Human Biomonitoring of Environmental Chemicals

Canadians are exposed to a variety of chemicals, both naturally-occurring and human-made, throughout their daily lives. We understand that many of these chemicals are in our bodies, and there are questions about the potential for these chemicals to affect our health. Public health officials and government regulators need better and more direct measurements of the exposure of Canadians to these chemicals in order to improve decisions for protecting health and preventing disease.

Biomonitoring is a key tool used as an indicator and quantitative measure of exposure to chemicals in the environment. Human biomonitoring data contribute to our understanding of exposure and provide information to inform the management of the health risks posed by chemicals.

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Canadian Health Measures Survey

Maternal-Infant Research on Environmental Chemicals Study

Northern Contaminants Program

What is Biomonitoring?

Chemical substances are everywhere - in air, soil, water, products, and food - and can enter the body through ingestion, inhalation, and skin contact. The Government of Canada uses a variety of methods, tools, and models to assess human exposure to chemicals (both natural and synthetic) and the potential effects that these exposures may have on human health. Human exposure to chemicals can be estimated indirectly by measuring chemicals in the environment, food, or products, or directly in the human body using biomonitoring (see Figure 1).

Biomonitoring is the measurement, in people, of a chemical or the products it makes when it breaks down. This measurement (called the level or concentration) is usually taken in blood and urine and sometimes in other tissues and fluids such as hair, nails and breast milk. The measurement indicates how much of a chemical is present in a person.

Figure 1 - Understanding Human Biomonitoring

Figure 1

Figure 1 - Understanding Human Biomonitoring - Text Equivalent

This figure shows how a person or population can be exposed to environmental chemicals. Once a chemical is released from its source, it can travel through various types of environmental media to points where human exposure can occur. Air, soil, water, products, and food are the major types of media from which chemical exposure can occur. When a person interacts with or is exposed to these media, chemicals can enter a person's body through ingestion, inhalation, and skin contact.

What Human Biomonitoring Studies Tell Us

Large national or regional-scale biomonitoring surveys can help measure our exposure to chemicals, and help us determine if the exposure is changing over time. An example of such a study is the Canadian Health Measures Survey (CHMS), a national survey being led by Statistics Canada, in partnership with Health Canada and the Public Health Agency of Canada. This survey collects information from Canadians about their general health and includes measurements of chemicals in blood and urine samples.

National studies such as the CHMS provide us with baseline levels of chemicals in Canadians and the basis for future monitoring and research activities.

Using Human Biomonitoring Data

Human biomonitoring data can be used by governments, researchers and health practitioners in a wide variety of ways:

  • Determine baseline levels of chemicals in the Canadian population.

    For the majority of chemicals, the data will serve as a starting point for comparison with data from future surveys, to determine how and why these levels may be changing over time.

  • Compare levels of chemicals among different populations.

    This could include comparisons with sub-populations within Canada or with populations of other countries.

  • Identify priority chemicals for which further action should be taken to protect the public's health.

    Risk management actions could include tighter restrictions on chemical use or even removal of use altogether. Information can also be provided to help Canadians reduce their own exposure to chemicals of concern.

  • Assess the effectiveness of health and environmental risk management actions intended to reduce exposure to specific chemicals and the associated health risks.

    Data from cycles 1 and 2 of the CHMS show a decline in lead levels in blood since the 1978-79 Canada Health Survey suggesting that public health measures to reduce lead exposure have been effective.

  • Support research on potential links between exposure to certain chemicals and specific health effects.

    Researchers can explore the relationships between the biomonitoring data and the other health measurements collected in the CHMS. This may, in turn, help focus future research efforts on the links between chemical exposure and health.

  • Contribute to international chemicals management programs.

    For example, to fulfill Canada's commitments for monitoring as a Party to the United Nations Environment Programme's Stockholm Convention on Persistent Organic Pollutants, as well as other international initiatives.

Limitations

Biomonitoring is a valuable tool to measure exposure to chemicals; however, its limitations, as well as the reasons for these limitations, must be understood in order to use the data appropriately.

  • Biomonitoring measures how much of a chemical is present in a person at a point in time, but when considered alone cannot tell you what health effects, if any, may result from that exposure.

    The ability to measure chemicals at low levels continues to progress. However, the presence of a chemical in a person's body does not necessarily mean that it will affect a person's health. Factors such as the amount to which a person is exposed, the duration and timing of exposure, and the toxicity of the chemical are important to determine whether adverse health effects may occur. In addition, the way a chemical acts in the body differs between individuals and cannot be predicted with certainty. Certain populations (for example, pregnant women and their developing fetuses, children, the elderly, and individuals with compromised immune systems) may be more susceptible to the effects of exposure to chemicals. Furthermore, certain chemicals, such as manganese and zinc, are essential nutrients required for the maintenance of good health and therefore are normally present.

    For chemicals such as lead or mercury, scientific studies have provided a good understanding of the health risks associated with elevated levels in blood. However, for many chemicals, further research is needed to understand what health effects, if any, are related to different levels of these chemicals in blood or urine.

  • The absence of a chemical does not necessarily mean a person has not been exposed.

    Existing technology may not be capable of measuring a very small amount, or the exposure may have occurred at an earlier time, allowing for the chemical to be eliminated from the person's body before measurement took place.

  • Biomonitoring cannot determine the source or route of the exposure.

    The measurement of a chemical indicates exposure from any or all sources (e.g., air, water, soil, food, products) and any or all routes (ingestion, inhalation, or skin contact). The detection of a chemical may be the result of exposure to a single source or multiple sources. As well, in most cases, biomonitoring cannot distinguish between natural and synthetic sources.

What Does Biomonitoring Say About Health Risk?

Biomonitoring provides an estimate of exposure to a chemical. However, a chemical's presence alone will not necessarily result in adverse health effects. The risk a chemical substance poses is determined by evaluating both its toxicity and the levels to which people may be exposed. The Government of Canada conducts risk assessments for chemicals used, manufactured, and imported into Canada, including the majority of chemicals measured in the CHMS. It has developed guidance values for mercury and lead in blood, to indicate what levels of exposure may be of concern. If measured levels are above the guidance values, actions may be considered to reduce exposure. The Government of Canada may consider developing guidance values for additional chemicals measured in the CHMS where there is enough information.

Government of Canada's Management of Chemicals

The Government of Canada plays a key role in protecting Canadians from exposure to chemicals through legislation that governs chemicals in food, soil, water, drugs, pesticides, and consumer products. This legislation includes the Canadian Environmental Protection Act, 1999, the Pest Control Products Act, the Food and Drugs Act, and the Canada Consumer Product Safety Act.

The Government of Canada takes a risk-based approach to the management of chemicals, using strong science, assessment, and monitoring, combined with a variety of tools to protect human health. Many standards and guidelines are in place (for example, Guidelines for Canadian Drinking Water Quality) to protect Canadians and the environment from the risks of potentially harmful chemicals.

Risk management strategies (such as the removal of lead from gasoline and other products) are designed to reduce exposure to chemicals. The effectiveness of these strategies may be observed by comparing biomonitoring data from future cycles of the CHMS with the current results.

Chemicals Management Plan

In 2006, the Government of Canada launched the Chemicals Management Plan (CMP) to further enhance its role in protecting Canadians and their environment from exposure to chemicals. In addition to risk assessment and risk management activities, research and monitoring initiatives, including biomonitoring, are key components that inform decisions made under this plan. Monitoring initiatives include a comprehensive national biomonitoring component, of which the CHMS is the cornerstone.

The CMP supports a number of additional research, monitoring and assessment activities to help Canadians better understand their exposure and the potential effects on human health. These activities include biomonitoring studies targeting vulnerable populations (such as the Maternal-Infant Research on Environmental Chemicals study), environmental monitoring studies, and research to support biomonitoring. Health Canada also partners with Indigenous and Northern Affairs Canada's Northern Contaminants Program to undertake health research and biomonitoring in Canada's northern populations. Detailed information about CMP-supported monitoring studies can be found on the Government of Canada's Chemical Substances website.

For more information

Additional information about how the Government of Canada manages chemicals can be found on the Chemicals Substances website.

Additional information about the CHMS can be found on the Statistics Canada website.

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