Influence of Human Activities and Land Use on Heavy Metal Concentrations in Irrigated Vegetables in Ghana and Their Health Implications

Abstract

Anthropogenic activities are major sources of heavy metal pollution which serve as major pathways for plant uptake of heavy metals like cadmium (Cd) and lead (Pb) to enter the human food chain from the soil and irrigation water. This study was conducted to investigate the levels of Cd, Pb, Zn, Fe, Ni and Cu concentrations in sampled vegetables (cabbage and carrots) from two major markets in Kumasi, a metropolis and two producing rural towns along the Accra — Kumasi road. Apart from Ni all other heavy metals in cabbage were far higher than the FAO/WHO permissible values of samples from both urban/peri-urban and rural communities. Cadmium content of the vegetables from the peri-urban communities were extremes (0.5–4.2 mg/kg) and were generally higher than produce from the rural communities with values between 1.6 and 1.9 mg/kg. However, cabbage from Asikam, a rural and mining community contained 2.9 mg/kg of Cd. Lead concentration levels in the sampled vegetables from the peri-urban communities ranged between 6–45 mg/kg whilst values from the rural communities were between 12 and 13 mg/kg. Cadmium and lead concentration levels in the sampled vegetables far exceeded FAO/WHO recommended maximum values of 0.3 and 0.2 mg/kg respectively with samples from urban/ peri-urban communities registering higher values than those from the rural towns.