Evaluation of Lead in Crops Grown along the Bank of River Tiga, Kano Nigeria

Contamination of vegetables (cabbage, tomatoes, onions and lettuce) with Lead (Pb) through the use of untreated irrigation water at farmlands located in the bank of River Tiga along Zaria-Kaduna road during dry season was determined. Samples of untreated water (as control) were collected from six different locations and vegetable crops were also collected from three different irrigation farms along the bank. The vegetable crop samples were digested using standard methods. Both the samples of water and vegetable were analyzed for Pb using atomic absorption spectrophotometry. The levels of Pb found in vegetables were: 2.5, 1.7, 1.8 and 1.8 parts per million (ppm) for cabbage, tomatoes, onions and lettuce respectively. These levels of Pb were within Food and Agriculture Organization/World Health Organization (FAO/WHO) limits in the vegetable crops. Also, concentration of Pb in the water was found higher compared to vegetable crops. Evaluation of transfer factor (TF) of Pb from water to vegetables showed: tomatoes > onions = lettuce > cabbage. Generally, lead has no benefit to human body. Despite the low level of Pb in the samples, vegetable crops grown from these farms may pose health risk to the consumers in a long-term.