The CDC notes that these levels are based on practical, not health, concerns, so take care with all suspect paint. DUST Lead does not biodegrade, therefore children who live and play in the vicinity of lead industries, heavy traffic, garages, or in older, painted homes, can be exposed to high levels of lead from contaminated soil and dust. The Ontario guideline for lead in soil is between 500-1000 ppm, depending on whether children have routine access. Soil removal and replacement has been done for homes, near a lead-battery industry, which had lead above 500 ppm in their yards. Soil removal was followed by specialized house and duct cleaning.
Most children get dirty, and it is normal for young children to put their hands in their mouths.
Don't grow vegetables in contaminated soil. Cover bare earth with grass and shrubs, or mats under swings in playgrounds. Wash windowsills and play areas rather than dusting. Bare floors are easier to keep clean, carpets trap lead. Wash toys and pacifiers regularly.