Assessment of heavy metal concentration in agricultural land near heavy industrial areas in Welkom, Free State

Abstract

Background: Food safety concerns arise from heavy metal contamination in the environment. This contamination comes from anthropogenic sources like urban and industrial waste, mining, and metallurgy. Through food consumption, toxic trace metals such as lead, cadmium, arsenic, and mercury can enter the human diet, causing health problems with prolonged exposure. People collecting vegetables near waste sites are at greater risk. Crops like maize, which are staples for millions worldwide, can absorb heavy metals from soil contamination from industrial pollution, mining, and contaminated fertilizers and pesticides. This study aims to assess the level of heavy metal exposure and potential health risks associated with consuming maize grown on agricultural land near mines in the Welkom area. Methodology: A human health risk assessment was conducted to determine the hazard quotient and hazard index for the non-carcinogenic effects of the selected maize crops. This was achieved through an experimental method that helped to determine the exposure limits of the detected heavy metals in the selected samples. A quantitative research technique was applied to prioritize quantification in data collection and analysis. Sixteen maize samples were collected separately from four distinct groups of farmlands, and an ICP-OES Spectrometer was used to determine the target metals in the maize samples. Results: The health risk assessment was conducted using EDI and THQ to assess the potential health risks associated with heavy metal exposure. The Hazard Index estimate indicates that consuming maize poses a non-carcinogenic risk. The concentration of Arsenic (As) in maize was above the maximum limit of 0.1 mg/kg in all farm groups. The concentration of Cadmium (Cd) in maize was below the maximum limit for all farm groups except one. The Lead (Pb) concentration in Farm Group 2 slightly increased, which may have been caused using fertilizers and pesticides. The average HQ of heavy metals in all farm groups was lower than 1, indicating no potential adverse carcinogenic health effects. This may be due to good agricultural practices, location away from heavy industries and polluted land, and the use of treated water, environmentally friendly fertilizers, and pesticides. Conclusion: This study has both experimental and theoretical implications. The study can guide government policymaking, inform farming practices, and educate consumers about food safety, thereby promoting public health and sustainable agriculture. It serves as a call to action for researchers, practising Environmental Health Practitioners, and environmentalists to delve deeper into environmental exposures, particularly focusing on food safety at the early stages of the food production chain. Furthermore, assessing heavy metal exposure in maize crops grown on agricultural land near heavy industrial areas is a critical issue that demands attention.