Protocol for the Derivation of Environmental and Human ... - CCME

Part B, Section 5
grazing herbivore soil and food ingestion exposures on agricultural lands for guidelines derivation. These
pathways also pertain to herbivorous wildlife that may graze on agricultural lands (Beyer et al., 1992).
Dermal contact by livestock and wildlife (resident and transitory) with contaminated soil may pose a
significant health risk to these organisms. In spite of this, information on the effects from dermal contact
with contaminated soil by livestock and wildlife is severely lacking (OECD, 1988). Because of these
data limitations, it is assumed that the level of protection offered to soil-dependent organisms from
dermal exposure is adequate to protect livestock and wildlife from the same exposure. This assumption
is based on the notion that soil-dependent organisms are more directly in contact with the medium for a
large portion of their life-cycle, and will experience adverse effects sooner than most organisms at higher
trophic levels. This assumption will be held except where explicit information to the contrary exists.
However, effects from dermal contact should be considered for guidelines derivation when information
becomes available.
5.2 Residential/Parkland Land Use
The combination of different activities under one land use category can complicate the decision of which
key receptors should be evaluated in an exposure scenario for residential/parkland land use. However,
a common requirement among these land uses is to provide landscape and ecological settings that
support the main land use activities (e.g., residential and parkland landscaping). Similar to agricultural
land use, the development of soil quality guidelines for residential/parkland land use must ensure that the
soil is capable of sustaining soil-dependent species and does not adversely affect wildlife from dermal
contact and ingestion of contaminated soil or food. A generic exposure scenario for the
residential/parkland land use category reflecting exposure pathways and receptors of choice is illustrated
in Figure 6.
5.2.1 Growth of Ornamental and Native Flora
To ensure that residential/parkland land use can support both ornamental and native flora, soildependent
biota (whose ecological function helps sustain plant growth) must be protected from adverse
effects as a result of dermal contact with contaminated soil (see Figure 6). Dermal contact by plant
roots and seeds must also be examined. Root uptake and accumulation of contaminants will be
examined as it relates to the ingestion of plant matter by wildlife.
Sufficient toxicological information exists to consider dermal soil contact by microbes (and their effect
on nutrient cycling), soil invertebrates (e.g., decomposers), and crops and plants (e.g., seeds and roots)
for guidelines derivation for the protection of ornamental and native plant growth (Figure 6). Currently,
there is insufficient information to incorporate dermal absorption and translocation of contaminants by
crops and plants via aerial deposition into generic guidelines derivation, but these exposure pathways
should be examined when information becomes available.
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