Cigarette filters as a major source of microfibers in aquatic environments

Cigarette butts (CBs) are known as one of the most prevalent forms of environmental waste, needing global attention to mitigate their detrimental health and ecological impacts. Owing to their filter composition, discarded CBs can persistently release microfibers (MFs) into the environment. In this research, the levels, characteristics, and ecological risks associated with MFs released from cigarette filters (CFs) into water (distilled and seawater) were investigated under various environmental conditions (laboratory and outdoor environments). The assessment focused on short-term exposure durations of 1, 2, 7, 15, 30, and 60 days, forming the initial phase of this research. The mean level of released MFs ranged from 5.78 to 92.43 items/g CFs. The results highlighted that more MFs were released from CFs into the seawater and outdoor environment at a contact time of 60 days. The predominant size and color of the released MFs were 20-50 μm and white/transparent, respectively. The main detected polymer composition of MFs was cellulose acetate. The computed pollution load index (PLI) values were > 30, indicating severe pollution. Additionally, the risk quotient (RQ) values were greater than 1, indicating a potential threat to the water environment. Based on mean levels of released MFs through CFs during contact times of 1 to 60 days and the amount of discarded CFs yearly on a global scale, CFs may release 14 × 10¹² to 51 × 10¹² MFs into the aquatic environments. The results of present research allow scientific society to better comprehend the CFs' role in transporting MFs in the aquatic systems as well as their potential environmental risks.