Some companies in Australia do believe it is an issue and have strict requirements regarding the reporting of "unusual smells" in aircraft.
To say
if there was some long term health issue to every one we would know by now.
is similar to "the earth is flat theory.
People smoked for years before governments stood up and confirmed that smoking was a health hazard. mobile phones, airport screening, aircraft fumes may well have long term issues. Until some one like CASA medical do a long term study we won't know.
What I do know is that I am aware of several people who have ceased flying using "fumes" as the likely reason for their medical condition.
I for one am not going to discount the possibility off hand.
Having said that I flew the 146 for many years without ever smelling fumes.