How has the California Workers' Comp. Board determined that a motor vehicle accident was 40-50 work related?

Insofar as causation is concerned, the board, without the aid of the statutory presumption, found that the injury was 40-percent work related. However, if petitioner had been entitled to the benefit of the presumption, the nonattribution clause of Labor Code section 3212 would have precluded apportionment of the disability to any disease existing before the injury. (Muznik v. Workers' Comp. Appeals Bd. (1975) 51 Cal.App.3d 622, 638-639, 124 Cal.Rptr. 407.)