TITLE:
Health Risk Assessment of Selected Heavy Metals in Vegetables Grown along River Kabuthi, Nairobi County
AUTHORS:
Kimani Ignatius, Nawiri Mildred, Nyambaka Hudson
KEYWORDS:
Daily Intake of Metals (DIM), Incremental Lifetime Cancer Risk (ILCR), Target Hazard Quotient (THQ), Health Risk Assessment (HRA), Heavy Metals (HMs), Potentially Toxic Elements (PTEs)
JOURNAL NAME:
Open Access Library Journal,
Vol.13 No.3,
March
26,
2026
ABSTRACT: The increased advocacy for the consumption of vegetables such as spinach, kale and African nightshade to promote good health has led to the use of irrigation water polluted with industrial and household waste. Use of such water results in the vegetables being contaminated with PTEs like lead, cadmium, copper, and zinc. This study investigated the health risk assessment (HRA) of heavy metals (HMs), Cu, Zn, Pb and Cd from consuming vegetables grown along River Kabuthi in Nairobi City County, where irrigation is practised during the dry season. Samples of vegetables were collected in five different blocks along River Kabuthi during the dry and wet periods, in February and May, respectively. Levels of heavy metals (HMs) determined using atomic absorption spectroscopy (AAS) procedure were used to calculate the daily intake of metals (DIM), incremental lifetime cancer risk (ILCR) and target hazard quotient (THQ) in both adults and children. The results indicated that the levels of HM in the dry season were generally higher than the levels in the wet season and were significantly different (p 1), implying that there is a possible health risk. ILCR for Cd was noted to be above the tolerable limits of 10−4 and 10−6 in adults in the dry season for kale and spinach in B1 and in the wet season in spinach in B1. In children, the ILCR for Cd was above the recommended limits in kale and spinach in B1 in the dry season and high in spinach in B1 in the wet season. The implication is that ingestion of the vegetables cultivated along the River Kabuthi may pose a health risk associated with Cu, Zn and Cd, such as liver and kidney problems as well as cancer.