Airtoxic syndrome has been a much discussed issue, most people don't realise that the cabin air supply on most aircraft comes from a bleed in the engines and can get contaminated. Apparently the Bae 146 was quite bad for this, though various investigations have failed to demonstrate unsafe levels of toxic compounds in Cabin air supplies.
That said I believe the 787's (and all future Boeing aircraft) air supply no longer comes from the engine.