Amends the Workers' Compensation Act. Provides that an injury arises out of and in the course of employment only if the accident significantly caused or contributed to both the resulting condition and the disability. Provides that an injury does not arise out of and in the course of employment if (1) the hazard or risk was not incidental to employment and was a hazard or risk to which the general public is also exposed, (2) the injury did not occur at a time and place and under circumstances reasonably required by the employment, or (3) the disability resulted from a personal risk. Limits conditions under which repetitive or cumulative trauma is compensable. Provides that gradual deterioration or progressive degeneration of the body caused by aging is not compensable as repetitive or cumulative trauma. Effective immediately.