Concentration and Health Risk Assessment of Heavy Metal in Roadside Soil in Eket, Akwa Ibom State, Nigeria

Abstract

Aims: This study determines the heavy metal impacts on roadside soils and its potential health hazards in Eket, Akwa Ibom State, Nigeria. Background: Roads affect natural environment to a large extent because automobile act as line sources of heavy metal pollutants. Emission from heavy traffic have been reported to contain Pb, Cd, Zn and Ni which are present in fuel as anti-knock agent. Heavy metals in the soil can also generate airborne particles and dust which may affect the quality of air. Inhalation of substantial quantities of heavy metal particle over period of time may add to human body burden of the metals and constitute health risk. Methodology: Roadside soil samples were collected from Mobile Matt (MM), Marina Junction (MJ), Uqua Junction (UJ) and Fongetok Junction (FJ) in Eket, a city in Akwa Ibom State of Nigeria and analysed using Atomic Absorption Spectrophotometer. Risk assessment quantification was calculated including potential ecological risk index Eri, health risk assessment, non-carcinogenic risk assessment and carcinogenic risk assessment. The concentrations of heavy metal were applied to assess the adult and children’s health risks both carcinogenic and non-carcinogenic. Hazard quotient (HQ) calculated to determine non-carcinogenic health risk for each individual heavy metal element. Results: The findings revealed that Eri is divided into three main categories, low, high and very high risk at the four sampling junctions in the study area. High and very high risk is due to high Potential Ecological Risk Index Eri of Cd 252.6 at MJ, 408 at UJ, 259.8 at FJ and 301.2 at MM. Risk index RI is also divided into considerable and high risk. High RI is due to high values of Eri caused by Cd and Pb at different sampling junctions. Heavy metals pose no harmful effect on both adult and children's health as HI  1. The LCR for ingestion, inhalation and dermal contact for adults and children resulted from Pb and Cd. For Cd, LCR is within the threshold value of 1 × 10-6 – 1 × 10-4 which is widely considered acceptable except at MJ adult is 1 × 10-7. For Pb, LCR is in the range of 1 × 10-4 which is considered to have significant health effects on adults and children. Conclusion: It is therefore expedient that measures to combat further contamination of soil by Cd and Pb be taken to keep the environment clean and safe for humans.