Martes, Agosto 7, 2012

introduction to toxicology




Toxicology (from the Greek words τοξικός - toxicos "poisonous" and logos) that can be defined as a branch of biology, chemistry, and medicine that deals with poisons and the adverse effects of chemicals on living organisms. A poison can be define as any substances that causes harmful effect when administered to a living organism, poisoning by a chemical agent is equivalent to chemically induce disease. Toxicity can be acute or chronic, it can be a simple headache that can lead to convulsion and coma and worst it can also lead to death.




 Toxicology can be measured as clinical “endpoints” which includes mortality (death), teratogenicity, carcinogenicity and mutagenicity. LD50 and LC50 are use to determine the mortality rate due to toxicology. LD50 is invented by J.W. Trevan in 1927 which stands for “Lethal Dose”, it is the amount of the drug given which causes the death of the 50% being tested, normally expressed as milligram of substance per kilogram of body weight. LC50 stands for “Lethal Concentration” it is the measure of concentration that will kill half of the sample population through exposure via inhalation. It is expressed as milligrams of substance per liter of air or water.




Toxicity is complex that it can vary from one organ to another as well as age, gender, genetics, diet psychological condition, or the health status of the organism. Toxicology is divided in 3 branches:
  • ·    Clinical toxicology – deals with the effect of drugs to human whose purpose is to prevent diseases.
  • ·   Forensic toxicology – it detects and identify the presence of drugs and poisons in the tissues, body fluids and organs of the living organisms.
  • ·   Environmental toxicology – the study of harmful effects of agricultural and industrial toxins.


Drugs are classified as:
  • ·    Opiates – a drug tending to induce sleep and alleviate pain
  • ·   Stimulants – a drug that induce the activity of nervous system or cardiovascular system (e.g. caffeine)
  • ·  Hallucinogens – a substance that causes excitation of the central nervous system, characterized by hallucination, mood change, anxiety, sensory distortion, delusion, and depersonalization.
  • ·    Depressants – a drug that slows down the normal function of the nervous system


Toxins can enter our body through inhalation, absorption, ingestion and injection, the response of our body depends of the route of exposure. Inhalation is the most important route that can lead to acute or chronic effects, in inhalation the toxin is breathed to the lungs through nose or mouth.  Absorption the most common effects are primary irritation from contact, sensitization from repeated exposure, and systemic poisoning from absorption. Ingestion is when the chemical is taken through the mouth and passed through the gastrointestinal tract. Injection occurs during the administration of drugs, from the use of high pressure, spray painting, or from the rupture of high- pressure lines.

To understand more about toxicology, here is a video that further explains toxicology and different drugs that can harm our body






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