Dataset for Pyrogenic Contamination and Carcinogenic Risk of Polycyclic Aromatic Hydrocarbons in Soils from Automobile Repair Workshops in Ilorin Metropolis, North-central Nigeria

The lowest PAH concentration was Fluorene at 77.9 µg/kg in P2 (0–10 cm), while the highest was Indeno(1,2,3-cd)Pyrene at 171,509.7 µg/kg in P9 (0–10 cm). Low Molecular Weight (LMW) PAHs were poorly distributed and mostly below detection; Naphthalene, Acenaphthylene, and Acenaphthene were lowest, with Anthracene highest among LMW compounds. High Molecular Weight (HMW) PAHs were evenly distributed across almost all samples, reflecting accumulation over time. By ring number, PAH distribution followed 6 > 5 > 4 > 3 > 2 rings. Six-ring PAHs had the highest share (51.6%), five-ring 26.0%, four-ring 18.5%, and three-ring 3.4%; two-ring PAHs were below detection, likely due to volatilization during extraction. Using the Maliszewska-Kordybach (1996) classification (>1000 µg/kg heavily contaminated, 600–1000 contaminated, 200–600 weakly contaminated, <200 non-contaminated), the study area soils are heavily contaminated, ranging from P3 (10–20 cm, lowest) to P9 (0–10 cm, highest). Source identification Diagnostic ratios were used to trace PAH sources. LMW/HMW >1 indicates a petrogenic origin; <1 indicates pyrogenic (Wang et al., 1999). All samples had LMW/HMW <1 except P3 (10–20 cm), indicating a pyrogenic source. Phen/Ant >10, Ant/(Ant+Phen) <0.1, and IcdP/(IcdP+BghiP) <0.2 indicate petrogenic sources. In this study, Phen/Ant was <10 and Ant/(Ant+Phen) was >0.1, both indicating pyrogenic sources; IcdP/(IcdP+BghiP) was >0.2, also indicating a pyrogenic source. Sources for P6 (10–20 cm) and P8 (0–10 cm) could not be determined (ND) due to zero numerator/denominator values. Carcinogenic potency IARC identifies seven priority carcinogenic PAHs: benzo(a)anthracene, chrysene, benzo(ghi)perylene, benzo(a)pyrene, dibenzo(a,h)anthracene, indeno(1,2,3-cd)pyrene, and benzo(j+k+b)fluoranthene. Carcinogenic PAH concentration (PAHcarc) ranged from 294.9 µg/kg (P4, 0–10 cm, lowest) to 535,243.5 µg/kg (P9, 0–10 cm, highest). All sampled workshops showed a high carcinogenic burden relative to the total 17 PAHs, indicating potential long-term adverse health effects. Long-term carcinogenic risk was further assessed via total Benzo(a)Pyrene equivalence: Total BaPeq = Σ(Ci × TEFi), using toxic equivalency factors (TEF) from Nisbet and LaGoy (1992). Total BaPeq values ranged from 1481.3 to 222,750.7 µg/kg, indicating long-term carcinogenic health risk. The high carcinogenic potency of PAHcarc across sites confirms significant environmental and human health risk, and these data contribute a baseline for future pollution monitoring in the study area.