The effects of population and regional economy on the levels and distribution of hexabromocyclododecanes in soils from Jiangsu, Southeast China.

Abstract

China used to be the major producer and consumer of hexabromocyclododecanes (HBCDs). Although HBCDs are restricted under the Stockholm Convention, emissions from the flame-retarded materials will continue for several decades and be potentially long-term sources of HBCDs leaching to the environment, and their adverse effects on human health and the environment will continue to raise concerns globally. The levels and distribution of HBCDs in soils of different land use types in the prosperous and densely populated Yangtze River Delta region, China were investigated. The total HBCD concentrations (ΣHBCDs) ranged between 0.17 and 6.28 ng g^-1 dw (dry weight) with a mean value of 1.20 ng g^-1 dw, which was at a low level worldwide. The three HBCD stereoisomers, α-HBCD, β-HBCD and γ-HBCD contributed 37%, 11% and 52% on average, respectively. The spatial distribution of HBCDs showed that northern and southern Jiangsu regions had higher HBCD levels than those in central region. HBCD contamination differed considerably among three type of lands, industrial land > urban and commercial land > agricultural and suburban land, suggesting that anthropogenic activities such as industrial production, urbanization and commercial activities etc. are the major sources of HBCDs, especially the influence of industries. No relationships were found between HBCD concentrations and per capita GDP (gross domestic product) in northern Jiangsu, while they were significantly positively correlated in southern Jiangsu. Mass inventory of HBCDs in the surface soils of Jiangsu was 38.6 tons. The estimated daily intakes (EDIs) of HBCDs for human via soil ingestion were 0.75, 1.68-3.77, 7.83-12.9 pg kg^-1 bw d^-1 for ages > 21, 6 to 21 years and under 6 years, respectively. The mean EDIs for children under 6 years old was approximately 13 times greater than that of adult.