Relevancy of human exposure via house dust to the contaminants lead and asbestos

The present report addresses the issues whether house dust is likely to contribute substantially to the exposure of humans, in particular for the contaminants lead and asbestos. House dust consists for 30-70% of soil material, indicating that contaminated soil can lead to contaminated house dust. It is concluded that exposure to lead via house dust should be included in risk assessment of soil contamination. The studies in which the amount of soil ingested by children are estimated use tracers in soil that are obviously both present in soil outdoors and in soil in house dust. Therefore, using this amount of soil ingested by children to cover both exposure of lead via soil outdoors and soil in house dust is reasonable. However, a correction factor of 2 is recommended to account for enrichment of lead in house dust in comparison with outdoor soil. This factor also accounts for other lead sources in house dust than contamination via soil. Significant contribution of asbestos to house dust from asbestos contaminated soil may occur at soil concentrations greater than 100 mg/kg. It is recommended to determine asbestos levels in house dust in houses adjacent to sites that are contaminated with asbestos above 1000 mg/kg for nonfriable asbestos, and above 100 mg/kg for friable asbestos. These recommendations are in agreement with a draft assessment protocol on site specific assessment of human risks to soil contamination with asbestos. A few comments on the protocol are made. For further recommendations for risk assessment of asbestos in house dust, we refer to this protocol