Cornish tin mines contained arsenic, and it was an advantage to the miner that they could hold the pasty by the convenient 'handle' that it provides to the eater.They would be able to eat the inside and discard the crust when they were finished.
There is no definitive answer to who originally created the pasty. Some people feel it was the Vikings, who brought it over when they invaded Britain. Whereas some feel it may have developed from the Italians, as the Cornish, who developed the pasty, were sailors. But the first written reference to the pasty was with the Cornish.
Here is the story about them originating in devon
http://observer.guardian.co.uk/uk_news/story/0 ,,1945876,00.html
My dear old Mum would ..a champion tatty oggie maker would have been flabbergasted to read that !