Assessment of water quality, heavy metal pollution and human health risks in the Canal system of Ho Chi Minh City, Vietnam

This study was conducted to determine the surface water quality and health risks in Ho Chi Minh City (HCMC) canals. 180 water samples and 180 sediment samples were collected from 15 canal locations in HCMC in 2021 and 2022. The Water Quality Index (WQI) assessment results indicated that the water quality in 2021 ranged from unsuitable to good, with a trend towards improvement in 2022, where good quality water was predominant. TMs PCA/FA identified domestic and agricultural wastewater from HCMC residents as influencing the water quality. Most TMs detected in surface water were within the limits the Vietnamese Ministry of Natural Resources and Environment allowed, except for Pb in 2022 (> 0.02 mg l−1). For sediments, TMs concentrations were higher than in water samples but showed a decreasing trend over the survey period in the order of Hg < Cd < As < Pb < Cu. The findings show that sediments are more strongly affected by TMs than surface water, with the main sources being industrial and agricultural human activities. The non-cancer risk assessment showed that children are more exposed to TMs than adults, mainly through ingestion. Additionally, the cancer risk assessment (CR) identified As in sediments as posing an unacceptable cancer risk (TCR > 1 × 10−4). Therefore, it is necessary to establish high-frequency monitoring policies to analyze and reduce TMs concentrations in water and sediments of the canals to protect human health.