Geophagia

Geophagia is the consumption of earth, typically earth that has a high percentage of clay. It is one of many types of pica.

The relative health benefits of geophagy are debated. Most scientists believe that it is only harmful, while others argue that there may be adaptive benefits to the practice, since humans and animal alike have engaged in it for thousands of years.

Like coprophagia, it may be dangerous because parasite eggs can be passed in animal feces. Baylisascaris eggs, for instance, are dropped millions at a time by raccoons and other wildlife. They can stay dormant for years, remaining viable even in extreme temperatures and drought. Some of these roundworm eggs may remain in the soil long after the feces have decomposed, and become active in the digestive tract upon being consumed. Children's predilection to engage in geophagia makes them more susceptible to worm infestations.

Other dangers associated with geophagia include damage to tooth enamel, the ingestion of a variety of bacteria, lead poisoning and intestinal obstruction.

In some parts of the world, geophagia is a culturally sanctioned practice. In many parts of the developing world, earth intended for consumption is available for purchase.

Classification and Diagnosis
The International Classification of Diseases includes geophagia among eating disorders (F50) as a variety of pica, the ingestion of non-foods. However, dirt can constitute a source of iron, although the bioavailability of such mineral has not been ascertained. For example, red clays often have iron in ferrous form, poorly absorbed by humans.

It is also associated with iron deficiency (see Health A to Z, below)

Geophagia can be diagnosed, in absence of other evidence, by measuring the concentration of silica in feces.