Assessment of Concentration Levels and Associated Health Risks of Arsenic, Cadmium, Lead, and Mercury in Selected Green Leafy Vegetables Irrigated by Morogoro River Using Atomic Absorption Spectroscopy

Morogoro River is among the tributaries of Ngerengere River, providing water for some domestic and agricultural activities to the community of Morogoro region. However, as it flows through Morogoro town, the river is increasingly subjected to pollution from various sources and contaminates the water. The contamination is likely due to a combination of industrial activities, agricultural runoff, domestic waste, and natural geological sources. This study aims to investigate the levels of toxic elements, lead (Pb), cadmium (Cd), arsenic (As) and Mercury (Hg) in green leafy vegetables grown near and irrigated by water from Morogoro River by using Atomic Absorption Spectrometry (AAS). Samples of three categories were collected, first category samples were collected before industrial areas, second category samples were collected after industrial effluent were discharged to the river and the third category are samples collected away from the vicinity of Morogoro River. The results were used to calculate Target Hazard Quotient (THQ), Total Target Hazard Quotient (TTHQ) and Cancer Risk for health risk assessment. Both first and second-category samples have TTHQ of 7.4 and 22.6 respectively which indicate a serious health risk and the value for third category is 1 which means no serious health risk. The cancer risk values are very high for second category samples which are intolerable. This means there is urgent need for immediate interventions, such as stricter regulations on domestic and industrial waste disposal, promotion of sustainable agricultural practices, and establishment of regular environmental monitoring systems