Mercury poison in country food could lead to more strokes, heart attacks

High levels of mercury in the blood of adults in Nunavik appear to be upping their blood pressure— which could be a cause for concern because high blood pressure can lead to heart attacks and strokes.

“Inuit from Nunavik are highly exposed to environmental mercury,” which influences their blood pressure, concludes research published Oct. 5 in the American Heart Association’s journal,

Hypertension.

For this study, public health researchers from Quebec looked at the association between mercury blood levels and blood pressure.

They considered all the possible factors which could play into producing higher blood pressure levels, such as age, sex, obesity, cholesterol levels, insulin sensitivity, smoking, alcohol consumption, physical activity, lead, and socioeconomic status.

But even after controlling for these factors and the positive impact of fish nutrients, people with higher levels of mercury in their blood had higher blood pressure.

“Mercury is associated with higher BP [blood pressure] and PP [pulmonary pressure] among Nunavik Inuit adults,” the researchers say in their study called Environmental Mercury Exposure and Blood Pressure Among Nunavik Inuit.

After analyzing blood samples collected during the 2004 Qanuippittaa Inuit health study in Nunavik, researchers found an average blood mercury level of 50 nanomoles per litre of blood.

That’s about seven times higher than the average blood mercury levels found among Canadians and 10 times higher than average levels found in the United States.

According to the findings from Qanuippitaa, blood mercury levels are higher in Nunavik adults 45 to 74, compared to younger adults, who may be eating less country food.

Mercury, a toxic heavy metal found naturally in the environment, accumulates in ringed seal, Arctic char, shellfish, beluga and lake trout throughout the Canadian Arctic.

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

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

Researchers tried to downplay the negative connection between eating mercury-laden fish and sea mammals and developing high blood pressure.

“The small increase of blood pressure due to methylmercury will never outweigh the benefits of omega-3 fatty acids,” Dr. Eric Dewailly, a professor in the department of social and preventive medicine at Laval University in Quebec and the research study’s lead author, told US News and World Report.

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

That’s because 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, may not be so self-cleansing.