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The most hazardous chemicals in the environment combine
biological activity and reactivity. They include polyaromatic hydrocarbons (PAHs),
heavy metals and halogenated hydrocarbons.
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Toxicology deals with the effects of chemical compounds on
living organisms
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A way to quantify acute toxicity is the LD50 value, which
means that the dose caused the death of 50% of the animals receiving this
dose.
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In nature orgaisms are exposed to a wide spectrum of harmful
compounds
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These compounds interact in three ways: An antagonistic
effect occur when the combined effect is less that the sum of the indvidual
compounds, an additive effect occur when the effect of the compounds is
equal to the sum of the individual effects and a synergistic effect occur
when the effect of the mixture is stronger than the sum of the effect of the
individual compounds.
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The understanding on how chemical compounds act on living
organisms come from studies on living animals
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Pollutants could affect both the muscular and nerve
functions.
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Reproduction an growth process are sensitive for pollutants.
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Eggshell thickness is directly related to DDT exposure and
has been used to estimate DDT content in the environment.
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Detoxification is process to eliminate compounds that have
entered the living organism.
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In the process of resourption toxic compounds are
taken up by the body usually through the skin, lungs or alimentory tract.
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In the toxicokinetic phase pollutants are absorbed ,
distributed, metabolised and eliminated.
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During the toxicodynamic phase the toxicant interact with a
cell component and exert its toxic effect.
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The effect of air pollution may take many forms from a
feeling of discomfort to rising mortality.
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Environmental epidemiology is concerned with the patterns of
distribution of disease in relation to environmental factors
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Environmental health policy focuses on prevention of
exposure to environmental hazards.
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The Minamata disease was a result of ignorance, lack of
concern and mismanagement of mercury containg compounds in Japan.
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There is a relationship between habits, life-style and
health, e.g. fatty food and smoking is bad for your health.
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Mutagenic substances and ionizing radiation may cause
cancers and mutations in the germ cells.
