Tracer studies of ingestion of dust by urban children

It has been known for many years that the eating of leaded paint is the prime cause of lead poisoning and elevated blood leads of children living in deteriorated housing. Recently, there has been speculation that children may eat dirt and dust contaminated with lead exhausted from cars and that this amount of ingested lead is sufficient to contribute significantly to the childhood lead problem. This study used a naturally occurring radioactive tracer (lead-210) to determine the relative amounts of dust and other lead-containing materials (e.g., paint) eaten by young children. This tracer is present in very low concentrations in paint and in significantly higher concentrations in fallout dust. Stable lead and lead-210 were analyzed in fecal material from 8 children suspected of having elevated body burdens of lead and 10 children living in good housing where lead poisoning is not a problem. The normal children averaged 4 micrograms lead per gram dry feces, with a range of 2 to 7. Of the eight children suspected of having elevated lead body burdens, two had fecal lead values within the normal range. However, the remaining six were 4 to 400 times higher. Despite these differences in fecal lead between the two groups, the groups were essentially identical in the lead-210 content of their feces. The "elevated" children averaged 0.040 picocurie lead-210 per gram dry feces, while the normal group averaged 0.044. The results provide sound evidence that these children suspected of elevated lead body burden were not ingesting dust or air-suspended particulate.