CORROSIVES (ACIDS AND ALKALIES)
Hazards of Chemicals and Gases
Alkalies (bases) are corrosive caustic substances that dissociate in water and yield hydroxyl ions
(OH ). Alkalies include: ammonia, ammonium hydroxide; calcium hydroxide and oxide;
potassium, potassium hydroxide and carbonate; sodium, sodium hydroxide; carbonate, peroxide
and silicate; and trisodium phosphate.
The alkalies, whether in solid form or concentrated liquid solution, are more destructive to tissue
than most acids. Alkali dusts, mists, and sprays may cause irritation of the eyes and respiratory
tract and lesions of the nasal septum. Strong alkalies combine with tissue, causing severe burns,
frequently deep ulceration, and ultimate scarring. Severe burns result not only from contact with
solid alkalies, but also from solutions of these compounds. Potassium and sodium hydroxide are
the most active materials in this group. Even dilute solutions of the stronger alkalies tend to
soften the epidermis (skin) and emulsify or dissolve the skin fats. Exposure to atmospheres
contaminated with alkalies may result in damage to the upper respiratory tract and to lung tissue,
depending upon the severity of the exposure. The effects of inhalation may vary from mild
irritation of the nasal mucous membranes to severe inflammation of the lungs.
Ingestion causes severe damage to mucous membranes or deeper tissues with which contact is
made. Perforation of these tissues may follow, or there may be severe and extensive scar
formation. Death may result if penetration into vital areas occurs.
Even though alkalies are not flammable and will not support combustion, much heat is evolved
when the solid material is dissolved in water. Therefore, cold water must be used to dissolve
solid alkalies, otherwise the solution may boil, and splatter corrosive liquid over a wide area.
General Safety Precautions
Corrosives are available in numerous forms and varying concentrations. Some forms and
concentrations are more hazardous than others, but the potential for serious accidents exists
regardless of the substance in question.
Many of the safety precautions necessary for safe handling and storage are equally applicable to
acids and alkalies. Some of the more common precautions are contained in this section. These
precautions are not all inclusive, nor are they meant to be. Specific corrosives may require
specific precautions, and Material Safety Data Sheets (MSDS) must be consulted in all cases.
The MSDS will be discussed later in this module.
Safety in handling hazardous chemicals depends to a great extent upon effective employee
education, proper safety practices, intelligent supervision, and the use of safe equipment.
Workers should be thoroughly informed of the hazards that may result from improper handling.
Each employee should know what to do in an emergency and should be fully informed about
proper first-aid measures. Hazards from spills and leaks should be minimized by an adequate
supply of water for washing-down. Drainage of hard-surfaced or diked areas should be directed
to minimize the exposure of personnel and equipment. Adequate ventilation should be provided
in areas where chemical mist or dust is present.