CHEMICAL POISONING
By Faudzil Harun
By Faudzil Harun
Route Of Entry Into The Body
Route of exposure describes the way the chemical enters the body. Chemicals may have serious effects by one route, and minimal effects by another. Hazardous chemicals may enter the body by:
1. Absorption through the respiratory tract via inhalation.
2. Absorption through the skin via dermal contact.
3. Absorption through the digestive tract via ingestion. (Ingestion can occur
through eating or smoking with contaminated hands or in contaminated
work areas.)
4. Injection: Introducing the material directly into the bloodstream.
(Injection may occur through mechanical injury from "sharps".)
In the laboratory the primary routes of chemical exposure is through inhalation and dermal contact. Working in a laboratory with good general ventilation and using a chemical fume hood can prevent inhalation exposures. Wearing appropriate chemical protective clothing prevents dermal contact. Good hygiene habits, such as regular washing your hands, and using tongs or other tools to pick up sharp objects, will prevent exposure through ingestion or injection
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Toxicity Of The Chemical
● It is a measure of the poisoning strength of a chemical.
● The amount or dose of a chemical entering the body determines whether a
chemical will cause poisoning.
● The amount of a chemical which causes poisoning depends on the chemical.
● Taking too much of a chemical into the body causes toxicity.
● Chemicals that are only weakly toxic require large amount to cause
poisoning.
● Lethal Dose (LD50) test measures the dose of a chemical (all given at
once) which causes death to 50% of the animals being tested.
● Lethal Concentration (LC50) experiments measures the concentration of
chemicals in air that kills 50% of the test animals in a given time (usually
four hours). It is usually refering to the concentration of a chemical in air,
but in environmental studies it can also mean the concentration of a
chemical in water.
Removal From The Body
● Many workplace chemicals which enter the body are excreted unchanged,
some are broken down.
● Many chemicals and their breakdown are stored temporarily in body organs
and are removed over a short period of time as waste in the feces, urine,
sweat or exhaled breath.
● Some chemicals are permanently stored and some may never be completely
removed.
● Risk of chemical poisoning is less if the body can break down the chemical
entering the body into less toxic products or rapidly remove the chemical
from the body.
Biological Variation
- Health condition of the exposed individual
● Healthy individual less susceptibility to toxic effect.
● Better able to detoxify, excrete the chemical and repair damage more
quickly.
Biological Variation
- Age
● Rapidly dividing body cells are more susceptible to toxic chemicals.
● Growing children are at greater risk.
Biological Variation
- Body Adaptation
● Body adapts and lear to cope with certain hazards increase its capacity to
detixify the effect of chemicals.