I spent a little more time to read the issues about it after these posts.
BobL is correct in pointing out that this is incidental contamination of food and that there are 100 other ways to die other than bulk ingestion from your chicken absorbing trace quantities off your chopping board. :)
I also thought about what was meant by "safe". Would I use it on my face every day? No. Dip my hands into it repeatedly daily as part of a job... no. I wouldn't eat it, but there are foods that are made with it such as "glossy" candies (its how it looks glossy apparently). We must also remind ourselves this isn't 1945 where uranium toothpaste, spraying kids with DDT and lead-based makeup was all the rage: http://nymag.com/thecut/2013/12/most...-the-ages.html .... we seem to know a bit more about things now. :)
Thinking about the nature of oils - mineral, avocado, nut, olive etc, they are all essentially the same thing. Hydrocarbons. What difference is one hydro over another? (Im asking as a question, as I don't know) One of the serious things to think about is that mineral oil is utterly inert. Nothing can grow in it. Not bacteria, viruses, fungus, nothing. When its made, it is heated and purified in an precise industrial process. Id imagine the end product is about as pure, clean and chemically homogeneous as you can get.
Comparing this with oils obtained from smaller organic or home processes are going to leave a product that isn't so... industrial. The olive oil will have Certain Beasties squashed in as part of the crushing, the nut and fruit oils will have other impurities. When I read about what to treat chop boards with, it was these impurities that create rancidity and other unwanted side effects. Being a food product it will decompose. Part of the board-soaking process injects these into the timber.....
But the chopping boards had me really stumped for ages. A kitchen store had me make an array of cutting boards, about 30 all up (it didn't "work out" with them. They were too hard to satisfy) and it was a real quandary what to finish them with. They needed something other than a very good polish sanding. I was watching a Russian dude who has a Youtube chanel (MTM woodworking http://mtmwood.com/ ) and he soaks his in a bath which I've since replicated https://www.youtube.com/watch?v=V2t8jXV3fNI . His videos are seriously impressive to watch on a dreary afternoon: https://www.youtube.com/user/mtmwood/