Medical professionals around the country rallied on Tuesday against the expansion of Enbridge’s Line 3 crude oil pipeline, calling it a threat to human and planetary health.

“The health of Minnesotans is at risk,” said Teddie Potter, director of planetary health at the University of Minnesota School of Nursing, addressing a crowd in St. Paul, Minnesota. “Tar sands oil threatens the health and wellness of future generations; we must stop the line.”

The events were part of a nationwide day of solidarity against the project from Enbridge, a Canada-based oil and gas company. In cities from Augusta, Maine, to Los Angeles, health professionals united with environmental groups and Indigenous water protectors to express their opposition to the firm’s controversial Line 3 replacement, which is already under construction. If completed, the upgrade would double the pipeline’s capacity, transporting vast amounts of tar sands oil from Edmonton, Canada, to Superior, Wisconsin — traveling over sacred Anishinaabe territory in Minnesota in the process.

Enbridge has said the upgrade is needed for safety reasons, to reduce maintenance needs, and to “create fewer disruptions to landowners and the environment.” But opponents from the medical community disagree. According to Health Professionals for a Healthy Climate, or HPHC — the advocacy group that organized Tuesday’s nationwide protests — the project poses both immediate and long-term threats to Minnesota communities and Indigenous peoples, whether from an oil spill or from the pipeline’s contribution to climate change.

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Vishnu Laalitha Surapaneni, an assistant professor of medicine at the University of Minnesota who helped organize the rally in St. Paul, told Grist she is particularly worried about the pipeline’s potential impact on water quality. “We’re in the Land of 10,000 Lakes,” she explained, using Minnesota’s unofficial nickname. “This is not something that is compatible with healthy water.”

In the case of an oil spill, Surapaneni and others have raised concern about the tar sands oil that will be transported through Line 3, a heavy kind of crude oil known as bitumen. To facilitate its flow through pipelines, Enbridge mixes bitumen with a diluent — a proprietary concoction whose specific ingredients are a trade secret. But if Enbridge’s diluent is anything like other companies’, HPHC says it likely contains a mixture of carcinogens such as benzene, toluene, ethyl benzene, and xylene, collectively known as BTEX. Enbridge’s response to Grist’s request for comment did not name the ingredients in its diluent.

There may also be threats from spills of drilling fluid, the substance that Enbridge has been using to lay new sections of pipeline into the ground across Minnesota. Already, Enbridge is under investigation by the Minnesota Pollution Control Agency for having spilled drilling fluid 28 times at 12 river crossings. Although Enbridge has said that the drilling fluid is nontoxic and that the spills had “no impacts to any aquifers nor were there downstream impacts,” geologists and environmental experts remain concerned. Spills elsewhere in the country — albeit larger than those in Minnesota — have polluted wetlands and drinking water, and can harm river and wetland ecosystems.

A protestor holds a sign reading "Treaty" at a drill site on the Red Lake River.
Migizi (Red Lake Nation) stands in front of a police line during a ceremony and demonstration for the water at an Enbridge drill site on the Red Lake River. August 3, 2021. Chris Trinh / Indigenous Environmental Network

Surapaneni also stressed that the rallies on Tuesday were executed in solidarity with Indigenous water protectors, who have led the fight against Line 3 and other fossil fuel infrastructure. Environmental advocates say that Enbridge’s construction on Anishinaabe territory threatens Indigenous sovereignty and violates Native treaty rights, in part by jeopardizing healthy ecosystems that support tribes’ abilities to fish, hunt, and cultivate wild rice.

“I see it as my responsibility to take a stand,” said Taysha Martineau, a water protector from the Fond du Lac Reservation who spoke at the St. Paul rally. “If they build Line 3, they might as well bury me beneath it. … I will do everything in my power to make sure that no oil flows through that pipe.”

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Martineau and many of the health professionals also raised the problem of gender-based violence at construction sites. According to the website for the movement against Line 3, the so-called “man camps” that are built to house pipeline construction workers — most of whom are male — put Indigenous women at a heightened risk of sexual violence and other violent crime. “It is an everyday nightmare for Indigenous mothers all across Turtle Island,” Martineau said, using an Indigenous name for North America. “We don’t know which one of us is next, and it’s a fear we face every day.”

One of the most common refrains from Tuesday’s rally in St. Paul, was that the expanded Line 3 pipeline would hurt public health by contributing to climate change. If the project were completed, the greenhouse gas emissions associated with Line 3 would be equivalent to those produced by 38 million cars — a massive amount of carbon that would require a forest more than twice the size of California to sequester. The planet-warming consequences of these emissions, physicians at the rally warned, would exacerbate health problems for Minnesotans and the broader U.S. population — but especially for lower-income and nonwhite communities.

“I’ve already seen it impact my patients,” Kelly Morrison, an obstetrician and state representative for Minnesota who was invited to speak at the St. Paul rally, told Grist. She cited increasing rates of asthma in Minnesota, as well as cardiovascular and pulmonary issues that have been made worse by wildfire smoke. This year, smoke from fires in Canada — fueled by climate change — has brought some of the worst air quality that the Twin Cities have ever seen.

Morrison noted that Tuesday’s demonstrations were emblematic of a growing willingness within the medical profession to highlight the connections between human and planetary health — “a real sea change for the good,” she said. The Lancet, a leading medical journal, has called climate change the “greatest global health threat facing the world in the 21st century,” with the potential to erase recent decades of health gains from economic development. According to the World Health Organization, global temperature rise may cause a quarter of a million deaths between 2030 and 2050 due to increased heat stress, malnutrition, and diseases like malaria.

While physicians,  Indigenous leaders, and policymakers addressed the crowd in St. Paul, a delegation of health care professionals led a short march to the Army Corps of Engineers’ office. They intended to deliver a letter addressed to President Joe Biden, urging him to revoke federal permits for Line 3, but were denied entry to the building. Other groups around the country also attempted to deliver letters to their local offices.

“As a health professional, I see it pure and simple: Climate change is a public health issue,” Surapaneni said. “We need health professionals out of our clinics, out of our hospitals and labs, out in the community and raising our voices.”