Acids and Bases Group - information sheet

Publications summarized:

• Draft Screening Assessment for the Acids and Bases Group (published on December 4, 2021 for a 60-day public comment period ending on February 2, 2022).
• Associated notice: Canada Gazette, Part I: Vol. 155, No. 49 – December 4, 2021

On this page

• Overview
• About these substances
• Human and ecological exposures
• Key health and ecological effects (hazard)
• Risk assessment outcomes
  • Proposed screening assessment conclusions
  • Where to find updates
• Related resources

Overview

• 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:
  1. Ammonia (hydroxylammonium chloride)
  2. Free available chlorine, chlorate and chlorite (FACCC; chlorine, sodium hypochlorite, calcium hypochlorite, sodium chlorate, and chlorine dioxide)
  3. Sulphite (sodium bisulfite and sodium metabisulfite)
  4. Hydrogen and hydroxide (potassium hydroxide, sodium hydroxide, potassium silicate, sodium silicate, hydrochloric acid, sulphuric acid, and potassium oxide)
  5. Phosphate (diphosphorus pentoxide and phosphoric acid)
  6. Nitrate and nitrite (sodium nitrate, sodium nitrite, nitric acid, potassium nitrate, and calcium nitrate)
• The two other substances in the Acids and Bases Group were determined to be of low concern to both human health and the environment through other approaches. Conclusions for these substances (CAS RN 18918-89-0 and CAS RN 68442-82-0) are provided in the Screening Assessment for the Rapid Screening of Substances with Limited General Population Exposure.
• 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, 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.

Human and ecological exposures

• Thirteen of 22 substances were addressed using the Low Human Health Hazard Potential Approach and therefore human exposure was not characterized for these substances.
• 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.

Key health and ecological effects (hazard)

• To help inform the health effects characterization in the draft screening assessment, international and national reports of data on these substances were considered, along with other sources of information. This included assessments by Health Canada, the European Union, the United States Environmental Protection Agency, the World Health Organization, the Joint FAO/WHO Expert Committee on Food Additives, and the European Food Safety Authority, among others.
• Critical effects, which were observed in studies with laboratory animals were identified for characterizing the risk to human health are as follows:
  • For 3 of the 5 substances in the FACCC subgroup: inhalation effects, neurobehavioral effects, and effects on the thyroid gland.
  • For the nitrate and nitrite subgroup: an effect on oxygen delivery by red blood cells.
• 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.
• 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.

Where to find updates

• Further information on what the Government is doing to address chlorine and ammonia may be found in the Proposed Risk Management Strategy.
• Additional information on the risk management of substances addressed under the CMP is available.
• 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. 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.
• The screening assessment focused on potential risks from exposure of the general population of Canada, rather than occupational exposure. Hazards related to chemicals used in the workplace are defined within the Workplace Hazardous Materials Information System (WHMIS). For information concerning workplace health and safety and what steps to take in the workplace, Canadians should consult their employer and/or the Occupational Health and Safety Regulator in their jurisdiction.