Boeing told Panorama: "As you are making clear these levels are very low and well within current international safety limits."
BAE Systems said the sample was just one thousandth of the limit for long-term exposure prescribed in the UK health and safety standard.
Within the industry, fumes have long been recognised as a hazard.
BAE Systems began notifying operators about problems with contaminated air, and the possibility of crew incapacitation, eight years ago.
BAE says only a small proportion of fume events are due to oil leaks.
It adds that it has updated 70 per cent of oil seals and has no reports of fume events since fitting them. It says the quality of air on the 146 has been proved by independent studies to exceed all international standards.
Boeing told Panorama it's committed to providing a safe cabin environment. And that studies show contaminant levels are low and health and safety standards are met.
The Government is currently conducting its own studies of cabin air during 'fume events'.
Panorama: Something in the Air, BBC One 8.30pm Monday 21 April 2008.