Division of Information Technology, Engineering and the Environment
Centre for Environmental Risk Assessment and Remediation
Centre for Environmental Risk Assessment and Remediation
CERAR has significant experience in determining contaminant
bioaccessibility/bioavailability using a variety of in vitro and in vivo
methodologies.
As incidental ingestion of soil is potentially a major non-dietary route
of exposure for many soil contaminants, determining the oral
bioavailability of ingested soil contaminants is essential for
accurately assessing the potential risk of contaminant exposure to human
health.
After ingestion of contaminated soil, contaminants (organic and
inorganic species) may be liberated or partially liberated from the soil
matrix during digestion. The bioaccessible fraction is deemed to be the
fraction of contaminants that are soluble in the gastrointestinal tract,
while the bioavailable fraction is the fraction of bioaccessible
contaminants that is subsequently transported across the intestinal
mucosa into systemic circulation and partitioned into organs and
tissues.
Therefore, since only a small fraction of any contaminant may actually
be bioavailable, and is therefore of risk, CERAR offers in vivo
assessment of contaminated soil and plant material using a young swine
model. Immature swine are the animal of choice for in vivo
bioavailability studies because their metabolism is similar to humans
and their weight, body size and weight to bone ratio is similar to young
children, the age group at the greatest risk of contaminant absorption
due to ingestion of soil. Animal feeding trails are used to assess
contaminant bioavailability following oral or dermal exposure by
monitoring urinary excretion products or other biomarkers such as the
activity of specific enzymes in vivo.
However, due to the time required to perform in vivo studies and the
expense, bioavailability testing using animal trials is usually not
practical. Therefore, CERAR offers less expensive and time consuming, in
vitro assays which simulate the gastrointestinal conditions in the human
stomach. These well established in vitro techniques (PBET, IVG) have
been shown to correlate well with in vivo techniques. These tests
therefore provide a surrogate measurement of contaminant
bioavailability, providing a method to assess the soil bound hazard that
is quick and inexpensive compared to animal trials.
For further information on Contaminant Bioaccessibility/Bioavailability
Assessment, please contact
Dr Albert Juhasz
