AFP: Hungary’s toxic sludge spill, which has killed four people, reached the Danube river Thursday, threatening to contaminate the waterway’s entire ecosystem, officials told AFP. "The red mud pollution has reached the Danube — its so-called Mosoni Branch, about 10 kilometres (six miles) from the main branch of the river — this morning," said Tibor Dobson, the local head of the disaster relief services. "At 09:27 am (0727 GMT), the pH level stood at 9.3. The experts are still …