Here's the reassuring part from the linked PDF:<p><i>On 8 September 2014, the Federal Public Service (FPS) Health, Food Chain Safety and Environment in Belgium confirmed that samples of mud and water taken from the Rosieres treatment plant, river Lasne and river Dyle, all tested negative for the presence of polio virus.</i><p>But... 45L of "concentrated polio virus"? Although it'd probably be classified, I'd love to see the full detailed report on how and why this happened.