Bioreactivity of Beijing Outdoor Ambient Particulates

Ambient particulates play an important role in human health; numerous studies have related ambient particulates levels with adverse health outcomes, primarily respiratory-related, in the general population. The health effect is closely correlated with properties of ambient particulates, toxicology mechanism is studied on the molecular level by means of molecular biology method mostly, the vitro plasmid assay together with FESEM (Field emission scanning electron microscopy) and ICP-MS (inductively coupled plasma-mass spectrometry) were employed to investigate the physico-chemical characteristics and the bioreactivity of ambient particulates in Beijing air. It was found that the TD20 (toxic dose of particulate matter causing 20% of plasmid DNA damage) of Beijing ambient particulates can be as low as 28 mug.m^-1 and as high as >1000 mug.m^-1. Comparison of the physical properties indicates that fine particles is more toxiferous than course particles, the bioreactivity of Beijing particulate matter is mainly sourced from the water-soluble fraction and water-soluble zinc is probably the major element responsible for the plasmid DNA damage.