Environmental Realty of Mercury Contamination in Grassy Narrows

Written by Abimbolo Badejo, Staff Reporter

Grassy Narrows, a First Nation community of 1,600 residents, landed on the world radar due to a tragic mercury poisoning accident, made possible by lax laws regarding environmental pollution in the 1960s. Affected policies have been amended to prevent further occurrences but solutions to the poisoning effects are yet to be addressed effectively.

Government officials discovered Mercury contamination in the English-Wabigoon River in the 1970s, caused by a chemical plant at the Reed Paper Mill in Dryden Ontario. The river flows beside two First Nations communities (Grassy Narrows and Whitedog), which depend on this river as their source of livelihood. The contaminated river poisoned the fish, and this caused a shutdown of the associated fishing industry, resulting in mass unemployment for the residents. In addition, various health defects ranging from neurological disorders  to digestive disorders have been observed among the residents (spanning three generations) with no encouraging end to the defects in sight.

Studies and Plans

Since the discovery of mercury contamination in the river in the 1970s, no major action has been taken besides the establishment of a Disability Board  in 1986, which was saddled with the duty of compensating affected residents; many of whose claims for compensation were denied. After decades of delay, pressures from concerned groups (First Nations and environmental Groups) finally elicited a somewhat response from the Ontario provincial government and the Federal government. The government of Ontario stated in June 2017 that it has secured  $85 million to  clean up the contaminated water and land, while the Federal Government has agreed to put a trust fund in place to ensure the establishment of a treatment center focused on ailments related to the mercury poisoning. The treatment facility is expected to cost about 88.7 million dollars, as estimated after a feasibility study. 1,2

Dryden Paper Mill

Mercury in the Environment

Mercury exists in nature in either the elemental, inorganic or organic forms. The organic form of mercury (Methyl mercury) is of greatest concern in the health industry.  Elemental mercury is transformed into the organic form in the aquatic environment by microbial activity, which is in turn bioaccumulated in the flesh of aquatic organisms  along the aquatic food chain. Biomagnified toxic methyl mercury in the aquatic apex predators is transferred to consumers via efficient absorption from the digestive tracts into the blood stream and eventually through  the blood-brain barrier. Excess concentrations of methyl mercury in the human body, with concentrations above 0.47 µg/day (per kg in adult body weight) and  0.2 µg/day (per kg in a child’s or pregnant mother’s body weight), results in deleterious neurologic effects in humans of any age. Additional health defects such as impaired vision, blindness and digestive disorders have been reported.3,4

Similar tragic occurrences of environmental mercuric contamination have been reported in some parts of the world. Between 1932 and 1968, a chemical plant in Minamata, Japan released mercury into a lake which resulted in the death of over 100 people. This occurrence was highly significant, coining the name “Minamata Disease” for syndromes associated with mercury poisoning, such as brain damage, paralysis, incoherent speech and delirium. Another memorable tragedy was reported in Iraq in the early 1970s, where methylmercury compounds were use in seed treatment in agriculture. Wheat grains that were treated with this toxic compound were planted, harvested and made into flour for human consumption. Bread made from the poisoned flour resulted in high mortality rate among the consumers. Occupational exposure is not left out of the list as reported in Ghana in the 1960s. Elemental mercury is used in artisanal gold mining,  where gold ores from near-surface deposits were mixed with the elemental mercury before heating to release the toxic mercury vapour into the environment, leaving the gold behind. Breathing in the mercuric vapour can lead to severe pneumonitis in humans. 5

Clean-up of Mercury Contamination

Clean-up of mercury contaminated sites, such as Carson River Mercury site and Sulphur Bank Mercury Mine in Clearlake California, have been reported by the United States Environmental Protection Agency (US EPA) . The technology used include ex-situ and in-situ treatment methods. The most common method reported is the excavation and disposal of mercury contaminated soil or sediment, as hazardous waste meant for landfill or treated at an approved thermal treatment facility.  The excavated land is backfilled with clean soil and ecologically restored. An in-situ treatment method can be the stabilization / solidification of the toxic substance by sealing in the contaminant with a mixture of cement and Sulphur containing compounds. This method is made possible using an auger-system to mix the soil and cement to immobilize the contaminant. Contaminated sediments can be sealed by a method called “capping”, where a layer of sand and gravel  is poured over the sediments to prevent contact further with the contaminant. These methods and technologies have been used effectively at various mercury contaminated sites in the United States. More information can be found here: https://www.epa.gov/mercury/what-epa-doing-reduce-mercury-pollution-and-exposures-mercury

Ideally, post remediation monitoring  should include restriction of the sealed-off area to public access, absolute cessation in the consumption of food sourced from the contaminated areas and an active reduction in all processes that release mercury into the environment. In situations where the mercury is an unavoidable  component of an industrial waste such as dental amalgam production wastes or battery chemical wastes, a preventive-control suggestion will be to discharge the liquid waste into a holding reservoir to allow mercury-settling into sludge, which can be collected and treated or appropriately disposed.

Since there is an immense need for more research in sustainable and environmental-friendly extensive mercury spill clean-up, more attention should be focused on proactively preventing further occurrences  by adhering strictly to the controls that have been put in place to manage all operations pertaining to the use of mercury.


  1. https://www.cbc.ca/news2/interactives/children-of-the-poisoned-river-mercury-poisoning-grassy-narrows-first-nation/
  2. https://globalnews.ca/news/5189817/grassy-narrows-liberals-mercury-treatment-facility/
  3. Pirkle, C.M., Muckle, G., Lemire, M. (2016) Managing Mercury Exposure in Northern Canadian Communities. CMAJ, 188 (14) 1015-1023
  4. Bernhoft R. A. (2011) Mercury toxicity and treatment: a review of the literature. Journal of environmental and public health, 2012, 460508. doi:10.1155/2012/460508
  5. Bonzongo JC.J., Donkor A.K., Nartey V.K., Lacerda L.D. (2004) Mercury Pollution in Ghana: A Case Study of Environmental Impacts of Artisanal Gold Mining in Sub-Saharan Africa. In: Drude de Lacerda L., Santelli R.E., Duursma E.K., Abrão J.J. (eds) Environmental Geochemistry in Tropical and Subtropical Environments. Environmental Science. Springer, Berlin, Heidelberg