Environmental Health Criteria 214

HUMAN EXPOSURE ASSESSMENT
dust to, conversely, low where there is a large volume of dust. The
only way to measure both lead concentration and dust loading is to
collect a house dust sample with one of the vacuum sampling methods,
or with one of the preweighed wipe sampling methods. Common wipe
sampling methods do not measure lead concentration.
Although research studies have shown that estimates of both lead
concentration and lead loading (area concentration) correlate
significantly with children's blood lead levels, it is unclear which
measure is better at predicting the true, long-term, lead dust
exposures to children. Results from Davies et al. (1990) suggest that
the average lead loading (lead area concentration) measured in a
child's environment expressed more realistically the exposure of
children to lead than did lead concentration (lead mass concentration)
measurements. Results from the Lanphear et al. (1995) study also
suggest that lead loading measurements correlate better with
children's blood lead levels than does lead concentration. However,
Bornschein et al. (1985) showed that, for their conditions, lead
concentration and lead loading have very similar correlations with
children's blood lead levels. Laxen et al. (1987) found that blood
lead levels did not correlate better with lead dust loading than with
concentration.
8.3.2 Collection efficiency
Another important concept to understand is that the type of
surface from which the dust is sampled directly affects the efficiency
of dust collection from the surface. Furthermore, different sampling
methods recover different amounts of total dust from the same sampled
surface. These differences are due to different collection
efficiencies of the methods. Differences in collection efficiency on
different surface types and among sampling devices may influence
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