“Expose” or “exposure” means any situation arising from work operation where an employee may ingest, inhale, absorb through the skin or eyes, or otherwise come into contact with a hazardous substance; provided, that such contact shall not be deemed to constitute exposure if the hazardous substance present is in a physical state, volume, or concentration for which it has been determined pursuant to Sections 6382 and 6390 that there is no valid and substantial evidence that any adverse acute or chronic risk to human health may occur from such contact.