(Source:Ap) The toxic red sludge that burst out of a Hungarian factory's reservoir reached the mighty Danube on Thursday after wreaking havoc on smaller rivers and creeks, and downstream nations rushed to test their waters. The European Union and environmental officials fear an environmental catastrophe affecting half a dozen nations if the red sludge, a waste product of making aluminum, contaminates the Danube, Europe's second-longest river.The Hungarian Academy of Science said sludge samples taken two days ago showed that the muck's heavy metal concentrations do "not come close" to levels considered dangerous to the environment. But the academy said Thursday it still considered the sludge dangerous — apparently due to its caustic characteristics. Officials from Croatia, Serbia and Romania were taking river samples every few hours Thursday but hoping that the Danube's huge water volume would blunt the impact of the spill. The Hungarian reservoir break on Monday disgorged a toxic torrent through three villages and creeks that flow into waterways connected to the Danube. Creeks in Kolontar, the western village closest to the spill site, were still swollen and ochre red days later and villagers said they were devoid of fish. The red sludge reached the western branch of the Danube early Thursday and its broad, main stretch by noon, Hungarian rescue agency spokesman Tibor Dobson told the state MTI news agency. Dobson said the pH content of the red sludge entering the Danube had dropped and was unlikely to cause further environmental damage. It had been tested earlier at a pH level of 13 and now was down under 10, and no dead fish had been spotted in the Danube, he said. 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.