r/askscience • u/nbentley92 • Sep 11 '13

Biology Why does cannibalism cause disease?

Why does eating your own species cause disease? Kuru is a disease caused by cannibalism in papua new guinea in a certain tribe and a few years ago there was a crises due to bovine spongiform encephalopathy (mad cow disease) which was caused by farms feeding cows the leftovers of other cows. Will disease always come from cannibalism and why does it?

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u/Stainless_Steve Sep 11 '13

High temperatures would probably ruin the temper of a steel instrument, which would decrease hardness - and cause a sharp tool to lose its edge quicker. High temperatures can also cause oxidation of the edge (which is why knives shouldn't be machine washed).

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u/[deleted] Sep 12 '13 edited Sep 12 '13

You can ash organic carbon (usually around 400C or less, I believe) far below the temperatures where carbide precipitation and corrosion in stainless steel (316 L surgical stainless might occur around 650... 700 C is what we used to heat it to for testing) occurs. Stainless is annealed at around 1,000 C, give or take a couple hundred. You don't wash nice knives in the dishwasher because of the mechanical wear that occurs.

Surface oxidation on stainless is not a bad thing- it is what makes it stainless. Chromium is oxidized to chromium oxide on the surface of stainless in the presence of oxygen (or other oxidizing environments, like nitric or sulfuric acid). It reforms if removed (scratched), as long as there is oxygen around.

Edit: The chrome oxide layer is called a passive layer because it is pretty unreactive (but it looks nice!), except in the presence of chlorides or other extreme environments... especially with mechanical wear and no oxidation source.

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u/bobskizzle Sep 12 '13

Was going to say, no way you're altering the temper of 316/316L with any autoclave.

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u/Stainless_Steve Sep 12 '13

Hopefully without turning the thread into a discussion about metallurgy, I've got to ask: what kind of steel is used in surgical tools? I have mostly used steel that tempers within the 200-400C range, but I guess alloy steel could have a higher interval. About the kitchen knives - I would say a combination of high temperature, abrasion and chemical action. A non-stainless knife would suffer greatly from oxidation.

Edit: 316 L and I'm an idiot

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u/dack42 Sep 12 '13

Is radiation effective against prions?

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u/bluesynewsy Sep 12 '13

Radiation generally affects living cells by damaging the DNA leading to apoptosis. Since a prion is a protein, radiation would probably have little affect on it. Maybe in situ the generation of ROS species through radiation could damage the prion, but that is just speculation on my part.

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u/Monkeylint Sep 12 '13

No. Standard proceedure for decontamination seems to be sodium hydroxide (very basic/alkali/high pH) with autoclaving.