Trace metals in resuspended fraction of settled bus dust and assessment of non-occupational exposure.

Trace metals (TMs) within urban public transportation systems have rarely been studied and information on related health risks is scant. This study measured TM (arsenic, chromium, cadmium, nickel, zinc, copper and lead) concentrations in resuspended fractions of settled bus dust in Harbin, China, and estimated the exposure and health risks. The incremental lifetime cancer risk (ILCR) for commuters was estimated for TM exposures. The average concentration of total TMs was 559μg/g (ranges from 312 to 787) among 45 bus routes in Harbin. The hazard quotient of three selected commuter groups increased in the following order: teenagers<children<adults. Pb had the highest hazard index among six non-carcinogenic risk TMs. The ILCR for passengers was estimated for TM exposure and was shown to be acceptable (1.00E-07-1.00E-05); the sequence of ILCR assessments followed this ascending trend: ingestion>dermal contact>inhalation.