Environmental Health Criteria 214

HUMAN EXPOSURE ASSESSMENT
The choice of sampling type is dependent upon the analyte of
interest, the pattern of exposure, the anticipated concentration and
the population. Urine samples should be refrigerated before analysis
to reduce biological degradation and bacterial growth. Sample
processing and storage should occur as soon as possible after
collection in the manner required for the analyte of interest.
To make the results of urine monitoring comparable between
individuals, analytical results are frequently standardized to
creatinine concentration or specific weight. Standardization reduces
some of the variability of body size and urinary output (Lauwerys,
1983; Sato, 1993). However, kidney damage can alter the creatinine
excretion and therefore standardization may not be appropriate in all
cases. Clinical data can be used to evaluate kidney function.
10.6.3 Exhaled breath
Exhaled breath analysis has been used in both occupational and
environmental settings. Breath analysis is useful for assessing recent
exposure to gases (e.g., carbon monoxide) and organic vapours and
solvents (e.g., acetone and toluene). Limited studies have been made
on the use of breath analysis for airborne particles and associated
PAHs (Sugita et al., 1997). To be useful, breath measurements must
relate both to exposure and to blood concentration (Bond et al.,
1992). Breath sample concentrations of contaminants can vary as a
function of body build, metabolism, sex, physical activity and
ventilation rate as well as the exposure route (Que Hee, 1993). Two
types of samples are available for collection: mixed exhaled breath
and alveolar air, or end-expired air (Wallace, 1987; Wallace et al.,
1991a,b; Que Hee, 1993).
* Exhaled breath can be a mixture of inhaled and exhaled air. If
the exhaled biological marker is not present in inhaled air, then
exhaled breath analysis is an effective means to measure internal
exposure. For example, when alcohol has an internal source only
(i.e., ingestion) a mixed breath sample is appropriate.
* Alveolar air provides a measure of the air that is in equilibrium
with the blood in the deep lung (Bond et al., 1992). For analytes
present in inhaled air, it is necessary to collect an alveolar air
sample.
Breath samples can be used to assess microenvironmental exposure
as well as exposure to chemicals with short biological half-lives that
enter the body through non-inhalation routes (Wallace, 1987; Levesque
et al., 1994). A number of methods are available to collect exhaled
breath samples for organic and other gaseous contaminants (Wallace,
1987a; Pellizzari et al., 1988; Periago et al., 1992). Exhaled breath
collection is quick and easy for the participant, but the actual
sample collection can involve complex air collection apparatus to
gather a sufficient sample. The sampling tools are similar to those
currently employed for sampling of air contaminants. Methods for
airborne particles and components thereof have been used to a limited
extent (Goto et al., 1997, Sugita et al., 1997). Potential sample
collection error concerns in sample collection include loss of sample
volume, sample storage prior to analysis and cross-reaction among
analytes.
10.6.4 Saliva
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