It is possible the toxic defoliant Agent Orange was sprayed in Toronto and the Greater Toronto Area between the 1950s and 1980s.
Hydro One spokesman Daffyd Roderick tells CTV News "it was the practice" over that 40 year period to use the dangerous chemical to clear brush in hydro corridors and around hydro towers.
He added it is possible it was employed for that purpose in the City of Toronto and the surrounding region. Hydro One is now checking all of its files in a massive effort to pinpoint more details of its use.
CTV News has learned Ontario's Minister of Natural Resources is urging for a national effort to determine where and when the herbicide was used.
Ontario's Linda Jeffrey sent a letter on Monday to Federal Minister of Health Leona Aglukkaq recommending a nation-wide investigation to find out where and when the toxin was deployed.
Queen's Park is already coordinating a massive government response to trace the historic use of Agent Orange, previously a federally-regulated herbicide.
Agent Orange was the most widely used chemical in the Vietnam War for clearing jungle brush.
Ontario says it was used by the Ministries of Transport, Natural Resources and the old Ontario Hydro to clear power line pathways and fields.
It may have also been used by municipalities such as Toronto.
Exposure to Agent Orange has been linked to skin disorders, liver problems, certain types of cancers and impaired reproductive functions.
