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Microplastics (MPs) are a group of emerging contaminants that attracted increasing scientific and societal attention over the past decade. So far, most studies on MPs focus on characterizing their occurrence, fate, and impact in the aquatic environment. In contrast, very little is known about the magnitude, patterns, and associated risks of human exposure to MPs, particularly indoors, despite people spending most of their time indoors. This paper provides the first study hitherto of MPs in indoor air via both active and passive sampling from 30 homes and 30 workplaces in Birmingham, UK. The average concentration of MPs in the active air samples was 15.6 ± 5.4 MP/m 3 in homes and 13.1 ± 6.5 MP/m 3 in workplaces. For atmospheric deposition samples (passive sampling), the average MPs concentrations were 3735 ± 1343 MP/m 2 /day in homes and 3177 ± 1860 MP/m 2 /day in workplaces. Mean concentrations of MPs in UK homes were significantly higher (P<0.05) than those in workplaces for both active and passive air samples. This was mainly driven by carpeted floors in all the studied homes, while 13 of the sampled workplaces were uncarpeted. MPs concentrations in atmospheric deposition (passive) samples were significantly higher (P < 0.05) than airborne (active) MPs samples in the studied microenvironments. Nonetheless, a strong correlation (P < 0.01) was observed between the concentrations of MPs measured by active and passive sampling, indicating common sources of MPs to both active and passive samples collected from the same microenvironments. In terms of morphology, fibres were the dominant shape of MPs, followed by fragments, constituting together ≥90% of the identified MPs in all samples, with the remaining minor percent made up by foams. Airborne MPs were dominated by particles in the size range (10-25 μm), and the particles abundance decreased with increasing particle size. MPs in atmospheric fallout particles, were dominated by larger particles (50-100 μm) with lower contribution from smaller particles (10-25 μm) compared to airborne particles. Nonetheless, combined with the predominance of fibres, this raises concern over the risk from inhalation exposure because MPs fibres in the detected size ranges were observed to penetrate into human lung tissue. PET and PVC were the most abundant polymer types in the studied samples followed by PP and PE. The average daily inhalation exposure of UK adults and toddlers was estimated at 3.0 and 6.3 MP/kg body weight/day, respectively. The higher inhalation exposure of UK toddlers raises concern due to their incompletely developed immune and nervous systems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Concentrations of polybrominated diphenyl ethers, hexabromocyclododecane (HBCDD), and novel brominated flame retardants (NBFRs) were measured in indoor dust, indoor air, and outdoor air in Birmingham, UK. Concentrations of ΣBFRs ranged from 490 to 89,000 ng/g, 46-14,000 pg/m 3 , and 22-11,000 pg/m 3 , respectively, in UK indoor dust, indoor air, and outdoor air. BDE-209 and decabromodiphenyl ethane (DBDPE) were the main contributors. The maximum concentration of DBDPE (10,000 pg/m 3 ) in outdoor air is the highest reported anywhere to date. In contrast with previous studies of outdoor air in Birmingham, we observed significant correlations between concentrations of tri- to hepta-BDEs and HBCDD and temperature. This may suggest that primary emissions from ongoing use of these BFRs have diminished and that secondary emissions (e.g., evaporation from soil) are now a potentially major source of these BFRs in outdoor air. Conversely, the lack of significant correlations between temperature and concentrations of BDE-209 and DBDPE may indicate that ongoing primary emissions from indoor sources remain important for these BFRs. Further research to clarify the relative importance of primary and secondary sources of BFRs to outdoor air is required. Comparison with earlier studies in Birmingham reveals significant ( p < 0.05) declines in concentrations of legacy BFRs, but significant increases for NBFRs over the past decade. While there appear minimal health burdens from BFR exposure for UK adults, dust ingestion of BDE-209 may pose a significant risk for UK toddlers.

Investigations into the impacts of regulated electrical and electronic waste (e-waste) recycling activities on urban environments in Europe remain rather scarce. In this study, dust samples taken both inside and outside of five UK e-waste recycling facilities were analysed for concentrations of polybrominated diphenyl ethers (PBDEs), novel brominated flame retardants (NBFRs), and hexabromocyclododecane (HBCDD). Average concentrations of ∑BFRs in dust inside and outside UK e-waste recycling facilities were 12,000 ng/g and 180 ng/g, with median concentrations of 7500 ng/g and 85 ng/g, respectively. BDE-209 and decabromodiphenyl ethane (DBDPE) were the most abundant BFRs in both indoor and kerb dust, making a combined contribution to ∑BFRs of ~90 % on average. While four out of the five studied e-waste facilities showed a lack of significant impact on BFR contamination in surrounding environment, one of the studied e-waste recycling facilities was identified as a likely source of BFR contamination to UK urban environments, with industrial activities as another potential source of NBFRs. Occupational exposure of UK e-waste recycling workers to BFRs via dust ingestion was generally lower than that estimated for e-waste recyclers from other countries, but was comparable to BFR exposure via dust ingestion of UK office workers. Our estimates suggested that health burdens posed by dust ingestion of BFRs were minimal for UK e-waste recycling workers., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Global restrictions on use of legacy brominated flame retardants (BFRs) such as polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCDD) have generated demand for novel BFRs (NBFRs) as substitutes. Our research group has previously reported decreased concentrations of PBDEs and HBCDD and increased concentrations of NBFRs in UK indoor environments, suggesting that restrictions on PBDEs and HBCDD are exerting an impact. In this study, we analysed UK foodstuffs collected in 2020-21 and compared the BFR concentrations found with those found in similar samples collected in 2015 to investigate whether similar trends in BFR concentrations would be observed. Concentrations of PBDEs and HBCDD isomers detected in our samples had declined by 78-92 % and 59-97 % since the 2015 study, respectively. Moreover, concentrations of NBFRs (dominated by 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE or TBE), and bis(2-ethyl hexyl) tetrabromophthalate (BEH-TEBP or TBPH)) in UK foodstuffs increased significantly (28-1400 %) between 2015 and 2020-21. Combined, these findings suggest that restrictions on use of PBDEs and HBCDD have had a discernible impact on concentrations of these legacy BFRs and their NBFR replacements in UK foodstuffs. Interestingly, given recent reports of a significant increase in concentrations of decabromodiphenyl ethane (DBDPE) in UK house dust between 2014 and 2019, a significant decline (70-84 %) in concentrations of DBDPE was observed in UK foodstuffs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

Food ingestion has been established as an important human exposure route to many environmental contaminants (brominated flame retardants, dioxins, organochlorine pesticides etc). However, information regarding dietary exposure to organophosphate esters (OPEs) in the UK remains limited. This study provides the first comprehensive dataset on OPEs in the UK diet by measuring concentrations of eight OPEs in 393 food samples, divided into 15 food groups, collected from Birmingham, UK. All target OPEs were measured above the limit of quantification in at least one of the food groups analysed. Concentrations were highest (mean ∑ 8 OPEs = 18.4 ng/g wet weight (ww)) in milk and milk products, followed by those in cereal and cereal products (mean ∑ 8 OPEs = 15.9 ng/g ww), with concentrations lowest in chickens' eggs (mean ∑ 8 OPEs = 1.61 ng/g ww). Interestingly, concentrations in animal-derived foods (mean ∑ 8 OPEs = 44.2 ng/g ww) were statistically indistinguishable (p˃0.05) from plant-derived foods (mean ∑ 8 OPEs = 36.8 ng/g ww). Estimated daily dietary intakes (EDIs) of ∑ 8 OPEs under mean and high-end exposure scenarios for the four age groups considered were: toddlers (420 and 1547 ng/kg bw/day) ˃ children (155 and 836) ˃ elderly (74.3 and 377) ˃ adults (62.3 and 278) ng/kg bw/day, respectively. Baby food contributed 39 % of ∑ 8 OPEs exposure for toddlers, with non-alcoholic beverages contributing 27 % of exposure for children, while cereal and cereal products (25 %) and fruits (22 %) were the main contributors for adults and the elderly. The concentrations of OPEs in UK foodstuffs were generally of the same order of magnitude as those reported for other countries and our estimates of dietary exposure were well below the corresponding health-based limit values., Competing Interests: Declaration of competing interest All the authors declare that they have no known competing interest that could appear to influence the work/data reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)