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

Part B, Section 7
a soil quality guideline based on a single class of organisms (e.g., when scientific evidence suggests that a
single organism group is the most threatened).
7.4 Environmental Behaviour Considerations
Studies which have examined the environmental fate and behaviour of contaminants in soil and terrestrial
biota must be critically reviewed. Fate processes such as biodegradation, photolysis, hydrolysis,
volatilization, adsorption, mobilization, and leaching should be examined. Physiological processes in
biota including uptake, accumulation, metabolism, and elimination should also be reported. It is not
necessary to have all the environmental fate information listed above to derive a guideline. However, it
is necessary to have descriptive information on the major environmental factors that influence the
potential hazard of the contaminant and its fate in the environment. Although derivation of environmental
soil quality guidelines relies on toxicological data only, environmental behaviour data is critically
examined and evaluated for pertinent information. During the assessment of individual contaminants,
this information may play a key role in determining, for example, the derivation approach applied,
chemical form of importance, usefulness of available toxicological data, or relevance of the final guideline
in light of environmental behaviour.
7.5 Derivation of Soil Quality Guidelines for Soil Contact
7.5.1 Overview
The following sections describe the methods for deriving soil quality guidelines for soil contact (SQG SC )
by soil-dependent organisms. Based on the exposure scenarios previously discussed, guidelines derived
using this procedure apply to all land use categories (i.e., agricultural, residential/parkland, commercial,
and industrial). The methods are presented in order of preference. When minimum data are not
available for a particular method, a measure of conservatism is added to each subsequent method to
account for the inherent uncertainties of deriving guidelines from a less preferable data set. In all, five
methods are available for deriving SQG SC . An overview of the soil contact derivation procedure for
agricultural and residential/parkland land uses is provided in Figure 10. An overview of the derivation
procedure for commercial and industrial land use is provided in Figure 12.
7.5.2 Methods for Agricultural and Residential/Parkland Land Use
There are three methods to derive guidelines for agricultural and residential/parkland land use. In the first
method, guidelines are derived using a weight-of-evidence approach to estimate the threshold effects
concentration (TEC). Alternatively, if minimum data requirements cannot be met in order to use this
method (as specified below), the second method is used. In the second method, the TEC is estimated
by extrapolating from the lowest observable "adverse" effect concentration (LO(A)EC). If the
minimum data requirements cannot be met using this method, then the third method is used. In this
method, the TEC is determined by extrapolating from the median effective concentration (EC 50 ) or
median lethal concentration (LC 50 ). If minimum data requirement cannot be met using this method, no
environmental guideline can be set for soil contact, but data gaps and research needs will be identified.
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