Environmental Health Criteria 214

HUMAN EXPOSURE ASSESSMENT
Food consumption data is often collected for nutritional or
economic purposes, and foods may not be described in the detail
required for exposure assessment (e.g., fish consumption may be
recorded but the contaminant of interest may be found primarily in
fatty fish or fish caught in a particular location). There are number
of difficulties using the different types of consumption data. A
report from the European Commission provides a good summary of the
practical problems in using consumption data to estimate dietary
exposure (EC, 1997a).
7.4.4 Contaminants in food
The vast majority of food that is actually consumed has undergone
some form of processing, ranging from simple washing to complete
reconstitution, as it progresses from the producer to ultimately being
ingested by a consumer (FAO/WHO, 1995b). Several factors can influence
contaminant concentrations in foods that are ready to eat. These
factors include those that may vary by season and/or geographic
region, such as food source (e.g., homegrown, locally grown by a small
producer, domestically grown by a mass producer and imported), and
former or current application of pesticides (US NRC, 1993). The form
in which food is consumed (e.g., raw apple, apple sauce, apple juice)
can be very different in different subpopulations (e.g., adults,
elderly or young children).
Residue levels measured in raw agricultural commodities collected
at the producer, processor or distribution level are unlikely to be an
accurate reflection of contaminant concentration in food as actually
consumed. With the exception of the GEMS/Food, which collects
contaminant and pesticide residue data from member countries, there
are no centrally coordinated reference databases for other food
chemicals in foods. Potential data sources at the national level may
include supervised trial data, government monitoring and surveillance
data (Pennington & Gunderson, 1987), national food composition
databases (nutrients) and industry funded surveys. A number of
analytical methods for contaminants in food have been published by the
US FDA, EOAC and US EPA (e.g., US FDA 1997a,b). Different approaches
have been used for calculating exposure when the contaminant
concentrations fall below the detection limit (e.g., assuming the
concentration is zero or some percent of the detection limit).
7.5 Summary
This chapter has introduced available sampling methodology for
chemicals in air, water, and food. Common to the selection of these
methods are considerations of detection limits, interferences, ease of
operation and cost. Personal, microenvironmental and ambient air
sampling methods are available for monitoring gases and vapours, both
passively and actively, aerosols, SVOCs and reactive gases.
Sampling considerations for assessing water quality are numerous.
An important consideration is that exposure to contaminants is not
limited to oral routes and that not all individuals have access to
treated water from distribution systems. Guidance for sampling and
monitoring programmes is provided.
http://www.inchem.org/documents/ehc/ehc/ehc214.htm
Page 136 of 284
6/1/2007