Estimation of concentration and risk assessment of PAHs in urban water resources due to cigarette butt littering.

Filtered cigarettes are now the dominant form of tobacco consumption worldwide, resulting in the production of 5 trillion/year cigarette butts as hazardous waste. Most cigarette butts are littered by smokers, and the trapped pollutants quickly leak into the environment. In this study, the density of littered cigarette butts in urban environment was interpreted by Cigarette Butt Pollution Index and the ecological risk and carcinogenic risk due to water pollution caused by leaked PAHs from the littered cigarette butts were assessed. The results showed that the density of littered cigarette butts in the most polluted location was 0.61 butts/m, while in the best conditions the density was 0.01 butts/m. According to the observed densities, the Cigarette Butte Pollution Index was 0.75 in the cleanest location and 12.2 in the most polluted location. The results showed that cigarette butt littering in the studied city caused the leakage of 88,181 g/year of polycyclic aromatic hydrocarbons. The average polycyclic aromatic hydrocarbons leakage into the urban environment was 0.2844 µg/m. The ecological risk associated with the three types of PAHs, including Dibenzo(a, h)anthracene, Naphthalene, and Acenaphthene, was moderate, while the ILCR was calculated to be 5.4E-08. Reducing the density of littered cigarette butts in the studied urban environment and preventing the health and environmental consequences resulting from them requires reduce cigarette butt littering by smokers and increase the efficiency of the urban cleaning system.