But that tsunami wave powered 4000 miles westwards right across the Indian Ocean to sweep over Somalia’s pristine beaches, and killed nearly 300 people outright.

The tsunami, however, also uncovered a hidden and altogether more serious problem for Somalis: along more than 400 miles of shoreline, the turbo-charged wave churned up reinforced containers of hazardous toxic waste that European companies had been dumping a short distance offshore for more than a decade, taking advantage of the fact that there was not even a pretend authority in the African “failed state”.

The force of the tsunami broke open some of the containers which held radioactive nuclear waste, lead, cadmium, mercury, flame retardants, hospital waste and cocktails of other deadly residues of Europe’s industrial processes.

As the contaminants spread across the land and in the air, the United Nations said that an unknown number of people died from breathing in toxic dust and fumes. Subsequent cancer clusters have also been linked to Europe’s special gift to the country, delivered by that tsunami.

Rumours had long circulated about European companies, mainly from Italy and Switzerland, taking advantage of the chaos in Somalia to strike immoral deals with local warlords to dump toxic waste. The arrangements, involving countless millions of pounds, inevitably financed the Somali war , offering a powerful incentive to ignore environmental concerns and carry on dumping the waste.

According to the French environment protection group Robin des Bois (“Robin Hood of the Forest”), it costs between €300-€500 (£200-£340) to treat a cubic metre of hazardous waste in Europe, while in Africa it is between six and 15 times cheaper because usually there is no real treatment process and no proper storage.

A report by the United Nations Environment Programme (UNEP) said the release of the deadly substances, resembling the devastation of chemical warfare, will cause serious long-term effects on human health – and there is no chance of a successful clean-up because of the violence and political instability currently plaguing Somalia.

The UNEP report said: “The health problems include acute respiratory infections, dry heavy coughing and mouth bleeding, abdominal haemorrhages, unusual skin chemical reactions and sudden death after inhaling toxic materials.”

It took a tsunami to reveal one of the many secret dumping sites in Africa of European industries’ deadly dregs.

But in recent weeks the voyage of the rust-streaked Probo Koala, a Korean-built, Greek-owned, Panama-flagged, Dutch-chartered 50,000-tonne tanker, has thrown yet more light on a trade that goaded one of Africa’s most distinguished ecologists, Senegal’s Haidar al-Ali, to observe: “We talk of globalisation, of the global village, but here in Africa we are under the impression of being that village’s septic tank.”

It is not yet clear where the Probo Koala’s voyage began, although seas off Gibraltar are believed to be a gathering place for “garbage cowboys”; where ships with unwanted poisonous cargoes transfer them to other vessels specialising in the illegal dispersal of waste in Third World states.

The scandal of the Probo Koala came to light last month, some two weeks after the tanker unloaded its cargo of black sludge in Abidjan, Ivory Coast’s capital , after being turned away from Amsterdam and several African ports. The poisonous sludge, spread on waste ground and in the sea and fresh water lagoons that festoon Abidjan, led to the deaths of at least eight people, including four children, while more than 80,000 others sought medical treatment for nosebleeds, diarrhoea, nausea, eye irritation and breathing difficulties.

When news broke of the first casualties, thousands of Abidjanis packed their belongings onto donkey carts and buses and moved into the surrounding rainforest . Many have fled that refuge in the past few months, trying to escape the violence of the West African country’s ethnic civil war between northerners and southerners.

The Ivorian and Somali tragedies are instructive: they represent what happens to Europeans’ trash more commonly than environmentally-aware citizens might like to think. When ever-stricter European environmental laws mean increasing costs of clearing up and disposing of our waste, criminal middle-men step in and offer low-cost solutions in Africa.

The Dutch authorities refused to accept the ship’s 530 tonnes of a highly toxic mixture of oil residue and caustic soda – and they failed to stop the ship sailing elsewhere. We also know that the Estonian government arrested the ship last week after the Greenpeace vessel Arctic Sunrise blockaded the Probo Koala in the port of Paldiski, where the Tallinn government had refused to accept its bilge contents.

In Amsterdam three months ago, the Probo Koala attempted to unload a cargo of a sticky black liquid described by the tanker’s owners as “waste water” used to clean its crude oil tanks. But residents living near the Dutch city’s port complained when a sharp stench, described as being like a cross between rotten eggs and blocked drains, drifted across their suburb.

A waste disposal company took a sample from the Probo Koala’s “waste water” – it proved to be a highly lethal cocktail of petroleum, caustic soda and other agents that had accumulated in the ship’s lower tank after multiple cleanings.

The port authorities reclassified the tank contents as toxic waste and then instructed the ship’s captain to take the waste to a special facility and dispose of it, at a cost of £150,000 . The Probo Koala’s captain angrily refused and sailed for Estonia to pick up petroleum products destined for Nigeria.

Meanwhile, an off-the-shelf company called Tommy was quickly formed between two French commodity traders and executives of a waste disposal company in war-torn Ivory Coast. After the Probo Koala’s arrival in Abidjan on its return trip from Nigeria, trucks hired by Tommy dumped the ship’s lower tank cargo around the city under cover of darkness. Fumes given off by the waste then led to deaths and widespread illness.

This story is a common one. All down the West African coast, European- and North American-hired ships unload containers filled with old computers, noxious slops and used medical equipment. Scrap merchants, corrupt politicians and underpaid civil servants take charge of this rubbish and, for payment, dump them in landfill sites and off the coastline.

Back in 1988, some 134 states adopted the Basel Convention, drawn up in the Swiss city , which set out to control the export of most forms of hazardous waste from industrialised states to developing countries – although the US, Canada and Australia have refused to ratify the treaty.

“Now, despite the treaty, there is more evidence of death and disease from waste trade than ever before,” said Jim Puckett, an expert in hazardous waste trade with the Seattle-based Basel Action Network. “Unfortunately, if it’s easy to poison the poor for profit, unscrupulous operators and businesses will do it.”

The Probo Koala is believed to have violated at least two other post-Basel conventions on hazardous waste, as well as the Basel Convention itself.

Andreas Bernstoff, a German expert on the toxic waste trade and a former Greenpeace International activist, has identified more than 80 sites in Africa where the rich world’s dangerous trash has been dumped.

But Bernstoff said the global trade in hazardous chemicals is now less of a problem than the rapidly growing amounts of electronic waste and wreckage from computers and ships.

Old computers and cellphones are often not declared as waste, but are shipped abroad as material for repair or recycling, according to bills of loading. But when they arrive they are simply dumped. Electronic waste is mainly exported to West Africa and Asia. “Some 85% of the electronic parts that come out of Western Europe or North America land on a garbage dump in Nigeria, where they are burned,” said Bernstorff.

Some 500 containers of electronic junk arrive each month in the Nigerian port of Lagos. The waste, containing such carcinogenic elements as lead, cadmium and mercury, are then burned by contractors on dumps around the city. Experts such as Bernstoff say this practice will create long-term health time-bombs, leading to epidemics of “first world” diseases such as cancer in third world countries.

In “trash for cash” schemes elsewhere, bales of plastic waste collected under Germany’s widely praised Green Dot recycling programme end up in giant pits in the Egyptian desert.

The government of Benin, Nigeria’s neighbour, was paid more than £1million a year, and given enhanced development aid from its former colonial master to accept France’s hazardous waste, including radioactive materials.

And the German magazine Der Spiegel is investigating the burial of nuclear waste on the Equatorial Guinea island of Annobon.

There is almost nothing that Europe will not try to dump beyond it shores and nowhere where it will refuse to dispose of it. The Dutch, for example, had a huge problem with pig manure, poisoned by the copper products put into feed to expand the water content, and hence the weight, when packaged and sold to consumers, of bacon and pork chops. When environmentalists objected to the noxious dung being dumped in the country’s marshes, the government did a multi-million pound deal with Saudi Arabia to bury Dutch waste in the desert. However, when the Muslim Saudis discovered the waste was mainly pig droppings, they cancelled the contract.

However, some progress is being made. Two French commodity traders have been arrested in connection with the dumping of the Probo Koala cargo after arriving recently in the Ivory Coast on what they described as “a humanitarian mission”. Several Ivorian businessmen connected with the new Tommy company have also been arrested. In Estonia, the Probo Koala and its captain are under arrest on suspicion of trying to land another toxic cargo in the Baltic state.

In November, the Basel Convention countries meet in Kenya, with calls for the treaty to be more strictly enforced in the wake of Abidjan.

“It is shocking that toxic waste from Europe reached the Ivory Coast, causing so much human suffering and damage to the environment,” said European Union environment commissioner Stavros Dimas from Estonia last week.

“The case is a clear violation of European and international law with deadly results. But I fear that the Probo Koala incident is only the tip of the iceberg.”