Basic concepts in toxicology

A “Toxin” is defined as any compound that has a detrimental effect on cell function or structure. Toxins include: heavy metals, chemical toxins, microbial compounds, and breakdown products of protein metabolism (e.g., ammonia, urea). Many “Poisons” are derived from the plant kingdom, higher or lower ones (e.g., fungi)

In heavy metal toxicity, in general, the elemental metals are less toxic than their salts. Organic metals, where the metal is covalently-bound to carbon compounds such as methyl or ethyl groups, are highly toxic

Poisons can be grouped into 3 main groups according to the metabolic disturbances they create:

1. Group A: poisons that create “Macroscopic” anatomical changes in any organ. These include corrosive acids and alkaloids  

2. Group B: poisons that alter the “Blood” in the first place, presenting as a disease affecting the (Intestine, kidneys, and blood vessels)

3. Group C: poisons that are fatal without causing any striking pathological changes in an organ and these are mostly hit the “Heart & Central nervous system

Humans and animals possess 4 ways to render poisons partially or totally harmless:

1. Rapid elimination: via vomiting & diarrhea

2. Deposition: mostly into fatty tissues, bile acids alkaloids, and albumin-derivatives (Metalalbuminate)

3. Phagocytosis: the WBCs engulf poisons; mostly those derived from albumin (Toxalbumins) and heavy metals

4. Detoxification: by transforming toxins into partially-harmless, water-soluble compounds for elimination (e.g., conjugation of phenols with sulfur)

Important concepts in toxic-metabolic disorders include:

1. Total load concept: this concept states that: “the sum of all exposures and influences that bear on human physiology, which may overwhelm an individual’s system of metabolic management”. A toxic disease starts when the toxins overwhelms the body ability to excrete or detoxify them  

2. Genetic polymorphism: is a concept states that some genetics and enzymes present in nature in more than one form. Some of these enzymes are “sluggish” in some individuals, rendering these individuals to require “more” vitamins and nutrients to process the “regular” metabolic processes where other individuals require less to vitamins and nutrients to function normally

3. Biochemical individuality: is a concept coined by Roger Williams in 1956 to describe how different people react differently to chronic, subacute exposure to toxins. Some individuals can develop the symptoms within weeks while other may develop the symptoms within years after the initial exposure


Selected references

1. Klaassen C. Casarett & Doull's Toxicology: The Basic Science of Poisons. 2013; McGraw-Hill Education / Medical; 8th edition