Ex-Formula One driver Mika Salo has expressed fears about the long-term health of fellow racers after finding carbon-fibre dust in his lungs.
Salo raced in F1 from 1994-2002
The 38-year-old from Finland wants talks with the FIA, motorsport's governing body, after brake particles were discovered during an operation.
"There was really a lot of that dust in my lungs," Salo said.
"If I have this much of it, how much will Michael Schumacher, who has driven 10 years longer than me, have?"
An FIA spokesman said: "The specifics of Salo's problems have been brought to our attention and the FIA is discussing those with him."
He added that this was the first time carbon-fibre dust from the brakes of cars had been raised as a potential problem and there was as yet no wider investigation into the issue.
Salo, who said his doctors had been surprised by the amount of dust in his body, drove in 111 F1 Grands Prix between 1994 and 2002.
He had spells with Lotus, Tyrrell, Arrows, BAR, Ferrari, Sauber and Toyota but failed to win a Grand Prix.
He came closest in 1999, when he was forced to hand victory in Germany to Ferrari team-mate Eddie Irvine.
Salo has also driven in Japan, in sportscars and Formula 3000, and in the US-based Champ Car series.