Metallothionein - metabolism, Cholinesterase Inhibitors - toxicity, Humans, Helix (Snails) - enzymology, Mercuric Chloride - administration & dosage, Mercury Poisoning - blood, Soil Pollutants - toxicity, Dose-Response Relationship, Drug, Hemocytes - pathology, Food Contamination - prevention & control, Helix (Snails) - metabolism, Lysosomes - metabolism, Ti...