In a telephone interview late Thursday from Ajka, where the plant was located, Balazs Tomori, a Budapest-based campaigner for Greenpeace in central and Eastern Europe, described how Hungarian authorities tried to neutralize sludge in the Marcal River, about 40 to 60 miles from where the leak began.
"First, they wanted to add just water, then gypsum, then they went for chemical fertilizers, and in the end, they used acid."
The acid did help, he said. As the red sludge traveled down the Marcal River to the Raba River and into the Danube, he said, pH levels were falling. But because normal pH levels for water are 7 to 8, environmental officials remained worried that readings above 9 still posed dangers, especially to fish and wildlife.
The Danube, Europe's second-longest river after the Volga, flows through Croatia, Serbia, Bulgaria, Romania, Ukraine and Moldova before emptying into the Black Sea. It is a source of drinking water in Germany and in Romania, but it only rarely supplies drinking water to Hungary.
As of Thursday, Tomori said that more than 120 people had been treated in neighboring hospitals for burns. "This is the minimum number. It can be more by now." He also said a fifth victim had died.
Greenpeace campaigners on the scene told residents of Kolontar "how to decontaminate themselves, what kind of protection suit to put on, breathing mask, rubber boots. We also suggest gloves." He said they met a journalist whose shoes had been corroded away by the sludge "and had only the remaining rubber boots.
"Local people who are affected the most do not really want to move back, because it seems impossible to completely clean up this mess, and they have serious concerns about health. They are outraged against the company, because they had very, very unfortunate communication that this is not toxic."
He said that when Hungarian Prime Minister Viktor Orban visited Kolontar, he pronounced part of it uninhabitable, and said a protective barrier should be placed around it "to show the next generation, as a memento, this should not happen anymore."
The United States doesn't have any bauxite deposits to mine, said Alan Septoff, research director for Earthworks, a nonprofit organization focused on dangers of mineral development. However, it has other mining industries that store industrial waste in sludge-filled pits, ponds and embankments, which during heavy rains or earthquakes, could leak and destroy lives and property in their paths.
One of the most widespread worries focuses on storage of toxic coal ash, a byproduct of coal-burning. This waste contains heavy metals such as arsenic, cadmium, lead and mercury, which can slowly leach into local water supplies. Acute exposures have occurred when retaining walls surrounding coal ash ponds have failed:
On Dec. 28, 2008, an earthen retaining wall broke at the Tennessee Valley Authority's coal-fired Kingston Fossil Plant near Harriman, Tenn., releasing more than 1 billion tons of toxic sludge into two watersheds. The 300-acre flow of wet coal ash inundated homes and farmland, spreading heavy metals into the areas. Cleanup continues today and water monitoring is ongoing. As in western Hungary, environmentalists also worry about what happens to the metals and other contaminants left behind in the dusty residues after the water evaporates.