Evaluation of Trihalomethanes in Drinking Water of Mosul, Iraq

This study investigates the occurrence and associated health risks of trihalomethanes (THMs)—specifically bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform (BF)—in the domestic water supply of Mosul, Iraq. Water samples were collected from ten locations across the city between 2019 and 2020, including Al-Zuhoor, Al-Muthanna, Al-Sukar, Al-Mansour, Al-Majmoua Al-Thaqafiya, Al-Wahda, Al-Maliya, Al-Hadbaa, Al-Arabi, and Al-Tamim neighborhoods. Analysis was performed using gas chromatography with electron capture detection (GC-ECD) following USEPA Method 551.1. THM concentrations ranged from non-detectable to 69.4 μg/L, remaining below the WHO guideline of 100 μg/L. Health risk assessments were conducted using both WHO and USEPA models. Non-carcinogenic risks via ingestion pathways were found to be within acceptable limits (hazard quotient < 1), while the estimated total lifetime cancer risk from combined exposure (1.03 × 10⁻⁶) slightly exceeded the USEPA benchmark of 1.0 × 10⁻⁶, a threshold typically used for carcinogenic risk, indicating a marginal yet notable concern. The assessment primarily focused on oral ingestion, and further investigation into inhalation and dermal pathways, as well as impacts on sensitive subpopulations (e.g., children, elderly), is recommended. To mitigate potential health risks, improvements in water treatment—such as the implementation of advanced technologies like activated carbon filtration and better optimization of chlorination practices—are advised. The findings contribute valuable insights into water quality management and chemical exposure in urban environments of developing regions.