tin can-- the first cans were tin, which is a rather soft metal you could just stick a knife in, and rip open a jagged edge.
tin cans also bulged, and split and leaked if not properly sealed, and all instructions for canned food say don't eat the contents if the can has bulged, or split or leaked. but now days the cans are made out of light weight steel, and canning is so industrialied, there hasn't been a case of food poisoning or botillism in ages, in commercially canned food.
early tin cans where sealed with a lead solder, and poorly made tin cans could and did cause lead poisoning. (especially with high acid foods)
there is a famous case of one of the last british explorers looking for the "northwest passage" an artic route from atlantic to pacific, the officers food stores were tinned goods, the common sailors got hardtack and dried fish and other 'old time' foods. over time, all the officers started exhibitting evidence of lead poisoning, including irrational thinking.
Oh joy, to be frozen into a ice pack north of Hudson bay, and your commanders are going crazy!--i forget the commanders name, but googling 'northwest passage' i expect would find it
