Metals and other hazardous chemicals
Many metals and metal alloys are present at work. Some metals, such as lead, cadmium and mercury, can damage our bodies. Heated lead, as in the case of battery manufacturing or soldering, and mercury can easily concentrate in the air. Absorption of these by the body over a period of time may lead to various degrees of lead poisoning or mercury poisoning that also damages the nervous system.
Chromium, cobalt and nickel are examples of other dangerous metals. These metals can cause cancer, mainly of the respiratory system.
Dangerous metal dusts or fumes are formed in welding, grinding, paint spraying, etc. Some chromium and nickel alloys can be absorbed into the blood via the lungs, and can then damage other organs in the body. They can also cause allergies.
Occupational skin diseases
Various occupational skin diseases result from contact of the skin with hazardous chemicals. Occupational contact dermatitis (or eczema) account for the great majority of occupational skin diseases. Human skin, except for the palms and soles, is quite thin. Within certain limits, it is a unique shield for protection against mechanical trauma, heat and cold, micro-organisms and chemical agents. This defence by the skin is weakened by mechanical injury, contact with alkalis or other substances. Toxic materials can be absorbed through the skin itself; though frequent, whole body intoxication can result from the absorption through the skin, as in case of mercury, tetraethyl-lead and some pesticides. Eczema due to contact with chemicals is more common. In many country eczema accounts for nearly half of occupational diseases receiving compensation.
Occupational eczema is seen among workers in different industries like building, engineering, textile, chemical, printing workers, cleaners, painters, hairdressers, workers in plastics, rubber, electroplating, leather, electric apparatus industries, etc.
There are two types of occupational eczema. They are
1. Irritant eczema (non-allergic)
Irritant eczema is a skin disease produced by prolonged contact with certain chemicals. After a time the skin dries out, becomes tender, reddens and cracks. This type of eczema is caused by solvents, corrosive (alkali) substances, detergents, coolants and cutting fluids.
Once contact with the chemical that caused the eczema has ceased, the skin can heal and become healthy again. The healing process takes many months. During this period the skin is even more susceptible than usual and therefore must be protected.
2. Allergic contact eczema
Allergic contact eczema is a delayed type of skin disease caused by newly acquired high sensitivity to a chemical. Very small quantities of the chemical, which previously had come into, contact with the skin without causing any noticeable irritation, produce eczema due to this new sensitivity. Symptoms are irritation and swelling of the skin, with subsequent drying and flaking.
An allergy is not inherent but is acquired as a result of contact with a certain substance. Excess sensitivity or allergy usually persists for the rest of the personís life. The symptoms normally disappear once contact with the substance ceases.
Eczema of this type is caused by contact with substances such as chromium (present in cement, leather, rust-proofing agents, etc.), cobalt (present in detergents, colour pigments), and nickel (nickel plated objects such as keys, coins, tools). Rubber and certain types of plastics and adhesives can produce these effects.
Allergic eczema may not be limited to the site of initial exposure to the substance. It can take a very long time, even many years, for an allergy to develop. Knowledge of the chemicals contacting the skin is essential for preventive measures to be taken.
Allergic symptoms in the form of coughing and breathing difficulties can also occur after exposure to certain types of dust. The symptoms are colds, running eyes and nose, or asthma. The sources of this allergy include dusts of flour, cotton, hay and wood. Allergic respiratory complications can also be caused by certain artificial substances, e.g. in sprays.