Ontario Newsroom

2,4,5-T Use in Ontario

Archived Backgrounder

2,4,5-T Use in Ontario

2,4,5-T and its Use in Canada

  • 2,4,5-T (2,4,5-Trichlorophenoxyacetic acid) was used in the 1950s, 60s and 70s for weed and brush control by sectors such as forestry, transportation and agriculture (for non-crop land), as well as by municipalities, private companies and individuals.
  • There were over 200 herbicide products registered for use in Canada between 1948 and 1985 that contained some form of 2,4,5-T, either by itself or in combination with other herbicides.
  • In Canada, all pesticides must be registered as safe for our health and environment by the federal government before they can be sold or used.

2,4,5-T in Ontario

  • In 1970, the Ontario government at the time appointed a Task Force to study and report on the classification, distribution, sale, storage and transportation of pesticides in the province. The outcome was the introduction of the Pesticides Act, 1973. This was an amalgamation of all legislation respecting pesticides, which was administered by the newly formed Ministry of the Environment.
  • In the 1970s, studies began to look at the dioxin contaminant found in 2,4,5-T products to assess whether it posed human health risks. Although not all studies pointed to a problem, mounting evidence convinced the government of the day to take early action, despite the fact that 2,4,5-T was still being registered for use in Canada and the United States.
  • In 1979, Ontario proactively restricted the use of 2,4,5-T.
  • In 1980, a final decision to ban the use and sale of 2,4,5-T was made by the Ontario government.
  • 2,4,5-T was removed from the federal registry on December 31, 1985, and all use and sales of these products stopped in Canada.

Pesticide Management Improvements in Ontario

  • In 1990, requirements were introduced for public notification of pesticide use. This allowed the public to make personal decisions about whether to avoid areas where pesticides had been used.
  • In the early 1990s, the Ontario Pesticide Container Recycling Program was established, providing pesticide container depots across the province for growers and commercial applicators to return plastic pesticide containers for recycling.
  • In 1998, requirements were introduced for unlicensed assistants to licensed exterminators to successfully complete a training course, approved by the province, covering basic safety rules on the use of pesticides. 

Ontario’s Cosmetic Pesticides Ban

  • In 2009, Ontario introduced the cosmetic pesticides ban – one of the strictest in the world. It bans the sale and use of approximately 250 pesticide products and ingredients for cosmetic uses.
  • The provincial ban establishes one clear set of rules for the sale and use of pesticides for cosmetic purposes and supersedes local municipal pesticides bylaws.

Creation of Ontario Independent Fact-Finding Panel on Herbicide 2,4,5-T

  • In March of 2011, Ontario announced the establishment of an independent panel with a mandate to determine where, when and how 2,4,5-T herbicide was used in Ontario by provincial government ministries and agencies, and whether exposure may have potential health impacts. Dr. Leonard Ritter was named as the chair. Read the panel’s complete terms of reference.

Training, Compliance and Enforcement

  • Ontario has a comprehensive regulatory framework that controls how pesticides are sold, used, transported, stored and disposed.
  • Ontario government front-line staff conduct proactive outreach and inspections to ensure that companies and individuals are operating safely and in accordance with our protective standards and conditions.
  • A wide variety of compliance and enforcement tools exist to address environmental violations and bring facilities into compliance – ranging from education and voluntary action plans to mandatory measures like tickets, orders or environmental penalties.
  • More serious matters are referred to the Ministry of the Environment’s Investigations and Enforcement Branch for investigation and possible prosecution.

Media Contacts



Environment and Energy Government Health and Wellness Home and Community Rural and North