Human exposure to harmful substances

Summary

Key results

A decade of national biomonitoring conducted as part of the Canadian Health Measures Survey between 2007 and 2017 (cycles 1 to 5) showed that the average concentrations in Canadians of:

• bisphenol A (BPA), lead and cadmium generally decreased
• mercury remained stable

Changes in the average concentrations of selected substances in Canadians, Cycle 1 (2007 to 2009) to Cycle 5 (2016 to 2017)

How this indicator was calculated

Note: The chart presents the percentage change in the average (geometric mean) concentrations of selected substances in Canadians relative to Cycle 1 (2007 to 2009). The concentrations of mercury, lead and cadmium in blood and bisphenol A in urine are from participants aged 3 to 79 years, except for Cycle 1 when there were no participants under the age of 6 years. For Cycle 4, the average (geometric mean) for mercury was not calculated since more than 40% of the samples were below the limit of detection.
Source: Health Canada (2019) Fifth Report on Human Biomonitoring of Environmental Chemicals in Canada. Results of the Canadian Health Measures Survey Cycle 5 (2016-2017).

The average concentration of mercury in the blood of Canadians remained stable^{Footnote 1}  from Cycle 1 (2007 to 2009) to Cycle 5 (2016 to 2017).

There was a declining trend^{Footnote 2} in the average concentration of lead in the blood of Canadians from Cycle 1 to Cycle 5. It decreased 28% between Cycle 1 and Cycle 5 and 81% since 1978 to 1979.^{Footnote 3}

The average concentration of cadmium in the blood of Canadians showed a declining trend from Cycle 1 to Cycle 5. Between Cycle 1 and Cycle 5, the concentration decreased by 18%.

There was also a declining trend in the average concentration of BPA in urine of Canadians from Cycle 1 to Cycle 5. The concentration decreased by 33% during the period.

Mercury

Exposure to mercury is of global concern because it can cause adverse health effects, such as neurological effects, gastrointestinal damage or kidney failure. Mercury is found throughout the environment, including the atmosphere, water, soil, sediments and biota. It occurs naturally in the Earth's crust and is released into the air during forest fires, volcanic episodes and other geological activities. Mercury is also used in, and released from, industrial processes and commercial products.

Key results

Over the 5 cycles (2007 to 2017) of the Canadian Health Measures Survey, the average concentrations of mercury:

• remained stable^{Footnote 1} 
• were higher in adults than in children
• were similar in women and men

Average concentration of mercury in blood in Canadians, Cycle 1 (2007 to 2009) to Cycle 5 (2016 to 2017)

How this indicator was calculated

Note: For Cycle 1, data were not available for children under the age of 6 years, as they were not included in the survey. For cycles 3 to 5, averages (geometric means) were not calculated for some age groups, since more than 40% of the samples were below the limit of detection. Mercury is shown as total mercury (organic and inorganic).
Source: Health Canada (2019) Fifth Report on Human Biomonitoring of Environmental Chemicals in Canada. Results of the Canadian Health Measures Survey Cycle 5 (2016-2017).

Adults aged 40 to 59 years and 60 to 79 years consistently presented higher average concentrations of mercury compared to other age groups due to mercury accumulation in the body.

Mercury is widespread in the environment. It is a naturally occurring metal and is also released by many industrial processes, such as chemical manufacturing operations, metal mining and coal combustion. It can travel long distances in the atmosphere and settles everywhere in Canada, including sensitive areas such as the Canadian Arctic and the Great Lakes. Mercury exists in 3 forms: elemental mercury, inorganic mercury compounds and organic mercury compounds, such as methylmercury. Mercury is toxic to humans and accumulates in terrestrial and aquatic food chains over time.

Humans are exposed to methylmercury (neurotoxicant) primarily through consumption of contaminated fish and seafood. Marine mammals or fish that are long-lived and feed on other fish can accumulate high levels of methylmercury. To a much lesser extent, the general population is also exposed to inorganic mercury from improper disposal of products containing mercury such as switches, batteries, thermometers and fluorescent lamps and from the use of dental amalgam.

The human health effects depend on various factors, such as the form and amount of mercury encountered, the length of exposure, and the age of the person exposed. Oral exposure to organic mercury compounds can cause neurological damage and developmental neurotoxicity. Exposure of a fetus or young child to organic mercury can affect the development of the nervous system, including fine-motor function, attention, verbal learning and memory. High exposure to inorganic mercury can cause damage to the gastrointestinal tract and kidneys. Exposure to elemental mercury inhaled as mercury vapour may cause adverse neurological, respiratory and kidney effects.

Mercury is listed on the Toxic substances list (Schedule 1) of the Canadian Environmental Protection Act, 1999. It is also subject to numerous federal risk management initiatives directed towards consumer products, cosmetics, drinking water, food, therapeutic products and environmental media, including water and air.

Lead

Lead released from natural processes, such as weathering, erosion and volcanic activity, and from industrial emissions can be deposited on land or water surfaces and then build up in soils, sediments, humans and wildlife. Canadians are exposed to low levels of lead through food, drinking water, air, household dust, soil and various products. Exposure to lead, even in small amounts, can be hazardous to both humans and wildlife.

Key results

Over the 5 cycles (2007 to 2017) of the Canadian Health Measures Survey, the average concentrations of lead:

• showed a declining trend,^{Footnote 2}  with a decrease of 28% between Cycle 1 and Cycle 5
• were lower in children than in adults
• were highest in adults aged 60 to 79 years
• were higher in men than in women

Average concentration of lead in blood in Canadians, Cycle 1 (2007 to 2009) to Cycle 5 (2016 to 2017)

How this indicator was calculated

Note: For Cycle 1, data were not available for children under the age of 6 years, as they were not included in the survey. Average refers to geometric mean.
Source: Health Canada (2019) Fifth Report on Human Biomonitoring of Environmental Chemicals in Canada. Results of the Canadian Health Measures Survey Cycle 5 (2016-2017).

Adults aged 60 to 79 years consistently presented the highest concentrations of lead due to accumulation in teeth and bones over time. Children (especially 3 to 5 years) could be more vulnerable to exposure because of their hand-to-mouth behaviour, which increases their exposure to lead from dust and soil.

On average, men have greater concentrations of lead in their blood than women. This may be due in part to men having a higher volume of red blood cells, to which lead binds in the body.

Lead exposure in Canada has decreased by approximately 80% over the past 40 years.^{Footnote 4} This decrease is largely attributed to the phase-out of leaded gasoline, restrictions on the use of lead in consumer paints and other coatings on children's products, and elimination of lead solder in food cans.

Lead is a naturally occurring element found in rock, water and soil. It is used in the refining and manufacturing of products such as lead acid car batteries, lead shot and fishing weights, sheet lead, solder, some brass and bronze products, pipes, paints and some ceramic glazes. Exposure to trace amounts of lead occurs through soil, household dust, consumer products, food, drinking water and air because of its natural abundance in the environment and its widespread use for much of the 20th century.

Exposure to very high levels of lead may result in vomiting, diarrhea, convulsions, coma and death. Chronic exposure to relatively low levels may affect the central and peripheral nervous systems, blood pressure, and renal function and may result in reproductive problems and developmental neurotoxicity.

Lead is listed on the Toxic substances list (Schedule 1) of the Canadian Environmental Protection Act, 1999. It is also subject to numerous federal risk management initiatives directed towards consumer products, cosmetics, drinking water, food, natural health products, therapeutic products, tobacco and environmental media, including household dust, soil, and air.

Cadmium

Cadmium is a naturally occurring metal. It is used in batteries and in electroplating to protect other metals from corrosion. Exposure to cadmium can be hazardous to both humans and wildlife since it accumulates in the food chain over time.

Key results

Over the 5 cycles (2007 to 2017) of the Canadian Health Measures Survey, the average concentrations of cadmium:

• showed a declining trend^{Footnote 2} in the total population, with a decrease of 18% between Cycle 1 and Cycle 5
• were highest in adults aged 40 to 59 years and 60 to 79 years
• were higher in women than in men

Average concentration of cadmium in blood in Canadians, Cycle 1 (2007 to 2009) to Cycle 5 (2016 to 2017)

How this indicator was calculated

Note: For Cycle 1, data were not available for children under the age of 6 years, as they were not included in the survey. For cycles 3 and 5, averages (geometric means) were not calculated for some age groups, since more than 40% of the samples were below the limit of detection.
Source: Health Canada (2019) Fifth Report on Human Biomonitoring of Environmental Chemicals in Canada. Results of the Canadian Health Measures Survey Cycle 5 (2016-2017).

Adults aged 40 to 59 years and 60 to 79 years consistently had the highest average concentrations of cadmium. Cadmium has a biological half-life (the time it takes to reduce the concentration by half) of about 10 to 12 years in the kidney and accumulates with age.

Women on average have greater concentrations of cadmium in their blood than men. This is due in part to the average rate of gastrointestinal absorption of dietary cadmium. The gastrointestinal absorption rate in women is estimated to be 10% or higher, while in men it is estimated to be 5%.

Cadmium is released into the environment as a result of natural processes, including forest fires, volcanic emissions, and weathering of soil and bedrock. It is a metal used in batteries and in electroplating to protect other metals from corrosion. It may be released directly into air from human activities such as non-ferrous smelting and refining, and fuel consumption for electricity generation or heating. Inhalation of cigarette smoke is a major source of cadmium exposure in smokers. Non-smokers are exposed to cadmium through food, breathing in second-hand smoke and for some, occupational exposure can also be a source. Other minor sources of exposure include drinking water, soil or dust, as well as inhalation and releases from consumer products.

Exposure to cadmium has been associated with gastrointestinal irritation and harmful effects to the kidneys and lungs. Cadmium and its compounds have been classified by Environment and Climate Change Canada and Health Canada as a probable carcinogen in humans when inhaled. Inorganic cadmium compounds are listed on the Toxic substances list (Schedule 1) of the Canadian Environmental Protection Act, 1999. It is also subject to a number of federal risk management initiatives directed towards consumer products, cosmetics, drinking water, food and environmental media, including water and air.

Bisphenol A

Bisphenol A (BPA) is a synthetic chemical used in plastics, epoxy resins and thermal paper, that poses environmental and health concerns; it is known as a potential hormone disruptor and it can adversely affect reproduction, growth, and development in humans and wildlife.

Key results

Over the 5 cycles (2007 to 2017) of the Canadian Health Measures Survey, the average concentrations of BPA:

• showed a declining trend^{Footnote 2} in the total population, with a decrease of 33% between Cycle 1 and Cycle 5
• were higher in children than in adults
• were higher in men than in women

Average concentration of bisphenol A in urine in Canadians, Cycle 1 (2007 to 2009) to Cycle 5 (2016 to 2017)

How this indicator was calculated

Note: For Cycle 1, data were not available for children under the age of 6 years, as they were not included in the survey. Average refers to geometric mean.
Source: Health Canada (2019) Fifth Report on Human Biomonitoring of Environmental Chemicals in Canada. Results of the Canadian Health Measures Survey Cycle 5 (2016-2017).

The average concentration of BPA was lower in adults aged 40 to 59 years and 60 to 79 years and higher in the younger age groups. Overall, men have a higher concentration of BPA than women possibly due to differences in hormone levels. Further research is ongoing to better understand how BPA is absorbed, distributed, metabolized and excreted by the body.

BPA is found in food packaging and repeat-use plastic containers; it migrates from the packaging into food and drinks. Exposure can also occur from air, drinking water, soil, dust and the use of consumer products. The Government of Canada has concluded that current dietary exposure to BPA through food packaging is not expected to pose a health risk to the general population, including newborns and infants.

Bisphenol A is known as a hormone disruptor and can adversely affect the liver, the kidneys and reproduction, including fertility and development. Although dietary exposure to BPA through food packaging is not expected to pose a health risk to Canadians, a precautionary approach has been taken to limit exposure of infants and newborns to BPA from food packaging. As part of these efforts, BPA has been prohibited in baby bottles sold in Canada since 2010. It is listed on the Toxic substances list (Schedule 1) of the Canadian Environmental Protection Act, 1999 and is subject to federal risk management initiatives directed towards cosmetics, foods and industrial effluents.

About the indicators

What the indicators measure

These indicators present the concentrations of 4 substances (mercury, lead, cadmium and bisphenol A) in Canadians for the 5 survey cycles from 2007 to 2017 based on data collected as part of the Canadian Health Measures Survey. These substances were chosen from the Canadian Health Measures Survey because they complement other indicators from the Canadian Environmental Sustainability Indicators program. For each substance, the concentration in blood or urine is provided by age group and by sex when data are available.

Why these indicators are important

Chemical substances are everywhere, including in the air, soil, water, products and food, and can enter the body through ingestion, inhalation and skin contact. Mercury and its compounds, lead, inorganic cadmium compounds and bisphenol A are on the Toxic substances list under Schedule 1 of the Canadian Environmental Protection Act, 1999. This means that these substances are "entering or may enter the environment in a quantity or concentration or under conditions that (a) have or may have an immediate or long-term harmful effect on the environment or its biological diversity; (b) constitute or may constitute a danger to the environment on which life depends; or (c) constitute or may constitute a danger in Canada to human life or health."

The Government of Canada uses a variety of methods, tools and models to assess human exposure to environmental chemicals and their potential health effects. Human exposure to chemicals can be estimated indirectly by measuring chemicals in the environment, food or products, or directly by biomonitoring. The Canadian Health Measures Survey measures environmental chemicals and/or their metabolites in blood and urine of participants. These indicators provide a snapshot of the survey results.

Through biomonitoring, the government can identify priorities, develop or revise risk management strategies, and track progress on policies put in place to reduce or control these substances.

Safe and healthy communities

These indicators support the measurement of progress towards the following 2019 to 2022 Federal Sustainable Development Strategy long-term goal: All Canadians live in clean, sustainable communities that contribute to their health and well-being.

In addition, the indicators contribute to the Sustainable Development Goals of the 2030 Agenda for Sustainable Development. They are linked to Goal 12, Responsible consumption and production and Target 12.4, "By 2020, achieve the environmentally sound management of chemicals and all wastes throughout their life cycle, in accordance with agreed international frameworks, and significantly reduce their release to air, water and soil in order to minimize their adverse impacts on human health and the environment."

Related indicators

The Air pollutant emissions indicators track emissions from human activities of 6 key air pollutants: sulphur oxides (SO_X), nitrogen oxides (NO_X), volatile organic compounds (VOC), ammonia (NH₃), carbon monoxide (CO) and fine particulate matter (PM_2.5). Black carbon, which is a component of PM_2.5, is also reported. For each air pollutant, data are provided at the national, provincial/territorial and facility level and by source.

The Emissions of harmful substances to air indicators track human-related emissions to air of 3 toxic substances, namely mercury, lead and cadmium, and their compounds. For each substance, data are provided at the national, provincial/territorial and facility level and by source. Global emissions to air are also provided for mercury.

The Releases of harmful substances to water indicators track human-related releases to water of 3 toxic substances, namely mercury, lead and cadmium, and their compounds. For each substance, data are provided at the national, provincial/territorial and facility level and by source.

Data sources and methods

Data sources

These indicators are based on data from Health Canada's reports on Human Biomonitoring of Environmental Chemicals in Canada. The reports provide results from the Canadian Health Measures Survey (the survey). The survey started in 2007 and data are collected in 2-year cycles.

Methods

Selected environmental chemicals were measured in the blood and/or urine of survey participants. For the national summary, the geometric mean was calculated for each substance for all results. The geometric mean was also calculated for results within the different age and sex groupings. A trend analysis was done to support statements regarding change over time.

Caveats and limitations

The Canadian Health Measures Survey (the survey) is designed to provide national-level estimates, or regional level estimates when data from multiple cycles are combined, but it does not permit further breakdown of data by collection site. In addition, the survey design does not target specific exposure scenarios and consequently does not select or exclude participants based on their potential for low or high exposures to environmental chemicals.

Resources

References

Bushnik T, Haines D, Levallois P, Levesque J, Van Oostdam J and Viau C (2010) Lead and bisphenol A concentrations in the Canadian population. Health Report (3):7-18. Retrieved on June 8, 2020.

Centers for Disease Control and Prevention (2016) Biomonitoring Summary: Cadmium. Retrieved on June 8, 2020.

Health Canada (1986) Guidelines for Canadian Drinking Water Quality: Guidelines Technical Document – Cadmium. Retrieved on June 8, 2020.

Health Canada (2010) Health Canada's Report on Human Biomonitoring of Environmental Chemicals in Canada: Results of the Canadian Health Measures Survey Cycle 1 (2007-2009). Retrieved on June 8, 2020.

Health Canada (2013) Final Human Health State of the Science Report on Lead. Retrieved on June 8, 2020.

Health Canada (2013) Second Report on Human Biomonitoring of Environmental Chemicals: Results of the Canadian Health Measures Survey Cycle 2 (2009-2011). Retrieved on June 8, 2020.

Health Canada (2015) Third Report on Human Biomonitoring of Environmental Chemicals in Canada: Results of the Canadian Health Measures Survey Cycle 3 (2012-2013). Retrieved on June 8, 2020.

Health Canada (2017) Fourth Report on Human Biomonitoring of Environmental Chemicals in Canada: Results of the Canadian Health Measures Survey Cycle 4 (2014-2015). Retrieved on June 8, 2020.

Health Canada (2019) Fifth Report on Human Biomonitoring of Environmental Chemicals in Canada: Results of the Canadian Health Measures Survey Cycle 5 (2016-2017). Retrieved on June 8, 2020.

National Center for Biotechnology Information (2015) Exposure to Bisphenol a and Gender Differences: From Rodents to Humans Evidences and Hypothesis about the Health Effects. Retrieved on June 8, 2020.

Statistics Canada (2013) Blood lead concentrations in Canadians, 2009 to 2011. Retrieved on June 8, 2020.

United States Environmental Protection Agency (2017) America's Children and the Environment. Biomonitoring: Bisphenol A. Retrieved on June 8, 2020.

United States Environmental Protection Agency (2017) America's Children and the Environment. Biomonitoring: Mercury. Retrieved on June 8, 2020.

Vahter M, Akesson A, Liden C, Ceccatelli S and Berglund M (2007) Gender differences in the disposition and toxicity of metals. Environmental Research 104 (1): 85-95. Retrieved on June 8, 2020.

World Health Organization (1990) Environmental Health Criteria 101: Methylmercury. Retrieved on June 8, 2020.

World Health Organization (2017) Lead poisoning and health. Retrieved on June 8, 2020.

Related information

Bisphenol A (BPA)

Human Biomonitoring of Environmental Chemicals

Lead

Mercury