Defines an occupational disease as any disease or infection arising out of and in the course of employment caused by substances or activities in which an employee is not ordinarily subjected or exposed other than during a period of regular actual employment therein, and which requires medical services or results in disability or death, including: any disease or infection caused by ingestion of, absorption of, inhalation of or contact with dust, fumes, vapors, gases, radiation or other substances; any mental disorder, whether sudden or gradual in onset, which requires medical services or results in physical or mental disability or death; any series of traumatic events or occurrences which requires medical services or results in physical disability or death
The distinction between an accidental injury and an occupational disease can be elusive, but whether a claim is brought as an injury claim or as a disease can significantly affect a worker’s chance of recovery, because a worker’s burden of proof is higher for an occupational disease claim. The primary distinction between an accidental injury and an occupational disease claim is “time-definiteness.” Smirnoff v. SAIF, 188 Or App 438, 443, 72 P3d 118 (2003). Generally, an injury has a sudden onset, while an occupational disease develops gradually over time. The exception to this general rule is a mental disorder, which is classified as an occupational disease under the statute “whether sudden or gradual in onset.” ORS 656.802(1)(A)(B).
A compensable occupational disease is any disease or condition from which a worker suffers and for which the worker produces medical and factual evidence meeting the definitional standard. The primary focus is medical evidence identifying the particular work environmental conditions acting as the major contributing cause of the worker’s occupational disease
The first category of compensable occupational diseases contains those that arise from exposure to a substance. The statute defines this category as “[a]ny disease or infection caused by ingestion of, absorption of, inhalation of or contact with dust, fumes, vapors, gases, radiation or other substances.
The general compensability standard for occupational disease is the “major contributing cause” standard. ORS 656.802(2)(a). See Dietz v. Ramada, 130 Or App 397, 401, 882 P2d 618 (1994) (major contributing cause standard requires that work conditions contribute more than all other causes); McGarrah v. SAIF, 296 Or 145, 171-72, 675 P2d 159 (1983) (employment conditions must contribute more than nonemployment conditions). The burden of proof required to establish an compensable occupational disease lies with the worker, who must prove by a preponderance of the evidence that the worker suffers a compensable disability.