Mercury – a hazard in the oceans and on the land
Mercury vapour enters the body through the air. It destroys kidneys, brain and eyes. Symptoms include loss of teeth and neurological problems which leads to death. Methyl mercury accumulates in fish and passes up the food chain. It is found in high levels in the top carnivores, the larger older fish. Mercury is used by artisanal miners to extract gold. The mercury is removed from the gold as a vapour contaminating miners and those close by. In Colombia, high mercury vapour can be found in dense urban areas. Mercury is also a by-product of burning coal for electricity and is found around power stations. Mercury is used in the new compact fluorescent light bulbs and too often these are just dumped when they no longer work.
Robyn Williams: Fancy some fish for lunch or dinner? Why not go for something really large, some shark or swordfish, or something really old, like roughy? That's where you'll find an added ingredient, but you won't to taste it; mercury.
This will be a very fishy Science Show. Our oldest fish, not recommended for eating, will be 380 million years old, from Western Australia. I'm Robyn Williams. And we'll also have the odd crab. But now we approach fishes, crablike, from the side, and look to mercury itself and how the artisans who extract gold, mainly poor people around the world, are poisoning themselves and their neighbours on a staggering scale. This is Professor Marcello Veiga in Vancouver.
Marcello Veiga: Well, there are two types of mercury. The mercury vapour actually enters the body through the air, so it just accumulates in the lungs and then oxidises in the liver, accumulates in the kidneys, and then it goes to the brain. So what it can do is destroy the kidneys, usually a lot of people die because of kidney failure, and then it goes to the brain it starts creating a lot of neurological problems. Acute symptoms, they lose their teeth, and in the long term start tremors and then dementia and death.
Robyn Williams: Paralysis, yes. Minamata disease is very well-known, named after a town in Japan where a number of children really suffered indescribably, didn't they.
Marcello Veiga: Yes, this Minamata was caused by methylmercury and not by metallic mercury, so methylmercury accumulates in the fish extremely quickly, and then the fish, when it goes up in the food web, passes the entire methylmercury to the human beings, especially the fish with a top position in the food web, like carnivorous fish.
Robyn Williams: The top carnivores.
Marcello Veiga: Yes, the top carnivores, which are the tasty ones. Symptoms of Minamata disease with the methylmercury is different from the symptoms from metallic mercury vapour. So they started losing their peripheral vision, they started having problems with hearing and problems with walking, and then death.
Robyn Williams: Apart from the fishing, which is being well explored, you are exploring what the gold extractors are doing in various parts of the world.
Marcello Veiga: Well, a lot of artisanal gold miners, usually they are using now 1,400 tonnes per year of mercury. So just imagine probably it's close to 40% of total mercury used in the world is being used by these artisanal miners. They don't know how to use it, they just get the mercury, just mix with ore, like they do in Indonesia...
Robyn Williams: And that extracts the gold, does it?
Marcello Veiga: Yes, so the mercury just traps the fine particles of gold and form what is called an amalgam, the same we have in the mouth, and it forms this amalgam with 50-50 gold and mercury, and then after that they just burn off, evaporate the mercury and they have the gold. So they do this in the towns, in the home, they do it everywhere, and contaminate not just themselves but contaminate the neighbours as well.
Robyn Williams: In which countries?
Marcello Veiga: I know about 80 countries that do this. Now we have more problems because it's getting very difficult for them to find mercury, and they don't know how to make this transition from mercury to cyanide and they are using both.
Robyn Williams: What a combination, mercury and cyanide, there's a toxic mixture for you!
Marcello Veiga: It's a bomb I think. Mercury and cyanide, it's not well studied yet but I guarantee this is a bomb.
Robyn Williams: So you're telling me that these artisanal gold extractors around the world, places like Brazil and elsewhere, are using a system which is kind of free for all, where they are evaporating the mercury and it's travelling in the air in all sorts of places. Is it doing damage? Do people know yet?
Marcello Veiga: The worst case that I've seen is in Colombia. I just came from Colombia, just published recently a paper reporting the highest level of mercury in the air in an urban...people just burning mercury just beside a school, beside grocery stores. So the levels are absolutely outstanding. So you don't see the symptoms right away, but neurological effects you are definitely going to see in probably 10 years.
Robyn Williams: How do you differentiate the mercury from that sort of process involving gold from that involving coal fired power stations where I understand something like 60,000 babies in the United States are affected by the mercury coming from the coal that is burnt in that country.
Marcello Veiga: Well, the mercury that comes from the coal power, they're the same. So they go into the atmosphere, but with an exception that they have the big stacks and at a higher temperature in the coal sacks, so the mercury can stay in the atmosphere for longer than the guy just burning mercury in a little bowl. Artisanal miners, when they burn the mercury, this mercury contaminates themselves and the people around immediately. In the coal power they just have this mercury going into the atmosphere and coming down to the sea, coming down to other in low concentration because mercury is diluted in the air. So the low concentration over the years transformed this mercury into methylmercury and then this accumulates in the fish. It's a different factor.
Robyn Williams: Sure, a different sort of process. How many people do you think are affected by this gold processing of mercury around the world?
Marcello Veiga: Probably we have today in gold alone, directly involved, we have about 50 million goldminers, 50 million probably with people just assisting them, just working with them, probably we're talking about 100 million people involved, directly and indirectly in this. If you're going to see how many people are affected, I will not be mistaken if I say probably 300 million people on the planet.
Robyn Williams: 300 million people affected! Extraordinary. Jeffrey, would you introduce yourself? You're involved in the industry, are you?
Jeffrey Selder: Yes, I am, I'm a former graduate student of Marcello's and I now work in the mining industry.
Robyn Williams: And you've been out around various parts of the world to look at the ways in which this is happening. What have you found?
Jeffrey Selder: It's quite shocking really. What drives it is poverty and people are just trying to work and makes ends meet, and people are exposing themselves to these dangerous chemical, they really have no idea what they're doing. And it's shocking.
Robyn Williams: What happens when you turn up and talk to them about it?
Jeffrey Selder: Well, ultimately they're no different than I am, they're just trying to put bread on the table, and despite possible health scares or long-term consequences of using mercury, they're not dissuaded. To them, poverty is something that there is no short-term cure for. To them, life is short anyway, and actually…and that's one thing you see in these areas, is how cheap life seems. Coming from Canada where we are so privileged, it's very difficult to observe.
Robyn Williams: Which country are we talking about here?
Jeffrey Selder: Brazil in particular, that's one that I have some experience in, and those people are quite enterprising and hard-working. It's all about money. They are making money and they want to make more money. So that drives them to want to learn to not use the mercury. There are methods for recovering more gold without using mercury. Quite often they are losing up to 60% or 70% of the gold that they're working hard to extract, but they are losing that to the waste or to the tailings, which in many cases are discharged right into a river. So they're working extremely hard and they're not recovering as much as they could, even though they've already pulled it out of the earth. So, for example, Marcello has shown we can increase that recovery to a very high level and they don't need to use mercury to do it. Once it's been demonstrated to them, they are quite convinced.
Robyn Williams: Marcello, how was that done?
Marcello Veiga: Well, this is very simple, but unfortunately they have to use cyanide. So cyanide is the natural substitute that all the companies in the world use. Yes, it is toxic, but cyanide is degradable, so it doesn't stay too long in the environment, so it can degrade, you can eliminate completely the cyanide. If you use this properly it's much, much better...
Robyn Williams: Surely they know that cyanide itself...does it worry them that it is one of the most poisonous chemicals in the world?
Marcello Veiga: It is, cyanide is very poisonous. If you use it in a high grade, if you just drink it or if you get a smell, if you don't know how to use it, it's dangerous, definitely. But it's different from mercury, mercury just kills in the long term, and cyanide kills right away. But we have about 15% of the gold, 15% to 20% of the gold in the world just being produced by artisanal miners, and people don't recognise this. This is not even in the statistics.
The main society just overlooks these guys, and that's the main problem we have. If we have more participation of the government, more presence of the government helping them, not just putting the guys in prison, it would be much better.
Robyn Williams: Where are you from yourself, Marcello?
Marcello Veiga: I'm originally from Brazil, I'm from Rio, and I used to surf in Rio and the beaches are fantastic, so now I'm just suffering here with the winter in Canada.
Robyn Williams: Well, I come from Australia, where I live, and bringing it closer to home, every household has got some of these new lightbulbs which contain mercury. What are we supposed to do with them when they're dead?
Marcello Veiga: That's one of the major problems in the world. So in the West less than 2% of mercury in the lightbulbs is recovered. In Canada less than 1%. I don't know, in Australia...probably around 2%. Most of the people when they have lightbulbs with 10 or 15 mg of mercury in each lightbulb and these fluorescent lamps, they just throw it away. So again, the governments are not prepared to have an efficient way to recycle that, and even when you recycle...UBC for instance, is the main recycler of mercury in North America. So we recycle the mercury here from the fluorescent lamps, and where is the mercury going? Usually this mercury is recycled and is sent to artisanal miners. So you have to...when you recycle something, you have to be responsible for where the material is going. It's not just 'out of my backyard' is enough. So that's a very cynical position.
Robyn Williams: And there we were talking about those new twisty long-life bulbs used in every home now, containing mercury. So dispose of them with care. I was talking with Professor Marcello Veiga who is from Brazil, and Jeffrey Selder at the Institute of Mining Engineering at UBC in Vancouver.
- Marcello Veiga
- Associate Professor
Norman B. Keevil Institute of Mining Engineering
University of British Colombia
- Jeffrey Selder
- Research Associate
Norman B. Keevil Institute of Mining Engineering
University of British Colombia
- Robyn Williams
- David Fisher