The New Pollution
Take this story about biofuel plants dumping glycerin into rivers. Sure, it can be broken down by organisms, but it still causes big problems when dumped into ecosystems, just like the black stuff.
"They're really considered nontoxic, as you would expect," said Bruce P. Hollebone, a researcher with Environment Canada in Ottawa and one of the world's leading experts on the environmental impact of vegetable oil and glycerin spills.
"You can eat the stuff, after all," Mr. Hollebone said. "But as with most organic materials, oil and glycerin deplete the oxygen content of water very quickly, and that will suffocate fish and other organisms. And for birds, a vegetable oil spill is just as deadly as a crude oil spill."
Link to nytimes article