Just one more ditto on the pass... Food grade drums are easier to find than most think. You just have to get creative about where you look. Check with candy makers, honey bee keepers or anyone that manufactures a finished food product. It may seem like a pain but the health of those you care about make it an important consideration.
Another tip, food processors use a lot of veg/olive oil in 55 gal. drums. I contacted a guy that makes herbal soaps and he generates 3-5 drum a month that contain coconut oil. Found this outfit with some very cool unlined drums at an attractive price just begging to become UDS's!
I'd pass on them too it's just not worth the risk IMO. I think he is crazy trying to get $10 a piece for drums with polyurethane residue in them. If anything he should have offered them up for free...
Go ahead if you want to attempt to make next year's darwin Awards!
Definitely not worth the risk the first time or second or third.....even if you get past the first burn!