I got curious with Pica thus researched about it. Here's what I've learnt:
source
Pica (pron.: /ˈpaɪkə/ py-kə) is characterized by an appetite for substances largely non-nutritive, such as clay, chalk, dirt, or sand.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. There are different variations of pica, as it can be from a cultural tradition, acquired taste or a neurological mechanism such as an iron deficiency, or chemical imbalance. It can lead to intoxication in children which can result in an impairment in both physical and mental development. In addition, it can also lead to surgical emergencies due to an intestinal obstruction as well as more subtle symptoms such as nutritional deficiencies and parasitosis. Pica has been linked to mental disorders and they often have psychotic comorbidity. Stressors such as maternal deprivation, family issues, parental neglect, pregnancy, poverty, and a disorganized family structure are strongly linked to pica.