In Feb 2001 an accident happend from hydraulic fluid on the floor of the aircraft cockpit reacting with a foot and mouth disinfectant splashed onto the pilot. The mixture of the two produced organo phospahtes just as with bleed air and a faulty seal. The pilot was incapacitated in flight, which on a BN Islander, single pilot flying a BA scheduled service is significant. Radar tapes show the plane descend from 2000' to 200. The pilot was grounded for many years, assessed as disabled and still has significant health problems. The effects on the pilots health were no doubt magnified because management chose to check and test fly the aircraft after he landed rather than take the pilot to hospital immeadiatly.
That organo phosphates cause ill health doesnt need further studies. It doesnt need further studies that TCP in oil can get into cabin air by a variety of ways, especialy through faulty bleed air seals.
That airlines will destroy evidence, falsify evidence, commit purjury conduct court cases "unreasonably" and fail to report an accident to AAIB is controversial. It happens though - Air New Zealand and Loganair. As for the regulators AAIB refer to CAA who refer to HSE who refer to AAIB.
The following relates:
House of Commons - Transport - Written Evidence