A plastic contaminant linked to the death of belugas?

A chemical present in certain plastics could explain the increase in mortality observed in beluga babies in recent years, believe Quebec researchers.

This is one of the highlights of the great report Microplastics, broadcast on True. This investigation exposes the consequences of pollution by microplastics in the St. Lawrence, which is one of the most contaminated waterways in the world by these tiny fragments of plastics.

Since 2008, 6.2 baby beluga carcasses have been found on average each year in the St. Lawrence. Over the previous 26 years, the average was one carcass per year, reveal data compiled by veterinarian Stéphane Lair of the University of Montreal.

This is an increase of 520%. The methodology has been the same since 1982.

The phenomenon also affects females in childbirth, whose annual number of carcasses has fallen from 0.2 per year to 1.1 during the same period. An increase of 450%.

Our Investigation Office itself witnessed the phenomenon in the L’Isle-Verte region this summer, during the filming of the great report. Microplastics.

A female beluga carcass had run aground, and a baby’s little gray tail was sticking out of the white animal’s vaginal tract, a sign that the beast died during childbirth.

Carl Guimont, manager at Filmar is preparing the transport of the carcass of a female beluga that died in childbirth and was found near Île Verte last summer.

Screen capture, QMI Agency, Yanick Legrand

Carl Guimont, manager at Filmar is preparing the transport of the carcass of a female beluga that died in childbirth and was found near Île Verte last summer.

According to the necropsy carried out on this carcass by Stéphane Lair, the cause of death is dystocia, that is to say a laborious delivery.

“This mortality specific to pregnant females and young people is like a mortgage on the future of the population,” says Robert Michaud, scientific director of the Group for Research and Education on Marine Mammals (GREMM).

Several hypotheses are being studied to explain the increase in mortality, including diet, climate change and the disturbance of pleasure boats.

Only 889 beluga whales remain in the St. Lawrence, according to the last estimate made in 2012. The results of a survey made in 2019 are still pending (see below), but Robert Michaud fears that the decline of this endangered population will continue.

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“There is an urgent situation, we need explanations,” he claims.

Studying beluga whales, a wild species that cannot be put in the laboratory, is complex. Several years may pass before the results of the study on PBDEs are known, says the researcher.

Robert Michaud hopes, however, that the chemical industry will not wait to review its practices.

“Before we produce a new molecule to solve a challenge that we humans face, let’s make sure it won’t do more harm than good. ”

– With the collaboration of Sarah Daoust-Braun and Andrea Valeria


PBDEs are a family of bromine based flame retardants. Beginning in the 1980s, these chemicals were added to certain plastic objects to reduce the risk of fires, including:

  • electronic devices;
  • the rugs ;
  • upholstery of furniture;
  • synthetic building materials.

However, many studies have since found that PBDEs are toxic, says Roxana Suehring, associate professor of analytical chemistry at Ryerson University.

“They particularly affect the thyroid gland and the reproductive system. ”

Notable fact: the thyroid gland plays a role in childbirth in mammals, including the beluga.

PBDEs also have the unfortunate tendency to volatilize plastic and disperse in the environment. Small organisms, such as marine worms, which ingest contaminated particles, will store PBDEs in their fat.

A fish that would eat contaminated worms would in turn accumulate PBDEs, and so on to the top of the food chain, where the beluga is found.

PBDEs were banned in Canada in 2008, with the exception of two variants which were banned in 2016.

However, plastic objects containing this chemical remain in circulation. And PBDEs “are still very present in the tissue of belugas,” says Robert Michaud.



Photo d’archives

There are 10,000 belugas in the St. Lawrence

Prohibition of hunting

1017 beluga whales

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The St. Lawrence population is classified as “threatened species”

889 beluga whales

The population of the St. Lawrence is classified as “endangered”

Latest population assessment. Due to a change in its methodology, Fisheries and Oceans Canada will publish the results in 2023.

Sources: Fisheries and Oceans Canada, Committee on the Status of Endangered Wildlife in Canada

The St. Lawrence is also contaminated with nanoplastics

The St. Lawrence, the source of drinking water for nearly half of Quebecers, is contaminated with nanoplastics, our Investigation Office has learned.

Marc-André Sabourin, Investigation office

“I’m afraid of the long-term effects,” says Julien Gigault, the Laval University researcher who made the discovery.

Nanoplastics are particles invisible to the naked eye that come from the degradation of plastic objects. They are even smaller than microplastics and carry potentially toxic chemicals.

The water samples analyzed were taken from the river between Varennes and Trois-Pistoles, in collaboration with the Institut national de la recherche scientifique et Stratégies Saint-Laurent, a non-profit organization dedicated to the protection of the river.

Several types of nanoplastics have been detected, including polystyrene and rubber, which come from the degradation of polystyrene products and tires.

“This is the first time that I have had such an easy time finding nanoplastics, it’s crazy,” says Julien Gigault, associate professor in environmental chemistry.

Before taking an interest in the St. Lawrence, this researcher nevertheless studied places known for their high plastic pollution, such as the North Atlantic waste vortex and the beaches of Guadeloupe.

The preliminary results shared with our Bureau of Investigation do not allow us to determine the concentration of nanoplastics present in the water. Julien Gigault is reassuring, however, by speaking of “traces”. Nanoplastics are suspended in the St. Lawrence, but in tiny quantities.

Despite everything, the researcher believes that it is necessary to “turn off the tap” as of today to reduce the amount of plastic that ends up in the environment.

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The urgency is all the greater since the nanoplastics cannot be removed from the water, underlines the engineer Caroline Guilmette, of the National Center for Scientific Research, who took part in the work.

“It’s the most dangerous pollution: you can’t see it, it’s there, and you can’t do anything. ”

Worse, nanoplastics are so small that they “can cross all natural barriers” and enter the cells of our body, says Julien Gigault.

Once there, they can release the chemicals they contain, such as PBDEs or bisphenol A – known as BPA and banned in baby bottles – found in other objects.

The effects of nanoplastics on health are not well understood. Various animal studies indicate that there could be a negative effect on the immune system, the hormonal system or the microbiota. However, the concentrations of nanoplastics used were very high.

Julien Gigault’s concern is above all for future generations, who could suffer consequences “that to date, we are not able to imagine”.


Screen capture, QMI Agency, Yanick Legrand

In the lab, the amphipod pictured above was exposed to very high concentrations of microplastics – far greater than in the environment – to determine to what extent it was accumulating them. You can see in green how full his entire digestive system is.



Screen capture, QMI Agency, Yanick Legrand

  • Measurement between 5 mm and 2 micrometers
  • Usually expelled from the body if ingested or inhaled
  • Can be removed from the water with a filter

  • Measures less than 2 micrometers
  • Can enter body tissues and cells if ingested or inhaled
  • Impossible to filter



Screen capture, QMI Agency, Yanick Legrand

In 2020, researchers at McGill University discovered that the St.Lawrence would be one of the most microplastic-contaminated waterways in the world.

  • Wen-Rui Tang (China)
  • Mersey (UK)
  • Irwell (UK)
  • Canal d’Amsterdam (Netherlands)
  • Pearl River (China)
  • Beishagang (China)
  • Caohejing (China)
  • Jiangjiagang (China)
  • Saint Laurent (Canada)
  • Shajinggang (China)

Source: Anthony Ricciardy, McGill University