Petro-Chemicals and cancer. in VA Disability Compensation Benefits Claims Research Forum Posted 5 hours ago AJAXB37 To win a disability claim you need 1)a current diagnosis, 2) an event or illness in the service and 3)a connection, or nexus linking the two. You didn't post the denial decision, but I assume that the VA denied as not being service-connected. In other words, his evidence did not show that he was exposed to the chemicals and that they caused the disability. You need to establish that he was exposed. You also need to have a medical opinion, or nexus, connected that exposure to his current condition. Assuming you can prove by a buddy statement that he was exposed way back when, you still need to get a doc's opinion that it could cause his disabilities now. Start researching a doctor that can give you what you need.