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 USH>.\ pi'iority polycyclic aromatic hydrocarbons (PAHs) in commonly consumed tubers: Yarn (Dioscorea rot unclata). Cassava(Mciniho/ es cu/cub) Cocoyam (Coloccicia an/iquorum) and their rhizosphere soils from Aba and Nnewi. Average concentration of PAH in tubers from Aba was found rn be 0.45mg while samples from Nnewi had an average VPAI-1 concentration of 2.05mg. 'l'hough both values are above EU limits of 0.2mg/kg dw of PA I Is in foods, results indicated a greater risk of exposure to PAl-I through the Ibod chain for the populace in Nne\vi compared to those who live in Aba. IPAl-1 levels in rhizosphere soil from Nnewi (22. 12mg) was 42% greater than PA I concentration in rhizosphere soil from Aba (12.9mg) indicating a higher level ol' pollution in Nne\\ i. Among the analyzed samples. mean concentration of 2-ringed PAl--I range from below limit of detection (BDL) to 0.21mg. 131 )L to 1.13mg for 3-ringed PAH. BDL to 1 .3 1mg for 4-ringed PAl-I. Bl)L to 0.45mg for 5-ringed PAll and BDL to 0.62 for 6- ringed PAH. Total R(a)P concentration (B(a)P) concentration in tubers from Aba was approximately 0.0 1 mg/kg dw. this value is equivalent to the set regulatory limits. B(a)P levels in tubers from Nnewi was 0.1 mg/kg dw which exceeded DPR intervention limit of 0.01 mgkg dw lOr food.The LMW- PAH/l-IMW-PAH ratio ohser\ ccl in this study was <I br Aba and Nnewi suggesting that the PAl-Is crc mainly 1mm non-petrogenic sources. Daily dietar\ exposure to 131 a Peq \ ia tuber consumption br the two POPLll1tiOl studied ranged from 0.00 (rn.' I3aPeq/lcg bod\ eight pci' day) to 4.42mgl'- 02(ng BaPeq/kg body \veigh n-' da\). With regards In I .i l time cancer risk. average values lbr I ('ks 10 all population roup were less than one in a million chances of additional luman cancer over a 70-year lifetime (II .CR = 10 with values for Nnewi sLIccestin realer chances of contracting cancer compared to Aba. ' 13(a)P. PAH and 131a1 Peq were higher than limits set by DPR and the Ft. Key words: daily intake of AlIs. life time cancer risk. rhizosphere soils. polycvcl ic aromatic h\ di'ocLli'h1 os. Aba and N newi.