Caustics are substances that cause both functional and histologic damage on contact with body surfaces. Many household and industrial chemicals have caustic potential. Caustics are broadly classified as alkalis (pH >7) or acids (pH <7). In developed nations, increased education and product regulation (especially of acids) have decreased morbidity and mortality from caustic exposures in both adults and children. However, in underdeveloped parts of the world, exposure to caustics remains a significant problem.1-3 Alkaline ingestions predominate in the developed world,4 whereas acid ingestions are more common in developing countries.5
Caustic exposures tend to fall into three distinct groups: (1) intentional adolescent or adult ingestions with suicidal ideation; (2) unintentional ingestions (the majority of which are by curious children in the toddler age group); and (3) other incidental, often occupational or industrial contact exposures. The majority of reported exposures are unintentional or accidental, but intentional ingestions account for the majority of serious injuries.1 The geographic variation in caustic ingestion circumstances, such as involved substances, intention, age of the patient, and extent of evaluation, make it important to base treatment decisions on each particular patient’s presentation.
Many chemicals used in industry have caustic potential (Table 200-1). Household caustics are often less concentrated forms of industrial-strength cleansers.
TABLE 200-1Common Caustic Compounds ||Download (.pdf) TABLE 200-1 Common Caustic Compounds
|Compound ||Found In |
|Alkalis || |
|Sodium hydroxide ||Industrial chemicals, drain openers, oven cleaners |
|Potassium hydroxide ||Drain openers, batteries |
|Calcium hydroxide ||Cement, hair relaxers, perm products |
|Ammonium hydroxide ||Hair relaxers and perm products, dermal peeling/exfoliation, toilet bowl cleaners, glass cleaners, fertilizers |
|Lithium hydroxide ||Photographic developer, batteries |
|Sodium tripolyphosphate ||Detergents |
|Sodium hypochlorite ||Bleach |
|Sulfuric acid ||Automobile batteries, drain openers, explosives, fertilizer |
|Acetic acid ||Printing and photography, disinfectants, hair perm neutralizer, pickling solution |
|Hydrochloric acid ||Cleaning agents, metal cleaning, chemical production, swimming pool products |
|Hydrofluoric acid ||Rust remover, petroleum industry, glass and microchip etching, jewelry cleaners |
|Formic acid ||Model glue, leather and textile manufacturing, tissue preservation |
|Chromic acid ||Metal plating, photography |
|Nitric acid ||Fertilizer, engraving, electroplating |
|Phosphoric acid ||Rust proofing, metal cleaners, disinfectants |
The degree to which a caustic substance produces tissue injury is determined by a number of factors: pH, concentration, duration of contact, volume, and titratable acid or alkaline reserve. Acids tend to cause significant injuries at a pH <3 and alkalis at a pH >11. The physical properties of the product formulation (i.e., liquid, gel, granular, or solid) can influence the nature of the contact with tissue. Following ingestion, solid or granular caustics often injure the oropharynx and proximal esophagus, whereas liquid alkali ingestions are characterized by more extensive esophageal and gastric injuries. Titratable acid or alkaline reserve refers to the amount of acid or base required to neutralize the agent; the greater this value, the greater is the potential for tissue injury.