18 September 2013
How mercury poisons gold miners and enters
the food chain
By Linda Pressly BBC Radio 4, Crossing Continents
About 15% of the world's gold is produced by artisanal and small-scale miners, most of whom use mercury to
extract it from the earth. In Indonesia, the industry supports some three million people - but the miners risk
poisoning themselves, their children and the land.
Fahrul Raji, a man in his early 30s, is not feeling well. At the health centre in Kereng Pangi, a town in Central
Kalimantan surrounded by goldfields, he explains his symptoms.
"I often have a headache, and I am weak. I have a bitter taste in my mouth."
According to Dr Stephan Bose-O'Reilly, who is examining him, Fahrul is being slowly poisoned by mercury.
"Fahrul's been working with mercury for many years, and he's showing the typical symptoms of mercury
intoxication," says Bose-O'Reilly, a German medic who began studying the impact of mercury on Indonesians'
health a decade ago. "He also has a tremor and a co-ordination problem."
Although mercury use in small-scale gold mining in Indonesia is illegal, miners still use it to extract gold from
the rock or soil.
Fahrul isn't a miner, but he has a gold shop in Kereng Pangi. Every day miners bring him the fruits of their
labour - usually a pea-sized piece of amalgam that is mercury mixed with gold.
Fahrul burns it, and the mercury evaporates leaving the gold behind. But the fumes are highly toxic, which is
why smelters like Fahrul often show more severe signs of mercury poisoning than miners who use it in the
field.
"Mercury is a neuro-toxin," Bose-O'Reilly explains. "It affects the cerebellum, which is the part of the brain that
helps you move properly, and co-ordinate your movements. Mercury also harms the kidneys and other organs,
but the neurological damage it does is irreversible."
Fahrul's gold shop is on the main street of Kereng Pangi. He sits behind a wooden counter, his blow torch
behind him, waiting for business. At the end of the day, the miners arrive with their pieces of amalgam ready
for smelting. Fahrul says he's worried about the impact of mercury on his health, but he has no intention of
changing his job.
"This is a family business that's been handed down to me. My father was also a gold buyer. And he's about 65
now, and still looks healthy."
Even though he has symptoms, Fahrul has convinced himself that the risk he runs is small. And that is the
problem with mercury - its effects are not dramatic enough, in the short term, to act as a viable deterrent.
The worst case of mass mercury poisoning the world has ever seen happened in Japan in the first half of the
20th Century.
How do miners use mercury?
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Miners excavate and crush large quantities of earth or rock, containing a small quantity of gold
When mercury is mixed with the slurry, it amalgamates with the gold - and the amalgam sinks to the
bottom
The amalgam is separated out, some excess mercury is removed, and the rest is boiled off
A ton of ore may contain less than an ounce (28g) of gold
Symptoms appeared only gradually in the fishing village of Minamata. At first, nobody could explain why
people began to slur their speech, or stumbled when they walked. They would have trouble swallowing, or
tremble uncontrollably. Children were born with disabilities. Thousands would die with what became known as
Minamata Disease.
But it took 30 years - until the 1960s - to identify the cause of the suffering: a local plastics factory that was
dumping mercury into the bay. The mercury was contaminating fish, the staple food of the local population.
If Fahrul continues to smelt mercury in his gold shop, and inhale the poisonous fumes, it is likely his symptoms
will get worse. Bose-O'Reilly says his urine contains 697 micrograms of mercury per litre - far more than usual.
"This is incredibly high," he says. "Most people would have one or two micrograms at most."
There are an estimated 10-15 million unregulated gold miners around the world, operating in 70 countries.
Artisanal small-scale gold mining (ASGM) is the largest source of mercury pollution in the world after the
burning of fossil fuels.
Sumali
Agrawal: There will never be rainforest here again
And in Central Kalimantan the effects of this unregulated industry on the environment have been devastating.
Around Kereng Pangi, the miners have cleared virgin forest once home to orang-utans and hornbills. What is
left is a lunar-like landscape, its pools polluted with mercury.
"There are 60,000 hectares of denuded area that are completely pitted like this," explains Sumali Agrawal the
technical director of YTS, a local NGO working to mitigate the impact of mercury.
"You can see it on Google Earth - a white patch in the middle of a green landscape. This was formerly tropical
rainforest on a sand substrate. If you left it alone for 50 years, some vegetation would grow, but there would
never be a diverse rainforest here again."
There are no large nuggets of gold to be mined around Kereng Pangi - only tiny particles of the precious metal
are present in the tons of earth. Miners use mechanical sluices to trap the mud that is rich in gold. They mix
this with mercury in buckets using their bare hands.
Mercury is a persistent pollutant - it does not break down in the environment.
On the Indonesian island of Lombok, its potential for harm is multiplied because it is being used in conjunction
with cyanide.
"Together mercury and cyanide create double the problem in the environment," says Dr Dewi Krisnayanti, a
soil scientist specialising in heavy metals at Lombok's Mataram University.
Cyanide helps to dissolve the mercury, and when the waste is spilled into paddy fields it binds with organic
molecules in the environment, becoming methyl mercury. This is far more toxic - in Minamata it was methyl
mercury that poisoned thousands of people.
Dewi has analysed samples of rice seeds and leaves from the paddy fields in the south-west of the island.
Cyanide- and mercury-contaminated waste, next to working rice paddies on Lombok
"The concentration of methyl mercury was the highest ever recorded in a laboratory - 115 parts per billion," she
says. "I felt very sad when I saw the data, because methyl mercury can be absorbed by plants, get into the
food chain and affect human health."
The same methods are used to recover gold in other Asian countries too, and these are also rice-eating
nations. If the contamination of paddy fields was found to be widespread, it could be devastating.
The threat is there every day and it is escalating”
End Quote Dr Rachmadi Purwana University of Indonesia
Indonesian's Assistant Deputy Minister of the Environment, Halimah Syafrul, says controls on illegal imports of
mercury are being tightened. And the government hopes the forthcoming ratification of the UN treaty on
mercury - known as the Minamata Convention - will bring international assistance to help Indonesia's miners
find alternatives to the use of mercury.
"There is pollution in the environment, pollution in the rivers, destruction in the mountainous areas and
destruction of our protected forests. It's a similar situation in almost every province and we have 34 provinces
in Indonesia," says Halimah, an environmental scientist by training.
Dr Rachmadi Purwana, professor of Public Health at the University of Indonesia is worried.
"The threat is there every day and it is escalating. We have to remember that in Japan a small place like
Minamata shattered the whole world by revealing Minamata disease. In Indonesia, it's not only in one village,
it's throughout the country. In nearly every province, there is small-scale gold mining."
And what is Rachmadi's fear if there is no action?
"A national disaster."
30 November 2013
Mercury: A beautiful but poisonous metal
By Justin Rowlatt Presenter, Business Daily, BBC World Service
Mercury is the quixotic bad boy of the periodic table - exquisitely beautiful, but deadly. The ancients believed it
was the "first matter" from which all other metals were formed. Yet it is now in such disfavour that an
international treaty exists to curb its use.
It is easy to see why mercury holds such fascination. It is the only metal to be liquid at room temperature. It is
also one of the few things that reacts with that most alluring of all the elements: gold.
The process is extraordinary to see.
In his laboratory at University College London, chemistry professor Andrea Sella peels off a fragile leaf of gold
and places it on a shimmering ball of mercury.
Before my eyes the gold gradually vanishes, folding itself around the silver blob like bed sheets, before
dissolving away.
Mercury - key facts
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Formerly known as hydrargyrum, from Greek for water and silver
Symbol: Hg
Atomic number: 80
Weight: 200.59
Liquid at room temperature
Used for making industrial chemicals or for electrical and electronic applications
Cinnabar (mercury sulphide) is most common ore
Biggest producers: China and Kyrgyzstan
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US Geological Survey: Mercury
"Now boil off the mercury", explains Sella, "and you'll be left with a residue of pure gold."
It is mercury's unique relationship with gold that fascinated the alchemists.
But beware...
"Mercury is a profound, systemic and long-term poison for humans, but also for other organisms," says Sella.
"So getting mercury into the environment is a very serious issue."
About half the mercury that enters the environment every year comes from volcanic eruptions and other
geological processes. There is nothing we can do about it.
But the other half is released by mankind.
Mercury's bright red ore, cinnabar, has been employed as a pigment since Neolithic times. Some 10,000 years
ago, the earliest artists used it to daub pictures of aurochs, the now extinct giant wild cattle they hunted, on the
walls of caves in Turkey.
The Romans used it as a form of rouge make-up, and the Chinese to colour their lacquer, while in the Middle
Ages the pigment was mixed with wax to provide the seals placed on formal documents.
For centuries the metal was also used in medicine. Even fairly recently it was still used in antiseptics, laxatives,
anti-depressants, and drugs to combat syphilis.
Most adults will have used mercury thermometers, and many of us still have mercury amalgam fillings in our
teeth.
Some of the mercury in those medicines and tooth fillings will eventually find its way into the atmosphere.
Many of us can expect to be cremated, that means any mercury goes up in smoke along with our bodily
remains.
And tiny amounts of mercury vapour are the light source in fluorescent bulbs - that's why they need to be
disposed of very carefully.
Find out more
In Elementary Business, BBC World Service's Business Daily goes back to basics and examines key chemical
elements - and asks what they mean for businesses and the global economy.
But tooth fillings and smashed bulbs only account for a fraction of the 2,000 tonnes of mercury released by
humans into the environment each year.
About a quarter is a by-product of power generation. There are traces of mercury in coal, so coal-fired power
stations pump mercury vapour into the atmosphere.
Even more, over a third, is a consequence of our lust for gold.
Worldwide, an estimated 10-15 million small-scale miners dig, dredge, sluice and pan for gold, and many use
mercury to separate the pure metal from the silt.
Mercury forms
an amalgam with gold - it is then boiled off, leaving pure gold behind
The problem comes when they boil off the mercury to release the pure gold, or when they dump the mercurycontaminated tailings.
In water, mercury transforms into a highly toxic organic molecule - methyl mercury - which is readily absorbed
into the bodies of algae and plankton.
More from the Magazine
Fahrul Raji, a man in his early 30s, is not feeling well. "I often have a headache, and I am weak. I have a bitter
taste in my mouth."
Mercury is a neuro-toxin, explains Dr Stephan Bose-O'Reilly. "It affects the cerebellum, which is the part of the
brain that helps you move properly, and co-ordinate your movements. Mercury also harms the kidneys and
other organs, but the neurological damage it does is irreversible."

The metal poisoning millions of miners
Those algae and plankton are eaten by larger animals, which are in turn eaten by larger creatures, which in
turn are often eaten by us (and seals).
In the process, the toxic chemical becomes increasingly concentrated, posing a particular threat to the
developing brains of young and unborn children.
"What we are concerned about is fish at the top of the food chain, fish like swordfish, the predator fish", says
Dr Kate Spencer, an environmental geo-chemist.
"By the time you get to the top of the food chain, we are talking thousands of times more mercury in the flesh
of our fish."
The world's governments can't agree on much. So it is a measure of the concern about the effects of mercury
in the environment that 93 nations, including the United States, have so far signed the Minamata treaty,
designed to curtail mercury pollution.
That means installing equipment to collect it from the exhaust fumes of power stations, smelters and cement
works.
It means continuing to phase out of the use of mercury in medicines and equipment.
Continue reading the main story
Mercury in fish
Women who are pregnant or intending to have a baby, and children under 16:
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Avoid shark, marlin and swordfish
Do not eat more than four medium-sized cans of tuna or two fresh tuna steaks per week
Those over the age of 16:
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Do not eat more than one portion of shark, marlin or swordfish per week
But fish is important for a healthy diet and should be eaten twice a week. Oily fish contain nutrients such as
Omega 3 that are good for the heart and help the brain development of young and unborn children.
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UK Food Standards Agency
But most challenging is likely to be breaking the link between mercury and gold. How do you persuade millions
of small-scale gold miners to stop using the stuff?
One way is to use a device known as a retort, that collects the mercury vapour as it is boiled off.
It dramatically reduces how much vapour is released into the atmosphere, and means the miners can re-use
the mercury, saving them money.
Or you can use a substitute other things for mercury, says Chris Davis, who co-ordinates a campaign by the
Fairtrade Foundation to support small-scale gold miners.
He suggests some pretty unpleasant substances: borax - an aggressive chemical used for industrial cleaning or, even more hair-raising, cyanide,
Both "become safe with exposure to air after about 24 hours," he says.
Adopting one of these alternatives would require investment. And that makes it a tough sell for people who are
so poor that they willingly endanger the health of their families in order to scrape a living from gold.
But let's not forget the good news here - the world has come together to beat its mercury habit.
And if that's possible, then maybe there is still hope we can deal with some of the even bigger environmental
challenges we face.