|Al Jazeera obtained images which appear to show weaknesses in the breached reservoir dam back in June
Hungary is claiming to have tamed pollution levels from a red sludge that threatened to contaminate the Danube river, even as the death toll from the spill rose to seven.
A man injured in the toxic spill died in hospital early on Friday, while another body was recovered from a sludge-covered area in the village of Devecser later in the day.
But Sandor Pinter, the interior minister, told a news conference on Friday that the spill had not affected the drinking water supply so far, and Anna Nagy, the government spokesman, said the food chain was safe.
"Let's not even consider the pollution that got into the Danube as real pollution now," Pinter said.
"It will not be of an extent which would cause biological or environmental damage."
But the environmental group Greenpeace warned of "surprisingly high" levels of arsenic and mercury in the red sludge spewed from an alumina plant.
Environmental activists said samples taken on Tuesday in Kolontar, the worst-hit village in western Hungary, showed 110mg of arsenic, 1.3mg of mercury per kg of dry matter and 660mg of chrome per kg.
The figures could roughly be translated as 50 tonnes of arsenic, 300 tonnes of chrome and 500kg of mercury set free by the spill, Greenpeace officials said on Friday.
"This contamination poses a long term risk to both the water base and the [surrounding] ecosystem," the group said in a statement.
"As long as the environment is alkaline, these materials are bound in the mud. As soon as the alkalinity is reduced ... these heavy metals are gradually released to the environment."
The information contrasts with that given earlier in the week by Hungary's National Academy of Sciences, which said there were no heavy metals or mercury in the sludge that exceeded the normal environmental limit.
A photograph circulated by the environmental group WWF on Friday suggested the reservoir may have been leaking as far back as June.
Officials at the Ajkai Timfoldgyar plant had no comment.
Monitors in Hungary and in countries downstream on the Danube, including Croatia, Serbia and Romania, are checking the quality of the river every few hours.
Sporadic losses of fish have been recorded in the main branch of the Danube, Hungary's disaster relief services said, but added that it had not seen the same level of devastation that hit local waterways.
Officials said on Thursday that life had been extinguished from the Marcal river, which was struck by the spill first.
There are also fears that a change in the weather could pose greater health problems to local residents.
Zoltan Illes, the environment minister, said as rain gave way to dry, warmer weather over the past two days, the caustic mud is increasingly turning to airborne dust, which can cause respiratory problems and potentially lung cancer.
"If that would dry out then ... wind can blow ... that heavy metal contamination through the respiratory system," he said.
Illes said the long-term effects on the agricultural region were devastating, saying around 809 hectares of topsoil would have to be dug up and replaced because the highly alkaline sludge had killed off all the nutrients and organisms needed to keep the soil healthy.
|Dead fish has been collected at the bank of the polluted Marcal river [AFP]
The company at the centre of the leak said it had released $150,000 to local authorities to help deal with the disaster, and offered its condolences to the relatives of those who had lost their lives.
MAL, the Hungarian Aluminium Production and Trade Company, has come under fierce criticism, with officials suggesting too much of the caustic red sludge was being held in the reservoir.
Authorities have ordered a criminal inquiry into the accident.
MAL insists it has done nothing wrong and that the sludge is not considered hazardous under EU standards.
Tania Page, Al Jazeera's reporter in Kolontar, said 34 homes in the village have been made completely uninhabitable and that authorities said it may take up to a year to get the affected area back to normal.
"The locals have hired themselves a top lawyer. They're all pointing their fingers at the company [MAL]. The government also wants answers."