The Government of Canada conducts risk assessments of substances under the Canadian Environmental Protection Act, 1999 (CEPA 1999) to determine whether they present or may present a risk to human health or to the environment. The risks posed by a substance are determined both by its hazardous properties (potential to cause adverse human health or ecological effects) and the amount or extent of exposure to people and the environment. When needed, the Government implements risk management measures under CEPA 1999 and other federal acts to help prevent or reduce potential harm.
This page summarizes the Draft Screening Assessment for the Acids and Bases Group. The summary of publications for the Acids and Bases Group timeline includes details on the substance names and CAS Registry Numbers.
About these substances
The screening assessment focuses on 22 of 24 substances referred to collectively as the Acids and Bases Group 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)
Seven substances in the Acids and Bases Group are naturally occurring. According to information gathered by the Government, the 22 substances are generally used in paints and coatings, plant nutrients, pesticides, in chemical manufacturing, petroleum-refining, and cleaning products. Some of the substances may be found or used in natural health products, food packaging materials, as permitted food additives, in cosmetics, dyes, or in explosives.
The screening assessment indicates that Canadians 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).
Canadians 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).
Based on current use patterns in Canada, the screening assessment addresses ecological exposures in the aquatic environment.
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 (12 substances).
The 4 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.
Risk assessment outcomes
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 Canadians may be exposed to 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.
Proposed screening assessment conclusions
The Government is proposing that the 22 substances in the Acids and Bases Group are not harmful to human health.
The Government is also proposing 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 harmful to the environment.
Use the Substances Search tool to find substances that are referenced in certain legislative or regulatory instruments or on Government of Canada websites.
Substances in the Acids and Bases Group may be found in products available to consumers, including cleaning products. Canadians should follow any safety warnings and directions related to the product and dispose of products responsibly.
Some of the substances and/or 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). Canadians should visit Publications – Healthy Living for more information on substances with published Drinking Water Quality Guidelines.