The risks posed by a substance are determined by both its hazardous properties (potential to cause adverse human health or ecological effects) and the amount or extent that people or the environment are exposed.
When needed, the Government applies risk management measures under CEPA and other federal acts to help prevent or reduce potential harm.
Substances in the Acids and Bases Group are associated with health effects; however, at levels of exposure considered in the assessment, the Government concluded that these substances are not harmful to human health or to the environment.
The assessment focused on 22 substances, referred to collectively as the Acids and Bases Group under the third phase of the Chemicals Management Plan (CMP). The 22 substances in the Acids and Bases Group were further divided into 6 subgroups:
Ammonia (hydroxylammonium chloride)
Free available chlorine, chlorate and chlorite (FACCC; chlorine, sodium hypochlorite, calcium hypochlorite, sodium chlorate, and chlorine dioxide)
Sulphite (sodium bisulfite and sodium metabisulfite)
Hydrogen and hydroxide (potassium hydroxide, sodium hydroxide, potassium silicate, sodium silicate, hydrochloric acid, sulphuric acid, and potassium oxide)
Phosphate (diphosphorus pentoxide and phosphoric acid)
Nitrate and nitrite (sodium nitrate, sodium nitrite, nitric acid, potassium nitrate, and calcium nitrate)
From a human health perspective, hydroxylammonium chloride was evaluated as part of the Screening Assessment for the Rapid Screening of Substances with Limited General Population Exposure and determined to be of low concern for human health.
Based upon their physical-chemical properties, environmental fate and behaviour, and reported uses, the 6 substances in the ammonia and FACCC subgroups are considered to have been addressed previously for ecological concerns through the Priority Substances List (PSL) assessment reports for ammonia in the aquatic environment, effluents from pulp mills using bleaching, chlorinated wastewater effluents, and inorganic chloramines. These substances have not been re-assessed for their potential risk to the environment.
Seven substances in the Acids and Bases Group are naturally occurring.
According to information gathered by the Government, these substances are mainly used in Canada in paints and coatings, plant nutrients, in chemical manufacturing, petroleum-refining, and cleaning products. Some of the substances may be found in pesticides, natural health products, cosmetics, dyes, or in explosives; or used as food additives or as a component in the manufacture of food packaging materials.
Human and ecological exposures
Thirteen of 22 substances were addressed using the Low Human Health Hazard Potential Approach, and were considered to be of low concern for human health. Therefore, human exposure was not characterized for these substances.
The assessment indicates that people in Canada may be exposed to substances in the FACCC subgroup through air, drinking water, food, and products available to consumers (including odour control products, natural health products, cleaning products, and cosmetics).
People in Canada may also be exposed to substances in the nitrate and nitrite subgroup through food, drinking water, soil, dust, air, and products available to consumers (including cosmetics, cleaning products, and natural health products).
Information gathered from the National Pollutant Release Inventory, Canadian International Merchandise Trade Database and surveys issued pursuant to section 71 of CEPA was used to characterize exposure in the aquatic environment.
Based on laboratory studies, the critical effects identified for characterizing the risk to human health are as follows:
For 3 of the 5 substances in the FACCC group, inhalation effects, neurobehavioural effects and effects on the thyroid gland.
For the nitrate and nitrite subgroup, circulatory system effects.
Thirteen substances are considered to have a low health hazard potential based on the general principles outlined in the Science Approach Document for Substances with Low Human Health Hazard Potential.
Environmental effects information considered in the ecological assessment included data from international reports as well as water quality guidelines. The ecological effects for characterizing risk to the environment are as follows:
The hazard for substances in the phosphate, hydrogen and hydroxide subgroups, and nitric acid is associated primarily with changes in water pH, rather than direct effects (10 substances).
Four substances in the nitrate and nitrite subgroup and the 2 substances in the sulphite subgroup have hazards associated with direct effects on aquatic organisms.
While certain substances in the Acids and Bases Group are, or are precursors to, nutrients that can stimulate biomass growth in certain aquatic environments, the associated ecological effects are not in the scope of this assessment.
Consideration of subpopulations who may have greater susceptibility or greater exposure
There are groups of individuals within the Canadian population who, due to greater susceptibility or greater exposure, may be more vulnerable to experiencing adverse health effects from exposure to substances.
Certain subpopulations are routinely considered throughout the assessment process, such as infants, children, and people of reproductive age. For instance, age-specific exposures are routinely estimated and developmental and reproductive toxicity studies are evaluated for potential adverse health effects.
Risk assessment outcomes
Assessments focus on information critical to determining whether substances are harmful to human health or the environment under CEPA. This is done by considering scientific information, including information, if available, on subpopulations who may have greater susceptibility or greater exposure, vulnerable environments and cumulative effects and by incorporating a weight of evidence approach and precaution.
Thirteen of 22 substances were considered to be of low concern to human health based on the Low Human Health Hazard Potential Approach.
Based upon a comparison of levels to which people in Canada may be exposed to the 8 substances in the FACCC subgroup and the nitrate and nitrite subgroup, and levels associated with health effects, it was determined that the risk to human health is considered to be low.
The 6 substances in the ammonia and FACCC subgroups are considered to have been addressed previously for ecological concerns and have not been re-assessed for their potential risk to the environment.
Ten substances are considered to have low potential to cause ecological harm based upon measurements of pH levels in municipal wastewater system effluent. The remaining 6 substances are expected to have low concern for the environment based upon a comparison of their hazard and exposure potential.
Assessment conclusions
The Government concluded that the 22 substances in the Acids and Bases Group are not harmful to human health.
The Government also concluded that 16 substances in the Acids and Bases Group (sodium bisulfite, sodium metabisulfite, potassium hydroxide, sodium hydroxide, potassium silicate, sodium silicate, hydrochloric acid, sulphuric acid, potassium oxide, diphosphorus pentoxide, phosphoric acid, sodium nitrate, sodium nitrite, nitric acid, potassium nitrate, and calcium nitrate) are not causing harm to the environment.
Where to find updates
Updates on what the Government is doing to address chlorine and ammonia can be found on the Wastewater web page.
Use the Substances Search tool to find substances that are referenced in certain legislative or regulatory instruments or on Government of Canada websites.
Related resources
Substances in the Acids and Bases Group may be found in products available to consumers, including cleaning products. People in Canada should follow any safety warnings and directions related to the production and dispose of products responsibly.
Some of the substances and their breakdown products have been previously assessed by Health Canada through the Federal-Provincial-Territorial Committee on Drinking Water (including chlorine, chlorate/chlorite, and nitrate/nitrite). People in Canada should visit Publications – Healthy Living for more information on substances with published Drinking Water Quality Guidelines.
Assessments conducted under CEPA focus on risks of exposure of the general population. Hazards related to chemicals used in the workplace are defined within the Workplace Hazardous Materials Information System (WHMIS). If a substance is harmful to the general population, it could also be of concern for individuals in situations where a higher volume of the substance is used or where the substance is used for a longer duration (for example, the workplace). The Government of Canada recognizes that it is the responsibility of the federal, provincial and territorial occupational health and safety organizations to coordinate legislation for the safe use of chemicals in the workplace. We are working to support this role by integrating the information, tools, and/or technical expertise of the CMP and Health Canada's Workplace Hazardous Products Program.
