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Chlorpyrifos Insecticide Registration Discontinued

Chlorpyrifos is a non-systemic group 1B insecticide (organophosphate) and works by contact, ingestion and inhalation. It is an extremely toxic insecticide to mammals, bees, birds, fish and other aquatic organisms.

Chlorpyrifos has been around for over 50 years and is known by several trade names in Manitoba; Lorsban being the most well-known trade name, locally. According to the Guide to Field Crop Protection 2021 (page 664), chlorpyrifos is registered for use on barley, canola, corn, flax, lentils, oats, potatoes, sunflowers and wheat, targeting the following corresponding insects:

Chlorpyrifos crops and insects label

Since 2000, Health Canada has re-evaluated chlorpyrifos and its multiple uses a number of times and have implemented several risk reduction measures. In the most recent re-evaluation decisions, new studies related to human health assessment have been generated, and chlorpyrifos products have come under intense scrutiny.

Re-Evaluation Decision For Chlorpyrifos on the Environment

Under the authority of the Pest Control Products Act and based on the evaluation of currently available scientific information, Health Canada is cancelling outdoor uses of chlorpyrifos except those listed below, due to risks to the environment that have not been shown to be acceptable.

The following uses are acceptable from an environmental perspective with required mitigation measures:

  • Standing water – temporary pools for larval mosquito control.
  • Outdoor adult mosquito control.
  • Structural indoor and outdoor (non-residential).
  • Outdoor ornamentals (container stock root immersion only) for control of Japanese beetle larvae.
  • Elm bark beetle and mountain pine beetle control.
  • Greenhouse ornamentals

There are an additional two uses that are delayed from cancellation due to a lack of suitable alternative products, which includes alfalfa looper control in canola, and darksided and redbacked cutworm control in garlic.

What does this mean for producers?

The U.S. Environmental Protection Agency (EPA) announced it will stop the use of the pesticide chlorpyrifos on all food to better protect human health, particularly that of children and farmworkers.

In a final rule released today, EPA is revoking all “tolerances” for chlorpyrifos, which establish an amount of a pesticide that is allowed on food. In addition, the agency will issue a Notice of Intent to Cancel under the Federal Insecticide, Fungicide, and Rodenticide Act to cancel registered food uses of chlorpyrifos associated with the revoked tolerances.


As of February 2022 (6 months following EPA’s decision), all commodities for export to the United States, that have been treated with chlorpyrifos, will be denied.

Health Canada has issued a 3-year plan to ban chlorpyrifos, which could see all chlorpyrifos products leave the shelves as soon as December 2022. This is triggering users of Lorsban, or other chlorpyrifos products, to stockpile inventory for future use, following the ban. While this is a natural reaction to a product ban, it is being strongly recommended for producers to avoid using chlorpyrifos products beginning in 2022. The proper recommendation would be to start evaluating alternate insecticide products that will persist in the long-term, and assess what works best on the producer's operation.