PRINCIPLES OF TOXICOLOGY

550 CONTROLLING OCCUPATIONAL AND ENVIRONMENTAL HEALTH HAZARDS
evaluated in a public housing authority. The results of the study were also used to control exposures
to lead experienced by maintenance and renovation workers.
The risk assessment was conducted to permit the housing authority to acquire a lead-poisoning
insurance policy. To manage the risks and potential claims from poisoned resident children, the
insurance company required an evaluation of both immediate and long-term risks borne by the children
residing in housing units owned by the authority and, more importantly, a practical program to control
exposures.
A review of the childhood lead poisoning literature indicated that exposures occur through a number
of pathways. These pathways include ingestion of housedust through hand-to-mouth contact and
normal mouthing behavior in young children, ingestion of lead paint chips originating from deteriorated
paint films, and ingestion of soil. Inhalation and dermal transfer are not considered to be important
routes of exposure for young children. Drinking water was being evaluated under a citywide EPAmandated
program and was not repeated here. There were also no identifiable nearby sources of lead
air emissions. Therefore, air sampling and water sampling were not performed as part of this risk
assessment, which was aimed at evaluating the most likely sources of lead for the population under
consideration.
As a measure of the near-term risk, paint chips from deteriorated painted surfaces, soil, and wipe
dust samples were collected and analyzed for lead. Visual assessment of the condition of all paint films
was completed. The quality of house cleaning was also noted. Recommendations were provided to
control lead dust and soil hazards and to stabilize deteriorated leaded paint films temporarily until
full-scale abatement could be accomplished.
As a measure of the long-term risk, management and maintenance practices were studied and
modified so that intact lead-based paint was properly maintained. For example, the work order system
was changed so that trained maintenance workers would be informed when their jobs required them
to disturb surfaces coated with known or suspected lead-based paint. Interviews with various management
and maintenance personnel, with regard to occupational health and safety issues, were also
conducted. Methods for relocating resident children from units where dusty repair work was being
completed were examined.
The risk assessment did not include measurement of all painted surfaces for lead, which was
undertaken in a separate effort as a way of determining potential hazards. Ideally, both immediate and
potential exposure to resident children and to maintenance workers should be evaluated through a
lead-based paint risk assessment and a lead-based paint inspection, respectively.
Wipe sampling was performed in accordance with the procedure in “Guidelines for the Evaluation
and Control of Lead-Based Paint Hazards in Housing.” Diaper towel wipes were used as the wipe
media. Ordinarily used for qualitative wipe sampling, Whatman filters were found to be insufficiently
durable on housing surfaces, requiring the use of the more durable diaper wipes. Recent research has
shown that settled lead dust levels measured in this fashion can be correlated to blood lead levels in
resident children. Disposable gloves were used for each sample. The results of the wipe samples were
compared to settled lead dust standards adopted by HUD.
Composite soil samples were collected from bare areas along the building foundations and in play
areas. A single sample typically included about 50 mL of soil, which was collected as follows. The top
centimeter of soil from at least five distinct spots was drawn into a 50-mL centrifuge tube. The spots
were in a straight line immediately next to the building foundation, or parallel to the building face. In
those units where bare soil in play areas was found, samples were collected from a random grid in the
play area. Some soil samples were also collected in a line parallel to sidewalks or parking lot curbs to
determine whether previous gasoline emissions were a local problem.
Of the 75 dwelling units, 15 were sampled; one of these units was unoccupied. Since it was not
feasible to sample or conduct walk-through examinations of all 75 units, several criteria were developed
to identify those units that were most likely to be in worst-case condition to conservatively estimate
the risks in all 75 units. The units actually sampled met as many of the following criteria as possible:
• Presence of a resident child with an elevated blood lead level