Health Risk Assessment and Source Apportionment of PAHs in Rainwater Obtained in an Urban Area in Southern Nigeria

G. E. ODESA; D. U. OLANNYE; H. C. UWAJINGBA; E. E. ONUCHUKWU

G. E. ODESA Dennis Osadabey University Asaba
D. U. OLANNYE Dennis Osadabey University Asaba
H. C. UWAJINGBA Dennis Osadabey University Asaba
E. E. ONUCHUKWU Dennis Osadabey University Asaba

Keywords: Aromatic Hydrocarbons, Health risk assessment, molecular diagnostic ratios, Rainwater

Abstract

This study investigates the presence and composition of potential health risks from
the sources of Polycyclic Aromatic Hydrocarbons (PAHs) in rainwater collected
from urban rooftops in Asaba, Delta State, Nigeria. Ten rainwater samples were
analyzed for their PAH composition using Gas Chromatography Flame Ionization
Detection (GC-FID), HP5890 Series II model. Average Daily Dose (ADD),
benzo(a)pyrene toxic equivalence (B(A)Pteq), and carcinogenic toxic equivalence
(TEQs) were utilized to evaluate the potential health risks associated with the
consumption of the rainwater. Also, molecular diagnostic ratios were employed to
identify the sources of PAHs in the water. The results indicated the presence of
PAHs in all the samples, with average concentrations ranging from 0.21 to 6.4 μg/L.
The evaluated ADD values ranged from 0.006286 to 0.201143 μg/L, while B(A)Pteq
ranged from 0.0013 to 2.5, with a TEQ value of 5.1. The study established that most
PAH levels were below critical thresholds for non-carcinogenic effects. The
potential cancer risk assessment (B(A)Pteq and TEQs) revealed values exceeding
the USEPA's negligible risk threshold for cancer risk (CR), indicating significant
public health concerns. Furthermore, it was observed that lower molecular weight
PAHs accounted for 63.73% of the total composition. Inferences from the
molecular diagnostic ratio plots suggest that the pyrogenic processes, particularly
fuel combustion from industrial and vehicular emissions were dominant sources of
PAHs in the rainwater.