Some excerpts to cover what the title is referring to, please see the article for the original text in case my excerpt selection introduced any unintended biases:

Decades of gold mining at Giant Mine in Yellowknife, Northwest Territories, has left a toxic legacy: 237,000 tonnes of arsenic trioxide dust stored in underground chambers.

As a multi-billion government remediation effort to clean up the mine site and secure the underground arsenic ramps up, the Canadian government is promising to deal with the mine’s disastrous consequences for local Indigenous communities.

In March, the minister for Crown-Indigenous relations appointed a ministerial special representative, Murray Rankin, to investigate how historic mining affected the treaty rights of the Yellowknives Dene First Nation.

The story begins when prospectors discovered a rich gold ore body at Giant Mine in the 1930s. While mining started at the nearby Con Mine in the late 1930s, Giant’s development was interrupted by the Second World War. Only with new investment and the lifting of wartime labour restrictions in 1948 did Giant Mine start production.

Mining at Giant was a challenge. Much of the gold was locked within arsenopyrite formations, and to get at it, workers needed to crush, then roast the gold ore at very high temperatures.

This burned off the arsenic in the ore before using cyanide treatment to extract gold. One byproduct of this process was thousands of tonnes per day of arsenic trioxide, sent up a smokestack into the local environment.

Throughout the 1960s, public health officials continually downplayed concerns about arsenic exposure in Yellowknife, whether via drinking water or on local vegetables.

By the 1970s, however, latent public health concerns over arsenic exposure in Yellowknife became a major national media story. It began with a CBC Radio As it Happens episode in 1975 that unearthed an unreleased government report documenting widespread, chronic arsenic exposure in the city. Facing accusations of a cover-up, the federal government dismissed health concerns even as it set up a local study group to investigate them.

Yellowknife’s Giant Mine: Canada downplayed arsenic exposure as an Indigenous community was poisoned

Colonialism, corporate greed and lax regulation led to widespread pollution, particularly affecting Yellowknives Dene communities.

The Conversation (theconversation.com)