argument. However, Allan involved a petition to reopen, based on alleged error, mistake, or change in condition after a final order of the Commission had been entered. See § 8-53-119, C.R.S.1973 (1980 Cum. Supp.). In such circumstances, new evidence was necessary to alter the prior decision. Here, the order had not yet become final, and adoption of claimant’s argument would render ineffective the procedures on requesting the referee to alter his initial order before it becomes final.
In contending that the evidence was insufficient to sustain the Commission’s findings, claimant argues that the Commission ignored evidence which entitled him to compensation for either aggravation of a preexisting condition from accidental injury or for occupational disease. We disagree.
The burden was on the claimant to establish his right to compensation benefits, and whether he sustained his burden was a factual question for the Commission to determine. Wierman v. Tunnell, 108 Colo. 544, 120 P.2d 638 (1941); Matthews v. Industrial Commission, (No. 79CA0975, Nov. 13, 1980). Here, the Commission concluded that claimant had not sustained his burden of establishing a causal relationship between his permanent disability and the accidental injury. It is the Commission’s prerogative to determine the probative effect of conflicting testimony, to weigh the evidence, and to draw all reasonable inferences therefrom, and findings based on conflicting evidence are conclusive on review. Crandall v. Watson-Wilson Transportation System, Inc., 171 Colo. 329, 467 P.2d 48 (1970). While claimant did present evidence to the contrary, the record contains expert testimony to the effect that claimant’s condition was no worse approximately one month after the injury than it had been two years earlier, and that any aggravation he suffered from the January 24 accident was only temporary, not permanent.
Moreover, contrary to claimant’s contention, the Commission’s findings were fully supported by testimony of the examining physician, elicited in part on cross-examination, and do not reflect “inordinate” reliance on medical records. In any event, § 8-53-103(2), C.R.S.1973, provides for consideration of such reports “in addition to sworn testimony.”
To prevail on a claim for occupational disease disability benefits claimant was required to show, inter alia, a causal relationship between the nature of his employment and the disease. See § 8-41— 108(3), C.R.S.1973 (1980 Cum.Supp.). Here, too, the testimony of the examining physician supports the referee’s finding in his supplemental order that claimant did not sustain his burden of establishing the necessary causal relationship. And, since the Commission found that claimant had sustained a compensable injury, it could not also find the existence of the conditions necessary to sustain an award of benefits for an occupational disease. ' See Colorado Fuel & Iron Corp. v. Industrial Commission, 154 Colo. 240, 392 P.2d 174 (1964).
The order of the Industrial Commission is affirmed.
ENOCH, C. J., and SMITH, J., concur.