Zurich and a number of other insurers are facing industrial deafness claims worth over £8m.
Former workers at BMW plants in Swindon and Cowley are claiming for damage to their hearing after working on the production line at the car manufacturing plants between 1963 and 1990.
Peter Lodge, an industrial disease specialist at law firm BPE Solicitors, said he is now dealing with over 1,500 claims - more than double the amount he predicted last year.
"Between 1960 and 1970 there were between 20,000 and 30,000 people working there. There could be more," he said.
Lodge said the compensation bill is expected to rise above £8m.
BMW inherited the liability when it bought the plant. Lodge said claims are being handled by BMW's employers' liability insurer Zurich, which will then seek to recover from the insurers at the time the deafness was caused.
A Zurich spokeswoman said: "We have been dealing with claims for industrial deafness on behalf of BMW for a number of years.
"It would be inappropriate to discuss either individual settlements or speculate on the cost of compensation for these claims."