Anti-Doping in Sports: Introduction to Toxicology

Introduction to Toxicology

• The study of toxicology dates back to Paracelsus (1493-1541) who stated "All substances are poisons, there is none which is not a poison. The right dose differentiates a poison from a remedy."

What is Toxicology?

• Toxicology is the study of the adverse effects of chemicals on living organisms.
• It involves understanding the actions, adverse effects, and treatment of conditions produced by poisons.
• Toxicology encompasses household, environmental, industrial, and pharmacological substances or drugs.

Key Terms in Toxicology

• Toxicants: toxic substances from chemicals.
• Toxins: poisonous substances produced within living cells or organisms, e.g., venom.
• Toxicokinetics: the study of factors affecting the concentration of a toxic substance at its site of action.
• Toxicodynamics: the actions and mechanisms of action of toxins.

Sources of Toxicology

• Chemical sources: drugs and exposure to corrosive substances.
• Plant sources: cocaine, a Schedule II drug, isolated from the coca plant.
• Animal sources: venomous animals like scorpions, spiders, snakes, and wasps.

Sites of Toxic Actions

• Local (non-specific): wherever the poison contacts the biological system, it starts its harmful effects.
• Remote (systemic): the poison affects a system far from its portal of entry.
• Local & Remote: the poison has the capacity to act both locally and systemically.

Duration and Frequency of Exposure

• Acute: single or short-term (less than a day) dosing of a substance to cause toxicity.
• Sub-acute: toxicity expressed after repeated applications for a duration less than half of the organism's life expectancy.
• Chronic: expression of toxic symptoms only after repeated exposure to a chemical in doses regularly applied to the organism for a time greater than half of its life expectancy.

Measurements in Toxicology

• LD50: median lethal dose.
• TD50: median toxic dose.
• ED50: median effective dose.
• Chronicity Index: the ratio of the acute to chronic LD50 dosage.

Types of Toxic Mechanisms

• Direct: the poison itself causes toxic effects, as in corrosives.
• Indirect: toxicity results from the interaction of the poison with biological activities within the biological system.

Classification of Toxic Agents

• According to target organ affected (hepatotoxic, nephrotoxic).
• According to use (food additive, drug, pesticide).
• According to source (animal or plant).
• According to effects (carcinogen, mutagen).
• According to physical state (gas, liquid).
• According to chemistry (amine, hydrocarbon).
• According to poisoning potentiality (extremely toxic, slight toxic, etc).
• According to biochemical mechanism of action (alkylating agent, AchE inhibitor).

Factors Affecting Action of Poison

• Factors related to the poison:
  • Dose: a basic principle in toxicology, referring to the amount of chemical that comes into contact with the body or gets inside the body.