Routes of Entry of Hazardous Substances

Inhalation:
This is the most important route of entry as it allows the substance to directly attack lung tissue and, in some cases, to enter the blood stream and attack other organs of the body. The lungs are an active pump, drawing in air from the environment and the majority of occupational ill-­health produced by agents is caused by inhalation. Gases, such as carbon monoxide, enter the body by inhalation.

Ingestion:
occurs through the mouth. This can be accidental - such as by drinking from an unlabelled container or by poor hygiene -  eating, drinking or smoking in a contaminated environment. Respiratory defence mechanisms also push inhaled particles, such as dusts, into the throat and mouth, most of which will then be swallowed;

Absorption:
Occurs through the skin and across membranes, e.g. ammonia into the eye. Many solvents will penetrate unbroken skin and can enter the blood stream. Other substances can enter via cuts or abrasions;

Direct Entry:
Occurs through open wounds on the skin, such as dermatitis, tetanus infection and leptospirosis (Weil’s disease) from female rat urine;

Injection (skin puncture):
Caused by contact with liquids or gases under pressure or accidental puncture of the skin with contaminated sharp objects, e.g. HIV.

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Health Risks from Blood Borne Viruses

Blood Borne Viruses are Hepatitis (causative agent for jaundice nd liver damage) and HIV – Human Immunodeficiency Virus ( Causative agent for AIDS – Acquired Immune Deficiency Syndrome). Contaminated body fluids can cause infection by contact with damaged skin, needle-stick injury and even splashing to the eyes and mouth.

Circumstances that a worker may be exposed to Blood Borne Viruses

Health care workers are more vulnerable to infection while handling body fluids of infected patients and when disposing infected needles. Waste disposal workers are other category of people who may contract infection while incorrect handling of clinical waste. 

Workers who are engaged in the transportation of body fluids are also vulnerable, who may inadvertently contract infection. Other circumstances that would lead to exposure to BBVs may be through injuries to infected person when occur at workplace such as cuts, bruise crush etc., and workers engaged in acts of tattooing and body piercing.

Control Measures to overcome the Health Risks from Blood Borne Viruses

The control measures to overcome the health risks from blood borne viruses would be correct Disposal of potentially contaminated material such as clinical waste; 

Prevention of needle-stick injuries by correct disposal of sharps in a sharps bin; 

Use of PPE such as gloves and eye protection when handling potentially contaminated material; Drawing up and enforcement of decontamination and disinfection procedure; 

Vaccination where appropriate (for hepatitis) for vulnerable persons;

Covering up the wounds; 

Procedures to deal with accidental exposure.

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Biological Hazard - Biological Agents

Biological agents are micro – organisms such as:

Fungi

Moulds, yeast and mushrooms mostly harmless to human but some can cause disease such as athlete’s foot and farmer’s lung, both fungal infections.

Bacteria

Single celled organisms that are found in vast numbers in and on the human body. Some are beneficial while others can cause disease such as legionnaires, leptospirosis etc.,

Viruses

Very small infections organisms that reproduction on living cells of human body. Example – Hepatitis

Possible routes of Entry for a Biological Agent

The possible routes of entry for a biological agent into the body would be 

inhalation – airborne micro-organisms, 

absorption through the skin, injection for example through cut and grazes, exchange of body fluids, and 

ingestion – contaminated food.

Control Measures to Reduce Risk of Exposure to Biological Agent

• In order to reduce the risk of infection from biological organisms we can adopt a number of control Measures such as cleaning and disinfecting
• The use of personal protective equipment like respiratory protection, aprons and gloves
• Engineering controls such as containment for example in glove boxes, can also be provided with local exhaust ventilation and the use of microbiological safety cabinets
• The introduction of procedures for the disposal of waste
• The prohibition of eating or drinking in the work area
• Vermin control
• Procedures for site monitoring and health surveillance
• Immunization and a good standard of personal hygiene.

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