PRINCIPLES OF TOXICOLOGY - Biology East Borneo

550 CONTROLLING OCCUPATIONAL AND ENVIRONMENTAL HEALTH HAZARDSevaluated in a public housing authority. The results of the study were also used to control exposuresto lead experienced by maintenance and renovation workers.The risk assessment was conducted to permit the housing authority to acquire a lead-poisoninginsurance policy. To manage the risks and potential claims from poisoned resident children, theinsurance company required an evaluation of both immediate and long-term risks borne by the childrenresiding in housing units owned by the authority and, more importantly, a practical program to controlexposures.A review of the childhood lead poisoning literature indicated that exposures occur through a numberof pathways. These pathways include ingestion of housedust through hand-to-mouth contact andnormal mouthing behavior in young children, ingestion of lead paint chips originating from deterioratedpaint films, and ingestion of soil. Inhalation and dermal transfer are not considered to be importantroutes of exposure for young children. Drinking water was being evaluated under a citywide EPAmandatedprogram and was not repeated here. There were also no identifiable nearby sources of leadair emissions. Therefore, air sampling and water sampling were not performed as part of this riskassessment, which was aimed at evaluating the most likely sources of lead for the population underconsideration.As a measure of the near-term risk, paint chips from deteriorated painted surfaces, soil, and wipedust samples were collected and analyzed for lead. Visual assessment of the condition of all paint filmswas completed. The quality of house cleaning was also noted. Recommendations were provided tocontrol lead dust and soil hazards and to stabilize deteriorated leaded paint films temporarily untilfull-scale abatement could be accomplished.As a measure of the long-term risk, management and maintenance practices were studied andmodified so that intact lead-based paint was properly maintained. For example, the work order systemwas changed so that trained maintenance workers would be informed when their jobs required themto disturb surfaces coated with known or suspected lead-based paint. Interviews with various managementand maintenance personnel, with regard to occupational health and safety issues, were alsoconducted. Methods for relocating resident children from units where dusty repair work was beingcompleted were examined.The risk assessment did not include measurement of all painted surfaces for lead, which wasundertaken in a separate effort as a way of determining potential hazards. Ideally, both immediate andpotential exposure to resident children and to maintenance workers should be evaluated through alead-based paint risk assessment and a lead-based paint inspection, respectively.Wipe sampling was performed in accordance with the procedure in “Guidelines for the Evaluationand Control of Lead-Based Paint Hazards in Housing.” Diaper towel wipes were used as the wipemedia. Ordinarily used for qualitative wipe sampling, Whatman filters were found to be insufficientlydurable on housing surfaces, requiring the use of the more durable diaper wipes. Recent research hasshown that settled lead dust levels measured in this fashion can be correlated to blood lead levels inresident children. Disposable gloves were used for each sample. The results of the wipe samples werecompared to settled lead dust standards adopted by HUD.Composite soil samples were collected from bare areas along the building foundations and in playareas. A single sample typically included about 50 mL of soil, which was collected as follows. The topcentimeter of soil from at least five distinct spots was drawn into a 50-mL centrifuge tube. The spotswere in a straight line immediately next to the building foundation, or parallel to the building face. Inthose units where bare soil in play areas was found, samples were collected from a random grid in theplay area. Some soil samples were also collected in a line parallel to sidewalks or parking lot curbs todetermine 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 notfeasible to sample or conduct walk-through examinations of all 75 units, several criteria were developedto identify those units that were most likely to be in worst-case condition to conservatively estimatethe 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