Toxicology
Toxicology is the study of the adverse effects of chemicals on living organisms. It looks at the source, symptoms, distribution, short and long term effects, detection, mechanisms, and treatments of poisons, especially regarding human physiology. Toxins can come from virtually any source, but usually are from drugs, household supplies, cosmetics, industrial chemicals, biological sources, and chemicals used in agriculture. [1]
Almost any chemical can be toxic; it is the dose that determines the toxic effect. As Paracelsus, the father of modern toxicology said, “Sola dosis facit venenum” (only dose makes the poison). Paracelsus, who lived in the 16th century, was the first person to explain the dose-response relationship of toxic substances. Also, some things are not toxic at certain does, but when taken with another chemical, produce a synergistic effect that manifests as a toxicity. An example is acetaminophen and ethanol: when combined at their respective non-toxic doses, they can produce a toxic effect [2].
Chemicals can be toxic to certain organs, or produce widespread toxicity. Cyanide is a metabolic toxin that affects the mitochondria in every cell in the body. Sustained doses of gentamycin are nephrotoxic: they accumulated in the tissue of the kidney, and poison its fundamental unit, the nephron.
Epidemiology
Poisoning ranks as the second leading cause of accidental injury deaths in the United States, behind motor vehicle accidents. In the United States in 2003, 28,700 people died of poisoning, with 68% of those deaths unintentional. Poison control centers listed over 2 million poison exposure cases in 2004, and emergency departments reported 577.866 visits from accidental poisoning victims. [3]
Most unintentional poisonings were caused by legal and illegal drugs, such as opioids, cocaine, NSAIDS, benzodiazepenes, along with cosmetics, cleaning substances, foreign bodies, OTC drugs, and pesticides. [4]
Quantification
The classical toxicology test has been the LD50 (lethal dose 50), which refers to the concentration of drug required to kill 50% of the test subjects (usually mice or rabbits) in a certain amount of time. The higher the LD50, the more toxic the substance is. This test can also be applied to achieve other percentages, for example the LD10 (dose to kill 10% of the subjects), or the LD100 (the minimum dose to kill all of the subjects)
Toxins
Drugs
Drugs are the main cause of toxicity in modern times. Modern drugs are specific isolated and concentrated compounds used to produce a desirable effect in the body. This leads to the ability of drugs to produce a high concentration of drug with a reasonably low amount of exposure. They often are brightly colored, and many have an attractive taste to encourage routine use of the drug. These factors lead to a high amount of overdose and therefore poisoning with drugs.
Some drugs produce side effects: toxic effects that occur at routine and therapeutic levels. This risk must be carefully weighed when choosing a drug regimen.
- ↑ Chyka. Clinical Toxicology. Pharmacotherapy: A Pathophysiologc Approach.
- ↑ Draganov P. et al. Alcohol-acetaminophen syndrome. POSTGRADUATE MEDICINE. Vol 107, Num 1, 200.
- ↑ Poisoning in the United States: Fact Sheet. CDC. http://www.cdc.gov/ncipc/factsheets/poisoning.htm
- ↑ Clinical Toxicology, 2006:44:803.