Subject: Re: slow viruses and organic fertilizers
From: jshields@rigel.oac.uci.edu (Joan Marie Shields )
Organization: University of California, Irvine
Date: 12 Aug 1997 18:05:39 GMT
Message-ID: <MOD$970812.12977@rec.gardens.ecosystems>
References: <MOD$970809.15352@rec.gardens.ecosystems> <MOD$970810.24155@rec.gardens.ecosystems>
Tonymsrad wrote:
>> I know that slow viruses (such as "mad cow"disease, etc.,) are not killed
>> at temperatures lower than about 250 degrees. Are bone meal, blood meal,
>> etc., heated during processing?
Nospam wrote:
>I was leafing through a book called, I think, _Fatal_ _Feast_, and
>that author claimed that there has been at least one case, I think
>in England, of a farmer contracting "mad cow disease" (not a virus,
>a protein that acts like one) from bone meal. But the author seemed
>to be very much on a vegetarian soapbox, so I don't know what to
>think. Anyhow, I didn't buy the book, so I can't look up any
>references in it.
This is just a little FYI:
"Mad Cow Disease" aka: bovine spongiform encephalitis (BSE) (actually,
since the cows aren't really "mad" it's better to refer to it as BSE)
is a prion disease - not a virus.
Proteins are long chains of amino acids - they are also folded into
three-dimensional shapes - shape is very important to their function.
Prions are proteins that have somehow been bent out of shape - they
are able to alter the shape of other proteins by linking to them (there's
more to it than this but this is probably clear enough). Chains and
plaques are formed - this causes considerable problems.
Anyway, a big reason this is such a "new" thing is that when sheep
were processed (a disease called scrapie, similar to BSE, is known
in sheep) they were processed for bone meal as well as for tallow.
The fat was rendered off - the rest was used for feed etc. Prions
are very heat stable but they are also fat soluble which means that
when tallow was made the prions were brought along since chemicals
that solubilized fat were used in the processing - the prions didn't
make it into the parts that were left for meal. Anyway, pertrolleum
products have pretty much replaced the use of tallow and so it wasn't
made anymore - everything went into the meal, no use of fat solubilizers
and so the prions remained.
A little simplistic - maybe too simplistic - but a pretty good general
overview. For more information about BSE I'm sure there are numerous
www pages and such. The FDA probably has an information sheet available
as well.
Sorry to foist so much dry technical stuff on y'all - but I figured
someone might be interested.
joan
--
Joan Shields jshields@uci.edu http://www.ags.uci.edu/~jshields
University of California - Irvine
School of Social Ecology Department of Environmental Analysis and Design
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