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Mercury rising August 20, 2010

Posted by Andreas in Column, Environment, South Africa, Sustainable Living.

Mercury rising

(This column was first published on 2010-08-04 at News24 here)

Mercury is nasty stuff. Children whose parents have warned them of the dangers of old-fashioned thermometers know this. But our government and the captains of industry don’t seem to know it. Or perhaps they just don’t care.

The general consensus among scientists is that as a result of human activities, current levels of mercury in the environment are between two and five times higher than they were a century ago. Simply laying the blame at the door of the usual environmental culprits – the developed countries of the First World – would be erroneous. In fact, South Africa bears a particularly high burden of culpability when it comes to mercury pollution.

We are the seventh largest emitters of gaseous mercury in the world. In 2006 it was reported that South Africa is second only to China in terms of overall mercury pollution. A small, preliminary study has found dangerously high mercury levels, well above World Health Organisation guidelines, in fish caught off Durban, Cape Town and the West Coast. While detailed results from the South African Mercury Assessment Programme have yet to be released, we’d probably do well to brace ourselves for more bad mercury news.

The cruel irony is that our national mercury headache is a direct result of the exploitation of the two resources that have contributed more than any others to the country’s industrialisation and the incredible wealth of some of its citizens: cheap coal and abundant gold. Call it environmental karma.

Coal contains small quantities of mercury which are spewed into the atmosphere when it’s burned in power stations, making them the largest source of mercury air pollution worldwide. Mercury has been used traditionally to separate gold from ore and although this method is only used by artisanal miners these days, the toxic legacy remains in our soils and waters. Other sources of mercury pollution include chemical plants, cement kilns, automobile scrap, batteries, electrical equipment, dental amalgam, medical waste, metal smelters, waste incinerators, the paper industry and fluorescent light bulbs.

Mercury is a persistent pollutant that does not break down naturally over time and a potent neurotoxin that can be particularly damaging to the brains of developing embryos and infants. According to US federal agencies, exposure to mercury accounts for an estimated 300 000 to 600 000 American children born with learning deficits annually.

Its toxicity and effect depend on its particular chemical form, but the medical consequences of mercury are generally agreed to be irreversible. Mercury can have detrimental impacts on the human immune, genetic, enzyme and nervous systems, can affect fertility and blood pressure and can lead to memory loss, lowered IQ, tremors, gingivitis, kidney failure, cardiovascular disease, damage to the lungs and gastrointestinal tract, insomnia, mood swings, acrodynia and Hunter-Russell syndrome.

Like I said – it’s nasty stuff! Not something we really want to contaminate our environment with is it!?

Your best chance of exposing yourself to mercury is by eating fish and seafood. Mercury that is deposited in fresh and seawater is converted into a fat-soluble compound called methylmercury which enters the food chain and bioaccumulates. In other words, rather than being excreted, it builds up in the body’s fatty tissue and increases in concentration up the food chain as tiny critters get eaten by larger critters which get eaten by bigger and bigger animals in turn. The largest fish species – tuna, swordfish, barracuda, marlin – thus tend to be the most severely contaminated.

It doesn’t have to be this way. There are ways of curbing mercury pollution by using more eco-friendly industrial processes and scrubbing the stuff from power station smoke stacks. So what’s the problem? As usual, it’s cheaper to pollute than it is not to. Rather than shutting down our dirty coal-fired power stations, government is building more of them.

Mercury pollution represents a classic example of what economists call an externality – a detrimental side-effect of a process or policy that has not been accounted for economically, environmentally, socially or otherwise. It’s that which is ignored, swept under the carpet and left for others to deal with.

Externalities are the equivalent of collateral damage in modern warfare. And just as “accidental” civilian deaths are morally indefensible when you’re bombing enemy territory, “inadvertently” poisoning future generations with mercury is unforgivable. We must stop it!



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