Evaluation of Heavy Metals Concentrations in the Giant Land Snails (Archachatina marginata and Achatina achatina) as a Bioindicator of Environmental Pollution

Abstract

The environmental impact of heavy metal pollution is considerable, largely due to its persistent presence, bioaccumulative properties, and harmful toxicity to both ecosystems and human well-being. Land snails, particularly Archachatina marginata and Achatina achatina, are increasingly recognized as effective bioindicators of heavy metal contamination due to their limited mobility, feeding behaviours, and ability to bioaccumulate pollutants from their surroundings. This study investigates the presence, concentration, and accumulation of cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) in the soft body parts and shells of snails (A. marginata and A. achatina) procured from Oje Market, Ibadan, Nigeria, as well as comparing the concentration with established regulatory standards. Using Atomic Absorption Spectrophotometry (AAS), metal concentrations were analyzed and compared across different snail body parts (shell, foot, and digestive gland) to assess their distribution patterns. The results indicate significant variations in metal accumulation, with Zn (0.866 μg/g ± 0.2616, 0.377 μg/g ± 0.0954) predominant in A. marginata and A. achatina, while Cd has the lowest mean concentration (0.007 μg/g ± 0.0037, 0.005 μg/g ± 0.0070). Notably, Pb concentrations (0.190 μg/g, 0.235 μg/g) in edible snail tissues exceeded FAO/WHO safety limits. These results underscore the need to monitor heavy metal pollution in edible organisms and reinforce the role of land snails as reliable bioindicators for environmental contamination assessment.