Canadian Soil Quality Guidelines (CSoQGs)

Overview

Canadian Soil Quality Guidelines (CSoQGs) consider both human health and ecological receptors. The final guideline is set to protect the more sensitive of the two. These guidelines are intended as general guidance for the protection, maintenance, and improvement of specific uses of land and water. Recommended CCME Soil Quality Guidelines have been developed for four different land-uses with defined exposure scenarios:

• Agricultural;
• Residential/parkland;
• Commercial; and,
• Industrial.

Soil Quality Guidelines can be used as benchmarks to evaluate the need for further investigation or remediation with respect to a specified land use. Guidelines are applied to identify and classify sites, to assess the general degree of contamination at a site and to determine the need for further action, and as a basis for remediation objectives.

Development of Canadian Soil Quality Guidelines began in 1990.

Procedures for Guideline Development (Protocol)

Soil Quality Guidelines are derived based on the 1996 Protocol for the Derivation of Environmental and Human Health Soil Quality Guidelines. For each guideline, a comprehensive review of the literature is conducted and a detailed assessment of the substance is prepared. The assessment, which may be a useful decision support tool for the site manager, includes:

• Production and uses in Canada;
• Existing criteria and guidelines;
• Levels in the Canadian environment;
• Environmental fate and behaviour; and,
• Human, terrestrial plant and animal toxicology.

Each technical supporting document includes details used to derive the recommended CCME Soil Quality Guidelines for human health and/or for ecological receptors for each of the four land uses (i.e., agricultural, residential/parkland, commercial, and industrial).

Human health and environmental guidelines derivation is based on interpretation of a considerable amount of toxicity information. In most cases, existing data and information enables human health and environmental assessments to be integrated and summarized in a factsheet format. In some cases, existing data allows only the ecological or the human health assessment to be completed.

Chemical constituents in soil can migrate and contaminate other media. For example, soil contaminants can leach into groundwater used as a drinking water source, migrate (as vapour) into basements and contaminate indoor air, or be taken up by plants and garden produce. These important direct and indirect soil exposure pathways are considered in the development of a soil quality guideline through the use of appropriate check mechanisms. Checks may be made for groundwater contamination; off-site migration; effects on nutrient and energy cycling; inhalation of indoor air; and contamination of produce, meat and milk.

Before recommending a final guideline, the derived number is checked for potential conflicts with:

• Background concentrations;
• Plant nutritional requirements; and,
• Analytical methodologies.

Application of Guidelines

The Guidelines should not be regarded as blanket values for national soil quality. Variations in environmental conditions across Canada will affect soil quality in different ways and many of the guidelines may need to be modified according to local conditions, such as at sites where there are high natural background levels of a contaminant, where atypical levels of organic carbon content could affect the mobility and/or bioavailability of the contaminant, or where the data for a species are irrelevant to the site under investigation. Site-specific soil quality objectives are established to reflect the local environment and may be adopted by a jurisdiction into legislation to become standards. Where soils are of exceptional quality, or where they support valuable biological resources (e.g., endangered species), it is the policy of the CCME that degradation of the existing soil quality to the guideline value should always be avoided. Similarly, modifications of guidelines to site-specific objectives should not be made on the basis of soil characteristics that have arisen as a direct result of previous human activities.

The use of CSoQGs for site-specific soil quality objectives requires an understanding of the chemical, physical, and biological characteristics of the soil and an understanding of the behaviour of a substance once it is introduced into the environment. Factors affecting the application of the guidelines include:

• the general characteristics of soils and groundwater;
• the effect of local environmental conditions on soil quality;
• processes influencing the concentration of parameters in soil; and,
• factors that modify toxicity to terrestrial organisms.

To assist guideline users in the development of site-specific soil quality remediation objectives for contaminated sites in Canada, the CCME has prepared a guidance manual.

Products Available

Protocols

The Protocols of the Canadian Soil Quality Guidelines are available in HTML and PDF format. You need Adobe® Acrobat® Reader to view and print the PDF files. If you do not already have Acrobat® Reader, you may download it at no charge.

• Summary of A Protocol for the Derivation of Environmental and Human Health Soil Quality Guidelines (HTML) (PDF)
• Guidance Manual for Developing Site-Specific Soil Quality Remediation Objectives for Contaminated Sites in Canada (HTML) (PDF)