How does soil lead differ from dust lead in terms of exposure pathways?

• A. Soil lead is outdoors via ingestion; dust lead is indoors via inhalation or ingestion.
• B. Soil lead exposure is indoor via inhalation; dust lead exposure is outdoor via ingestion.
• C. Soil lead exposure generally does not occur via ingestion.
• D. Dust lead exposure is always outdoors.

Answer: (A)

Soil lead exposure tends to happen outdoors and is mainly through ingestion, especially for children who grab soil or dirt and put their hands or objects in their mouths. Outdoor soil often carries lead from historical uses of leaded gasoline, chipped lead paint, or nearby industrial sources, and the primary risk is a child swallowing small soil particles during play.

Dust lead exposure, on the other hand, is usually indoors and can occur by inhaling fine lead-containing dust or by ingesting dust that has settled on surfaces or hands. Indoor dust often comes from deteriorating lead-based paint, dust tracked in from outdoors, or dust released during renovations, and it presents exposure through both breathing and swallowing small particles.

So the key difference is outdoors-and-ingestion for soil lead versus indoors-and-inhalation-or-ingestion for dust lead.