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Title: The signiflcance of indoor air as a source of human exposure to polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs)
Author: Hazrati, Sadegh
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 2006
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In order to investigate the significance of indoor air as a source of human exposure to PBDEs and PCBs, 94 indoor microenvironments from 4 major indoor environment categories (i.e. offices, homes, public environments, and cars) were monitored in the West Midlands area between 2003 and 2005. Seasonal and within building variability in PCB and PBDE concentrations were studied by monitoring 8 indoor environments for a period of 12 months. The impact of contaminated indoor air on PCB and PBDE concentrations in outdoor air was also evaluated using both chiral techniques and a simple box model. The average concentration of 2PCB in homes, offices, and public indoor environments combined was 11.65 ng m"3 (median = 3.54 ng m"3 ), ranging from 0.49 to 101.8 ng m'3 . The most contaminated indoor environment category was public environments, followed by offices, homes, and cars. The average concentration of ZPBDE for all indoor *% <5 __ microenvironments studied was 0.269 ng m", ranging from 0.004 to 8.2 ng m" . Excluding cars, this figure for all other indoor microenvironments combined ranged from 0.004 to 1.416 ng m" 3 with average value of 0.109 ng m" 3 . Unlike PCBs, cars were identified as the most contaminated indoor microenvironment category studied with an average concentration of 0.709 ng m'3 . Based on records of time activity patterns and concentrations of PCBs and PBDEs found in indoor environments, the relative significance of inhalation exposure to ZPCB compared to diet ranged from 3.3 to 66.2% (average = 30.6%) for adults and from 0.98 to 20% (average = 7.4%) for toddlers. This figure for ZPBDE was between 0.2 and 15.3% (average = 2.3%) for adults and between 0.04 and 3.9% (average = 0.59%) for toddlers. The results obtained from monitoring 8 selected indoor microenvironments revealed that PCB and PBDE concentrations in warmer months are generally higher than those measured in colder months. Concentrations of some PCB and PBDE congeners also showed statistically significant (p<0.05) seasonal variations in some monitoring locations. The highest ZPCB concentrations were found in buildings constructed between 1950 and 1979 (average EPCB = 19.9 ng m" 3 and SD = 5 ng m"3 ) followed by those constructed prior to 1950 (average SPCB = 5.8 ng m' 3 and SD = 4 ng m' 3 ) and post 1979 (average EPCB = 2 ngm" 3 , and SD = 1.8 ng m" 3 ). ZPCB concentrations in buildings constructed in 1950-1979 were statistically significantly higher than those built post 1979 (pO.OOl). Concentrations of the major PBDE congeners were significantly positively correlated with the construction year of the buildings (p<0.05). However, although concentrations of PBDEs in one office fell appreciably following replacement of a PC manufactured in 1998 with one manufactured in 2003; no significant relationships were detected between concentrations of either PCBs or PBDEs and room contents such as numbers of PCs, other items of electronic equipment, or items of PUF-containing furniture. This suggests that the influence of room contents on the contamination of indoor environments with such compounds is complex, and that factors such as the age of electronic equipment and room ventilation may play an important role. Chiral signatures of PCBs in indoor air were essentially racemic with average EF values of 0.496 ± 0.003, 0.500 ± 0.003, and 0.500 ± 0.004 for PCBs 95, 136, and 149, respectively. EF values of all PCB atropisomers in one office microenvironment in monthly samples taken over a 12 month monitoring period displayed no statistically significant variations between warmer months and colder months (p>0.10). Direct comparison of EFs in indoor air, outdoor air, and soil for chiral PCBs revealed that on average >80% of atmospheric concentrations of PCB 95, 136, and 149 at the EROS monitoring site is derived from the ventilation of contaminated indoor air, which is consistent with the results obtained using a simple box model in the West Midlands. Applying the box model for PBDEs revealed an estimate of daily mass flux of 9.98x10 8 ng ZPBDE from indoor to outdoor air, which provides a predicted concentration of ~5 pg EPBDE m" 3 in outdoor air. This value is line with observed values reported elsewhere for the West Midlands, and suggests that ventilation of indoor air makes a significant contribution to outdoor air contamination with PBDEs.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available