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

Part C, Section 4
In the case of non-threshold substances, hazard is necessarily assessed for an adult, as exposure is
assumed to be continuous over 70 years. For threshold substances, however, exposure is averaged
over, and TDIs measured against, the most sensitive life stage. Generally, this is the "toddler" stage (six
months to four years).
4.3.2 Defined Scenario for Agricultural Land Use
The generic agricultural scenario envisioned by SEQCCS is a multi-functional farm with a family,
including children, resident on the property. This generic farm grows produce, raises livestock, and has
a dairy herd, with a large portion of the produce, meat, and milk being consumed by the family are
produced on the farm. The family residence would include a basement and groundwater may be used
as drinking water. The exposure assumptions for the agricultural site are shown in Fiqure 20. Other
land use options commonly occur within the agricultural category, but SEQCCS considers that these
will not often represent greater environmental sensitivity.
4.3.3 Defined Scenario for Residential/Parkland Land Use
The generic residential/parkland scenario is a typical single family home with a basement and a backyard
where the children play. Groundwater may be used as drinking water. Differences in soil remediation
guidelines between agricultural and residential/parkland land use will generally only arise when a
contaminant bioconcentrates in the food chain and results in contamination of food produced on the
agricultural site. The exposure assumptions for the residential/parkland site are shown in Figure 21.
4.3.4 Defined Scenario for Commercial Land Use
The Subcommittee recognises the existence of a "commercial" land use classification intermediate
between residential/parkland and industrial. Although the commercial category is considered a discrete
land use classification, exposure conditions and receptor characteristics at a particular site may
substantially overlap those defined for residential/parkland or industrial land uses.
Commercial sites are generically defined as sites where commercial as opposed to residential or
industrial activities predominate. An example of a commercial site as envisioned by the Subcommittee is
a typical urban shopping mall. As envisioned by the Subcommittee, individuals do not conduct
manufacturing activities or reside at commercial sites.
All age groups generally have full access to commercial properties. Hence, the child was chosen as the
critical receptor. In addition, the exposure period believed generally operative at commercial lands
differs from those for other land uses. Relative to residential lands, exposure to soils on commercial land
is expected to have less intensity, duration, and frequency. The exposure assumptions for the
commercial site are summarized in Figure 22.
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