Where does this 15 year period come from?
My father died of gastric ulcers when I was three.
When I was 14, our geography teacher, describing some part of this planet (but I can't remember which part!) mentioned the asbestos industry there and told us that death from gastric ulcers was common in asbestos workers ...
My father's death certificate shows his employment as "Labourer, Asbestos Factory" ...
However, from things my mum told me about other jobs he'd had, it's obvious that he hadn't worked there for 15 years, or anything like as long ...