PRINCIPLES OF TOXICOLOGY

• Housing or building code violations
• Chronic maintenance problems
• Dwellings with the most children
• Units reported by the housing authority to be in poor condition or where housecleaning
practices were known to be deficient
• Dwellings in which at least one of the sampled units would be a vacant unit recently repaired
and repainted
Dust wipe samples were collected in the following locations:
• Principal play area (living room)
• Kitchen
• Two children’s bedrooms
22.4 CASE STUDIES 551
Within each room, two wipe samples were collected, one from the midpoint or entryway floor and the
other from either a window sill or a window well.
Paint chip samples were collected by using a heat gun to soften the paint, followed by use of a
razor-sharp scraper to remove all layers of paint (lead-based paint is often the oldest paint layer).
Composite soil samples were collected using a 50-mL polypropylene centrifuge tube.
The results indicated that levels of lead dust on the floors were well below the HUD (Department
of Housing and Urban Development) clearance standard of 200 g/ft 2 . However, levels of lead dust in
exterior window wells and interior window sills were substantially higher, with the maximum over
9000 g/ft 2 and nearly all above the HUD standard of 500 g/ft 2 for window sills and 800 g/ft 2 for window
wells. This suggested that windows contained the highest levels of lead. Although children may not
contact window wells with as much frequency as floors, recent studies have indicated that lead dust
levels in window wells are correlated with blood lead levels.
Soil lead levels were all below 130 ppm, which is unlikely to pose a substantial risk, given the
USEPA Superfund cleanup guidance of 500—1000 ppm.
Deteriorated paint films were observed on exterior railings, exterior doors, and exterior window
frames. No interior paint was in a deteriorated condition. Results of paint chip analysis from the three
exterior surfaces indicated that all contained lead above 5000 ppm (the current HUD standard).
Since all surfaces had not yet been tested for the presence of lead-based paint, a management system
geared to keeping lead-based paint in a nonhazardous condition was needed. The current work order
system contained no warning for maintenance workers. Workers were not trained to work with
lead-based paint, had not had their exposure levels evaluated for routine maintenance tasks, were not
provided with respirators or protective clothing, and were not included in a medical surveillance plan.
The window wells and interior window sills were subsequently cleaned on a routine basis by
residents and at least annually by trained work crews. Trained work crews cleaned all windows before
residents were instructed to include them in their routine cleaning practices. The work crew cleaning
consisted of an initial pass with a high-efficiency particulate air (HEPA) vacuum cleaner followed by
a wet phosphate detergent (or other equivalent detergent) wash followed by a final pass with a HEPA
vacuum. Repeated wipe samples were collected annually to make certain that lead dust levels did not
reaccumulate to hazardous levels.
The deteriorated paint films on the exterior railings, doors, and windows were temporarily stabilized
by wet scraping and repainting. The condition of these surfaces were visually monitored annually.
Residents were encouraged to report cases of deteriorated paint to the housing authority and to wet
clean all surfaces on a routine basis. Residents were informed that they should not attempt to remove
any deteriorated or intact paint. If the paint is known to contain lead (or is suspected to contain lead),
the paint film should be stabilized on an emergency repair basis by trained work crews following
temporary relocation of residents during the work.
Employees involved in doing cleanup work of this sort on a routine basis wore half-mask
air-purifying respirators equipped with HEPA cartridges and were included in respirator and medical