Urinary Biomonitoring and Cancer Risk Assessment of Polycyclic Aromatic Hydrocarbon Exposure in Relation to Water Intake in Calabar, Nigeria

Abstract Non-smokers' exposure to polycyclic aromatic hydrocarbons (PAHs) through PAH-contaminated food, particularly barbecued food, which is widely consumed in Calabar, Nigeria. PAHs are known carcinogens that can accumulate in the body and pose long-term health risks. Studies have reported elevated PAH levels in populations consuming charred and grilled foods, with significant associations with increased cancer risk. This study evaluated urinary OH–PAH levels in individuals consuming barbecued food compared to non-consumers. It also explored the influence of daily water intake on PAH metabolite excretion. A cross-sectional study of seventy adults (aged 18–40) was conducted, including 35 barbecued food consumers and 35 non-consumers. Socio-demographic data were collected using a structured questionnaire. Body mass index (BMI) was calculated using standardized methods based on participants' height and weight measurements. Daily water intake was assessed using a standardized self-reported questionnaire. Urinary PAH metabolites, including 2-hydroxy-1-naphthalene (2-OHNaph), 9-hydroxyfluorene (9-OHFlu), 3-hydroxyphenanthrene (3-OHPhen), 1-hydroxypyrene (1-OHPyrene), and 3-hydroxybenzo(a)pyrene (3-OHBenzo), were quantified via Gas Chromatography Mass Spectrometry. Statistical analyses included ANOVA, t -tests, and correlation analysis, with a significance level of P ≤ 0.05. The mean (± SD) urinary concentrations of PAH metabolites were as follows: 2-OHNaph (2.83 ± 10.81 µg/gCr, range: 0.00–87.08), 9-OHFlu (1.46 ± 1.82 µg/gCr, range: 0.03–8.91), 3-OHPhen (1.89 ± 3.29 µg/gCr, range: 0.00–22.36), 1-OHPyrene (1.01 ± 1.44 µg/gCr, range: 0.00–8.78), and 3-OHBenzo (1.18 ± 1.64 µg/gCr, range: 0.15–10.58). Urinary 3-OHBenzo levels were significantly higher in barbecued food consumers compared to non-consumers (1.67 ± 0.36 vs. 0.68 ± 0.12 µg/gCr, P = 0.012). Individuals consuming > 1 L of water/day exhibited higher urinary levels of 9-OHFlu ( P = 0.031) and 3-OHBenzo ( P = 0.020) compared to those consuming ≤ 1 L/day. Significant correlations were observed between 3-OHBenzo and 1-OHPyrene ( r = 0.842, P < 0.001), 9-OHFlu ( r = 0.620, P < 0.001), and 3-OHPhen ( r = 0.683, P < 0.001). The Estimated Lifetime Cancer Risk (ELCR) of total barbecued food consumption was 2.99 × 10⁻⁶, indicating a potential long-term exposure risk. Consumption of PAH-contaminated barbecued food was associated with elevated urinary levels of 3-OHBenzo, while higher water intake correlated with increased excretion of 9-OHFlu and 3-OHBenzo. These findings suggest that hydration may influence PAH metabolite elimination; however, the cross-sectional design and limited sample size of this study necessitate cautious interpretation. Further longitudinal studies incorporating direct PAH quantification in food and a broader population sample are required to confirm these findings and assess potential long-term health risks associated with PAH exposure.