Mercury is back in the news. And it’s not good.
A new report just released by IPEN (a global network of public interest NGOs) documents the high levels of this potent neurotoxin found in women surveyed in 21 countries, including many small island states. Almost 75 % of the women surveyed had mercury levels greater than 0.58 ppm in hair samples—a level considered the threshold for potentially harmful effects in women of child-bearing age. The predominant cause of this toxicity is the mercury found in fish—the main source of protein in numerous populations on small islands and isolated coastal communities, particularly in regions close to the Arctic. The consumption of fish and other marine animals is considered to be the main source of methylmercury exposure in most populations worldwide.
But a more dramatic report was actually published a few weeks earlier–and seems to have gone unnoticed by the mainstream media. A comprehensive review of mercury levels in human populations over the period 2000 to 2018, was published in the journal Environmental Health Perspectives in October this year. Led by Dr Niladi Basu at McGill University in Montreal, the team analysed almost 435,000 mercury biomarker measurements from 335,391 individuals across 75 countries.
Within the cross-sectional studies, the researchers identified 71 populations from 18 countries that were specifically studied because of concerns associated with the consumption of fish and other aquatic animals. Exposure to mercury in this group of people was approximately four times higher than in the general background population.
Not surprisingly, populations associated with bodies of water tend to have higher levels of mercury. Inland groups that were linked to rivers and lakes had almost seven times more mercury in their blood than normal levels. The data also provided compelling evidence that Indigenous People in many areas of the world, and especially the Inuit in the Arctic, generally experience high exposure to mercury. Many of these communities are heavily reliant upon fish. One study estimated that per capita seafood consumption among Indigenous groups worldwide is as much as 15 times higher than non-Indigenous groups.
The Inuit in the Arctic are exposed to some of the highest methylmercury levels globally, largely due to their reliance on fish and marine mammals for protein. Data from 15 Arctic subpopulations showed median blood mercury concentrations of 8.6 µg/litre, substantially more than levels measured in Europe and the Americas–which generally fall below 2 µg/litre.
The Minamata Convention on Mercury entered in force in 2017. Both Canada and the US are signatories to the convention—which requires parties to apply best available technology to curb mercury emissions from new fossil-fuel power plants. Coal-fired power plants are the worst offenders in terms of mercury emissions.
However, the convention does not apply to existing coal-fired power plants, which are likely to have older equipment and higher pollution levels. And in spite of the rapid penetration of utility-scale solar power and wind energy, globally, coal remains the predominant fuel for power generation. Moreover, the Minamata convention does not set any limit on the number of new coal-fired power plant that a party can construct. Even with best available technology, mercury emissions from coal-fired power plants are not completely eliminated, which means that emissions of mercury are likely to rise even when control technology is installed—as long as coal continues to be used to generate electricity.
Canada doesn’t have a good track record when it comes to managing emissions of mercury. Although, many coal-fired power plants have been shuttered or switched to natural gas, mercury is still found in raw natural gas streams, although in much lower concentrations. The element is absorbed in gas processing facilities and disposed of as supposedly non-hazardous waste. But mercury is impossible to destroy and very difficult to permanently lock away.
During the 1960s, the Dryden pulp and paper mill operated by Reed Paper dumped 10 tonnes of mercury into the Wabigoon-English river system that runs close to the town of Grassy Narrows. The mercury contamination closed a thriving commercial fishery and devastated the Grassy Narrows economy. The people who ate locally-sourced fish developed tremors, slurred speech, tunnel vision and lost muscle coordination—all classic symptoms of Minamata disease. More than 200 people were affected. In September this year, the Ontario government finally said it would ensure that people who receive mercury disability payments are properly compensated.
But the pollution of the rivers close to Grassy Narrows has never stopped. An investigation by Toronto Star reporters in 2017 found heavily contaminated soil with high levels of mercury behind where the mill used to be located.
Globally, the two main sources of global mercury pollution are coal-fired power plants and artisanal gold production. Both technologies—one utility scale, the other small and local, produce substantial quantities of airborne mercury vapour that may literally travel around the world. While Canada can do little to control artisanal gold smelting, it can do a great deal on the global stage to reduce the use of coal for the generation of electricity.
But there is another problem in Canada: the oil sands.
A study published in 2014 measured levels of mercury in the snowpack close to the oils sands region in Athabasca. The Canadian team used spring-time sampling of the accumulated snowpack at sites located at various distances from the major mining and processing plants to estimate winter mercury loadings on a 20,000 km2 area. Levels of mercury increased with the proximity of the sample to major facilities. Maps of mercury levels showed a clear bulls-eye pattern on the landscape with the area of maximum contamination located between the Muskeg and Steepbank rivers. The team concluded that at snowmelt “a complex mixture of chemicals enters aquatic environments that could impact biological communities of the oil sands region.”
These measurements of mercury contamination were made in 2012. Since then, oil sands production has almost doubled.
Mercury pollution is a global problem. Could Canada step up to the plate and show some serious leadership? The federal government could start by not just insisting on a switch from coal to natural gas-fired power plants, but by mandating the closure of coal mines and all commerce and transport of coal. There are more than a dozen coal mines in western Canada. As coal-fired power plants get shut down in the US and Canada, the coal from the mines is now being carried in coal trains to the west coast, and exported to countries in Asia that are not overly concerned about either greenhouse gas emissions or emissions of mercury. Canada is shipping the dirtiest fuel on the planet to overseas markets where it will further exacerbate global warming, and spew neurotoxic mercury into the atmosphere just as if that coal had been burned in Canada.
For more information check out these sources:
The IPEN report is available here: https://ipen.org/documents/mercury-threat-women-children
See the paper by Niladri Basu et al.: A state-of-the-science-review of mercury biomarkers in human populations worldwide between 2000 and 2018. Environmental Health Perspectives, 126(10) October 2018.
The Toronto Star has run a whole series of investigative articles on the Grassy Narrows scandal. See for example: https://www.thestar.com/news/canada/2017/11/11/ontario-knew-about-mercury-site-near-grassy-narrows-for-decades-but-kept-it-secret.html
See: Kirk, J.L., et al “Atmospheric deposition of mercury and methylmercury to landscapes and waterbodies of the Athabasca oil sands region. Environmental Science and Technology. 2014 48, 7374-7383
Also check out this previous post which can be found here.