Concentration in humans increasing because of industrial pollution

Mercury levels affecting blood pressure, heart rate

By JANE GEORGE

High levels of mercury in the blood appear to be affecting blood pressure and heart rate of some adults in Nunavik.

According to recently-released results from Laval University's public health unit, more than one in five Nunavik adults have higher-than-average levels of mercury in their blood.

Overall, blood mercury levels are higher in adults 45 to 74, compared to younger adults.

And higher levels of blood mercury are linked to higher blood pressure and an increased heart rate.

Dr. Eric Déwailly, the director of the public health unit, said Nunavimmiut still have better cardiovascular health than most Quebec residents, despite the connection between high mercury blood levels and changes in blood pressure and heart rate.

Déwailly said a poor diet and sedentary lifestyle likely lead to a higher risk of developing cardio-vascular disease than mercury exposure does.

However, other health researchers have suggested mercury exposure may somehow spur the development of cardio-vascular disease, which can lead to heart attacks and stroke.

Mercury is a toxic heavy metal found naturally in the environment.

But the amount of mercury in the environment has increased substantially over earlier natural levels because many industries and coal-burning power plants spew inorganic mercury into the air, which is then carried to the Arctic.

Once mercury rains down and hits water, it undergoes a chemical transformation into a much more toxic form of mercury, called methyl mercury.

This mercury accumulates in ringed seal, Arctic char, shellfish, beluga and lake trout throughout the Canadian Arctic.

Rising mercury levels may also be due to the warming of Arctic waters.

Each spring, when sunlight returns to the northern latitudes, the sun triggers chemical reactions that release mercury from the atmosphere. At the same time, this sunlight also removes mercury from Arctic lakes.

Some studies suggest warmer, cloudier lakes, which contain more tiny vegetation, might not be so self-cleansing.

Nunavik isn't the only Arctic region facing rising levels of mercury in the food chain.

The mercury content in hair of children in Greenland just north of Ilulissat was compared with the mercury content in Greenlandic mummies of humans from the 15th century.

The level of mercury had tripled, from 3.1 ppm at that time to 9.8 ppm in 1985.

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