-183. Statistically significant positive correlation (p < 0.01) was obtained for BDE-99 and the number of household's members. Estimated daily intakes (EDItot) were calculated for ingestion and dermal absorption of dust for two age groups-adults and toddlers. These are the first data on PBDE status in the area of the Western Balkan, and the health risk assessment indicates that PBDE levels obtained in household dust do not pose a risk for human health.

Optimization and validation of a two-step method for the determination of polybrominated diphenyl ethers in Croatian house dust samples

Microwave-assisted extraction was applied as a method for extraction of seven polybrominated diphenyl ether (PBDE) congeners (28, 47, 99, 100, 153, 154, and 183) from house dust samples. Optimization of MAE experimental conditions was achieved using a multivariate design approach, and the results indicated that only the choice of extraction solvent had a statistically significant influence on extraction efficiency. The extract purification step was also investigated in detail with a goal to achieve effective cleaning, with minor solvent consumption. As the final operating conditions, 20 min MAE extraction from 1 g of dust with 20 mL of n-hexane : acetone (1 : 1, v/v) at 80 °C and extract purification on an in-lab prepared column containing 2 g of neutral silica and 4 g of acidified silica, whereby the PBDEs were eluted from the column with 15 mL of n-hexane : dichloromethane (4 : 1, v/v), were selected. The extracts were analyzed on a dual GC-μECD system, and GC-MS/MS was used as a confirmatory method. The performance of the optimized method was validated by analyzing spiked dust samples and a standard reference material (NIST 2585 "Organic Contaminants in House Dust"). Congener specific PBDE recovery ranged from 76% to 90% for the spiked samples (with very good repeatability; RSD < 7%) and the measured mass concentrations of selected PBDEs were in excellent agreement with certified values for a standard reference material. The proposed method was successfully applied to the analysis of targeted PBDEs in house dust samples.

Disturbance of the Dlk1-Dio3 imprinted domain may underlie placental Dio3 suppression and extracellular thyroid hormone disturbance in placenta-derived JEG-3 cells following decabromodiphenyl ether (BDE209) exposure

Decabromodiphenyl ether (BDE209) has been widely used as a flame retardant in the past four decades, leading to human health consequences, especially neurological impairments. Our previous in vivo studies have suggested that developmental neurotoxicity in offspring may be the result of BDE209-induced placental type III iodothyronine deiodinase (Dio3) disturbance and consequent thyroid hormone (TH) instability. Dio3 is paternally imprinted gene, and its balanced expression is crucial in directing normal development and growth. In this study, we used placenta-derived cells to investigate how BDE209 affected Dio3 expression through interfering imprinting mechanisms in the delta-like homolog 1 (Dlk1)-Dio3 imprinted region. Gene chip analysis and RT-qPCR identified miR409-3p, miR410-5p, miR494-3p, miR668-3p and miR889-5p as potential candidates involved in Dio3 deregulation. The sodium bisulfite-clonal sequencing revealed the BDE209 affect methylation status of two differentially methylated regions (DMRs), intergenic-DMR (IG-DMR) and maternally expressed gene 3-DMR (MEG3-DMR). Our data indicate that placental Dio3 may be a potential molecular target for future study of BDE209 developmental toxicity. In particular, miRNAs, IG-DMR and MEG3-DMR in the Dlk1-Dio3 imprinted locus may be informative in directing studies in TH disturbance and developmental toxicity induced by in utero exposure to environmental persistent organic pollutants (POPs), and those candidate miRNAs may prove to be convenient and noninvasive biomarkers for future large-scale population studies.

A comprehensive risk assessment of human inhalation exposure to atmospheric halogenated flame retardants and organophosphate esters in an urban zone

Inhalation exposure to flame retardants used as additives to minimize fire risk and plasticizers is ubiquitous in human daily activities, but has not been adequately assessed. To address this research gap, the present study conducted an assessment of human health risk for four age groups through inhalation exposure to size fractionated particle-bound and gaseous halogenated flame retardants (polybrominated diphenyl ethers (PBDEs) and alternative halogenated flame retardants (AHFRs)) and organophosphate esters (OPEs) at indoor and outdoor environments (school, office, and residence) in three districts of a megacity (Guangzhou, China). Results demonstrated that OPEs were the dominant components among all targets. Indoor daily intakes of PBDEs and OPEs were 13-16 times greater than outdoor levels for all age groups. Gaseous OPEs contributed significantly greater than particle-bound compounds to daily intakes of all target compounds. Based on the different life scenarios, hazard quotient (HQ) and incremental life cancer risk (ILCR) from adults exposure to PBDEs and OPEs in indoor and outdoor settings were the greatest, followed by adolescents, children, and seniors. The estimated HQ and ILCR for all age groups both indoors and outdoors were lower than the safe level (HQ = 1 and ILCR = 10^-6), indicating that the potential health risk for local residents in Guangzhou via inhalation exposure to atmospheric halogenated flame retardants and OPEs was low.

Exposure of Canadian electronic waste dismantlers to flame retardants

Exposure of e-waste workers to eight halogenated and five organophosphate ester flame retardant chemicals (FRs) was studied at a Canadian e-waste dismantling facility. FR concentrations were measured in air and dust samples collected at a central location and at four work benches over five-24 hour periods spanning two weeks. The highest concentrations in air from workbenches were of BDE-209 (median 156 ng m^-3), followed by Tris(2-chloroethyl) phosphate (TCEP, median 59 ng m^-3). Dust concentrations at the workbenches were higher than those measured at the central location, consistent with the release of contaminated dust during dismantling. Dust concentrations from the workbenches were also dominated by BDE-209 (median 96,300 ng g^-1), followed by Triphenyl phosphate (TPhP, median 47,000 ng g^-1). Most FRs were in coarse particles 5.6-18 μm diameter and ~30% were in respirable particles (<~3 μm). Exposure estimates indicated that dust ingestion accounted for 63% of total FR exposure; inhalation and dermal absorption contributed 35 and 2%, respectively. Some air and dust concentrations as well as some estimated exposures in this formal facility in a high-income country exceeded those from informal e-waste facilities located in low and middle income countries. Although there is demonstrated toxicity of some FRs, FR exposure in the e-waste industry has received minimal attention and occupational limits do not exist for most FRs.