Occupational Hazards

A worker may be exposed to five types of hazards, depending upon his/her occupation:

•       Physical Hazards

•      Chemical Hazards

•       Biological Hazards

•       Mechanical Hazards

•       Psychosocial Hazards

• Physical Hazards

1.Heat and Cold

In India, the most common physical hazard is heat. The direct effects of heat exposure are burns, heat exhaustion, heat stroke and heat cramps; the indirect effects are decreased efficiency, increased fatigue and enhanced accident rates. Many industries have local “hot spots” – ovens and furnaces, which radiate heat. Radiant heat is the main problem in foundry, glass and steel industries, while heat stagnation is the principal problem in jute and cotton textile. High temperatures are also found in mines. Physical work under such conditions is very stressful and impairs the health and efficiency of the workers. For gainful work involving sustained and repeated effort, a reasonable temperature must be maintained in each work room.

Important hazards associated with cold work are chilblains, erythrocyanosis, immersion foot, and frostbite as a result of cutaneous vasoconstriction. General hypothermia is not unusual.

2. Light

The workers may be exposed to the risk of poor illumination or excessive brightness. The acute effects of poor illumination are eye strain, headache, eye pain, lachrymation, congestion around the cornea and eye fatigue. The chronic effects on health include “miners’s nystagmus”. Exposure to excessive brightness or “glare” is associated with discomfort, annoyance and visual fatigue. Intense direct glare may also result in blurring of vision and lead to accidents. There should be sufficient and suitable lighting, natural or artificial, wherever persons are working.

3. Noise

Noise is a health hazard in many industries. The effects of noise are of two types:

(i)    Auditory effects - which consist of temporary or permanent hearing loss

(ii)   Non-auditory effects – which consist of nervousness, fatigue, interference with communication by speech, decreased efficiency and annoyance.

The degree of injury from exposure to noise depends upon a number of factors such as intensity and frequency range, duration of exposure and individual susceptibility.

4. Vibration

Vibration, especially in the frequency range 10 to 500 Hz. May be encountered in work with pneumatic tools such as drills and hammers. Vibration usually affects the hands and arms. After some months or years of exposure, the fine blood vessels of the fingers may become increasingly sensitive to spasm (white fingers). Exposure to vibration may also produce injuries of the joints, of the hands, elbows and shoulders.

5. Ultraviolet Radiation

Occupational exposure to ultraviolet radiation occurs mainly in arc welding. Such radiation occurs mainly affects the eyes, causing intense conjunctivitis and keratitis (welder’s flash). Symptoms are redness of the eyes and pain, these usually disappear in a few days with no permanent effect on the vision or on the deeper structures of the eye.

6.  Ionizing Radiation

Ionizing radiation is finding increasing application in medicine and industry, e.g. x-rays and radio active isotopes. Important radio-isotopes are cobalt60 and phosphorus32. Certain tissues such as bonemarrow are more sensitive than others and from a genetic standpoint, there are special hazards when the gonads are exposed. The radiation hazards comprise genetic changes, malformation, cancer, leukaemia, depilation, ulceration, sterility and in extreme cases death. The International Commission of Radiological Protection has set the maximum permissible level of occupational exposure at 5 rem per year to the whole body.

• Chemical Hazards

There is hardly any industry which does not make use of chemicals. The chemical hazards are on the increase with the introduction of newer and complex chemicals. Chemical agents act in three ways: local action, inhalation and ingestion. The ill-effects produced depend upon the duration of exposure, the quantum of exposure and individual susceptibility.

1. Local Action

Some chemicals cause dermatitis, eczema, ulcers and even cancer by primary irritant action; some cause dermatitis by an allergic action. Some chemicals, particularly the aromatic nitro and amino compounds such as TNT and aniline are absorbed through the skin and cause systemic effects. Occupational dermatitis is a big problem in industry.

2. Inhalation

(i)                  Dusts – Dusts are finely divided solid particles with size ranging from 0.1 to 150 microns. They are released into the atmosphere during crushing, grinding, abrading, loading and unloading operations. Dusts are produced in a number of industries – mines, foundry quarry, pottery, textile, wood or stone working industries. Dust particles larger than 10 microns settle down from the air rapidly, while the smaller ones remain suspended indefinitely. Particles smaller than 5 microns are directly inhaled into the lungs and are retained there. This fraction of the dust is called “respirable dust”, and is mainly responsible for pneumoconiosis. Dusts have been classified into inorganic and organic dusts; soluble and insoluble dusts. The inorganic dusts are silica, mica, coal, asbestos dust, etc.; the organic dusts are cotton, jute and the like. The soluble dusts dissolve slowly, enter the systemic circulation and are eventually eliminated by body metabolism. The insoluble dusts remain, more or less, permanently in the lungs. They are mainly the cause of pneumoconiosis. The most common dust diseases are silicosis and anthracosis

(ii)                Gases – Exposure to gases is a common hazard in industries. Gases are sometimes classified as simple gases (e.g. oxygen, hydrogen), asphyxiating gases (e.g. carbon monoxide, cyanide gas, sulphur dioxide, chlorine) and anesthetic gases (e.g. chloroform, ether, trichlorethylene). Carbon monoxide hazard is frequently reported in coal-gas manufacturing plants and steel industry.

(iii)               Metals and their Compounds – A large number of metals and their compounds are used throughout industry. The chief mode of entry of some of them is by inhalation as dust or fumes. The industrial physician should be aware of the toxic effects of lead, antimony, arsenic, beryllium, cadmium, cobalt, manganese, mercury, phosphorus, chromium, zinc and others. The ill-effects depend upon the duration of exposure and the dose or concentration of exposure. Unlike the pneumoconiosis, most chemical intoxications respond favourably to cessation, exposure and medical treatment.

3. Ingestion

Occupational diseases may also result from ingestion of chemical substances such as lead, mercury, arsenic, zinc, chromium, cadmium, phosphorus, etc. Usually these substances are swallowed in minute amounts through contaminated hands, food or cigarettes. Much of the ingested material is excreted through faeces and only a small proportion may reach the general blood circulation.

• Biological hazards

Workers may be exposed to infective and parasitic agents at the place of work. The occupational diseases in this category are brucellosis, leptospirosis, anthrax, hydatidosis, psittacosis, tetanus, encephalitis, fungal infections, schistosomiasis and a host of others. Persons working among animal products (e.g. hair, wool, hides) and agricultural workers are specially exposed to biological hazards.

• Mechanical hazards

The mechanical hazards in industry centre round machinery, protruding and moving parts and the like. About 10% of accidents in industry are said to be due to mechanical causes.

• Psychosocial hazards

The psychosocial hazards arise from the workers’ failure to adapt to an alien psychosocial environment. Frustration, lack of job satisfaction, insecurity, poor human relationships, emotional tension are some of the psychosocial factors which may undermine both physical and mental health of the workers. The capacity to adapt to different working environments is influenced by many factors such as education, cultural background, family life, social habits and what the worker expects from employment.

The health effects can be classified in two main categories –

a)      Psychological and behavioural changes – including hostility, aggressiveness, anxiety, depression, tardiness, alcoholism, drug abuse, sickness absenteeism

b)      Psychosomatic illhealth – including fatigue, headache; pain in the shoulders, neck and back; propensity to peptic ulcer, hypertension, heart disease and rapid aging.

The physical factors (heat, noise, poor lighting) play a major role in adding to or precipitating mental disorders among workers. The increasing stress on automation, electronic operations and nuclear energy may introduce newer psychosocial health problems in industry. Psychosocial hazards are there fore assuming more importance than physical or chemical hazards.