Risk assessment of chemical substances

Substances, such as chemicals, polymers, and products of biotechnology, have many different properties and many different uses. Some are used to make plastics flexible. Some help to put out fires quickly and efficiently. Some are products of common chemical reactions that occur naturally in the environment. Still others are present in products we use as part of our day-to-day activities, such as shampoos, floor cleaners, clothing fabrics and children's toys.

In the same way that substances have different uses, some can also be harmful in different ways. For instance, some may harm fish, while some are linked to life threatening diseases such as cancer. Others may be carried long distances through the air and affect people or the environment far away.

The risks posed by a substance are determined both by its hazardous properties and the nature of the exposure that takes place. Scientific evaluations, or risk assessments are conducted under theCanadian Environmental Protection Act, 1999 (CEPA 1999) to determine whether there are risks resulting from exposure of Canadians to the substance or releases of the substance into the environment, and the specific ways Canadians or the environment can be affected.

On this page, you will find information about the following topics:

The CEPA 1999 risk assessment process

The Minister of Health and the Minister of the Environment conduct risk assessments of substances in commerce in Canada (existing substances) or proposed for introduction to the Canadian market (new substances) to determine whether these substances present or may present a risk to the environment or to human health. Decisions are based on a scientific evaluation of the risk posed by a substance, which considers both the hazardous properties of the substance (such as toxicity to aquatic organisms or cancer-causing properties) and the nature of the exposure of Canadians or the environment to the substance. This allows the Government of Canada to identify whether or not a control is needed, and if so, what type of control is best suited for reducing or preventing the potential harm.

The unique characteristics of substances need to be considered when making decisions about the need for control. For example, it may be straightforward to assess a substance that has a single use. It gets more complicated, though, for substances that have many different uses, enter the environment in many different ways, and may affect humans or non-human organisms differently depending on the nature of the exposure.

As a result, there are various types of risk assessments that may be undertaken. These are described within the Risk Assessment Toolbox. In addition, new priorities for risk assessment are identified through the ongoing consideration of new information.  An approach outlining the process for identification of risk assessment priorities (IRAP) was published in 2014.

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Principles and approaches

In conducting a risk assessment, a weight of evidence approach and precaution are applied. Key information across multiple lines of evidence is taken into consideration, along with uncertainties.

Data on the amount that a substance may enter the environment, as well as its chemical properties, provides information about how the substance may be distributed in the environment, how long it will remain in the environment, and whether it is present at levels that may be harmful to Canadians or the environment. Different approaches for characterizing exposure may be used depending on the information available regarding sources, uses, handling and disposal of the substance.

The potential effects of the substance on humans and the environment are evaluated (hazard characterization). The most susceptible populations (such as children) or receptors (such as early life stages of fish) as well as critical effects (such as mortality, reproductive impairment, and carcinogenicity) are identified. Information on endocrine-related effects is also considered, when available and relevant. A combination of qualitative and quantitative approaches may be used to characterize the overall risk of a substance. Data generated through laboratory or field testing, modelling approaches and data from other substances that are structurally and/or functionally similar to the substance being assessed are all used, as appropriate. The results inform both ecological and human health assessments.

Approaches used to carry out risk assessments are similar to those used by other regulatory jurisdictions. The results of international assessments on substances will also be used to inform CEPA 1999 risk assessments.

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The risk assessment process for existing substances

An essential first step in risk assessment is the collection of information on each substance or substance group. A range of information is considered in an assessment, including: chemical properties, quantities manufactured in or imported into Canada, releases to and concentrations in the environment, environmental fate and behaviour, hazards, and nature of exposure.

Information gathering encompasses a wide variety of published and unpublished sources. These include literature and database searches, information submitted by stakeholders through voluntary or mandatory surveys, and previous reviews or assessments of substances conducted by national or international agencies. Information is also generated by government researchers or stakeholders carrying out studies, testing and monitoring of substances. For example, biomonitoring surveys on humans provide data that represents sources of exposure to a given substance. Throughout the risk assessment process, expert and stakeholder engagement is a crucial component. The assessment reports undergo external peer review and/or consultation involving experts from government, academia, industry, and non-governmental organizations, to obtain expert input on critical technical issues. As well, draft screening assessments are subject to a 60-day public comment period. While all comments are taken into consideration, the final content and conclusion of screening assessments remain the responsibility of Health Canada and Environment and Climate Change Canada.

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The risk assessment process for new substances

Prior to a substance being permitted into commerce in Canada, the new substance must undergo an ecological and human health risk assessment. This process begins with a pre-import or pre-manufacture notification of the substance. This means that any person intending to import or manufacture a new substance in Canada is required to submit a package containing all information prescribed in the New Substances Notification Regulations.

In general, the risk assessments of new substances are conducted similarly to those for existing substances. See the New Substances Program for more information.

CEPA 1999 conclusions

For the purposes of section 64 in Part 5 of CEPA 1999, a substance is toxic if it is entering or may enter the environment in a quantity or concentration or under conditions that:

  1. have or may have an immediate or long-term harmful effect on the environment or its biological diversity;
  2. constitute or may constitute a danger to the environment on which life depends; or
  3. constitute or may constitute a danger in Canada to human life or health.

A conclusion is made for a substance or group of substances taking into consideration the relevant information available as well as any uncertainties. Maintaining transparency is key to a credible assessment process. Therefore, care is taken to ensure uncertainties are captured and communicated in the assessment reports.

If a substance is determined to be toxic or capable of becoming toxic as defined in section 64 of CEPA 1999, then risk management measures are considered to prevent or control risks identified. Follow up activities may be undertaken for those substances recognized for their potential effects of concern.

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