Health and Safety: Agent Orange Exposure Report Released by Government

On June 13, 2013, the province publicly released its long-awaited report on the exposures of provincial government workers to the herbicide 2,4,5-T, commonly known as Agent Orange.

The report, produced by the “Independent Fact-Finding Panel on Herbicide 2,4,5-T,” confirms what OPSEU members and retirees have told us – that some MTO and MNR workers in the 1950s, 60s and 70s were exposed to large amounts of this dangerous herbicide containing the contaminant TCDD (dioxin). However, the report stopped short of concluding that exposure to the chemicals has caused illnesses. Instead the Panel concludes, “Although individuals exposed to these chemicals may have experienced some of these [adverse health] outcomes, it cannot be concluded that the outcome was due to the exposure.”

This finding by the Panel is not surprising, and was in fact predictable. The Panel was not charged with the task of assessing individual exposures to the herbicide, but was asked to assess historical potential exposures and risks that the government’s use of 2,4,5-T could pose to population health. Given the scope of the investigation, the Panel was not expected to come to conclusions on the relationship between exposures and individual illnesses which may have developed.

The Panel, chaired by Dr. Leonard Ritter, was made up of four other senior scientists with expertise in a range of disciplines – pathology, physiology, pharmacology, epidemiology, exposure assessment and risk assessment. In their work over the past two years, they reviewed over 4700 documents submitted by the Ministries of Natural Resources, Transportation and others, as well as completing a review of scientific literature on 2,4,5-T, the contaminant TCDD and links between exposure and adverse health effects.

Because no assessments of worker exposure to the chemicals were done when the herbicide was being used, the Panel had to use a complex process to develop models to make assumptions about worker exposures over the years. Exposure assessment models were used to develop a range of exposure estimates for different scenarios using assumptions ranging from best to worst-case conditions.

The Panel provided the following opinions based on its review of government documents about the use of 2,4,5-T, the scientific literature and the exposure assessment scenarios it developed:

  • MTO: Exposures exceeded the benchmark for a relatively small number of individuals involved in ground mixing/loading and application by MTO employees.
  • Ontario Hydro:  Exposures exceeded the benchmark for some individuals involved in ground mixing/loading and application by Ontario Hydro employees.
  • MNR: Exposures exceeded the benchmark for some individuals involved in backpack mixing/loading and application by MNR employees and junior rangers.
  • MNR: Exposures exceeded the benchmark for some individuals involved in aerial mixing/loading and flagging by MNR employees.

Since this story first broke in early 2011, many retired OPSEU members (and some who are still working) have contacted OPSEU to ask for advice. Many have also provided their names and some exposure information and/or filed claims with the Workplace Safety and Insurance Board (WSIB). To date, the WSIB has not made any decisions in regard to claims, because it was awaiting the release of this report.

The Panel recognized and agreed with a list of diseases developed by the U.S. Institute of Medicine for which individuals exposed to 2,4,5-T and its contaminants may be at increased risk. For example, the Panel agrees that various cancers, neuropathy, skin conditions, and diabetes may be linked to exposures. However, it is not at all clear how WSIB will now adjudicate the claims that have been made or how long it will take. While the Panel report provides ample evidence that workers were exposed to large amounts of the herbicide over the years, all of their conclusions are based on assumptions based on many sources of information. We don’t know how WSIB will choose to interpret all of this information or what evidence of exposure, it may require from individual claimants.

Advice to OPSEU members and retirees who were exposed to 2,4,5-T

  • If you have already filed a claim with WSIB and have a contact name/number of a person at the Board, you can contact them to ask for updates.
  • If you have health concerns which you think may be related to exposures to 2,4,5-T in the 1950s, 60s or 70s, contact WSIB at 1-800-387-0750 or through the WSIB website:
  • If you have questions about health concerns related to 2.4.5-T exposures and wish to speak to an OPSEU staff person before contacting WSIB, please contact the OPSEU Head Office Pension and Benefits area at 1-800-268-7376.
  • If you would like to speak with an OPSEU member of the Ministry of Natural Resources MERC committee about the report or related issues, contact Dave Fluri (Local 635) at 705-475-5604 (w) or
  • If you are notified by WSIB that your claim has been accepted or denied, please contact the OPSEU Pension and Benefits area to advise them of the decision.


MNR webpage with the report, backgrounder and other important documents:

WSIB page and links re 2,4,5-T exposures: