In "There's Something in the Water", the "Juno" Oscar nominee spotlights the practice of using economically marginalised communities of colour as a location for hazardous projects such as dumps.
Page, also known for her roles in "X-Men: Days of Future Past" and "Inception," based her documentary on a book of the same name by Ingrid Waldron, a nursing professor at Canada's Dalhousie University.
"It's not just about physical harm and health impacts," said Waldron of risky development projects.
"When you just impose yourself on communities ... with no consultation, it's a huge slap in the face and disrespect," she told the Thomson Reuters Foundation in a phone interview.
Page's film follows stories in three historically black or indigenous rural communities in Nova Scotia, a province with about one million residents, some 2.7% of Canada's entire population.
It features communities battling to stop the construction of a new dump, while others push for the clean-up of a contaminated waterway or oppose the construction of a natural gas storage facility.
The documentary was filmed in less than two weeks in April when Page travelled to interview activists and "water protectors", she told the Thomson Reuters Foundation in emailed comments.
Page said she was "thrilled" the documentary had been accepted for the Toronto festival and was "hopeful that the large platform TIFF provides will help spark the change that is needed".
According to Waldron, one of the film's producers, a lack of land rights belies some of the environmental problems featured in the documentary.
African Nova Scotian communities, many of whom were British loyalists, resettled in Canada after the American Revolutionary War in the 18th century and were promised farmland by the British on territory that was then a British colony, Waldron said.
But when they arrived, many black loyalists were placed on rocky scrub land outside of cities which was ill-suited to farming, Waldron added.
Large numbers of dumps and other environmental hazards were then relocated to these areas, compounding their plight.
"African Nova Scotian communities were promised lands that were never given to them," Waldron explained.
Indigenous people, meanwhile, were meant to have been guaranteed land access under treaties signed with Canadian authorities, but Waldron said the government has often failed to respect those rights.
A spokeswoman for the provincial government acknowledged "there are instances of environmental racism stemming from past practices" in Nova Scotia, but said authorities were working to fix the problem.
"Today, the Department of Environment has strong regulations in place to protect the environment for all citizens," Adele Poirier told the Thomson Reuters Foundation in emailed comments.
The provincial government has committed to spend more than 100 million Canadian dollars (76 million US dollars) to clean up Boat Harbour, she said of the polluted waterway highlighted in the film.
