Water monitoring for pesticides
On this page
- How do pesticides enter water
- Why Canadians may be concerned about pesticides in water
- How water monitoring data are used in pesticide risk assessment
- Contact the water monitoring program
Health Canada's Pest Management Regulatory Agency (PMRA) is working to establish a national water monitoring program for pesticides. This program will collect more water monitoring data and be supported by sampling partners across Canada. To ensure consistency in the data, a framework is being developed to establish guidance for items such as site selection and sampling frequency. To inform framework development a pilot sampling program is underway.
Data from this program will help the PMRA make more informed and timely regulatory decisions about pesticides. These data will also allow for the identification of areas where risks to human health and aquatic organisms may be present and further investigation is needed to inform regulatory action.
Learn more about:
- The pilot water monitoring program
- Aquatic Life Reference Values (ALRVs)
- Human Health Reference Values (HHRVs)
How do pesticides enter water?
Pesticides are chemicals that are used to control pests. When pesticides enter the environment, various chemical reactions and biological processes break them down over time into other chemicals. Those chemicals are called transformation products. Pesticides and their transformation products can move through the environment:
- within water
- attached to soil particles
- in the air
Pesticides may enter Canada's waters many different ways. When pesticides are applied in agricultural and forestry environments, they can travel in the air (called spray drift) and unintentionally land in a body of water. After pesticides are applied, they may enter surface water through runoff or move through soil to groundwater. Pesticides can also enter surface water through rainfall and when they are attached to dry particles such as dust. See Figure 1 below. Pesticides used indoors may enter surface water through wastewater discharge.
Why Canadians may be concerned about pesticides in water
Some Canadians are concerned about pesticides in Canada's waters and how they may affect their health and/or the health of our ecosystems.
Drinking water is collected from both surface water and groundwater and may be treated by communities to reduce contaminants such as bacteria, viruses, debris and chemicals. The level of treatment and methods used to treat drinking water can differ across Canada. For example:
- Surface water is usually treated at community water treatment facilities before it is consumed.
- Groundwater is usually not treated at community water treatment facilities before it is consumed because it is typically cleaner than surface water.
Pesticides that enter freshwater environments, such as lakes and rivers, may cause effects to non-target organisms that live in and around these environments. The possible effect on non-target organisms depends on the amount and type of pesticide that may enter these environments and how long the organisms are exposed in the water.
How water monitoring data are used in pesticide risk assessment
The PMRA determines the possible risks to humans from pesticides that may be found in drinking water (surface water and groundwater) and the possible risks to aquatic non-target organisms (surface water).
PMRA's scientists use a combination of computer modelling and real-world data to predict if there may be risks to human health and aquatic organisms.
Computer models are used to estimate the concentration of a pesticide in groundwater and surface water. These estimations are based on the chemical and physical properties of the pesticide and how it is used based on the product label.
When water monitoring data is available from Canada (and sometimes other countries), it can be used to further investigate if there are risks to humans or aquatic organisms. If possible risks are identified, PMRA may put in place measures to manage the risk from that pesticide. These measures would appear on product labels and are legal requirements that must be followed to use the pesticide.
Measures to protect human health and the aquatic environment from pesticides can include spray drift buffer zones, vegetative filter strips or a reduction in the amount of pesticide applied.
Contact the water monitoring program
PMRA continues to welcome feedback from all stakeholders and partners about our pesticide water monitoring work at: firstname.lastname@example.org.
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