Aerotoxicity, if it exists, has nothing to do with recycled air in the air-con system. It is a reaction to oil contamination in the air-con which is caused by low pressure bleed air at the labyrinth seals that keep the engine oil in the engine where it should be. The only thing keeping the oil from entering the bleed air system is the pressure of the bleed air itself. This means that oil can contaminate the system when the bleed pressure is low such as during engine start.
I seem to recall the toxicity of jet engine oils being discussed way back when we were doing engines and systems and if I remember correctly this was cited as the reason early jets like B707s and DC-8s ran turbo compressors for cabin pressure instead of using direct bleed air. Seems like a good idea if you ask me and I guess the B787 will be a different kettle of fish regarding this problem.