Environmental Health Criteria 214

HUMAN EXPOSURE ASSESSMENT
sampling methods, methods of analysis, and advantages and drawbacks of
the different methods. Seasonal variations in mite allergen and fungi
are illustrated by showing the summary results of an extensive survey
conducted in Australia. Mite and pollen antigen as well as fungal
organisms can vary substantially within homes and buildings, as
illustrated in the figures in this chapter. The reader is referred to
texts such as ACGIH (1989) and Burge (1995) for details on
instrumentations, specific information relevant to the allergenic,
infectious and toxigenic properties of many microorganisms and their
constituents and metabolic by-products.
There are three different basic approaches for the exposure
assessment of biological particles: observational sampling, reservoir
sampling (dust, surfaces, water) and air sampling.
* Observational sampling means that one uses sensory perception to
collect data about potential sources of exposure to biological
particles (e.g., visible fungal growth).
* Reservoir sampling refers to the collection of bulk material
(e.g., surface contact, bulk material, water sample or dust sample)
to estimate the potential exposure.
* Air sampling is the most likely to be representative of human
exposure.
This chapter will emphasize reservoir (primarily indoor dust) and
air sampling of bioaerosols and not gaseous metabolic products.
Designing a specific sampling programme requires consideration of
the aim of the sampling, the nature of the biological particles
(including size and expected concentrations) and parameters that
influence the actual exposure to these particles. These parameters
determine the choice of the sampling and quantification method, the
sampling strategy (e.g., location, season, duration and frequency),
and approaches for statistical analysis and interpretation of the
data. For most situations, the exposure route of interest is
inhalation. Therefore, ideally, the exposure should be assessed by
personal air monitoring. As will become clear from the remainder of
this chapter, however, no single sampler fulfils the characteristics
of the ideal sampler to measure the total exposure to biological
particles. Many of the methods used for estimating environmental
concentrations of biological particles are not truly representative of
an individual's exposure to these particles. As stated earlier, this
is, in part, because the exposure measure of biological importance is
not well understood. In addition, the field of environmental
aeromicrobiology developed from a laboratory biology base that
borrowed sampling techniques and equipment from other fields. Until
recently there had been little convention or need for uniformity of
methods. It is not surprising, therefore, to find a general lack of
data regarding the validity of the methods used to estimate the
exposure to biological particles. This situation has certainly changed
as those investigating exposure assessment aspects of aerobiology have
cooperated with environmental epidemiologists.
Useful reference texts with regard to sampling and analysis of
biological particles include those by the American Conference of
Governmental Industrial Hygienists (ACGIH, 1995), the European
Commission (EC, 1993), Hamilton et al. (1992), Pope et al. (1993),
http://www.inchem.org/documents/ehc/ehc/ehc214.htm
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