This study investigated two methods for analyzing composite dust wipes for lead. The term composite means two or more wipes collected from common components in a dwelling that are combined in the field and analyzed as a single sample. Two methods—a modified Environmental Protection Agency (EPA) Method 3050A and a Wisconsin Occupational Health Laboratory (WOHL) method—were selected based on their anticipated ability to handle the added mass of materials and dust expected in a composite. The study used off-the-shelf wipes to prepare single-, two-, and four-wipe samples. Wipes were spiked with a standard reference material at either a low dust loading level or a high level, and three laboratories analyzed the samples using both methods and both flame atomic absorption spectrometry and inductively coupled plasma-atomic emission spectrometry techniques (ICP). Good agreement with known spiked levels was possible using either method; the modified EPA 3050A showed particular promise. When up to four wipes were combined, all three laboratories found that modified EPA Method 3050A resulted in recoveries between 89 and 101% of the known standard. Although it was possible to achieve good agreement with spiked levels using the WOHL method, some difficulties were encountered, particularly when followed by ICP analysis and when using four wipes. The increased time required to digest the multiwipe composites was not proportional to the number of wipes in a composite: the two- and four-wipe composites did not take two to four times as long as a single-wipe sample. Laboratory analysis of a four-wipe sample cost an average of 65% less than analysis of four single-wipe samples for each method.

The purpose was to examine the effectiveness of low-cost abatement on children's blood lead levels. Blood lead was analyzed before and after abatement in 37 homes of children under 7 years old with initial blood lead levels of 25–44 μg/dL. Ninety-five percent of homes were built before 1950. Abatement methods used were wet-scraping and repainting deteriorated surfaces and wrapping window wells with aluminum or vinyl. A control group was retrospectively selected. Control children were under 7 years old, had initial blood lead levels of 25–44 μg/dL and a follow-up level at least 28 days afterward, and did not have abatements performed in their homes between blood lead levels. After abatement, statistically significant declines occurred in the intervention children's blood lead levels. The mean decline was 22%, 1 to 6 months after treatment. After adjustment for seasonality and child's age, the mean decline was 6.0 μg/dL, or 18%. The control children's blood levels did not decline significantly. There was a mean decline of 0.25 μg/dL, or 0.39%. After adjustment for seasonality and age, the mean decline for control children was 1.6 μg/dL, or 1.8%. Low-cost abatement and education are effective short-term interim controls.

Lead hazard interventions have reduced children's blood-lead concentrations, but do not eliminate lead altogether from the bloodstream. Several studies suggest that blood-lead concentrations, measured 6 to 12 months after such interventions, decline by approximately 25%. The Environmental Protection Agency is preparing to promulgate a rule prescribing residential lead levels in paint, dust, and soil that constitute a lead-based paint hazard. Such a rule will prompt interventions of primary prevention character (i.e., precluding exposure before it occurs) rather than the secondary prevention character interventions (i.e., alleviating exposure after it has adversely affected the resident child) documented in the literature. It is important to attempt to estimate the efficacy achieved from the primary prevention interventions prompted by the rule's promulgation. As bone-lead stores represent the principal confounding factor to relating secondary prevention results to primary prevention, this paper addresses the impact of lead stored in bone, which may later be released to the blood and other parts of the child's body. A simple, but thoroughly documented, modeling exercise is presented to estimate the maximum length of time for which bone-lead stores alone could account for continuing elevated blood-lead levels observed in children following an intervention. The approach is based on a two-compartment model for the transfer of lead between blood and bone tissues within the body and the elimination of lead from the body. Modeling results suggest that bone-lead mobilization can impact blood-lead levels of young children for considerably long periods following an intervention. These results may explain the seemingly contradictory fact that low declines in blood-lead concentrations are observed despite the significant reduction in residential dust-, paint-, and soil-lead levels observed following lead hazard interventions. An intervention which reduces a 5-year-old child's total lead exposure by 50% might, due to mobilized bone-lead stores, produce only a 25% decline in the child's blood-lead concentrations measured 12 months following the intervention. The results also suggest, however, that those intervention strategies for which less than 25% declines were observed 12 months following the intervention likely eliminated less than 50% of the children's total lead exposure.

The U.S. Environmental Protection Agency sampled air in 49 government-owned buildings (six buildings with no asbestos-containing material, six buildings with asbestos-containing material in generally good condition, and 37 buildings with damaged asbestos-containing material). This is the most comprehensive study to date of airborne asbestos levels in U.S. public buildings during normal building activities. The air outside each building was also sampled. Air samples were analyzed by transmission electron microscopy using a direct transfer preparation technique. The results show an increasing trend in average airborne asbestos levels; outdoor levels are lowest and levels in buildings with damaged asbestos-containing material are highest. However, the measured levels and the differences between indoors and outdoors and between building categories are small in absolute magnitude. Comparable studies from Canada and the UK, although differing in their estimated concentrations, also conclude that while airborne asbestos levels may be elevated in buildings that contain asbestos, levels are generally low. This conclusion does not eliminate the possibility of higher airborne asbestos levels during maintenance or renovation that disturbs the asbestos-containing material.

Transmission electron microscopy (TEM) is the preferred method of measuring airborne asbestos in buildings, but TEM measurements cannot be used directly in the existing equations relating risk to exposure because the equations are based on measurements made with a different technique--phase contrast microscopy (PCM). Comparison between measurements made by different methods is not simple because the methods differ in the size of particles they can detect, and the relationship between exposure and disease is thought to depend on, among other things, asbestos fiber size. Previous suggestions for converting TEM measurements to PCM equivalents lack generality because they fail to take into account the size distribution of the asbestos particles and the expectation that fiber-size distributions in current nonoccupational environments could differ from the workplaces of the past on which the risk equations are based. A mathematical model is presented for investigating the conversion of airborne asbestos measurements made by one method to an equivalent measurement made by another method. "Equivalent" means having the same potential to cause disease. The model clarifies the issues of concern and suggests approaches for obtaining meaningful conversion factors that will allow TEM measurements to be used in PCM-based risk equations.