Environmental Health Criteria 214

HUMAN EXPOSURE ASSESSMENT
provide sufficient time resolution, free from interferences and
cost-effective. Consideration should be given to the likelihood that
the inconvenience of complying with personal monitoring protocols may
alter the normal behaviour of the study participants. For example,
participants tend to wear personal air monitors on days that they do
not go to work. In duplicate portion studies, participants may not
provide equal portions of expensive or well-liked foods, leading to
underestimation of intake. Approaches to personal monitoring of
inhalation, dietary and dermal exposures are discussed below.
Table 6. Summary of personal monitoring approaches
Exposure route Media Environmental sample Biological sample
Inhalation air personal monitor breath
urine
Ingestion water tap water blood
Ingestion food duplicate portion faeces
breast milk
Dermal soil/dust dermal patch others
3.5.1.1 Personal monitoring of inhalation exposures
Personal monitoring of human exposure to air pollutants requires
that study participants transport their sample collection device with
them at all times during the assessment period. Examples include a
diffusion tube used for passive sampling of gases, such as VOCs, or a
filter with a battery-operated pump for active sampling of aerosols
and their components (ACGIH, 1995).
Personal air monitors can be grouped into two general categories:
integrated samplers that collect the pollutant over a specified time
period and then are returned to the laboratory for analysis, and
continuous samplers that use a self-contained analytical system to
measure and record the pollutant concentration on the spot.
Instruments in both categories can be either active or passive.
Active monitors use a pump and a power source to move air past a
collector or sensor. Passive monitors depend on diffusion to bring
the pollutants into contact with the collector or sensor. Additional
information may be found in Chapter 7 and ACGIH (1995).
As Wallace & Ott (1982) pointed out, the direct measurement of
exposures using personal monitors raises several methodological
issues. Personal monitoring studies are complex, expensive, time
consuming and labour intensive. Other challenges include selection and
recruitment of representative subjects; distribution, maintenance and
retrieval of many monitors; laboratory analysis of many air samples
returned from monitors in the field or calibration and validation of
many real-time monitors; and the transcription and statistical
analysis of data on pollutant concentrations and time-activity
patterns.
3.5.1.2 Personal monitoring of dietary exposures
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