routesofentry

Routes of Entry

A toxic substance is one that has negative effect on the health of a person or animal. Toxic effects are a function of several factors, including the following:

Properties of the substance

Amount of the dose

Level of exposure

Route of entry

When a toxic chemical acts on the human body, the nature and extent of the injurious response depends upon the dose received. Response can vary widely and might be as little as a cough or mild respiratory irritation or as serious as unconsciousness and death.

Routes of Entry:

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. The most common routes of entry are:

Inhalation

Absorption

Ingestion

Injection

Inhalation:

The route of entry about which health and safety professionals should be most concerned is inhalation. Airborne toxic substances can be inhaled and pass through the nose, throat, bronchial tubes and lungs to enter the bloodstream. The amount of the substance that can be inhaled depends on the following factors:

Concentration of the substance

Duration of exposure

Breathing volume

Absorption:

The second most common route of entry in an industrial setting is absorption, or passage through the skin and into the bloodstream. With many substances the rate of absorption and, in turn , the hazard level increases in a warm environment.

Ingestion:

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:

Injection involves introducing a substance into the body using a needle and syringe. Consequently, this is not often a route of entry for a toxic substance in the workplace.

Types of Health Hazards Due to Chemical Exposures:

Acute Effects

Chronic Effects

Acute Effects:

Acute effect is an immediate effect of a chemical exposure which is usually from a single dose of exposure. Acute effects are clear warnings of overexposure, which are:

Irritation of eyes

Skin irritation

Nausea

Dizziness

Coma

Death

Chronic Effects:

Chronic effects are long term and persistent effects of chemical exposure. Chronic effects result from repeated exposures over many years, which are permanent and irreversible. Examples for chronic effects are:

Skin diseases

Bronchitis

Liver cirrhosis

Cancer

Part of the Body	Acute Effects	Chronic Effects
Skin	Redness, itching, burning, blistering, discoloration	Dermatitis (inflammation of the skin), cancer
Eye	Tearing, burning, stinging	Clouded cornea, blindness
Lung, nose, throat	Coughing, Burning, bleeding, shortness of breath	Pulmonary disease, cancer
Nervous system	Dizziness, lightheadedness, nausea	Brain/nervous system damage, cancer
Systemic effects (When substances enter the body and produce damage to organs or biological functions)	Irregular heart beat, upset stomach, kidney pains, jaundice	Kidney, heart or liver failure, leukemia, sterility, birth defects, impotence, cancer

Table 1. Acute and chronic effects caused by toxic chemicals

Controls:

There are three classes of control for protecting people from exposure to toxic chemicals:

Engineering Controls

Administrative Controls

Personal Protective Equipment

Engineering Controls:

Substitution

Replace a hazardous material with a non hazardous one if possible

Isolation

Enclose hazardous process equipment

Workers can work in an enclosed cabin with controlled, uncontaminated atmosphere

Use glove-box systems

Separate hazardous operations from non-hazardous ones.

Ventilation

Useful for airborne contaminants. Two types of ventilation are used:

General (dilution) ventilation (requires high volume of air, very expensive)

Local exhaust ventilation (requires small volumes of air, removes the hazardous fumes before they reach the breathing zone of people)

Administrative Controls:

Housekeeping : (Use vacuum cleanup equipment, do not use sweepers or compressed air)

Removal of dust accumulation

Rapid cleanup of spills

Materials Handling and Transfer Procedures:

Liquid material containers usually are covered with residual vapors or condensations. Transfer of these containers may spread the vapors.

Pouring or dumping dusts into open containers may create airborne substances

Use a container to collect overfill spills or leaking materials.

Leak Detection Programs

Visual inspections

Automatic sensors

Training

OSHA and State Right-to-Know laws require training workers to understand the hazards associated with materials they encounter on the jobs and how to protect themselves from those hazards.

Modifying the Work

Having more workers share the activity which will ensure reduction in exposure time.

Personal Hygiene

Clean the skin that might be exposed to the chemicals (use soap, emergency showers, emergency eye wash fountains)

Personal Protective Equipment (PPE)

Necessary when adequate engineering and administrative controls cannot be achieved. Maintenance workers, spill cleanup and work that has to be performed in a confined space require personal protective equipment, which includes:

Eye protection

Face protection

Protective Clothing

Respiratory Protection

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Last Update: February 25, 2000

By: Serdar Z. Elgun