Does children that eat there nails may develop lead accumulation ?

No: Do you mean fingernails? No, unless there is lead-based materials on the nails.

Lead: If there is lead under the nails, and the child is exposed to lead paint, maybe a little. The concern is, if child has lead paint, under the fingernails, is he/she also eating it, as well? The only way to determine this, for sure, is to have your child's lead level checked.