Human Exposure Assessment to Brominated Flame Retardants

Abstract

Brominated flame retardants (BFRs) are organobromine compounds that inhibit combustion and are used in consumer products to decrease flammability. BFRs can leak from consumer products during usage, recycling or disposal, enter to the environment and cause negative effects on humans from fetal life to adulthood. In this study the concentrations of two brominated flame retardants hexabromocyclododecane (HBCD) and tetrabromobisphenol-A (TBBPA) were reported in the variety of food items, indoor dust and urban atmosphere. Then, the obtained concentrations were combined with food consumption and accidental dust ingestion rates and used for the estimation of human body burden. Finally, the possibility of using hair as a bioindicator of exposure to HBCD and TBBPA were examined. Food In this study a total of 521 food samples from eight food categories were sampled and analyzed for their HBCD content. Based on consumption data, the average dietary intake of the general Korean population and specific subgroups was calculated. The highest levels of HBCD were found in fish and shellfish (0.47 ng g-1 ww), and this was attributed to natural exposure to the contaminated marine environments and the HBCD bioaccumulation. In addition, the use of expanded polystyrene buoys in aquaculture was also found to be a potential source of HBCD in bivalves. The high solubility of α-HBCD in water and the persistence of this diastereomer compared to β- and γ-HBCD in biological tissues, led to higher accumulation of α-HBCD in animal-based foods. In contrast, the diastereomeric selectivity and lower metabolic capacity in plants compared with animals led to the predominance of γ-HBCD in plant-based foods. The dietary intake of HBCD was estimated to be 0.82 ng kg-1 bw d-1 in the general population and 2.89 ng kg-1 bw d-1 in children up to 5 years of age. The high HBCD intake in children was found to be a result of their lower body weight and their high consumption of milk and homemade Korean baby foods that usually contain fish. Indoor dust In this study, the BFR concentrations in 124 vacuum dust samples of six categories of indoor environments (homes, offices, kindergartens, cars, schools, and public indoor environments) and 32 surface dust samples were investigated. The median ΣHBCD concentrations ranged from 106.30 ng g-1 in home dust to 496.13 ng g-1 in office dust. The TBBPA concentrations in indoor dust (from 78.87 to 463.81 ng g-1) were among the highest compared to other countries because of the high market demand for this flame retardant in Korea. The TBBPA concentrations in surface dust of living rooms were significantly higher (p<0.05) than sleeping rooms, due to the presence of more electrical equipment in living rooms. The estimated daily intakes (EDI) of ΣHBCD and TBBPA (dust+diet) for toddlers were 6.18 ng kg-1 bw d-1 and 2.54 ng kg-1 bw d-1, respectively. In general, the ΣHBCD estimated body burden of Korean adults showed good agreement with the reported ΣHBCD median concentrations in their sera. Since the developmental health effect of exposure to HBCD was categorized as “high hazard” by the US Environmental Protection Agency, the estimated high body burden of ΣHBCD in Korean toddlers (7.91 ng g-1 lw) warns us of possible adverse effects on the development of essential systems in their bodies. Atmosphere The concentrations of two brominated flame retardants, HBCD and TBBPA, were measured in the atmosphere (particle and gas phases) of two Korean cities: Seoul, a metropolitan city, and Jeonju, a mid-sized non-industrial city. The atmospheric ΣHBCD and TBBPA concentrations ranged from 8.08 pg m-3 to 69.23 pg m-3 and from 1.83 pg m-3 to 50.14 pg m-3, respectively. Winter measurements revealed that the TBBPA concentrations in three districts of Seoul appeared to correlate directly with the local population density whereas the ΣHBCD concentrations of Seoul atmosphere varied in cold and warm seasons. Results of this study revealed that the atmospheric BFR concentrations in urban areas varied locally with population density and season. Scalp hair In this study we examined methods for extraction and analysis of HBCD and TBBPA in human hair. Validation of the selected method was shown by performing a spiking experiment. Scalp hair samples (~ 1 g) were collected from individuals in Korea (n = 24) and Iran (n = 15) and the concentrations of HBCD and TBBPA were quantified. Obtained HBCD and TBBPA concentrations in the collected hair samples ranged from ND to 3.24 ng g-1 and ND to 16.04 ng g-1. Significantly higher concentrations of TBBPA were found in hair samples collected in Korea to those in Iran (p< 0.05) which is due to the high consumption of TBBPA in Korea. The significant correlation between HBCD and TBBPA in hair samples from Korea, as well as the HBCD concentration trend in age groups and genders demonstrated that the major pathways of hair contamination for those BFRs are through dietary intake.