Black Oxide and food prep?

[captain spaulding]

Just wondering what your opinions are on using Black Oxide blades/tools for food prep. I personally would never use certain Black Oxide (cheap/painted) on food and my normal rule of thumb is to not use any Black Oxide on food. I have used my Spyderco Pacific Salt on food though. I guess my question is, is there any health risks in using Black Oxide coated blades to prep or cut prepared food that you ingest? Thoughts, comments, links, are all appreciated.

[Steinar]

Well, I would avoid it. No matter what the non-iron compound is in the oxide is. Iron becomes toxic pretty quickly with high intakes, and I have hemochromatosis in the family for good measure. (Yes, the blade is of iron, but that's in metallic form, which will obviously rub off much less into the food. The same way VG-10 contains cobalt, which is pretty toxic, but VG-10 is still accepted for food prep.)

I guess some extremely wear-resistant layer would be OK, but then you'd have to start checking whether it was acceptable for contact with food, since you then get funky chemicals in the mix.

[Syph007]

The BO is iron oxide, specifically Magnetite.  (Fe3O4)

Here is the material data safety sheet for it.

http://fscimage.fishersci.com/msds/09765.htm

"The toxicological properties of this substance have not been fully investigated. "

[Syph007]

Heres a study on the toxicity in mice.

http://www.worldscientific.com/doi/abs/10.4015/S1016237212500056?journalCode=bme

"LD50 of naked Fe3O4-nanoparticles in mice was 163.60 mg/kg of body weight"

LD50 means lethal dose for 50% of population of those mice... so you can figure out how much would kill a human by scaling that value up.

[Nhoj]

I would think when you can avoid it for food prep do, and when you can't you'll be fine as long as you don't do it often.

[captain spaulding]

Thanks guys. Kinda what I thought. Thanks Syph for the links. I will have to look those over tomorrow when i'm not tired. 

[Steinar]

LD50 is informative, but not that useful for foodstuff for humans. We want difficult stuff like "will it lead to cancer or other problems in 10 years, or even more?" not only acute poisoning. Also, permanent organ damage will happen long before lethal dosage with many chemicals.

[dks]

I assume the major manufacturers would use a stable/safe black oxide coating
Imagine if you sued Leatherman or Victorinox  for poisoning you. (try  , I want 10% as it was my idea)

1095, D2 etc. steel knives rust and people still use them to cut food without any problems either.

[Syph007]

LD50 is informative, but not that useful for foodstuff for humans. We want difficult stuff like "will it lead to cancer or other problems in 10 years, or even more?" not only acute poisoning. Also, permanent organ damage will happen long before lethal dosage with many chemicals.

Ah that makes sense.  When I used to work in a lab I used to look at how much of something would kill me, but then again, lots of things are insidious and carcinogen too.  Or make you sterile... lol.  I used to work with nasty stuff that was newly synthesized so no MSDS, so I was just extra careful.

I suspect you'd have to ingest an awful lot of magnetite to cause any damage.  And how much would really come off anyway?  Mostly it comes off when new, but very little after its broken in.  So while I wouldn't use it for food prep, I dont think Id worry too much about it either.

[Steinar]

Yeah, that seems reasonable.

[Styerman]

I've done it before , nothing happened . I don't know about protracted , or everyday use . On a picnic/camping trip , no biggie .

Chris

[nervium]

many times i used my carbon coated st 200 to prepare food.no problem.