The rust-colored flood that has been spreading across Hungary all week after an alumina plant accident on Monday is far from contained, and five deaths have been attributed to the wave of toxic sludge so far. Responders there say, however, that at least the worst has been avoided.

The blue Danube turned red?

After the spill began spreading, the concern that jumped off the page when you looked at a map was that the stuff would reach rivers that feed the Danube. Europe’s second-longest river (after the Volga in Russia) weaves its way past Hungary through Croatia, Serbia, Bulgaria, Romania, Ukraine, and on into the Black Sea.

Indeed, parts of the spill reached the Danube on Wednesday, but Hungarian responders say today that pH of the main river is just over 8, down from about 9 when the material first arrived. Neutral pH is 7, but a range of about 6.5 to 8.5 is considered a safe zone for consumption.

Hungarian disaster officials said alkaline levels in the Danube were normal after emergency crews poured plaster and acetic acid (vinegar) into rivers that flowed into it. “These data give us hope … and we have not experienced any damage on the main Danube so far,” Tibor Dobson, a Hungarian disaster spokesman, told Reuters. [The Guardian]

There were reports of dead fish in several of the smaller tributaries that feed into the Danube; in the small Marcal river, the first to be hit by the spill, all wildlife reportedly died. But officials are relieved that the much larger Danube doesn’t appear to be in serious danger. If the industrial waste that reaches the Danube is sufficiently neutralized and diluted, then the main worry is back in Hungary where the breadth of the red sludge remains, flooding the village of Kolontar. If weather turns warmer, the material could start to dry out and potentially get into the air, creating the danger of inhalation.

How toxic is this stuff?

The red sludge, which now reportedly covers an area of 16 square miles, is waste created by an industrial plant that processes bauxite (an ore made of several aluminum minerals) into alumina (or aluminum oxide—a molecule of two aluminum atoms and three oxygen atoms), which will later be refined into aluminum.

Much of the spill is iron oxide, which is why it has that rust color. The other ingredients, like calcium oxide and silicon dioxide, help to make the sludge itself highly basic, up to around 13 in pH. Hydrogeologist Paul Younger explains:

In the most concentrated areas, he says, it could be compared to products you would clean your kitchen with, causing dry or cracked skin, or — in cases of prolonged contact — it can “lift off the top layer of your skin.” Scores of people have already suffered burns in affected areas, with at least 120 receiving treatment. [BBC News]

So how much should we worry about it making people sick in the long term?

Dr John Hoskins, a consultant toxicologist, says that while the initial spill was quite dangerous, there should not be any long-term impact on human health as long as the waste is cleaned up. “It will be neutralised by nature, because of rain which will dilute it and because of the chances that it will come into contact with slightly acidic substances in soil… but that will take a little time,” he says. For humans, he says, “the danger would essentially be in ingestion, which is unlikely.” [BBC News]

That’s the official consensus at the moment. But Greenpeace scientists are on the ground in Hungary, and they say they’ve found “surprisingly high” levels of arsenic and mercury in the red muck.

Could it happen in the United States?

Probably not, the AP reports, because alumina plants here don’t store their waste as a liquid. The few such plants that operate in the United States dry the material before it goes into storage, leaving it in a consistency more like damp earth than water.

The three U.S. facilities are not required to “dry stack” the waste. But Sandra Bailey, environmental manager at the Sherwin Alumina Co. in Gregory, Texas, said dry waste is easier to handle and is less toxic. Most of the waste in Sherwin’s facility is 80 percent solid and strong enough for heavy equipment to ride on, she said. [AP]

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Image: Google Maps