Exposure estimates of brominated flame retardants and lead in children's toys and indoor urban dust using spectrometric techniques.
Nkabinde, Sylvia Nomusa
Nkabinde, Sylvia Nomusa
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Abstract
Brominated flame retardants (BFRs) such as hexabromocyclododecane (HBCDD), polybrominated diphenyl ethers (PBDEs) and “novel” or “alternate” (NBFRs) are a group of man-made organobromine compounds that are incorporated into a variety of day-to-day products for flame retardancy. As a result of migration during use, they have been shown to have contaminated living organisms, the surrounding environment and the food chain. Furthermore, various studies have associated BFRs such as PBDEs and HBCDD as well as some NBFRs with adverse health issues. In addition, studies have identified BFRs in products designated for children’s play such as toys which is also cause for concern due to the mouthing habit of children. On the other hand, there is an emerging concern regarding the presence of lead (Pb) in children’s toys due to the fact that Pb has been associated with various health issues. Despite the progress made in developed countries over the past few years in reporting the presence of BFRs and metals, there is still a knowledge gap with regards to the presence of BFRs and Pb in children’s toys and the presence of NBFRs and HBCDD in indoor dust in Africa. This study, therefore, focused on the determination of PBDEs, HBCDD and some NBFRs in dust collected from electronics and furniture, as well as in children’s toys. Furthermore, this study measured the levels of lead present in children’s toys.
The approach followed was to first use a portable XRF (p-XRF) analyser to identify and measure bromine content in office equipment and furniture which serves as the first indication of the possible presence of BFRs; and secondly, to measure levels of BFRs present in 21 dust samples collected from the identified products. A suitable and optimised gas chromatography-mass spectrometry (GC-MS) method was developed for the simultaneous determination of PBDEs,
HBCDD and NBFRs. The sample preparation method involved ultrasonication and column chromatography. The concentrations of Σ7BDE congeners ranged from 50 – 3 350 ng/g. The BDE-99, -183 and -209 congeners were predominantly detected with maximum concentrations of 543, 401 and 1 760 ng/g, respectively. Hexabromocyclododecane (HBCDD) was also analysed and reported as the sum of all three isomers (α, β, and γ) and was detected in 57% of all dust samples analysed with a maximum concentration of 385 ng/g. In the case of NBFRs, 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE) was the most frequently detected (81%) with a maximum concentration of 1 400 ng/g. Along with the legacy BFRs, the NBFRs were frequently detected indicating the probability of increased usage as substitutes for the banned PBDEs.
In the case of children’s toys, portable XRF was first used to identify and measure bromine and Pb in 103 toys. In total, eleven toy samples with significant levels of bromine (exceeding100 μg/g) were selected for a more compound-specific determination using GC-MS. Sample preparation involved vortexing, ultrasonication and acid wash clean-up methods. The concentrations of BDE congeners ranged from <dl – 609 000 ng/g and BDE-209, -183 and -153 were found to be the most predominant congeners. Furthermore, this is the first study to report the presence of pentabromotoluene (PBT) and pentabromoethylbenzene (PBEB) in toy samples. Because PBDEs have been associated with numerous adverse health effects and subsequently have been shown to migrate from the toys into saliva, this present study evaluated their migration rates using artificial saliva solution prepared in the laboratory. Using GC-MS, seven BDE congeners were measured in five toy samples with the sum of BFRs exceeding 100 μg/g. Migration rates varied between 0.6 – 15.3 x 104 pg/cm2. The lower-brominated BDEs were the least detected; however, there is still concern due to the possible debromination of higher-brominated BDE congeners to the more toxic lower-brominated congeners. Children’s exposure risk through mouthing was also estimated and the following trend was observed: 76.5 – 787 (infants) and 6.18 – 63.6 pg/kg bw/d for pentaBDE, from 20.6 – 85 500 (infants) and 1.66 – 7 150 pg/kg bw/d (toddlers) for octaBDE and from 874 – 214 000 (infants) and 70.6 - 17 300 (toddlers) pg/kg bw/d for decaBDE. According to the estimated risk, the hazard quotient (HQ) values were all far below 1, indicating that there is no appreciable risk associated with the toys evaluated. However, concerns remain due to the limited number of BDE congeners used for estimation.
On the other hand, the levels of Pb in the 103 toys varied significantly giving concentrations ranging from ND to 1 960 μg/g. A total of 19 toy samples were quantitatively tested for total and bioaccessible Pb using flame atomic absorption spectrometry (F-AAS). Total Pb concentrations were found to be ranging from 12.4 – 1 440 μg/g. Assessment based on bioaccessible Pb showed that concentrations of Pb observed using the two methods (mouthing and ingestion) in the same sample varied significantly. Results showed that all samples analysed exceeded HQ > 1 in at least one or both methods used, indicating that there is an appreciable risk of exposure associated with the toys evaluated.
Description
Submitted in partial fulfilment of the requirements for the degree, Magister Technologiae: Environmental Management in the Department of Environmental, Water and Earth Sciences, Faculty of Science at the Tshwane University of Technology.
Date
2018-09-02
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Tshwane University of Technology
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Keywords
Brominated, Polybrominated, Children, Toys, Retardants