KOLONTAR, Hungary — Red sludge flowed into the Danube River on Thursday, threatening a half-dozen nations along one of Europe's key waterways. Monitors took samples every few hours to measure damage from the toxic spill, and emergency officials declared one Hungarian tributary dead.
As cleanup crews gathered deer carcasses and other wildlife from the villages in southwestern Hungary flooded by the industrial waste, environmental groups warned of long-term damage to the farming region's topsoil.
Conflicting information swirled about the dangers posed by the ankle-deep muck coating the most seriously hit areas after the collapse Monday of a waste-storage reservoir at a nearby alumina plant.
The Hungarian Academy of Sciences maintained that while the material was a continued hazard, its heavy metal concentrations were not considered dangerous to the environment.
"The academy can say whatever it wants," fumed Barbara Szalai Szita, who lives in Devecser, one of the hardest-hit villages. "All I know is that if I spend 30 minutes outside I get a foul taste in my mouth and my tongue feels strange."
Hungary's environment minister, Zoltan Illes, said the henna-colored sludge covering a 16-square-mile swath of countryside does have "a high content of heavy metals," some of which can cause cancer. He warned of possible environmental hazards, particularly if it were to enter the groundwater system.
With rain giving way to dry, warmer weather over the past two days, the caustic mud is increasingly turning to airborne dust, which can cause respiratory problems, Illes added.
Officials did have one piece of encouraging news: The mighty Danube was apparently absorbing the slurry with little immediate harm beyond sporadic sightings of dead fish.
The red sludge, a waste product of aluminum production, reached the western branch of the Danube early Thursday and was flowing into its broad main stretch by noon. By evening, it was moving south toward Serbia and Romania. Monitoring stations in Croatia, Serbia and Romania were taking river samples every few hours, though experts hoped the river's huge water volume would blunt the impact of the spill.
Hungarian rescue agency spokesman Tibor Dobson said the pH content of the sludge entering the Danube had been reduced to the point where it was unlikely to cause further environmental damage. The waste, which had tested at a highly alkaline pH level of 13 soon after the spill — similar to lye or bleach — was under 10 by Thursday.
A neutral pH level for water is 7, with normal readings ranging from 6.5 to 8.5. Each pH number is 10 times the previous level, so a pH of 13 is 1,000 times more alkaline than a pH of 10.
The tributaries feeding the Danube from the area around the spill were not so fortunate. The Marcal River, stained ochre and devoid of fish and other aquatic life, was declared a dead zone.