Environmental Health Criteria 214

HUMAN EXPOSURE ASSESSMENT
disposing of any human biological samples. All personnel must be
trained for the proper handling of biological samples and protocols
must include instructions for this.
10.6 Media available for use
Numerous biological media are available for use in environmental
exposure assessment. Selection of sampling media depends on the
contaminant of interest, the pattern of exposure, the timing of
exposure, the population studied, ease of collection and storage and
participant burden. Biological monitoring is frequently considered
invasive; however, several media are available for exposure assessment
that can be collected in a non-invasive manner. For occupationally
used chemicals, biological exposure indices and monitoring protocols
are available (Lauwerys, 1983; ACGIH, 1991; Que Hee, 1993); these may
be regarded as starting points for biological sampling in
environmental studies.
Historically, blood and urine have been the primary media for
biological exposure markers. Blood and urine, as well as exhaled
breath and saliva, can be used to document recent exposures; past
exposure can be evaluated using blood and urine as well as keratinized
tissues (hair and nails), ossified tissue (teeth and bone), adipose
tissue and breast milk. Adipose tissue and bone can also represent
future sources of internal exposure. Other media available for
biomarker studies include faeces, nasal lavage, tears, sputum, semen,
cord blood and buccal cells, which can be feasible means for
population exposure monitoring. Other media from cadaver or biopsy
specimens (e.g., liver and kidney samples) have been collected in
select populations but these cannot be used for exposure assessment of
healthy individuals. Table 35 summarizes the media available for use
in biological monitoring in environmental settings.
10.6.1 Blood
Blood has been frequently used for biological monitoring,
especially in clinical settings such as occupational medicine. Blood
can integrate all sources of exposure, including internal sources, and
provide an indication of current internal dose. Since blood transports
all agents throughout the organism, it represents an opportunity to
sample all types of contaminants, such as gases, solvents, metals and
fat-soluble compounds. Both specific (e.g., blood lead) and
non-specific (e.g., sister chromatid exchange) analyses can be
performed. Components of blood available for sampling are whole blood,
red blood cells, white blood cells, plasma, serum and blood proteins,
primarily haemoglobin and albumin.
* Whole blood consists of all the blood components and is
preferable when the distribution of the analyte between plasma and
cellular elements is unknown (Que Hee, 1993).
* Red blood cells make up a large portion of blood and their
primary role is to transport oxygen via haemoglobin throughout the
body. Mature red blood cells contain no nucleus and therefore no
DNA, and have a 120-day lifetime. Chemicals that interact with
haemoglobin, such as carbon monoxide, are found in red blood cells.
Table 35. Biological media available for sampling
http://www.inchem.org/documents/ehc/ehc/ehc214.htm
Page 178 of 284
6/1/2007