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 hour to measure damage from the toxic spill and emergency officials declared one Hungarian tributary dead.

Family photos on a wall Thursday show the height of the sludge after a flood of toxic mud broke into a home in the village of Kolontar, Hungary. Monday’s flooding was caused by the rupture of a red sludge reservoir at a metals works in western Hungary and has affected seven towns near the Ajkai, 100 miles southwest of Budapest.

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 of a waste-storage reservoir at a nearby alumina plant Monday.

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 swathe 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.

“If that would dry out then … wind can blow … that heavy metal contamination through the respiratory system,” he said.

Amid the conflicting reports, officials had 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 southward toward Serbia and Romania.

At monitoring stations in Croatia, Serbia and Romania, officials were taking river samples every few hours, though experts hoped the river’s huge water volume would blunt the impact of the spill.