Toxicologie environnementale et analytique

A review has been made of current knowledge, published and unpublished, relating to cadmium toxicity. Cadmium is a heavy metal that occurs as a natural constituent in earth crust along with Copper, Lead, Nickel and Zinc. Cadmium is vastly used in batteries, coating, plating, alloys etc in various industries. Human are commonly exposed to cadmium by inhalation and ingestion. Cadmium enters in air and binds to small particles where it can combine with water or soil causing contamination of fish, plants and animal in mono form. Spills at hazardous waste sites and improper waste disposal can cause cadmium leakage in nearby habitats. Foodstuff like liver, mushroom, shellfish, mussels, cooca power and dried seaweeds are cadmium rich increasing the concentration in human body and in food chain lead to acute and chronic intoxication due to bio magnification. Health effects include diarrhea, stomach pain, bone fracture, reproductive failure and possibly even infertility, damage to central nervous system, psychological disorders. The organic matter in soil absorbs cadmium increasing the risk of survival of various plants and also increase uptake of toxin metal in food. The review is about the study of toxicity mechanism of cadmium in human beings and plants and biological phenomena involved.

Pesticides usage in agricultural fields to control pests could be extremely toxic to non-target organisms like fish and affects fish health through impairment of metabolism, sometimes leading to mortality. The present study was carried out to assess the presence of organochlorine pesticide residues in sediment samples and Oreochromis niloticus obtained from River Galma. Soxhlet extraction process was employed for fish while sediment extraction was done using a mixture of n-hexane and acetone. The extracts were cleaned-up and analyzed using a gas chromatograph mass spectrometer (GC-MS). DDT, Mirex, Pentachlorophenol, Malathion, Chlordane and TNT were detected in the study area. Endrin, aldrin, dieldrin, endosulfan I, endosulfan II, alpha BHC and heptachlor were not detected in all the samples analyzed. Chlordane was the only detected pesticide in fish sample during wet season. The findings provide evidence of pollution of some of the organochlorine pesticide residues in River Galma. This shows that the River Galma is contaminated with organochlorine pesticides. Hence, serious need for continuous monitoring of these pesticide residues in water, sediments, fish and the environment is required in order to prevent various environmental and public health hazards that may arise from these pollutants.