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Old 06-29-2013, 11:50 PM   #1
ShootsNRoots
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Default Urea - Carcinogen Precursor

According to various sources across the internet, Urea, commonly found in yeast energizer or yeast nutrient is a precursor to urethane or Ethyl Carbamate.

I'm looking for facts regarding the levels necessary to be considered dangerous.

Bottles containing Urea + DAP have directions calling for '1 tsp per gallon'; though that seems to apply to wine, mead, cider.

Facts pertaining to its usage in beer would also be helpful.

Any other facts regarding the hazards of urea would be appreciated.

http://www.thebrewingnetwork.com/for...php?f=&t=23065
http://home.comcast.net/~mzapx1/FAQ/Urea.pdf

http://www.homebrewtalk.com/f30/new-...orming-289949/
http://www.homebrewtalk.com/f39/ammo...ea-beer-95876/

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Old 06-30-2013, 01:28 PM   #2
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Urea is a nitrogen source for yeast so I think that the urea is mostly metabolized by the yeast and would't be around or would be at very low levels by time the yeast is done fermenting. I cant find any articles beer related regarding urea conc post fermentation though but it would be interesting to see what is left.

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Old 07-01-2013, 01:46 AM   #3
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your body makes urea

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Old 07-01-2013, 02:09 AM   #4
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Yeah your kidneys put urea in your bladder all day long.

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Old 07-01-2013, 02:20 AM   #5
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grr

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Old 07-01-2013, 03:01 PM   #6
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The yeasts we use are rich in urease, the enzyme that speeds the breakdown of urea into ammonium ions and CO2. Urea wouldn't make a very good nutrient for yeast if they didn't. Other pathways producing nasty things? Perhaps but I can't imagine that much product comes out of those pathways. After all, the commercial yeast nutrients are approved for use in food products.

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Old 07-01-2013, 03:25 PM   #7
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Can you expand on the precursor concern? Just because urea is used in a chemical process to make something else that is toxic doesn't mean it is toxic itself. If it metabolizes in the body into something toxic, that is a different story.

There was some PR stunt playing on this concept a while back but I forget what it was...maybe some sugar substitute. It was something like "product X is made from toxic chemicals but our product is synthesized from a natural product so it is safer" As long as an end product is purified and there are no traces of the precursors, it doesn't matter what it starts from.

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Old 07-01-2013, 03:44 PM   #8
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The Wikipedia article on Ethyl Carbamate (Urethane) is quite interesting. Doesn't really answer the OP's questions but it turns out we are drinking it every time we tip a beer, wine or distilled beverage glass. Urea reacts directly with ethanol to produce it (and an ammonium ion). Whether using yeast nutrient that contains it is an appreciable source of urea (i.e. if the yeast don't convert it all) I have no idea.

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Old 07-01-2013, 11:14 PM   #9
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Quote:
Originally Posted by ajdelange View Post
The Wikipedia article on Ethyl Carbamate (Urethane) is quite interesting.
That's enough to convince me to switch to Fermaid or DAP. That sucks, since I just bought a new bag of DAP + Urea nutrients (LD Carlson) and just added some to my mead batches . Hopefully, the staggered additions will reduce the chances of conversion. I'll try my best to keep the temps down too.
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Old 07-01-2013, 11:29 PM   #10
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MSDS:

Quote:
Toxicological Data on Ingredients: Urethane: ORAL (LD50): Acute: 1809 mg/kg [Rat]. 2500 mg/kg [Mouse].
Meh.
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