Environmental Health Criteria 214

HUMAN EXPOSURE ASSESSMENT
Toenails metals single toenail or non-invasive, sample
composites requires participant and ar
to collect sample
Urine low molecular spot or grab samples, non-invasive, 24-h sample
weight first morning void, urine sample requires
metabolites, 24-h urine samples motivated participant
metals, mutagens, for accurate sample
pesticides, collection
semivolatile
organics
* Numerous types of white blood cells are present in blood. These
cells have a half-life ranging from 18-20 days to decades
(Carrano & Natarajan, 1988). Since these circulating cells have
DNA which can itself be altered or the expression of which can be
changed as a result of exposure to a genotoxic agent, they may be
used for biomarkers of exposure to genotoxic agents (Carrano &
Natarajan, 1988; Kelsey, 1990). Interpretation of genotoxic
response is complicated because DNA damage can result in either
cell death or removal of the marker by DNA repair, or may alter
cell functions (Perera, 1987). Regardless of this, correlations
have been seen between environmental exposures and DNA adducts
and other cytogenetic responses (Perera et al., 1988; Heddle et
al., 1991; Santella et al., 1993; Yager et al., 1993).
* Plasma and serum represent the non-cellular component of
blood. Plasma is a straw-coloured aqueous solution of
electrolytes, non-electrolytes and macromolecules (including
clotting factors); serum is plasma without the clotting factors
(Que Hee, 1993). Plasma represents a component of whole blood
(approximately 60%), and it may contain the most biologically
active fraction of blood borne contaminants, since plasma is in
more immediate contact with tissues (Silbergeld, 1993). Plasma
can be used for analysis of lipophilic chemicals, thereby
avoiding the need for fat sampling.
* Blood proteins can be sensitive monitoring tools for chemicals
that bind to macromolecules including DNA (Osterman-Golkar et
al., 1976; Bond et al., 1992). Protein adducts, unlike DNA
adducts, are not repaired and may prove to be a useful dosimeter
of mutagen exposure (Grassman & Haas, 1993; Que Hee, 1993).
Haemoglobin and albumin are two proteins available for use in
exposure assessment. Haemoglobin is located in red blood cells in
high concentration and has the half-life of red blood cells (120
days); albumin is present in serum and has a half-life of 21
days. Because of their differing biological half-lives, these
proteins can be used to investigate the timing of exposure.
Collection, storage, and shipping of blood samples can be
resource-intensive. Blood sampling is invasive to the subject and
requires a trained phlebotomist. Two primary methods of blood
collection are venipuncture and finger stick. Blood from finger sticks
is more subject to surficial contamination, has a higher percentage of
red blood cells and is a smaller volume than that collected using
venipuncture (Graziano, 1994). However in some populations, such as
small children who have veins that are hard to find or who have fears
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