Page 150 - Materials Chemistry, Second Edition

L1644_C04.fm Page 125 Tuesday, October 21, 2003 3:13 PM

Second, whether the data are representative must be established. The type,
location, duration and frequency of sampling should be evaluated. The selected
representative measured data need to be allocated to specific exposure scenarios to
allow meaningful exposure assessment.
The types of environmental monitoring can be classified as follows:

• Biological monitoring allows actual measurement of exposure and accu-
rate assessment of likely health outcomes. It involves analyzing human
biological samples (i.e., blood, urine, hair, nails, or breast milk) for the
presence of target chemicals.
• Environmental monitoring allows actual measurement of exposure and
accurate assessment of likely ecological outcomes. It involves analyzing
environmental samples (i.e., air, grass, soils, fish or shellfish) for the
presence of target chemicals.

Monitoring is useful in assessing occupational exposures to airborne chemicals
because workplaces typically involve exposure to a single or only a few chemicals
at relatively high concentrations (in contrast to typical environmental concentrations)
and exposure activity is well known. Although monitoring is a useful method, some
disadvantages can be found. The main advantages and disadvantages of environ-
mental monitoring are:

Advantages:
1. Defines environmental exposure accurately and precisely
2. Identifies associated health effects in a good way
3. Improves the determination of susceptibility to target pollutants
Disadvantages:
1. Biomarkers integrate all routes and sources of exposure; thus, it is
impossible to distinguish whether the exposure is due to the chemicals
in air, water, or food.
2. A distinction between variations in the exposed populations, such as
health status and individual lifestyle, cannot be made.
3. The timing of sample collection in relation to exposure that is critical
to the successful measurement of a biomarker cannot be considered.

The best marker would be one that was chemical specific, measured well in
trace quantities, measurable in easily sampled biological media or by noninvasive
techniques (i.e., blood, urine, hair or nails), and well correlated with a previous
exposure. For instance, a good biomarker to assess the municipal solid waste incin-
erator (MSWI) emissions of our case study would ideally be associated with a
chemical unique to the emissions, easily monitored in the stack, and associated only
with inhalation exposure. Inorganic tracer chemicals for MSWI emissions include
antimony, arsenic, beryllium, cadmium, chromium, lead, mercury, nickel and tin.
Organic tracer chemicals include benzo(a)pyrene, polychlorinated biphenyls and
dioxins. None of these chemicals is good for biomonitoring because each one exists
naturally in the environment, so exposure may occur naturally via air, water, soil,

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