Pica is an eating disorder typically defined as the persistent eating of nonnutritive substances for a period of at least 1 month at an age in which this behavior is developmentally inappropriate (eg, >18-24 mo). The definition occasionally is broadened to include the mouthing of nonnutritive substances. Individuals presenting with pica have been reported to mouth and/or ingest a wide variety of nonfood substances, including, but not limited to, clay, dirt, sand, stones, pebbles, hair, feces, lead, laundry starch, vinyl gloves, plastic, pencil erasers, ice, fingernails, paper, paint chips, coal, chalk, wood, plaster, light bulbs, needles, string, and burnt matches.
Although pica is observed most frequently in children, it is the most common eating disorder seen in individuals with developmental disabilities. In some societies, pica is a culturally sanctioned practice and is not considered to be pathologic. Pica may be benign, or it may have life-threatening consequences.
In children aged 18 months to 2 years, the ingestion and mouthing of nonnutritive substances is common and is not considered to be pathologic. Consider pica when the behavior is inappropriate to the developmental level of the individual, is not part of a culturally sanctioned practice, and does not occur exclusively during the course of another mental disorder (eg, schizophrenia). If pica is associated with mental retardation or pervasive developmental disorder, it must be sufficiently severe to warrant independent clinical attention. In such patients, pica typically is considered to be a secondary diagnosis. Furthermore, the pica must last for a period of at least 1 month.
Pica is a serious behavioral problem because it can result in significant medical sequelae. The nature and amount of the ingested substance determine the medical sequelae. Pica has been shown to be a predisposing factor in accidental ingestion of poisons, particularly in lead poisoning. The ingestion of bizarre or unusual substances also has resulted in other potentially life-threatening toxicities, such as hyperkalemia following cautopyreiophagia (ingestion of burnt match heads).
Exposure to infectious agents via ingestion of contaminated substances is another potential health hazard associated with pica, the nature of which varies with the content of the ingested material. In particular, geophagia (soil or clay ingestion) has been associated with soil-borne parasitic infections, such as toxoplasmosis and toxocariasis. Gastrointestinal (GI) tract complications, including mechanical bowel problems, constipation, ulcerations, perforations, and intestinal obstructions, have resulted from pica.
- In the US: Prevalence of pica is unknown because the disorder often is unrecognized and underreported. Although prevalence rates vary depending on the definition of pica, the characteristics of the population sampled, and the methods used for data collection, pica is reported most commonly in children and in individuals with mental retardation. Children with mental retardation and autism are affected more frequently than children without these conditions. Among individuals with mental retardation, pica is the most common eating disorder. In this population, the risk for and severity of pica increases with increasing severity of mental retardation.
- Internationally: Pica occurs throughout the world. Geophagia is the most common form of pica in people who live in poverty and people who live in the tropics and in tribe-oriented societies. Pica is a widespread practice in western Kenya, southern Africa, and India. Pica has been reported in Australia, Canada, Israel, Iran, Uganda, Wales, and Jamaica. In some countries, Uganda for example, soil is available for purchase for the purpose of ingestion.
- Ingestion of poisons: Lead toxicity is the most common type of poisoning associated with pica. Lead has neurologic, hematologic, endocrine, cardiovascular, and renal effects. Lead encephalopathy is a potentially fatal complication of severe lead poisoning, presenting with headache, vomiting, seizures, coma, and respiratory arrest. Ingestion of high doses of lead can cause significant intellectual impairment and behavioral and learning problems. Studies also have demonstrated that neuropsychologic dysfunction and deficits in neurologic development can result from very low lead levels, even levels once believed to be safe.
- Exposure to infectious agents: A variety of infections and parasitic infestations, ranging from mild to severe, are associated with the ingestion of infectious agents via contaminated substances, such as feces or dirt. In particular, geophagia has been associated with soil-borne parasitic infections, such as toxocariasis, toxoplasmosis, and trichuriasis.
- GI tract effects: GI tract complications associated with pica range from mild (eg, constipation) to life threatening (eg, hemorrhages secondary to perforations or ulcerations). Sequelae in the GI tract may include mechanical bowel problems, constipation, ulcerations, perforations, and intestinal obstructions caused by bezoar formation and the presence of undigestible materials in the intestinal tract.
- Direct nutritional effects: Theories regarding the direct nutritional effects of pica are related to characteristics of specific ingested materials that either displace normal dietary intake or interfere with the absorption of necessary nutritional substances. Examples of nutritional effects that have been linked to severe cases of pica include iron and zinc deficiency syndromes; however, the data are only suggestive, and no firm empirical data exist supporting these theories.