Spatiotemporal Variations And Human Health Risks Of Brominated Flame Retardants In Soils And Air Of Five Asian Countries

Brominated flame retardants(BFRs),including polybrominated diphenyl ethers(PBDEs)and novel brominated flame retardants(NBFRs),are a diverse group of chemicals added to commercial products such as furniture,electronics,and construction materials to reduce their flammability.BFRs were used in large quantity worldwide,accounting for 25% of the flame retardants market.BFRs were detected in the multi-media environment around the globe.BFRs may cause cancer,nervous system damage and other diseases.Surface soil and air samples were collected across five Asian countries(China,Japan,South Korea,Vietnam and India),and were analyzed for the pollution characteristics and spatiotemporal distribution of BFRs.For the soil samples,the concentrations of total PBDEs(ΣPBDEs)and total NBFRs(ΣNBFRs)were 49 ± 140 ng/g dw and 12 ± 28 ng/g dw,respectively.For the air samples,the concentrations of ΣPBDEs and ΣNBFRs were 140 ± 370 pg/m3 and 240 ± 730 pg/m3,respectively.The concentrations of BFRs in China,Japan and South Korea were higher than those in India and Vietnam.BDE-209 and DBDPE were the dominated compounds among all BFRs.Significant and positive correlations were observed among BFRs compounds,indicating that they were of common sources and/or similar environmental chemical behavior.Principal component analysis(PCA)was applied to analyze the sources of BFRs in soil and air for the five Asian countries.At the same time,PCA combined with multivariate linear regression method was used to obtain the contribution of each source.Results indicated that the sources of BFRs in soils and air were mainly from commercial deca-BDE and their alternatives,while the contribution of commercial penta-BDE,octa-BDE and their alternatives were low.In soil samples,the dominated source of PBDEs was from commercial deca-BDE,which accounting for 55.8 ± 2.5% to 100 ± 1.2% of the ΣPBDEs collected from four countries(excluding Vietnam).These results indicated that PBDEs in soils were mainly from commercial deca-BDE,and/or commercial deca-BDE is easy to deposit to the soil due to the higher molecular weight.Models were applied to simulate the spatial distribution of BFRs in soils and air of Asia,which showed that temperature and population density had significant effects on the distribution characteristics of BFRs.Radial dilution model was als o applied for locating the source regions of target compounds on a large scale,showing that the potential source regions of BFRs were from Laizhou Bay,Shandong Province.The pollution levels of BFRs in soils and air from BFR-manufacturing plant were significantly higher than those from other regions(p < 0.001).The modeling results of radial dilution model explained 72% and 80% of the total variance.The distance from source center and wind directions showed significant influence on the spatial distributions of BFRs in the soils around the BFR-manufacturing plant.Temporal trends of BFRs in the atmosphere before and after the ban of PBDEs in Asia were explored.Results showed that,the levels of commercial penta-BDE were significantly decreased in the atmosphere,indicating the effective of the regulation on commercial penta-BDE in Asia.The percentage of commercial deca-BDE in the atmosphere of China rose from 57.6 ± 33.1% in 2005 to 78.7 ± 22.3% in 2012,and the percentage of DBDPE was also increasing significantly.The concentrations of commercial penta-BDE and octa-BDE were significantly declined in the atmosphere of Northeast China,with the halving times of 6.8 ± 2.0 years and 4.1 ± 0.9 years,respectively.The concentrations of NBFRs were increasing with the doubling times ranged from 0.89 ± 0.05 years to 8.4 ± 4.0 years.The levels of BFRs in soil and air were used to evaluate the estimated daily intake(EDI),hazardous index(HI)and cancer risk(CR)of BFRs.The results showed that the values of EDI,HI and CR of BFRs via soil and air increased with decreasing age.The values of EDI,HI and CR of BFRs via soil and air exposure in Japan,China and South Korea were generally higher than those in India and Vietnam.The human exposures and health risks of BFRs for people live in BFR-manufacturing and e-waste regions were 1~4 orders of magnitude higher than those from other regions,indicating that the health risks were greater for people live near BFR-manufacturing and e-waste regions than that for people live in less polluted regions.Monte Carlo simulations,sensitivity and uncertainty analyses were performed for estimating the hazardous index via soil and air intake of BFRs.The results showed that the most influential parameter of the Monte Carlo simulation was the concentrations of BDE-209,followed by the concentrations of DBDPE,BDE-28 and BDE-47.This results reflecting the fact that BDE-209 and DBDPE were the dominated compounds,and BDE-28 and BDE-47 have greater toxicity.The simulation results for the health risks of BDE-209 via soil and air intake showed that the most sensitive parameters was BDE-209 concentrations in the soil,with the correlation coefficient between input and output ranged between 0.56 ~0.58,followed by the concentration of BDE-209 in air and the body weight of the exposure population.