Food Toxicology 2(2+0)

Lesson 5 : General Principles of Toxicology

Categories of toxicity

When classifying compounds as toxic, extremely toxic, or nontoxic, a practical and useful consideration is where to draw the line in toxicity classification. It is apparent that toxicity is relative and must be described as a relative dose–effect relationship between compounds. However, it is also clear that the concept of toxicity as a relative phenomenon is true only if the dose–response relationships for the compounds are essentially identical. The Table is a useful guide that categorizes toxicity on the basis of amounts of a substance necessary to produce harm, i.e., a lethal dose, based on metric concentration. This information helps classify substances based on weights. Another way to categorize lethal doses is by comparing compound ratios of minimal toxic level to the minimal adequate level, as might be done for nutrients. For example, when comparing biotin (toxic dose of 50 mg) and vitamin A (a toxic dose of 5 mg), it is observed that it takes 10 times more of the toxic oral dose of biotin to produce an adverse effect. Toxicity is relative and must be described as a relative dose–effect relation among compounds.

Source: Food and nutritional toxicology by Stanley T. Omaye