This page has been archived on the Web

Information identified as archived is provided for reference, research or recordkeeping purposes. It is not subject to the Government of Canada Web Standards and has not been altered or updated since it was archived. Please contact us to request a format other than those available.

Information update

Health Canada is advising Canadians to not use malathion products older than one year

Starting date:
August 23, 2016
Type of communication:
Information Update
Source of recall:
Health Canada
Identification number:


Health Canada is advising Canadians to stop using pesticides that contain malathion when products are older than one year due to chemical changes in the product over time.

In Canada, malathion is a registered insecticide mainly used to control insects in agriculture, but it can also be used in and around the home. When used according to label directions, malathion is effective in killing mosquitoes and other pests without posing unacceptable risks to human health or the environment.

However, over time a toxic chemical called isomalathion can naturally form in malathion products, particularly when they are stored at elevated temperatures. After storage for more than a year, it’s possible that levels of isomalathion could become a concern, even when containers are stored correctly.

What you should do

Make sure any products containing malathion are stored in a cool (around 20-23°C), dry, well ventilated place away from seed, fertilizer or other pesticides and for no longer than one year.


While it’s possible to test products for elevated levels of isomalathion, this is not likely to be feasible for individual Canadians. As a result, Canadians are advised not to use products that contain malathion that are older than one year. If you need to dispose of any existing products, you should contact your provincial regulatory agency or local municipality for information on how to dispose of household hazardous waste properly in your area.

Canadians should always read the entire pesticide label before use and follow all label directions. To check for the most recent product information, use Health Canada’s new pesticide label search mobile app.

Commercial users

As most end-use products are formulated to be stable over a reasonable amount of time, Health Canada does not object to the use of malathion product which is older than one year when all of the following are met:

  • An accredited laboratory test results show that the malathion remains within accepted standards, (for example, it meets the [NJS_FILE:087f057b-9361-4440-9531-4780c12fbb8a:85734226-0b2a-4029-bcf0-6f344122fdbe]);
  • The test results are maintained for compliance verification purposes; and
  • The product continues to be used in accordance with the other label directions (including storage conditions).

Report health or safety concerns

Report any adverse events to the manufacturer, who is required by law to report to Health Canada. You may also report an incident directly to Health Canada by completing an incident report form.

Media enquiries

Health Canada
(613) 957-2983

Public enquiries

(613) 957-2991
1-866 225-0709

What Health Canada is doing

Health Canada will be working with the manufacturers to modify the labels of products that contain malathion to include date information, and the requirement for laboratory testing beyond this date to ensure the product is within acceptable specifications.