Health Risk Assessment of Heavy Metals (Cr, Ni, Pb and Zn) Contamination of Edible Vegetables in Ogoja Urban Area of Cross River State

Akpe Michael Akomaye, Ubua Placidus Unimuyi , Apebende Gloria Chioma

The mean concentration of Cr, Ni, Pb and Zn in edible vegetables grown in Ogoja Urban area of Cross River State was determined both in the vegetables and the soil. The Target Harzard Quotient (THQ) was also calculated to assess the possible health risk associated with the consumption of the vegetables. To achieve this, samples of eight vegetables namely: Amaranthus spp, Corchorus olitoruis, Murraya koenigii, Ocininum grattissimum, Solanum melongena, Talinum triangulare, Telfairia occidentalis and Vernonia amygdalina were collected together with the soil samples where they were planted during the rainy and dry seasons of the year. They were digested and analyzed for mean metal concentration using Atomic Absorption Spectrometer (AAS). The results show that the mean concentration range of Cr and Zn in the soil was 0.004-0.016 mgkg-1 and .329 – 1.077mgkg-1 respectively in dry season, and 0.004-0.018 mgkg-1 and 0.333 – 1.265 mgkg-1 respectively in rainy season. The mean concentration of Cr and Zn accumulated by the vegetables ranged from 0.002 – 0.008mgkg-1 and 0.015 – 0.083 mgkg-1 respectively in dry season, and 0.003 – 0.008 mgkg-1 and 0.017 – 0.087 migkg-1 respectively in rainy season. Ni and Pb were string variables as their concentration was not detected both in the soil and in the vegetables. The Target Harzard Quotient (THQ) values of Cr and Zn for all the vegetables were less than 1 indicating there is no health risk associated with the consumption of the vegetables at the moment. The results also reveal that there is some level of heavy metal (Cr and Zn) contamination in the area and the vegetables, though very low, and within the permissible limits of World Health Organisation ( WHO). There is no significant difference between the results of the dry and rainy season, indicating the source of contamination of not necessary from air pollution source or irrigation water but from indiscriminate disposal of waste (anthropogenic sources). The government and relevant agencies should monitor and evaluate the environment in this aspect and create awareness for public health.