ABSTRACT

 Owing to the increased rate of environmental pollution in industrialized and commercial cities which pose health risk to residents, this study investigated the concentrations of 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs) in common!) consumed tubers: Yam (Dioscorea rotundata), Cassava{Munihol esciilenla) . Cocoyam (Colocacia antiquorum) and their rhizosphere soils from Aba and Nnewi. Average concentration of YPAH in tubers from Aba was found to be 0.45mg while samples from Nnewi had an average \PAH concentration ol 2.05mg. Though both values are above EU limits of 0.2mg kg dw ol PA Ils in foods, results indicated a greater risk of exposure to PAH through the lood chain lor the populace in Nnew i compared to those who live in Aba. \PA1I levels in rhizosphere soil from Nnewi (22.12mg) was 42°o greater than \PAI 1 concentration in rhizosphere soil from Aba (12.9mg) indicating a higher level of pollution in Nnew i. Among the analyzed samples, mean concentration of 2-ringed PAH range from below limit of detection (BDL) to 0.21 mg. BDL to 1.13mg for 3-ringed PAH. BDL to 1.31 mg for 4-ringed PAH. BDL to 0.45mg for 5-ringed PAH and BDL to 0.62 for 6- ringed PAH. Total B(a)P concentration (VB(a)P) concentration in tubers from Aba was approximately O.Olmg/kg dw, this value is equivalent to the set regulator) limits. VB(a)P levels in tubers from Nnewi was 0.1 mg/kg dw which exceeded DPR intervention limit of 0.01 mgkg~' dw for food.The LMWPAH HMW-PAH ratio observed in this study was <1 for Aba and Nnewi suggesting that the PAHs were mainly from non-petrogenic sources. Daily dietary exposure to B|a|Peq via tuber consumption for the two population studied ranged from 0.00 (mg BaPeq/kg body weight per day) to 4.42mgE02(mg BaPeq kg body weight per day). With regards to Life time cancer risk, axerage values for LCRs for all population groups were less than one in a million chances of additional human cancer over a 70-year li fetime (1LCR = 10’ (’) with values for Nnewi suggesting greater chances of contracting cancer compared to Aba. Values for ^B(a)P. VPAH and B|a]Peq were higher than limits set b) DPR and the EU. Key words: daily intake of PAHs, life time cancer risk, rhizosphere soils, polycyclic aromatic hydrocarbons, Aba and Nnewi.