Burnt toast, or any burnt food is only carcinogenic if you eat it regularly and substantially for several years.The odd slice of burnt toast, with the carbon scraped off, who wants it the carbon left on,anyway, will do no one any harm.
The damage is done by people eating burgers, sausages and such like which are burnt round the edges and the burnt area is full of concentrated flavour and absolutely delicious so gobbled up by the eater. possibly on a daily basis.
Another Tired Kicking For The Sick And Disabled By Rishi