On researching the various toxic metals and what metal we can truely blame for detrimental effects on human health I have dicovered the following website:
http://www.dartmouth.edu/~toxmetal/index.html
The Dartmouth Toxic Metals Superfund Research Program (DTMSRP), based in Hanover, is committed to researching the effects of heavy metals, predominatly Mercury and Arsenic, on ecosystems and human health. Their research is fundamental to public awareness and contributes to policy and understanding for communities, organisations and federal agencies.
On their website is a very effective and comprehensive breakdown of toxic metals that are released into the environment via industry that could be a threat to public health. Nearly three quaters of elements are metals and most are very important to sustain life on our planet, despite their toxicity. DTMSRP focus mainly on Mercury and Arsenic but also have brilliant overviews of Lead, Cadmium, Chronium, Copper, Nickel and Silver. Specifying the chemical componants of the metals, where they naturally occur, how they have been used and their effect on ecosystems and public health. They also cover a broad stretch of use through history of each element. Cadmium, Chronium, Lead and Copper will all be covered in this blog.
Wednesday, 9 March 2011
Tuesday, 8 March 2011
Minatmata
One cannot talk about Mercury poisoning and pollution without discussing the Minamata disaster, which is considered one of the greatest tragedies of industrial pollution. Hylander and Goodsite's paper in 'Science of the Total Environment' journal, 'Environmental costs of Mercury Pollution', outlined very clearly the grave repercussions of the Minamata disaster.
In the early 1950's people began to report ecological changes in the area, seabirds had begun to fall out the sky, fish dying unexpectedly and, perhaps most famous, the cats began to 'dance'. A year after the emergence of 'dancing' cats the same symptoms appeared in humans who lived around the bay of Minamata, resulting in the name 'Minamata Disease'.
By 1959, it was established that the source of the disease was pollution from Chisso, a company that had previously established itself decades before in Minamata. Yet, despite confirmation and with the backing of the Japanese government, Chisso continued to emit Mercury (Hg) to the environment. In 1968 a special pond was set up for the waste but, as Highlander and Goodsite point out, this only contributed further via ground flows. The factory was shut down three years later, however, the same methods are still employed in the creation of vinyl chloride in China 'showing that short sighted economy still outweighs human and environmental health' (Hylander and Goodsite 2006:362).
Studies show that between 1932 and 1968 more than 225 tons of Mercury was emitted to the ocean, directly causing 100 deaths and indirectly causing the deaths of the tens of thousands diagnosed with brain damage. Between 1980 and 1990 there was a large scale effort to clean up Minamata. The bay was split in two by a large concrete wall and any sediment that contained 8.75 mg kg-1 of Mercury was placed on one side of the bay and buried under a layer of fabric and virgin soil. 10-30% of the Mercury emitted was distributed through out the ocean around the bay but despite this effort Hylander and Goodsite estimate that only 50% of the mercury has been dealt with.
Reference: Hylander and Goodsite (2008) 'Environment costs of Mercury,' Science of the Total Environment 368 (1) 352-370.
In the early 1950's people began to report ecological changes in the area, seabirds had begun to fall out the sky, fish dying unexpectedly and, perhaps most famous, the cats began to 'dance'. A year after the emergence of 'dancing' cats the same symptoms appeared in humans who lived around the bay of Minamata, resulting in the name 'Minamata Disease'.
By 1959, it was established that the source of the disease was pollution from Chisso, a company that had previously established itself decades before in Minamata. Yet, despite confirmation and with the backing of the Japanese government, Chisso continued to emit Mercury (Hg) to the environment. In 1968 a special pond was set up for the waste but, as Highlander and Goodsite point out, this only contributed further via ground flows. The factory was shut down three years later, however, the same methods are still employed in the creation of vinyl chloride in China 'showing that short sighted economy still outweighs human and environmental health' (Hylander and Goodsite 2006:362).
Studies show that between 1932 and 1968 more than 225 tons of Mercury was emitted to the ocean, directly causing 100 deaths and indirectly causing the deaths of the tens of thousands diagnosed with brain damage. Between 1980 and 1990 there was a large scale effort to clean up Minamata. The bay was split in two by a large concrete wall and any sediment that contained 8.75 mg kg-1 of Mercury was placed on one side of the bay and buried under a layer of fabric and virgin soil. 10-30% of the Mercury emitted was distributed through out the ocean around the bay but despite this effort Hylander and Goodsite estimate that only 50% of the mercury has been dealt with.
Reference: Hylander and Goodsite (2008) 'Environment costs of Mercury,' Science of the Total Environment 368 (1) 352-370.
Thursday, 3 March 2011
Mercury from Industrial Pollution
Mercury pollution is not something we should be taking lightly and to quote one of the papers I will be discussing, ‘no one is safe’ (Zahir et al. 2005:352). Mercury is present in the air, water and our food. Approximately 20,000 tons per year is added to the natural environment through anthropogenic activity and comes primarily from coal smoke. This production is not under control and mercury emissions are set to rise by 5% each year (Zahir et al. 2005).
Mercury is used in many industrial processes but none as famous as gold mining. During its application in the extraction nearly 40% of mercury is lost directly to rivers and lakes where it collects in fish and sediments. The affects the trophic levels in ecology creating greater collections of fish the higher up the food chain. I would like to draw attention to the study by Boischio and Henshel (1999), where they studied the consumption of fish in the Maderia River People in the Amazon. The graph they created, shown below, clearly demonstrates the collecting levels of mercury passing through the trophic levels.
Herbivores, those that graze on plants, have the lowest levels of mercury since it takes longer for plants to collect mercury from the sediments on an individual level. Once the herbivore has devoured enough plants, significant levels of mercury being to collect in the blood, this process is repeated up the food chain with increasing levels of mercury from one level to the next. This was discussed in my previous post, where people in the ocean.org video were demonstrating high levels of mercury and health symptoms due to the consumption of fish.
Mining has been shown as one of the key reasons behind mercury pollution; its use in gold extraction has been around since antiquity, along with the health consequences of its use on local communities. Mercury persists in the environment and has severe health consequences. Organic mercury is most toxic to humans, it is able to pass the blood brain boundary and thus affect our motor skills and neurology, encouraging the onset of disease such as Alzheimer’s and Parkinson’s (Zahir et al., 2005). In 1999, a health survey was done of Lake Victoria in Tanzania by Harada et al., they found that some gold miners and fishermen had begun to suffer considerably from the classical symptoms of mercury poisoning; tremors and trouble conceiving.
The table above shows the different health problems reported in the area surrounding the small gold mine in Lake Victoria. Here we see that over a fifth of the study population had begun to suffer from trembling, as well as headaches and numbness. Although everyone in the study were displaying health issues that can be attributed to Mercury, the researchers concluded that this was not a severe situation but needed to monitored and maintained to avoid a health catastrophe.
The release of mercury to terrestrial and water ecosystems is not the end of industrial mercury contamination. During gold purification, the remaining 60% of mercury is released into the atmosphere and affects gold workers by coming into contact with skin whilst being inhaled and ingested (Harada et al., 1999). Due to mercury’s unique chemical makeup it is easily transported through atmospheric circulation around the globe. It then settles in sediments and lakes almost anywhere it is dropped by the wind and thus is considered a global contaminant (Hylander and Goodsite (2006), this brings us full circle to Zahir’s statement ‘no-one is safe.’ Mercury is still heavily used in mining in developoing nations, such as Peru, Columbia, Brazil, Equador and the Phillippines (Harada et al., 1999) it is far from a local problem. It affects developed nations as much as it effects developing regions, all be it indirectly, and thus should start being addressed more radically by the international community.
Mercury is used in many industrial processes but none as famous as gold mining. During its application in the extraction nearly 40% of mercury is lost directly to rivers and lakes where it collects in fish and sediments. The affects the trophic levels in ecology creating greater collections of fish the higher up the food chain. I would like to draw attention to the study by Boischio and Henshel (1999), where they studied the consumption of fish in the Maderia River People in the Amazon. The graph they created, shown below, clearly demonstrates the collecting levels of mercury passing through the trophic levels.
Herbivores, those that graze on plants, have the lowest levels of mercury since it takes longer for plants to collect mercury from the sediments on an individual level. Once the herbivore has devoured enough plants, significant levels of mercury being to collect in the blood, this process is repeated up the food chain with increasing levels of mercury from one level to the next. This was discussed in my previous post, where people in the ocean.org video were demonstrating high levels of mercury and health symptoms due to the consumption of fish.
Mining has been shown as one of the key reasons behind mercury pollution; its use in gold extraction has been around since antiquity, along with the health consequences of its use on local communities. Mercury persists in the environment and has severe health consequences. Organic mercury is most toxic to humans, it is able to pass the blood brain boundary and thus affect our motor skills and neurology, encouraging the onset of disease such as Alzheimer’s and Parkinson’s (Zahir et al., 2005). In 1999, a health survey was done of Lake Victoria in Tanzania by Harada et al., they found that some gold miners and fishermen had begun to suffer considerably from the classical symptoms of mercury poisoning; tremors and trouble conceiving.
The table above shows the different health problems reported in the area surrounding the small gold mine in Lake Victoria. Here we see that over a fifth of the study population had begun to suffer from trembling, as well as headaches and numbness. Although everyone in the study were displaying health issues that can be attributed to Mercury, the researchers concluded that this was not a severe situation but needed to monitored and maintained to avoid a health catastrophe.
The release of mercury to terrestrial and water ecosystems is not the end of industrial mercury contamination. During gold purification, the remaining 60% of mercury is released into the atmosphere and affects gold workers by coming into contact with skin whilst being inhaled and ingested (Harada et al., 1999). Due to mercury’s unique chemical makeup it is easily transported through atmospheric circulation around the globe. It then settles in sediments and lakes almost anywhere it is dropped by the wind and thus is considered a global contaminant (Hylander and Goodsite (2006), this brings us full circle to Zahir’s statement ‘no-one is safe.’ Mercury is still heavily used in mining in developoing nations, such as Peru, Columbia, Brazil, Equador and the Phillippines (Harada et al., 1999) it is far from a local problem. It affects developed nations as much as it effects developing regions, all be it indirectly, and thus should start being addressed more radically by the international community.
Subscribe to:
Posts (Atom)