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

Part A, Section 1
of, and establish standards for, site risk assessment in Canada. The provinces may also have other
documentation that will need to be consulted when conducting a site-risk assessment.
1.2.5 Guidance on Bioassays Methods for Assessing Ecological Effects
Standardized bioassay methods generate biological effects data for deriving toxicologically-based
environmental quality guidelines, evaluating site-specific hazards to organisms, and evaluating the
effectiveness of cleanup operations. A review of available whole organism bioassays for freshwater,
freshwater sediment and soil was conducted (Environment Canada, 1994). The review identifies the
most useful ecological effects tests for the NCSRP.
Guidance for applying these recommended bioassays for ecological impacts within the NCSRP
framework, and for sample handling and preparation for biological testing is also being prepared.
1.2.6 Evaluation and Distribution of Master Variables Affecting Solubility of
Contaminants in Canadian Soils
Soil toxicological data establish a link between the level of a contaminant in soil and the response of an
organism. Soil toxicological data are required for deriving generic environmental guidelines, and are
influenced by many soil factors (e.g., soil pH, soil organic matter content, clay content, clay type, cation
exchange capacity, redox potential, and soil moisture regime). Soil factors are important because they
may influence the bioavailability, transport, and toxicity of contaminants.
The Subcommittee has commissioned a review of the key factors, (soil pH, soil organic matter and clay
content, and redox potential surrogate) to describe a reference condition that approximates an upper
sensitivity limit of the normal distribution for most Canadian soils. Based on this review, the
Subcommittee will attempt to identify a reference condition where toxicity and transport of most
contaminants will be relatively insensitive to small changes in key soil factors.
The reference soil conditions identified in this report will also play a role in the development of sitespecific
objectives for ecological effects. For example, the remediation guidelines will be most
applicable as remediation objectives for a contaminated site whose soil conditions are within the range
of the reference conditions. A site with a tolerable defined reference condition may have the
remediation guidelines modified to remediation objectives. However, for a contaminated site with
physical conditions beyond the determined reference range, it may not be appropriate to adopt or adapt
the generic guidelines as a site-specific remediation objective, and a site-specific risk assessment may be
required. See Guidance for Developing Site-specific Remediation Objectives (Section 1.3.3) for further
details.
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