The findings challenge a long-standing assumption that indoor lead exposure is primarily an old-house problem caused by deteriorating paint. That pattern supports the conclusion that contaminated soil was contributing to indoor lead dust independently of paint deterioration. Lead exposure is associated with impaired brain development, learning difficulties, behavioral changes and damage to vital organs. There is no known safe level of lead exposure for children, and exposure can occur through inhalation or ingestion of contaminated dust and soil. However, the combination of heavily contaminated surface soil, elevated indoor dust and similar floor-lead levels in homes with and without lead paint provides strong evidence that soil tracking is an important pathway.