Hungary opened a criminal investigation yesterday into an escape of deadly toxic sludge from an industrial plant, amid fears that it could grow into a regional environmental disaster.
Four people were killed, about 120 were injured and three are still missing after a dam holding waste slurry collapsed at an alumina works in the south-west of the country, sending a wave of poisonous red mud racing through nearby villages and into a tributary of the River Danube.
Rescue teams are searching for the missing people, cleaning up the caustic grime and pouring tonnes of gypsum into the River Marcal to try to prevent contamination of the Danube, Europe's second-longest river, which from Hungary flows through Croatia, Serbia, Bulgaria, Romania, Ukraine and Moldova on its way to the Black Sea.
"Our hope is that we'll be able to contain this and it won't get to the Danube," said the Interior minister, Sandor Pinter, as the European Union and environmental groups assessed the potential wider impact of Hungary's worst chemical spill.
"This is a serious environmental problem," said Joe Hennon, a spokesman for the EU. "We are concerned, not just for the environment in Hungary, but this could potentially cross borders."
Philip Weller, the executive secretary of the International Commission for Protection of the Danube, said the spill had triggered his organisation's warning system, which meant that factories and towns along the Danube might have to stop using water from the river.
"This is what you call a significant event," Mr Weller added. "It is a potential threat to neighbouring countries."
Herwit Schuster, a spokesman for Greenpeace, called the mud spill "one of the top three environmental disasters in Europe in the past 20 or 30 years".
"It is clear that 40 sq km [15.5 sq miles] of mostly agricultural land is polluted and destroyed for a long time. If there are substances like arsenic and mercury, that would affect river systems and ground water on a long-term basis," he added. Another major fear is that fish will ingest the heavy metals, so endangering anyone who eats them.
The Hungarian company that runs the alumina plant insisted that safety tests gave no indication of the impending disaster. It was announced yesterday, however, that the national police chief, Jozsef Hatala, will lead an investigation into an accident that unleashed more than one million cubic metres of corrosive crimson sludge.
"There was no natural disaster in the area. If there was no natural disaster, then we have to look for human responsibility," said Mr Pinter, echoing Prime Minister Viktor Orban's earlier comments that human error may lie behind what officials have called an "ecological catastrophe".
The disaster presents Mr Orban's centre-right government with its first major challenge since taking office in April, and one volunteer worker complained yesterday that the clean-up operation was "chaos".
"I think it's a disgrace," he said, while asking not to be named. "Things are going so slowly. The flood was on Monday and now on Wednesday we're still waiting for orders."
The village of Kolontar, just a few hundred metres from the plant, was among the worst affected. The sludge smashed through the main door of the home of Kati Holtzer, trapping her and her three-year-old son inside.
She saved her son by placing him on a sofa that was floating in the muck. She then called her husband Balazs, who was working in Austria, to say goodbye. "We're going to die," she told him, chest-deep in sludge. She was eventually rescued but was left suffering from the effects of chemical burns from her waist down. Her husband said yesterday that both were in hospital.
In Kolontar, a team of military engineers built a pontoon bridge across a toxic stream yesterday so that residents could return briefly to their homes and retrieve some belongings. Many villagers said they were unlikely to return to their houses.
Red sludge is a by-product of the refining of bauxite into alumina, the basic material for manufacturing aluminum. It contains heavy metals and is toxic if ingested. Treated sludge is often stored in ponds where the water eventually evaporates, leaving behind a dried, red, clay-like soil.