Lead was a problem for hundreds of San Diego children even before the latest scare involving San Diego Unified, records from the county health department show. Last year, public health officials found hundreds of children in San Diego County with elevated levels of lead in their blood. The children are at risk for a host of health problems, including behavioral disorders. The county health department’s Childhood Lead Poisoning Prevention Program collected blood test data from 37,574 of the county’s 250,000 children under the age of 6, which is when children are at most risk of problems from lead exposure.