Answer: Make changes in the home
Step-by-step explanation:
Based on the information given, the best next step is to make changes in the home. This is still a mild elevation which occurs typically from level 10 to 20.
In this case, treating with chelation isn't needed. The assistance of public health and the education for the parents are important in this case. The family should also move out of the lead-contaminated apartment as this isn't good for the child.