Concentration, dietary exposure and human health risk assessment of total petroleum and polycyclic aromatic hydrocarbons in seafood from coastal communities in Rivers State, Nigeria

Abstract

The total petroleum hydrocarbons (TPHs) and polycyclic aromatic hydrocarbons (PAHs) present in some seafood samples namely Tympanostomus fuscatus (periwinkle), Crassostrea rhizophorae (Oyster) and Penaeus monodon (Shrimps) from three riverine communities - Buguma, Krakrama, and Bonny - in Rivers State, Nigeria and associated health risks were analyzed. Three samples of seafood were collected using fishing nets, knife and handpicking. The TPHs and PAHs levels were determined using the Gas Chromatography – Flame Ionization Detector (GC-FID) instrument. The highest concentrations of TPHs were observed in C. rhizosphere (90.60 ± 5.39 mg kg−1) samples from Buguma River, T. fuscatus (86.65 ± 2.92 mg kg−1) and P. monodon (83.90 ± 3.66 mg kg−1) samples from Krakrama River while the least value of 60.60 ± 2.14 mg kg−1 was recorded in P. monodon from Bonny. The highest concentrations of PAHs deposits were observed in T. fuscatus (62.28 ± 0.75 mg kg−1), and C. rhizophorae (50.40 ± 0.73 mg kg−1) samples from Buguma, and P. monodon (53.86 ± 1.66 mg kg−1) sample from Bonny River. The ratio of low molecular weight (LMW)/high molecular weight (HMW) PAH for seafood collected from all the locations was> 1 except T. fuscatus (0.95) collected from Krakama, these results, suggests that the PAH source may be petrogenic. The calculated toxic equivalency quotient (TEQ) values of carcinogenic PAHs ranged from 1.2E-02 to 9.7E-01 which is above the screening value (SV) of 2.5E-03 suggesting possible cancer risk. Risk index (RI) based on carcinogenic (and mutagenic) quotient due to PAHs via consumption of seafood indicate that the congeners present in T. fuscatus and C. rhizophorae obtained from Buguma and P. monodon from Bonny locations can cause cancer in receptors and therefore, the need for quick intervention by environmental agencies.