Pica is an appetite for non-nutritive substances (e.g., coal, soil, chalk, paper etc.) or an abnormal appetite for some things that may be considered foods, such as food ingredients (e.g., flour, raw potato, starch). In order for these actions to be considered pica, they must persist for more than one month, at an age where eating such objects is considered developmentally inappropriate. The condition's name comes from the Latin word for the magpie, a bird which is reputed to eat almost anything. Pica is seen in all ages, particularly in pregnant women and small children, especially among children who are developmentally disabled, where it is the most common eating disorder.

It is much more common in developing countries and rural areas than elsewhere^{[citation needed]}. In extreme forms, pica is regarded as a medical disorder.

Pica in children, while common, can be dangerous. Children eating painted plaster containing lead may suffer brain damage from lead poisoning. There is a similar risk from eating dirt near roads that existed prior to the phaseout of tetra-ethyl lead in gasoline or prior to the cessation of the use of contaminated oil (either used, or containing toxic PCBs) to settle dust. In addition to poisoning, there is also a much greater risk of gastro-intestinal obstruction or tearing in the stomach. This is also true in animals. Another risk of dirt eating is the possible ingestion of animal feces and the accompanying parasites.

 Causes

The scant research that has been done on the root causes of pica suggest that the majority of those afflicted tend to suffer some biochemical deficiency and more often iron deficiency. Often the substance eaten by those with the disorder does not even contain the mineral they are deficient in. In cases where a biochemical deficiency is the problem, pica is generally not discovered until the deficiency is addressed. Once the deficiency has been identified and treated with vitamins or minerals, the pica is usually resolved. If a mineral deficiency is not identified as the cause of pica, it often leads to a misdiagnosis as a mental disorder. If the deficiency continues to go unnoticed it can become severe if the root of the deficiency is a disease or internal problem.

Treatment

Treatment emphasizes psychosocial, environmental, and family guidance approaches. Treatment options include: discrimination training between edible and nonedible items, self-protection devices that prohibit placement of objects in the mouth, sensory reinforcement involving screening (covering eyes briefly), contingent aversive oral taste (lemon), contingent aversive smell sensation (ammonia), contingent aversive physical sensation (water mist), brief physical restraint, and overcorrection (correct the environment, or practice appropriate alternative responses).

This involves associating negative consequences with eating non-food items and good consequences with normal behavior. Medications may be helpful in reducing the abnormal eating behavior, if pica occurs in the course of a developmental disorder, such as mental retardation, or pervasive developmental disorder. These conditions may be associated with severe behavioral disturbances, including pica. These medications enhance dopaminergic functioning, which is believed to be associated with the occurrence of pica.