TORONTO - Ontario is launching what's believed to be the first government-wide review of Agent Orange in Canada.

Toxicology expert Dr. Leonard Ritter will lead an independent panel that will investigate Ontario's use of the now-banned herbicide 2,4,5-T over three decades, the government announced Friday.

It's also urging Ottawa and other provinces and territories to do the same, given that the chemical was federally approved until 1985.

"I would love the federal government to come on board," Natural Resources Minister Linda Jeffrey said in an interview. "We've reached out to them and it's not too late. I understand that they were the body that approved this particular herbicide for municipalities and provinces across Canada. I think we're all in this together."

The Ontario Liberals have acknowledged that Agent Orange was "widely used" in the province, and warned that it may have been used elsewhere in the country.

"We know it was used in B.C., New Brunswick and Nova Scotia, as well as Saskatchewan," Jeffrey said. "The first three provinces, it was used in forestry and in Saskatchewan, it was used in the agricultural sector -- not in food production."

A mixture of two chemicals -- 2,4-D and 2,4,5-T -- was used in Ontario during the 1950s, '60s, '70s and possibly the '80s to control growth along provincial highways, transmission lines and on vast tracts of Crown land. Ontario farmers and municipalities also used the chemical, though not on crops, Jeffrey said.

The combination of those two herbicides in equal parts comprised Agent Orange -- the most widely used defoliant in the Vietnam War.

The dioxin-laced component of Agent Orange, known as 2,4,5-Trichlorophenoxyacedic acid, was approved by Health Canada at the time, but it's now known that exposure can lead to skin disorders, liver problems and certain cancers.

Former government workers have come forward saying they were exposed to the chemical and have suffered health problems as a result.

In the wake of those claims, the Ontario government started its own internal investigation and set up hotlines that received hundreds of calls over the last few weeks.

The new fact-finding panel, led by Ritter, will investigate the "scope and scale" of the use of 2,4,5-T by Ontario government ministries and agencies, as well as its potential impact on health, Jeffrey said.

The panel will determine when, where and how the herbicide was used, prepared and stored, as well as whether exposure to 2,4,5-T may have affected people's health.

Ritter, a university professor and executive director of Canadian Network of Toxicology Centres, will have the full-time job of managing, directing and overseeing the daily activities of the panel. He will be assisted by part-time members and support staff.

The panel has been asked to deliver a final report by June 2012, which Jeffrey promised will be made public.