Perfluorooctane sulfonate  (PFOS), its salts and precursors - information sheet

Update:

Per- and polyfluoroalkyl substances (PFAS) are a class of over 4,700 human-made substances. In April 2021, the Government of Canada indicated that it is considering activities that would address PFAS as a class. Visit the PFAS web page for the latest information on publications and actions being considered under the Government’s Chemicals Management Plan related to PFAS.

On this page

• Overview
• About this substance
• Human and ecological exposures
• Key health and ecological effects (hazard)
• Risk assessment outcomes
  • Screening assessment conclusions
• Preventive actions and reducing risk
• Related information

Overview

• The Government of Canada conducted science-based evaluations of PFOS, its salts, and its precursors to address the potential for harm to Canadians and to the environment. These assessments were completed in 2006.
• Under the Canadian Environmental Protection Act, 1999 (CEPA 1999), the risk posed by a substance is determined by considering both its hazardous properties (its potential to cause adverse human health or ecological effects) and the amount of exposure there is to people and the environment. A substance may have hazardous properties; however, the risk to human health or to the environment may be low depending upon the level of exposure.
  • More information on assessing risk can be found in the Overview of Risk Assessment and related fact sheets.
• The health assessment of PFOS, its salts and its precursors found that PFOS exposures were below levels that would be harmful to human health. However, the ecological assessment concluded that PFOS is entering or may enter the environment at concentrations that are harmful to the environment.

About this substance

• Perfluorooctane sulfonate, also known as PFOS, is a man-made chemical substance belonging to a large family of compounds known as perfluoroalkyl substances (PFASs).
• Prior to the announcement of a global voluntary phase-out of the production of PFOS by a major manufacturer beginning in 2000, PFOS was imported into Canada and used primarily in water-, oil-, soil- and grease-repellents for use on paper and packaging, carpets and fabrics, and in fire-fighting foams used to fight fuel-based fires.
• According to information gathered by the Government and a 2004 industry survey of remaining PFOS uses, only 3,000 kg of PFOS was imported into Canada for use as a surfactant in the chromium electroplating sector.
• There are no manufacturers or exporters of PFOS in Canada.
• The assessment was undertaken in response to a public nomination to the Minister of Environment to add these substances to the Priority Substances List. Precursors considered to have the potential to degrade to PFOS were included in the assessment.
• The ecological assessment focused on PFOS, but also considered its precursors given similar use applications and given that PFOS is the final degradation product of precursors. While the assessment did not consider the additive effects of PFOS and its precursors, it is recognized that the precursors contribute to the ultimate environmental loading of PFOS. Precursors may also play a key role in the long-range transport and subsequent degradation to PFOS in the Canadian Arctic.

Human and ecological exposures

• Given the historic use patterns, exposure of Canadians to these substances would likely result from contact with, and/or the use of products available to consumers that contain PFOS.
• Human exposure may also occur from environmental sources (for example, air) as well as food; however, given that environmental data are limited, exposure was assessed using levels of these substances measured in humans (human biomonitoring data).
• Human biomonitoring is the measurement of substances in blood, urine or breast milk. The presence of a substance in the body does not necessarily mean that it is causing harm. Harmful effects will depend on the levels and the properties of the substances. The information on measured levels in humans is important to estimating exposure to Canadians.
• At the time of the assessment, globally, PFOS could be released to the environment throughout its lifecycle, from the handling of the chemical to the use and disposal of products which contain it.
• Exposure of the Canadian environment would likely result from the release, transformation, and movement of PFOS and its precursors in effluents, emissions to air and water from manufacturing sites elsewhere in the world, and releases from wastewater effluents.

Key health and ecological effects (hazard)

• The critical or important effects considered in the human health assessment of PFOS and its salts included effects on the liver and thymus, as well as effects on blood chemistry.
• PFOS and its salts are considered to have ecological effects of concern (such as growth, survival, and reproductive effects) due to their persistence and their potential to accumulate in and cause harm to organisms.

Risk assessment outcomes

• Results of the assessment for human health indicated that levels of exposure to PFOS, its salts and its precursors were below levels that would have an adverse effect on human health.
• However, it was determined that there is risk of harm to the environment from PFOS and its salts based on a weight-of-evidence approach. Considerations included the persistence, bioaccumulation, widespread occurrence, and concentrations of PFOS in the environment and in biota (including remote areas of Canada). As well, current levels showed that some wildlife (for example, polar bears and birds) could be harmed by current exposures to PFOS.
• Additionally, PFOS and its salts meet the persistence criteria but not the bioaccumulation criteria as set out in the Persistence and Bioaccumulation Regulations of CEPA 1999. Nevertheless, the weight of evidence was sufficient to conclude that PFOS and its salts bioaccumulate (the increase in concentrations of a substance in the tissues of organisms due to uptake from all sources, such as water and food) and biomagnify (the increasing concentration of a substance in the tissues of organisms at successively higher levels in a food chain) in marine and terrestrial mammals and piscivorous birds.
• The State of the Science Report for a Screening Health Assessment: Perfluorooctane Sulfonate, its salts, and its Precursors that contain the C₈F₁₇SO₂ or C₈F₁₇SO₃ moiety was published in January 2006.
• The Ecological Screening Assessment Report on Perfluorooctane Sulfonate, Salts and Precursors was published in June 2006.

Screening assessment conclusions

• As a result of the state of science report for human health, it was found that PFOS, its salts and its precursors are not harmful to human health at the levels of exposure current at the time of the assessment. 
• However, the Government concluded that PFOS, its salts, and its precursors are entering the environment at levels that are harmful to the environment.

Preventive actions and reducing risk

• The Government published the risk management strategy for perfluorooctane sulfonate its salts and precursors in June 2006 for public comment.
• Perfluorooctane sulfonate, its salts and its precursors were added to Schedule 1 to CEPA 1999, also called the List of Toxic Substances.
• The Government took risk management action on PFOS, to address ecological concerns, including the use of the Prohibition of Certain Toxic Substances Regulations, 2012.
• Additional information on the risk management of substances addressed under the CMP is available.

Related information

• These substances may be found in products available to consumers. Canadians should follow any safety warnings and directions on product labels and dispose of products responsibly.
•  Health Canada has developed Guidelines for Canadian Drinking Water Quality for PFOS and PFOA and drinking water screening values for 9 PFASs. These guidelines establish health-based values that are protective of human health and set out basic parameters that every water system should strive to achieve in order to provide safe drinking water to Canadians. Drinking water screening values are provided as guidance and apply to water intended for human consumption. In February 2023, a consultation document was published on a proposed objective that recommends a single treatment-based value for a group of PFAS in drinking water.
• Canadians who may be exposed to these substances in the workplace should consult with their employer and an occupational health and safety (OHS) representative about safe handling practices, applicable laws, and requirements under OHS legislation and the Workplace Hazardous Materials Information System (WHMIS).