Lead soil contribution to dust loading in urban homes built before and after 1978, measured through a community...

Lead exposure in U.S. communities is typically attributed to indoor sources, particularly lead-based paint in pre-1978 homes. However, exterior sources may contribute substantially to lead contamination, especially in heavily impacted communities.

To determine whether soil lead is tracked into homes in East Trenton, NJ, a community with extensive historical environmental lead contamination, using a community-based participatory approach.

Through a community-academic partnership, community scientists sampled soil from 122 homes in East Trenton. In a subset of 42 homes, lead-based paint was measured using X-ray fluorescence, and dust lead loadings were measured from interior floors, windowsills, and window wells using a modified HUD method.

Of 242 soil samples, 86.4% exceeded EPA's 200 ppm residential lead hazard level. In homes built before 1978 with lead-based paint present (n = 33), mean (SD) dust lead loadings were: floors (n = 72) 135.4 (311.9) μg/ft², windowsills (n = 39) 3,372.2 (19,688.4) μg/ft², and window wells (N = 36) 7,675.1 (34,041.1) μg/ft². In homes without lead-based paint (n = 11), loadings were: floors (n = 20) 263 (1006) μg/ft², windowsills (n = 11) 23.6 (26.2) μg/ft², and window wells (n = 10) 312.5 (307.1) μg/ft². Wilcoxon ranked sum test showed no observed difference in loadings on floors between homes with and without lead paint identified (p = 0.28); however, there were significant differences in lead loadings for both windowsills (p < 0.001) and window wells (p = 0.009), with homes with lead paint having higher windowsill and window well lead loadings. Notably, in homes without lead-based paint, 80% of floor samples exceeded 10 µg/ft², indicating substantial lead hazard without the presence of lead-based paint.

Elevated dust lead in homes built or renovated after 1978 without interior paint hazards suggests that lead is tracked indoors from exterior sources. Regulatory policies relying solely on housing age to assess lead exposure risk may overlook critical community-level contamination pathways, inadequately protecting residents in heavily impacted areas.

Homes with no interior lead-based paint hazards are susceptible to interior dust lead loadings greater than the U.S. Environmental Protection Agency (EPA) hazard level for floor dust if located in a community with elevated lead soil levels.