Acute poisonings
by Hans Persson
Introduction
01 Cancer
02 Ozone
03 Urban air
04 Air pollutants
05 Blue-green algae
06 Water mutagens
07 Contamination
08 Chernobyl
09 Radon
10 Medical geology
11 Renal hazards
12 Organohalogens
13 Estrogens
14 Food hazards
15 Mycotoxins
16 Poisoning
17 Genetics
18 Risk
(Excerpt from Chapter 16)
Two of the most dreaded and insidous mushrooms found in Swedish forests are here displayed in the sunshine on the balcony of the Swedish Poisons Information Centre: the hepatoxic Amanita virosa and the nephrotoxic Cortinarius speciocissimus. |
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Poisoning
Poisoning can be defined as a chemical injury to body organs or a chemically induced disturbance of the functions in biological systems. Such toxic effects may follow the exposure to exogenous (environmental) substances. By tradition an agent has been considered as a poison if it may damage the organism in a very small dose. The toxic properties of a certain poison are often specific, and hence the clinical symptoms after exposure to a poison may be quite characteristic. Substances that normally are considered as harmless may also, if the dose is big enough, cause deleterious effects and thereby act as poisons. Examples of this are sodium chloride, oxygen and water.
The science devoted to the study of the structures, effects and fate of poisonous substances is called toxicology. This is nowadays a wide, heterogeneous and rapidly expanding discipline. Clinical toxicology is a subentity that deals with problems related to poisonings in humans and their treatment.
Poisoning may be acute or chronic. In acute poisoning the body is exposed to the toxic substance in a high dose, on one occasion and during a short period of time. Symptoms of poisoning develop in close relation to the exposure. Examples of acute poisonings are massive drug overdoses, poisonings after mushroom meals, alcohol poisonings, and venomous bites or stings.
In chronic poisoning the organism is on the contrary exposed repeatedly to toxic agents during a long period, but every exposure means that just a low dose of the poison is entering the body. Normally no symptoms develop in relation to each exposure, although that may happen (e.g. in chronic exposure to solvents). Instead the patient gradually becomes ill after a period of months or years. In chronic poisoning the toxic substance may accumulate in body tissues or cause a small irreversible damage at each exposure. After a long time, enough poison has been accumulated in the body, or the damage has become significant enough, to cause clinical symptoms. Examples of typical chronic poisonings are long-term exposure to heavy metals like lead, mercury or cadmium, inhalation of organic solvents in the occupational context, and exposure to pesticides.
The circumstances around an acute poisoning are often obvious and easy to detect, whereas the slow and insidious onset of a chronic poisoning may cause considerable diagnostic difficulties. This chapter is mainly devoted to environmentally induced acute poisonings.
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Hans Persson, MD, qualified from Karolinska Institutet, Stockholm, and specialized in anaesthesiology and intensive care. His main interest is clinical toxicology and he became director of the Swedish Poisons Information Centre in 1982. Research interests include poisoning by North European snakes and mushrooms.
