Evaluation of nicotine consumption in Türkiye cities by wastewater-based epidemiology: a quantitative risk assessment

Wastewater-based epidemiology (WBE) was used to estimate nicotine consumption in several major cities across Türkiye. To realize this, 24-h composite wastewater samples were taken each season at 42 wastewater treatment plants (WWTPs). Cotinine was measured to estimate the daily nicotine consumption. The nicotine consumption data were used for the risk assessment of nicotine utilizing two health endpoints that represent severe and more subtle adverse effects, including a mortality-based margin of exposure (MOE) approach and a human-relevant MOE approach based on the lowest LOAEL identified by the European Food Safety Authority (EFSA). The EFSA ADI was also used to calculate hazard quotient (HQ) estimates. The population-weighted average per capita nicotine consumption for the sub-population aged 15 and above was 3.18 ± 0.48, 2.78 ± 0.40, 2.48 ± 0.40, and 2.72 ± 0.41 mg/person/day for 2019 (n = 71), 2020 (n = 125), 2021 (n = 166), and 2022 (n = 161) years, respectively. These estimated values exceed the nicotine intake typically associated with smoking one cigarette per day. Based on mortality-based MOE values, nearly 78% of the sampled cities exhibited mortality-based MOE values below 100, indicating relatively higher mortality-related risk in a comparative context. EFSA-based MOE values ranged from 0.101 ± 0.016 to 0.693 ± 0.229. Furthermore, HQ values exceeded 1 in all studied cities, suggesting a potential health concern based on EFSA reference values.