Pica symptoms include:

Persistent eating of nonnutritive substances for a period of at least 1 month.

The eating of nonnutritive substances is inappropriate to the developmental level.

The eating behavior is not part of a culturally-sanctioned practice.

If the eating behavior occurs exclusively during the course of another mental disorder (e.g., mental retardation, pervasive developmental disorder, schizophrenia), it is sufficiently severe to warrant independent clinical attention.