Exposure and Bioaccumulation of Mercury Impacted the Extent of Cellular Damage and Oxidative Stress in Local Chickens Around Ilesha Gold Mining Areas of Nigeria

Abstract

Mercury (Hg) is a well-known global pollutant of environmental concern. Uncontrolled mining activities represent an avenue for its release and possible environmental contamination. Ilesha gold mining areas are characterized by extensive artisan and small-scale gold mining (ASGM) activities. However, it is largely unknown to what extent Hg pollution has occurred as well as the environmental and ecological deterioration in the area. Here, we studied Hg in soil, sediments, water, chicken blood, liver, muscle (chest), and kidney. Oxidative stress, hepatorenal damage, heat shock response, cellular DNA damage, and mRNA levels of apoptosis-related genes were analyzed using qPCR. All analyses were done in chickens from gold mining (GMA) and non-gold mining areas (NGMA). This study reported that the levels of Hg in soil (range: 1.637 ± 0.237-1.796 ± 0.104 μg/g), sediment (range: 1.424 ± 0.046-1.450 ± 0.062 μg/g), and water (range: 1.255 ± 0.071-1.378 ± 0.145 μg/mL) in GMA far exceeded Hg levels in NGMA. This might imply the extent to which ASGM activities have contributed to the Hg contamination in the areas. Chickens from GMA exhibited significantly high Hg levels, with the largest proportion bioaccumulated in the kidney (range: 0.596 ± 0.057-0.605 ± 0.028 μg/g) and lowest proportion in blood (range: 0.215 ± 0.023-0.226 ± 0.043 μg/g), suggesting the health risks dwellers in the area are prone to. Cellular damage biomarkers were significantly elevated in the tissue of Hg-exposed chickens from GMA compared to those from NGMA, demonstrating the significant health risks associated with Hg pollution and/or uptake in the areas.