pica
n. a rare eating disorder marked by a persistent craving for unnatural, nonnutritive substances, such as plaster, paint, hair, starch, or dirt. In DSM–IV–TR, it is classified with the feeding and eating disorders of infancy or early childhood; in DSM–5, it falls within a broader category of feeding and eating disorders that can affect individuals at any age. Onset of the disorder does, however, most commonly occur in children, and it can have serious consequences, depending on the substance ingested. For example, lead pica, often found in children living in older housing with lead paint, can result in irreversible mental impairment. Studies on rats and monkeys have also demonstrated that lead pica can be induced by calcium deficiency. Animals with normal nutrition learn that lead ingestion is aversive, but calcium-deficient animals do not learn aversions to lead.