Atmospheric levels and cytotoxicity of PAHs and heavy metals in TSP and PM_2.5 at an electronic waste recycling site in southeast China

Twenty-nine air samples of total suspended particles (TSP, particles less than 30-60 μm) and thirty samples of particles with aerodynamic diameter smaller than 2.5 μm (PM_2.5) were collected at Guiyu, an electronic waste (e-waste) recycling site in southeast China from 16 August 2004 to 17 September 2004. The results showed that mass concentrations contained in TSP and PM_2.5 were 124±44.1 and 62.12±20.5 μg m^-3, respectively. The total sum of 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs) associated with TSP and PM_2.5 ranged from 40.0 to 347 and 22.7 to 263 ng m^-3, respectively. Five-ring and six-ring PAHs accounted for 73% of total PAHs. The average concentration of benzo(a) pyrene was 2-6 times higher than in other Asian cities. Concentrations of Cr, Cu and Zn in PM_2.5 of Guiyu were 4-33 times higher than in other Asian countries. In general, there were significant correlations between concentrations of individual contaminants in TSP with PM_2.5 (i.e. PAHs, Cd, Cr, Cu, Pb, Zn, Mn except Ni and As). The high concentrations of both PAHs and heavy metals in air of Guiyu may impose a serious environmental and health concern. Cytotoxicity of the extract of TSP and PM_2.5 of ten 24 h samples collected against human promonocytic leukemia cell line U937 (ATCC 1593.2) was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cytotoxicity assay. The results showed that under the same concentrations of extract, PM_2.5 cytotoxicity was 2-4 times higher than TSP.