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Case Study Of Mercury Poisoning In Canada Environmental Sciences Essay

Paper Type: Free Essay Subject: Environmental Sciences
Wordcount: 3619 words Published: 1st Jan 2015

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Between 1962 and 1970, the Wabigon river which was considered as a very important freshwater resource in the north-western part of Ontario, and a major source of food supply for the people of Grassy Narrows and the Wabasseemoong First Nation communities was poisoned when a pulp and paper mill industry known as Dryden paper mill, situated in the north of the river was believed to have pumped about 10 tonnes of mercury into the river with the permission of the Ontario government.. Until 1970, the Ojibwe and other Aboriginal communities along the English-Wabigon River had built their livelihood around this river for nourishment and economic activities. The people were however shocked with a CBC news on November 1, 1970 that this life-giving water was also a source for potential death through mercury poisoning. This paper provides a review of the health effects of mercury poisoning on exposed people and how this goes a long way to affect their way of life. The paper will also look at the interventions put in place by the government, whether those policies were helpful and what could have been done differently. The paper will also review the available regulations in Canada protecting people from such dangerous elements. A review was conducted searching data bases as well as using indexes of published papers to understand the health effects. Contamination of mercury comes from natural and artificial/industrial sources. Naturally, this element appears in small concentrations in many rocks, soils, air and water around the world (Environment Canada). It has been shown that the worst forms of mercury contaminations have all resulted from human activities such as damping of industrial wastes which contain mercury in water bodies and the use of mercury in the mining industry. Mercury has a long standing history of health effects among exposed citizens and has been associated with neurological, cardiovascular, immune system, central nervous system, and kidney problems as well as many other health outcomes (Passos & mergler, 2008). In small-scale gold mining, gold is extracted using mercury amalgamation thus posing a considerable threat to both human and environmental health (Spiegel, Savornin, Shoko, & Viega, 2006). Viega et al (2006) as cited in Mohapatra and Mohapatra (2009) states that artisanal and small-scale gold mining remains the largest global user of mercury and is still increasing mostly in developing countries. Findings have revealed that elevated mercury exposure rates among the exposed are directly related to negative health outcomes. In a recently published report of Dr. Harada, a Japanese mercury expert reveals that the people of Grassy Narrows and whitedog reserve are worse off than they were in 40 years ago when he first visited the community to study the impacts of mercury poisoning on the people. Two of such communities that have suffered from mercury contamination are Grassy Narrows and whitedog first nations reserve in northwestern Ontario, Canada.

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Mercury is a potent toxin, exposed people all over the world at serious risk. Many studies have confirmed mercury toxicity among specific populations and various environmental compartments (National Research Council, 2000). Health outcomes among exposed populations have been shown to be directly correlated with mercury exposure in the environment (Passos & Mergler, 2008). The purpose of this review is to critically evaluate the recent reports involving exposure levels to mercury of Grassy Narrows and whitdog community of Northwestern Ontario and the associated health outcomes on the people.

Between 1962 and 1970, the traditional lifestyles of these two Northwestern Ontario First Nations communities (Grassy Narrows and whitedog) were detrimentally affected by mercury contamination due to a chemical plant upstream from their communities (CBC, 1970). The primary effects of mercury contamination occurred in the main staple of food, fish, which had record-high levels of mercury. The secondary effects of mercury contamination affected the economic resources of these two communities when they were forced to close their commercial fisheries and fishing guides which rendered them unemployed (CBC, 1970).

Dryden Chemicals Ltd. pumped 10 tonnes of mercury during this period (1962-1970) into the Wabigoon River which spread into the English River, the Winnipeg River and eventually into Lake Winnipeg. This plant used mercury to make chlorine for bleaching paper. On provincial orders, Dryden Chemicals greatly restricted its mercury emissions in 1970 and ultimately halted mercury emissions in 1975.

As indicated earlier, there are other activities in Canada such gold mining which expose the populations of the rural communities to mecury. One of such mines located in the first nation communities is the Musselwhite Mine which is owned by Goldcorp Inc (68% and operator), and Kinross Gold Corporation (32%). It is an underground gold mine and processing plant producing nearly a quarter of a million ounces of gold annually. It is situated on traditional First Nations land and works in partnership with First Nation communities. It is however worth mentioning that the relationships and agreements between this gold company and the First Nations have been recognized as best practices within the mining industry (Musselwhite Joint Venture Mine Report, 2006).

Notwithstanding, all these activities directly or indirectly affect water bodies and fist in particular, in these communities. Fishing is an activity considered by some people in Canada as leisure but for aboriginal communities, fish consumption is considered as part of the culture and this constitutes an important source of livelihood for many Aboriginal communities (CBC, 1970).

Mercury exists in three forms; elemental (vapour), inorganic (mercury compounds formed with other metals), and organic (elemental mercury with carbon) (Selid, Xu, Collins, Striped Face-Collins, & Zhao, 2009; Health Canada, 2010). Sources of mercury range from a variety of natural sources, such as volcanoes and soils, to intentional human release activities, such as that in some mining and other industrial operations (Santos, Jesus, Brabo, Camara, Loureiro & Macarenhas, 2000). Mercury has a relatively high vapour pressure, which means that it constitutes a significant amount of volatile chemical being released into the air (World Health Organization [WHO], 2008). Continuous exposure to contaminated air, through direct inhalation of burning amalgam or through consumption of mercury contaminated products, especially fish, are easy source of absorption into the lungs and other organs which results in a significant amount of mercury related health effects (WHO, 2008). Miners also have a high risk of exposure due to direct absorption through the skin while handling the mercury.

Concentrated mercury exposures, such as that in contaminated fish and other consumable products, cause serious health problems. Health effects have shown to be correlated with level and form of mercury exposure, whether it is elemental, organic, or inorganic. Vapour is the most readily transmitted exposure pathway into the body, followed by inorganic exposure on skin (Health Canada, 2010). Biomarkers and bio-monitoring are defined methods to understand levels of environmental chemicals through hair, blood, and urine samples (Wong & Lye, 2008). Biomarkers measure mercury concentrations and all biomarkers identified in literature are accepted as valid indicators of mercury exposure, although each independent marker provides a different interpretation of level or type of exposure. All methods are important in understanding testing levels of mercury exposure, as most literature studies do vary on testing type. The health effects of mercury are highly dependent on its chemical form. In addition, the definition of exposure has been defined differently in most literature, although as a global definition, it is defined as contact over time between a person and one or more biological, chemical, or physical agents (WHO, 2008).

According to Selid, Xu, Collins et al (2009), human related mercury emissions from the work of industries have increased with respect to natural emissions. The Agency for Toxic Substances and Disease Registry (1999), as cited in Selid, Xu, Collins et al (2009), reported that approximately 80% of anthropogenic mercury emissions release elemental mercury into the air through industrial processes, almost 15% of this mercury is released into the terrestrial environment, and 5% of anthropogenic mercury emissions is carried from industrial wastewater to the aquatic environment, instigating food contaminants based on natural resources.

Health Canada defines the blood mercury concentration guidance value, or threshold, of 20µg/L for adults. According to this parameter, any environmental mercury level above this defined amount must have follow up action to reduce the effects of human exposure (Statistics Canada, 2008). Within this paper, the Statistics Canada level will be used as a set point in which comparisons can be made. It should also be noted that occupational exposure to mercury vapour occurs mainly in fishing and gold mining industries where usually people are employed (Vahter, Akesson, Liden, Ceccatelli, & Berglund, 2006).

History: Brief Global Picture.

Globally, mercury poisoning has been documented in countries such as Japan (1953-65), Iraq (1971-72), Pakistan in 1969 and my own country Ghana in 1969. The mercury poisoning in in Japan attracted a lot of interest. This was after some residents of Minamata with strange symptoms of an unknown disease were admitted at the Minamata Health center in 1956. Health officials were able to link this strange disease to mercury poisoning. An industry which used involved mercury in its processes was allowed to release its waste into the Minamata Bay. The authorities detected that people who depended on the fish and shell fish from Minamata Bay were the only people affected by this strange disease. It was realized that the fish and fish shell of the Bay had been poisoned with mercury. The use of mercury however increased drastically throughout the world after world war two in various industries including the paint, agriculture, electrical, leather tanning and paper producing industries.

History of Mercury Poisoning in Canada (Grassy Narrows and Whitedog reverves)

Mercury poisoning in Canada was accorded the necessary attention after the people of Grassy Narrows and whitedog reserves were affected by this ongoing menace at the time. Grassy Narrows is a reserve located about 80km at the northeast part of Kenora. Whitedog, on the other hand is located about 70km to the west, off the Manitoba border. Altogether, there were approximately 850 inhabitants in the two reserves during the late 1960s when the issue of mercury poisoning erupted (CBC, 1970).

The issue of mercury poisoning of Canadian waters and fish became evident to the public in 1969 after the Federal Department of Fisheries and Forestry embarked on the commercial catching of fish from the Lakes of Cedar and Winnipeg as well as the Saskatchewan river and Red river, all in Manitoba (Bligh 1970). This revelation prompted the federal government to inform the owners of the commercial fishermen and tourist centers along the English-Wabigoon river of an impending closure of their facilities because the fish in those rivers were unsafe for both animal and human consumption. Fish in the rivers were testing very high levels of methylmercury (I have not finished this section. Will continue after getting more literature)

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Effects of Mercury on Exposed Populations

Over the last three decades, many human health studies have been executed in many communities to understand the exposure effects of mercury on humans. There is a large body of research evidence that supports a relationship between occupational exposure to mercury amongst exposed people and negative health outcomes. According to a systemic review assessing decade’s worth of data, Passos and Mergler (2008) denote that gold miners are the most critical population with the highest reported levels of mercury in the world today. However, in Canada, where small scale gold mining is not common, the next most critical populations exposed to mercury are those who consume fish from mercury contaminated water bodies either knowingly or unknowingly (Health Canada, 2010). According to the health Canada, Canadians in general are mostly not at risk from Mercury poisoning but there is still a concern especially for people who consume large amounts of fish, marine mammals and wild game as part of their daily diet.

Data was extracted to identify the most prevalent health issues among the exposed people. All studies used cohort or cross sectional designs. The most prevalent health effect noted in the data collected was neurological deficits. Some studies attempted to understand signs and symptoms of past mercury toxicity, while others tested dose level exposure as a risk factor for future neurological effects.

Neuropsychological effects

Multiple references, consisting of cross sectional, cohort and peer reviewed literature were used to depict the effects of mercury exposure on neurological functioning. Results revealed a significant dose response effect between mercury and neurological deficits (Passos & Mergler, 2008). Studies including those who have used rigorous neurological examinations, found neuro-toxic effects including reduced cognitive functions, decreases in attention or spatial performance, poor leg coordination, multiple sensory difficulties, tremors, concentration difficulties, insomnia, memory loss and kidney dysfunction (Counter, Buchanan, & Ortega, 2005; National Research Council, 2000; Passos & Mergler, 2008). One independent study, as well as documented findings within reviews, indicated that hearing loss was associated with mercury exposure among exposed populations, however it is to be noted that authors could not delineate whether the toxicity was strictly due to occupational exposure through inhalation, or if it was through dietary consumption of contaminated area food, such as fish (Counter, Buchanan, Laurell, Ortega, 1998; Passos & Mergler, 2008, National Research Council, 2000). It is difficult to identify comparison factors from each study as results were subtle amongst independent and systemic reviews, as well as most studies did not detail biomarkers.

Immune system effects

Recent studies have narrowed focus in on the impact mercury exposure has on immune system functioning. Studies delineating the relationship of mercury exposure in the Amazon mine workers found a strong correlation between mercury exposure and malaria (Passos & Mergler, 2008). One study reported that malaria was four times higher for those individuals reporting a history of working with inorganic mercury than those who did not (Crompton et al, 2002). A review on evidence in Amazonian mining populations illustrate results consistent with other findings that mercury induced effects are evident including autoimmune dysfunction (Passos & Mergler, 2008). Reports based on urinary biomarkers identified exposure rates ranging from 0 to 240 µg/L and concentrations in the blood samples varied from 0 to 30 µg/L (Crompton et al, 2002, Passos & Mergler, 2008). According to environment Canada, because Mercury exists in three different forms (gas, organic and inorganic), the level of toxicity and persistence in exposed individuals vary depending on this form an individual is exposed to. Silva et al (2004) documented effects of mercury on activated immune cells and documented the response of both inflammation and anti-inflammation and found significantly increased inflammation in those who had been exposed to inorganic mercury and noted that mercury may also be related to other chronic auto-immune diseases such as Lupus and arthritis.

Central Nervous System Effects

The effect of mercury on the central nervous system has been extensively studied in high and low-dose exposures. However, much of the literature identified within the context of the systemic reviews. As part of this review, the initial studies are not included due to the dates completed, however, it is to be noted that Passos and Mergler (2008) and the National Research Centre (2000) found that several signs and symptoms related to the central nervous system deficits are evidential features of chronic high-dose exposures to Mercury in adults. These included sensory impairment of the extremities, disturbance of equilibrium, and subjective symptoms such as headache, muscle and joint pain, forgetfulness, and fatigue (Passos & Mergler, 2008; National Research Council, 2005).

Cardio-vascular effects

Mercury accumulates in the heart, and exposures have been associated with blood pressure changes and abnormal cardiac functioning (National Research Council, 2000). Based on the inclusion criteria of the review, only three studies evaluated mercury exposure and cardio-vascular effects (Passos & Mergler, 2008; Fillion, Mergler, Passos, Larribe, Lemire, & Guimaraes, 2006). Numerous studies of cardiovascular effects have been referenced in the systemic reviews, although all fall outside inclusion criteria for this review. One independent study by Kobal et al, found that chronic exposure in populations has been suggestive of cardiovascular toxicity, however evidence is not clear (Kobal, Horvat, Prezelj Briski, Krsnik, Dizdarevic et al, 2004). Other studies reported hypertension and abnormal heart rate among exposed workers (National Research Council, 2005). It should be noted that all studies, including those within the systemic reviews, reported or referenced that higher blood pressure was significantly related to high mercury levels. It is also to be noted that the biomarker means could not be used as they varied within each study and were not comparable.

Kidney functions

The kidneys are sensitive to mercury following inhalation exposure. Several investigations have found renal changes in populations chronically exposed to mercury poisoning (National Research Council, 2000; WHO, 2008; Passos & Mergler, 2008). One study done in 1993 measured 50 workers in a cohort study looking at exposure level differences on kidney excretions between mining workers and control workers (Cardenas, Roels, Bernard, Barbon, Buchet, Lauwerys, et al, 1993). The statistical analysis resulted in workers excreting a mean mercury level of 22 micrograms over 11 years (Cardenas, 1993). The main renal changes associated with the exposure to mercury were mainly found in workers excreting more than 50 micrograms/g and resulted in increased leakage of tubular enzymes and antigens and biochemical alterations (Cardenas, 1993).

Health Canada also acknowledges that mercury poisoning can be very detrimental to infants, especially when the poison is easily passed on to the infants through breast milk. This is based on the fact that the nervous system of infants and children is very sensitive to mercury and a minimal exposure can cause symptoms such as decreased IQ, delays in walking and talking, lack of coordination, blindness and seizures. The findings of mercury poisoning in adults postulated by health Canada is consistent with the reviews I have done with few additions. High exposures of adults to mercury poisoning leads to detrimental problems such as personality changes, tremors, changes in vision, deafness, loss of muscle coordination and sensation, memory loss, intellectual impairment and in some cases death (Health Canada, 2010)

Effects on the people of Grassy Narrows and Whitedog reserves

Relating the adverse effects of the mercury exposure in Grassy Narrows and Whitedog reserves, the effects manifested in two folds. The primary effects of the contamination occurred in the main staple of food and fish, which had record-high levels of mercury (Harada et al, 1976). The secondary effects affected the economic resources of these two communities when they were forced to close their commercial fishing activity which rendered vast number of people unemployed (CBC, 1970). The exposed communities were affected by a disease known as Minamata disease (Named after a strange disease which affected the people of Minamata in Japan after severe mercury poisoning). Minamata disease is a neurological syndrome caused by severe mercury poisoning. The symptoms of this disease were noticed in the late 1960s among the people in Grassy Narrows and whitedog first nation communities. As indicated earlier, the symptoms being experienced were similar to that which occurred in Minamata, Japan after the severe mercury poisoning in that community. Most Japanese doctors who had been involved in studying this disease came to Grassy Narrows and the whitedog community only to realize that the mercury levels in the bloods of the inhabitants measured between 100ppb and 200ppb, far exceeding the health Canada limit (committee for Native concerns, 2007). According to Harada et al (1976), the people had symptoms such as sensory disturbances, narrowing of the visual field, impaired hearing, abnormal eye movements, tremor, impaired balance and poor articulation of speech.


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