Development of a Mechanistic Model of Acute Heavy Metal Toxicity

A theoretical model of heavy metal toxicity based on inhibition of respiratory functions is proposed. The model is based on the concept that heavy metals competitively interfere with respiratory carbon dioxide (CO₂) excretion at carbonic anhydrase enzyme sites in the gill membranes of fish. In this regard, the model presents equations which are descriptive of toxification and detoxification processes within the organism. It is proposed that the death of the organism is caused by buildup of CO₂ in the blood, reduced oxygen-carrying capacity within the blood, and, ultimately, acute hypoxic stress. The implications of this work in developing water quality criteria for heavy metals are also discussed.