Heavy Metal and Microbial Contaminants of Some Vegetables Irrigated With Goo Reservoir Water, Navrongo, Ghana

Abstract

Globally, the safety of vegetables for consumption is becoming an increasing concern to consumers because of the risk associated with eating of vegetables contaminated with heavy metals and microbial organisms. An assessment of the extent of microbial contamination and also levels of heavy metals and the risk associated with the consumption of the vegetables irrigated with polluted Goo reservoir water in the Navrongo municipality was carried out. Site A used the channel flooding irrigation method whilst site B used watering cans for watering during the latter part of the dry season when the pressure of the water is low. A total of 128 vegetables samples were taken for microbial and heavy metals determination each. Samples of leafy vegetable and fruit vegetables were randomly taken from the two sites for microbial and heavy metal analysis. The reservoir was divided to North, South, East and West and water samples taken from each location. The concentrations of heavy metals in the reservoir exceeded the Food and Agricultural Organization (FAO) recommended levels of metals in water for irrigation. Site B recorded the highest microbial counts likewise heavy metal contaminants in the sampled vegetables. Levels of cadmium in the vegetables exceeded the World Health Organization/FAO permissible levels. Copper (Cu) had the highest concentration in both sites. Faecal Coliform (FC) levels in the vegetables were above the International Commission on Microbiological Specifications for Food (ICMSF) allowable limits. The high quantities of Total Coliform, Faecal Coliform, E. coli, helminthes eggs and salmonella contamination of the vegetables indicate high risk of getting diseases through the consumption of these vegetables. The hazard quotient of all the metals exceeded one in both sites except Zinc (Zn). The hazard index (HI) of heavy metals studied was above one in both sites, indicating they could have adverse health effect to human life. The analysis showed there was significant difference in microbial counts and levels of heavy metals in the vegetables in the two different sites. The consumers of these vegetables were at risk of contracting water-borne diseases like typhoid fever, cholera among others and also a high risk of heavy metal poisoning especially from cadmium.