A new study says a hydroelectric dam currently in the works in Newfoundland and Labrador could expose more than 200 Inuit people to excessive levels of methylmercury, the most toxic form of mercury.

The report was commissioned by the Nunatsiavut Government, which governs an autonomous Inuit area in the province, to look at the downstream impacts of Nalcor Energy’s 824 megawatt, Muskrat Falls’ hydroelectric dam on the lower Churchill River in Labrador.

The team of independent research from the U.S. and Canada, including scientists from Harvard University and the University of Manitoba, found that flooding the Muskrat Falls reservoir could cause an “overall increase” in the exposure of local Inuit people, with between 32 and 200 individuals being affected depending on the clearance of trees and brush.

Thousands of Inuit live downstream on the shores of Lake Melville, and have relied on the waters for food for centuries.

“Our culture and the health of our people is being threatened directly by this development,” Sarah Leo, president of the Nunatsiavut Government, told NTV.

The findings contradicted an environmental assessment by Nalcor, which showed no measurable of effects of methylmercury at Lake Melville. It said that the toxin would break down as it moved downstream.

“Scientific evidence demonstrates both that there will be substantial downstream impacts, and also that Nalcor’s premise for predicting no downstream impacts was false,” said the authors of the study.

Muskrat Falls dam mapMethylmercury is a toxin that primarily affects the central and peripheral nervous system in humans.

Exposure in adults can affect cardiovascular and immune health, as well as hormone function.

Chronic exposure from seafood has been associated with brain impairment in children, including IQ deficits, attention deficit behaviour, as well reductions in verbal function and memory.

The developing fetus is most vulnerable to effects of methylmercury.

Concentrations of the toxin increase substantially as it makes its way up the food chain. Levels in fish and marine mammals are usually up to 10 million times higher than the water they live, and spikes in exposure can be felt for decades.

The formation of Methylmercury, which occurs naturally by specialized bacteria, is “dramatically enhanced” during flooding thanks to abundant decomposing vegetation in reservoirs, according to the study.

“We are running out of time,” said Darryl Shiwak, Nunatsiavut Minister of Lands and Natural Resources.

“This reservoir will be flooded at some point, (and) when that happens it is too late.”

The study found that experimentally flooded soils from the Muskrat Falls reservoir area showed a jump in methylmercury concentrations within 72 hours, and a 14-fold increase with 120 hours.

The researchers anticipated the elevated levels could last decades.

The Harvard team involved in the study also constructed three possible scenarios that would affect methylmercury levels in Lake Melville in the event of the flooding of the Muskrat Falls reservoir.

The scenario where topsoil, vegetation and trees were completely removed resulted in “significantly lower increases” of methylmercury exposure, whereas only partial clearance of trees and brush led to the funnelling of high amounts of the toxin into Lake Melville.

The current plan is to only partially clear the reservoir, according to the study, and its impacts are “much greater than previously assessed.”

Even if the first scenario took place, the scientists said there would still be an “overall increase in Inuit methylmercury exposure.

The worst outcome could see methylmercury exposure in those who consumer high amounts of local foods increase by up to 1,500 per cent.

“We haven’t considered what we would do … if (Nalcor doesn’t) decide to fully clear Muskrat Falls, but at this point all options would be on the table,” said Shiwak.

The study also called Nalcor’s plan to issue consumption advisories, as a way to mitigate exposure, is a “flawed health-protection strategy.” It added that current impact monitoring plans are “inadequate.”

The researchers also made several recommendations, including:

  • Requiring Nalcor to fully clear the Muskrat Falls reservoir of wood, brush, vegetation and topsoil.
  • Requiring Nalcor to negotiate an impact-management agreement with the Nunatsiavut Government before flooding the Muskrat Falls reservoir.
  • Requiring Nalcor to establish an independent expert advisory committee to advise on mitigation measures and monitoring programs.

Nalcor says it is studying the effects of the dam and monitoring exposure to methylmercury, but it does not believe the Muskrat Falls reservoir poses an increased risk to the people of Lake Melville.

The Muskrat Falls hydroelectric project was green lit by the Government of Newfoundland and Labrador in December 2012. Construction is currently underway and it is expected to take five years to complete.