Response can vary widely and might be as little as a cough or mild respiratory irritation or as serious as unconsciousness and death. An important consideration relating to toxic substances is the route of entry. In order for a toxic substance to cause health problems it must first enter the bloodstream. Airborne toxic substances can be inhaled and pass through the nose, throat, bronchial tubes and lungs to enter the bloodstream. With many substances the rate of absorption and, in turn , the hazard level increases in a warm environment.
Ingestion is entry through the mouth.
It is not a major concern in an industrial setting. However, the key concern is that employee's food and hands might come in contact with a toxic substance and as a result the substance would be ingested. If the amount of toxic chemical that enters the body through ingestion is low, the liver may be able to convert it to a nontoxic substance or decrease the level of toxicity. Some substances pass through the kidneys and can be eliminated in the urine. Injection involves introducing a substance into the body using a needle and syringe.