Health risk assessment of polycyclic aromatic hydrocarbons and heavy metals via dietary intake of vegetables grown in the vicinity of thermal power plants

Six different vegetables grown in the vicinity of three thermal power plants and a background site in Delhi, India were analyzed for 16 priority polycyclic aromatic hydrocarbons (PAHs) and 7 heavy metals (Cd, Cu, Cr, Ni, Zn, Fe and Mn). Annual mean concentrations of PAHs and all metals were found to be significantly higher (ANOVA, p < 0.001) at power plant sites as compared to the background site. Higher abundances of coal tracer PAHs such as Phen, Anth, Flan, Pyr and Chry in power plant vegetables suggested possible impacts of coal combustion emissions. Higher ratios of polluted sample-to-background sample of vegetables were found especially for Cr, Cd, Ni and Zn. Spinach and radish showed greater accumulation of PAHs and metals on a mass basis at the power plant sites while vegetables belonging to the gourd family showed highest relative enrichment. Power plant samples showed 184-475% greater metal pollution index (MPI) values as compared to the background location while health risk indices (HRI) for Cd and Ni exceeded the safe limit for most vegetables. Incremental lifetime cancer risk (ILCR) assessment showed that up to 58 excess cancer cases are likely in Delhi for lifetime ingestion exposure to PAHs at their observed concentrations.

► Very high PAH and metal levels found in vegetables at power plant sites in Delhi. ► Power plant samples had higher levels of Cr, Cd, Ni and Zn than background ones. ► Spinach and radish showed higher accumulation of metals and PAHs. ► Carcinogenic PAHs contributed 0.4-50% to total PAHs in vegetables. ► Health risk for dietary intake of metals and PAHs in vegetables assessed.