A STUDY OF SOME HEAVY METAL CONTENT IN SELECTED VEGETABLE TYPES IRRIGATED WITH WASTE IN TAKORADI METROPOLIS OF GHANA

One of the easiest ways of ameliorating the effect of fresh water scarcity created by climate change among resource poor farmers in the developing countries world - wide is the use of waste water for vegetable production in irrigated fields. Unfortunately, it often results in heavy metal contamination of th e vegetables produced. This development is a major concern among food producers and health professionals all over the world due to the systemic health problems which can develop as a result of excessive accumulation of dietary heavy metals such as iron (Fe ), copper (Cu) and zinc (Zn) in human body . The aim of this study wa s to establish the effect of waste water source location within Takoradi metropolis of the Western Region of Ghana on their heavy metal content and the vegetables produced with them under full irrigation systems . The objectives were to: i) determine the iron, copper and zinc content of the waste water used for irrigating the vegetable crops. ii) determine the iron, copper and zinc content of the veg etables produced with the waste water used during irrigation of the crops. iii) Compare the heavy metal content of the vegetables produced with the maximum recommended level by the FAO / WHO . The concentration of heavy metals ( iron, copper and zinc) in samples consisting of six types of the vegetables (cabbage, lettuce, spring onion, onion, garden eggs and tomatoes ) collected from ten ( 10 ) different sites in Takoradi metropolis were determined in micrograms with the use of the Atomic Adsorption Spect rophotometer (AAS) in a 50 ml solution volume and later converted into concentration in milligrams per kilograms (mg/kg ). With the use of Microsoft EXCEL Statistical package, the mean values of the heavy metal concentrations were determined for each of the vegetable studied at each site ( Takoradi New Site 1, 2, 3 and 4, Takoradi Pioneer Tobacco Company (PTC), Takoradi Anaji 1,2, 3 and Tanokrom 1 and Tanokrom 2) . The study showed that the i ron concentrations of the sampled vegetables ranged between 26.32 ? 91.28 mg/kg with copper concentration levels ranging between - 50.43 mg/kg, zinc concentration levels between 11.56 - 38.69 mg/kg. Iron concentration levels of sampled wastewater were between 6 . 95 ? 28 . 20 mg/kg with copper concentrations levels in the sampled wastewater ranging between 1 .72 ? 2.2 8 mg/kg , zinc concentrations levels between 3 . 64 ? 25 . 50 mg/kg. The Iron, copper and zinc concentration levels in the sampled vegetables far exceeded the FAO/WHO recommended maximum levels of 5.0 for Fe, 0.4 for Cu and 1.0 mg/kg for Zn. The Iron, copper and zinc concentration levels in the sampled wastewater used for irrigation were also not within the FAO /WHO recommended maximum values of 50 mg/kg for Fe, 1 mg/kg for Cu and 20 mg/kg for Zn. The water samples col lected from the New Site 3 recorded the highest level of Fe content, followed by those from New Site 1 and Tanokrom 1 respectively. The water samples collected from Takoradi Anaji 1 had the highest level of Cu content followed by those collected from Takoradi Anaji 2. The water samples collected from Takoradi Anaji 1 had the highest Zn content. It was concluded in the study that vegetable consumers in New Site 3, Tanokrom 1 and Takoradi Anaji 1 and 2 are more prone to the health hazards posed by heavy metals than any other vegetable consumers in the study areas .