A caustic is a xenobiotic that causes both functional and histologic damage on contact with tissue surfaces. As early as 1927, legislation in the United States governing the packaging of alkali- and acid-containing products mandated that warning labels be placed on these products. In response to the recognition that caustic exposures were more frequent in children, the Federal Hazardous Substances Act and Poison Prevention Packaging Act were passed in 1970. These acts mandated that all caustics with a concentration greater than 10% be sold in child-resistant containers. By 1973, the household concentration triggering mandatory child-resistant packaging was lowered to 2%. In addition, the subsequent development of poison prevention education dramatically decreased the incidence of unintentional caustic injuries in children in the United States. The positive impact of both regulatory legislation and public health intervention is evident when observing the decreasing number of significant exposures in the United States compared to the number of exposures in developing nations that lack these policies.
In the United States, even though legislation limiting the concentration of caustics has existed since the early 20th century, exposures to both acids and alkalis continue to be significant. Data collected from the 5 most recent years of the American Association of Poison Control Centers Annual Reports of the National Poison Data System revealed 37,272 acid exposures and 18,801 alkali exposures. Of these, 4,405 (12%) of acid and 3,153 (17%) of alkali exposures resulted in moderate to major outcomes and a total of 26 deaths occurred (Chap. 130).
Caustic exposures follow a bimodal age distribution pattern with peak occurrences in the pediatric population age 1 to 5 years and again in adulthood. In children, exposures usually consist of household products and occur most often in an unsupervised setting. In adults, exposures to household or industrial products result from occupational exposure, suicide attempts, and assaults. Although less frequent, intentional exposures by adults are invariably more significant. One study noted that although children comprised 39% of admissions for caustic ingestions, adults comprised 81% of patients requiring treatment.38
Exposure to caustics occurs via the dermal, ocular, respiratory, and gastrointestinal route. Caustics cause diverse histologic and functional damage on contact with tissues depending on the tissue and caustic involved. Table 103–1 lists common caustics and the products that contain them. Many are available for home use, in both solid and liquid forms, with variations in viscosity, concentration, and pH.
TABLE 103–1Sources of Common Caustics ||Download (.pdf) TABLE 103–1 Sources of Common Caustics
|Caustic ||Common Applications |
|Acetic acid ||Permanent wave neutralizers, photographic stop bath, concentrated solution for food purposes |
|Ammonia (ammonium hydroxide) ||Toilet bowl cleaners, metal cleaners and polishes, hair dyes and tints, antirust products, jewelry cleaners, floor strippers, glass cleaners, wax removers |
|Benzalkonium chloride ||Detergents |
|Boric acid ||Roach powders, water softeners, germicides |
|Formaldehyde, formic acid ||Deodorizing tablets, plastic menders, ...|