Biological effect of airborne contaminants

An airborne contaminant is a potentially harmful substance that is either naturally absent from air or is present in an unnaturally high concentration, and to which workers may be exposed in their working environment. During contact with human organism it can cause injury, disease or illness, that can be detected by modern methods, as during occupational activity so in some periods of life of this and future generation.

The uptake of airborne contaminants occurs throughout the respiratory system, digestive organs, skin and mucous membrane. The dominant driving force in the uptake of gases, vapors and dust is in respiratory system, liquid substances – through the skin. Contaminants get into alimentary tract while swallowing due to dirty hands.

Poisoning by harmful substances depends on their toxicity, quantity, exposure time and individual organism. Acute poisoning occurs after one-time exposure of contaminant in large quantity. Chronic poisoning develops during longtime exposure of the person to contaminant in low concentration. Harmful substances uptaken by organism distribute in it irregularly. Lead accumulates basically in bones, fluorine – in teeth, manganese – in liver.

Airborne contaminants introduced in work areas are divided into chemical substances and dust.

Chemical substances are divided by character of influence into 6 groups:

1. toxic - inducing poisoning of the whole organism (carbon oxide, lead, mercury);

2. irritant - inducing irritating of respiratory tract and mucous membrane (chlorine, acetone, ozone);

3. sensitizer - influencing as allergen (formaldehyde, various lacquers, solvents);

4. carcinogenic - inducing cancer (nickel and its compounds, chrome oxide, asbestos);

5. gene-mutating - changing heredity information (lead, manganese, radioactive substances);

6. teratogenic (mercury, lead, manganese, radioactive substances).

It’s possible to use anther classifications, such as contaminants which effect exact organs (liver, kidneys, heart, alimentary tract) and also asphyxiating, nervous ones etc.

Dusts are solid particles generated and dispersed into the air by, for example, handling, crushing and grinding of organic or inorganic materials such as rock, ore, metal, coal, wood and grain.

The health effects caused by particulate exposure are equally diverse. Skin contact with some dusts, such as organic dusts from flour and grains, may cause irritation or allergic responses in sensitized persons, while inhalation of other organic dusts, particularly some wood dusts, has been shown to cause nasal cancer in heavily exposed workers. However, the major health effects are usually found in the lungs, where particulate matter may penetrate deep down to the gas exchange region (the alveoli) and cause severe fibrotic reactions. An example of this is silicosis, which results from exposure to silica. Other lung reactions include bronchitis, which is over-production of mucous associated with inflammation of the bronchi; asthma which is a constriction of the bronchial tubes; and cancer. Restricted lung function can place burden on the right side of the heart and this additional strain can result in irreversible heart damage over time.

Floating in the air dust is called aerosol and that adhered to surface – aerogel.

It’s classified by toxicity and particulate size.

As for toxicity dust can be toxic such as lead, manganese, or cadmium being absorbed into the blood it can exert an adverse effect on tissues or organs that may be remote from the site of entry, or untoxic (having no poisoning effect). Toxic dust dissolved by saliva or on mucous membrane of respiratory tract converts into poison.

Particle size is critical in determining where particulates will settle in the lung.

By its size dust is classified as following:

- INHALABLE dust has a 50% cut-point of 100 m m

- THORACIC dust has a 50% cut-point of 10 mm

- RESPIRABLE (smoke) dust has a 50% cut-point of 5 mm; that dust is so small in size that it can get through the lung defense mechanisms of the human body and get down deep into the gas exchange (alveolar) region of the lung.