Road Salts – Canadian Environmental Protection Act, 1999, Priority Substances List Assessment Report for

Click here or on the pdf file to read the full report or an excerpt below. The Ministers of Environment and Health have released for final publication the assessment report for the priority substance road salts. Notice concerning the assessment of this substance and a summary of its assessment report was published in the Canada Gazette, Part I December 1, 2001.

3.8.4 Conclusions

Almost 5 million tonnes of road salts that contain inorganic chloride salts with or without ferrocyanides are used every year in Canada. All of these salts are ultimately found in the environment, whether as a result of dispersive use on roadways or through losses from patrol yards and snow dumps. The report has identified situations where the resulting environmental concentrations approach or exceed those associated with harmful effects on physical properties of soils or water bodies or on organisms associated with freshwater and terrestrial habitats at numerous sites across Canada.

Local and regional contamination of groundwater can lead, sometimes after several years or decades, to high concentrations of chloride, including concentrations that exceed acute and chronic toxicity values for organisms that may occur in springs.

For surface waters associated with roadways or storage facilities, episodes of salinity have been reported during the winter and spring in some urban watercourses in the range associated with acute toxicity in laboratory experiments. Reports of lower levels of exposure ranging from near those associated with chronic toxicity in laboratory experiments to those modestly above background salinity levels are more frequent and widespread. Some measurable changes in aquatic biota and/or communities have been found in laboratory experiments and in field studies at these lower concentrations, including possible impacts on lake stratification.

Increased salt loadings into soils can lead to modification of soil properties critical for soil health. A number of field studies have documented damage to vegetation and shifts in plant community structure in areas impacted by road salt runoff and aerial dispersion. Elevated soil levels of sodium and chloride or aerial exposure to sodium and chloride have been recorded frequently at levels impacting growth, reproduction and survival of sensitive plant species along roadways and watercourses that drain roadways and salt handling facilities.

Behavioural and toxicological impacts have been associated with exposure of mammalian and avian wildlife to road salts. Road salts may also affect wildlife habitat, with reduction in plant cover or shifts in communities that could affect wildlife dependent on these plants for food or shelter.

Since ferrocyanides can dissociate in the environment to form cyanide, there is a potential for certain aquatic organisms to be adversely affected by cyanide in areas of high use of road salts.

While the ecological significance of many of the potential impacts outlined above cannot be quantified, it is clear from available information that there is a reasonable probability that road salts that contain inorganic chloride salts with or without ferrocyanide salts may be having an immediate or long-term harmful effect on some Canadian surface water organisms, terrestrial vegetation and wildlife and may also constitute a danger to the environment on which life depends through its impacts on aquatic systems and soils and terrestrial habitats. Thus, road salts that contain inorganic chloride salts with or without ferrocyanide salts should be considered “toxic” under CEPA 1999 because of tangible threats of serious or irreversible environmental damage.

CEPA 1999 64(a): Based on the available data, it is considered that road salts that contain inorganic chloride salts with or without ferrocyanide salts are entering the environment in a quantity or concentration or under conditions that have or may have an immediate or long-term harmful effect on the environment or its biological diversity. Therefore, it is concluded that road salts that contain inorganic chloride salts with or without ferrocyanide salts are “toxic” as defined in Paragraph 64(a) of CEPA 1999.

CEPA 1999 64(b): Based on the available data, it is considered that road salts that contain inorganic chloride salts with or without ferrocyanide salts are entering the environment in a quantity or concentration or under conditions that constitute or may constitute a danger to the environment on which life depends. Therefore, it is concluded that road salts that contain inorganic chloride salts with or without ferrocyanide salts are “toxic” as defined in Paragraph 64(b) of CEPA 1999.

Overall conclusion: Based on critical assessment of relevant information, road salts that contain inorganic chloride salts with or without ferrocyanide salts are considered to be “toxic” as defined in Section 64 of CEPA 1999.

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