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Re: Bone Meal---Is it harmful?

>Last night watching TV (*Dateline* --NBC) I heard a very scary thing and
>am writing this to seek verification.
>
>The segment was about "Mad Cow Disease" and its apparent relation to
>human disease in the form of a brain degeneration (CJ Disease).  The
>mechanism for spread is apparently the  ground-up remains of sheep and
>cattle, some of which are sick with this brain infection, being added as
>a feed supplement to healthy animals.  Humans may get sick when they eat
>the now infected meat.
>
>Problem is that this feed supplement is BONE MEAL.  The british scientist
>noted that several persons who died of CJ Disease were gardeners.  The
>commentator added that the British Horticultural Society had advised
>wearing a mask when using bone meal.

Thank you, Bill, for bringing this TV show and related questions concerning
bovine spongiform encephalopathy (BSE) to the attention of the List. I am an
editor for USDA's Animal and Plant Health Inspection Service, the federal
agency charged with keeping BSE out of the United States.  I videotaped the
show you are referring to and planned to write to the List about it.

The show was pretty well balanced, though of course the information it
conveyed must come as a very disturbing scenario to Americans who have not
been following the BSE issue in the press on this side of the pond.  Please
permit me a somewhat more lengthy response than the List is used to.  We are
talking matters of life and death here.

In the middle 1980's cattle in Great Britain began showing nervous-system
abnormalities including tremors, stumbling, and fearfulness/shyness.  As the
animals got sicker, they invariably lost the ability to walk and,
eventually, died.  The symptoms matched those of sheep afflicted with
scrapie, a disease that got its name several hundred years ago because
affected sheep itch a great deal and scratch (scrape) themselves against
fenceposts, etc., to find temporary relief.  Scrapie-affected sheep also die.

Britain has had scrapie endemically for more than 250 years, and no other
animal species (including humans) have gotten the disease.  The causative
agent for scrapie has not been characterized, and there is no diagnostic
test for scrapie in live sheep and no cure for the disease once an animal is
infected by the scrapie agent.

As the TV program explained, pretty much all over the developed world there
are rendering plants--factories where the unwanted parts of animal carcasses
are processed into a protein-based meal that is subsequently fed to
livestock to supplement grain and grass feedings and help the stock grow faster.

The connection between scrapie in sheep and BSE in cows is believed to
involve precisely this practice of feeding ruminants (sheep and cattle--any
animal species that chews its cud) protein-enhanced feed made of ground-up
and processed animal parts.  When scrapie-infected sheep carcasses were
processed in the United Kingdom into meat- and bonemeal, the processing
method in use before the 1980's is believed to have safely managed to kill
the scrapie agent.  The process, at that time, involved both high heat and
the use of certain chemical solvents.  However, British renderers adopted
cheaper rendering practices some years ago (probably in the late 1970's) and
eliminated the use of the solvent-extraction process while retaining the
heat (cooking the refuse at very high temps).  Scientists have now concluded
that the heat-only processing method is not sufficient to kill whatever it
is that causes scrapie.

Therefore, scientists mainly agree, the scrapie agent survived in the feed
product made without solvent extraction and was consumed by cattle in
Britain.  Years passed.  Eventually, by the middle 1980's, cows that ate
scrapie-infected meal lived long enough to develop the symptoms of scrapie.
In bovines, the disease was given the name BSE because, on necropsy (the
animal equivalent of autopsy), the brains of affected cattle were found to
have spongelike holes.  The brains of scrapied sheep also exhibit this
appearance.  Scrapie, like BSE, is classed as a "transmissible spongiform
encephalopathy."  However, British people eat a great deal of lamb and
mutton from their own livestock, and no people have come down with scrapie yet.

There are a few other TSE's, transmissible mink encephalopathy being one in
that species, and kuru, Creutzfeldt-Jakob disease (CJD), and
Gerstman-Straussler syndrome being three other TSE's that affect people.

USDA's Animal and Plant Health Inspection Service veterinarians realized the
threat to the American cattle industry if BSE were somehow to get into this
country and took immediate steps (way back in 1989) to shut our borders to
British beef and cattle-generated products for consumption.  No British
cattle have been imported into this country since then.

Until March 1996, virtually nobody in the scientific community believed that
BSE could be transmitted to people.  The one early exception to this
conclusion was a Dr. Gadjusek, an epidemiologist at the U.S. National
Institutes of Health who won a Nobel Prize in Medicine for his studies of
TSE's in the aborigines of New Guinea.  Dr. Gadjusek discovered that the
disease named kuru (for the New Guinea word for "shakes") is spread because
mothers and young children in New Guinea (when he was doing his field work,
in the 1950's and 1960's) routinely ate their dead.  This cannibalism was a
form of religious observance (showing respect and love for the body of one's
dead relatives), not a matter of eating their enemies as cannibalism is
usually portrayed.  Kuru developed almost entirely in the women and young
kids there, not in the men.  It took a while, but Dr. Gadjusek eventually
put together the link between cannibalism and women/kids in that culture and
those segments of the aboriginal population coming down with the fatal TSE
called kuru.

In a subsequent experiment described on the TV show, Gadjusek and a coworker
implanted into the brain of a healthy chimpanzee cells from the brain of a
kuru-infected human being.  More than 3 years passed without the chimp
developing symptoms, but in the fourth year, it sickened and died.
Symptoms:  trembling, inability to walk, falling over, fearfulness/shyness
in a formerly outgoing, lovable lab animal.

Here are some facts that may help Americans sleep easier.  First, since
1989, my agency's veterinarians have done necropsies on the brains of nearly
5,000 U.S. cattle that died or were slaughtered after showing symptoms like
those of BSE-affected cattle.  NOT ONE COW had BSE.

Second, American rendering plants never abandoned solvent extraction as part
of their processing methodology.  Therefore, although U.S. livestock is
indeed fed protein-enhanced meat- and bonemeal, this material has been
processed using heat and solvents and does not allow the scrapie agent to
survive.  (We do have a small amount of scrapie in this country's sheep
flocks, particularly in certain bloodlines.  But Americans eat relatively
small amounts of lamb and virtually no mutton, compared to the quantities of
beef we consume.  Most of our national sheep flock is raised for wool and
lanolin production, not food.)

Before the BSE business in Britain, the prevalence of TSE's in human beings
was extremely rare.  Kuru, I believe, never made it out of New Guinea as the
primitive tribes affected by it do not travel and the disease is not caused
by a virus or a bacterium.  In the normal usage of the term, kuru is not
"infectious."  Creutzfelt-Jakob disease has always been very rare.

But several years into the BSE epidemic in Britain, the incidence of CJD
rose slightly in prevalence and the character of the disease altered:  it
began to afflict younger people, whereas before the BSE period, CJD almost
always occurred in the elderly.  In March 1996, a British scientific team
revealed that 10 cases of CJD in much younger people than normal had showed
up.  Most of the 10 were already dead when the announcement was made.
Several were under 30, and one was a teenage boy.  The new variant of CJD
began to be called v-CJD just to differentiate it from the "normal" CJD
still occurring worldwide at its normal, very low rate.  At present, 30
people in the British Isles and France are believed to be affected by v-CJD
(including the original 10).

Most of these people are thought to have become infected by consuming
British beef that came from a cow whose BSE remained undetected at the time
of slaughter.  (In many cows, the disease takes several years to show via
symptoms.)  Normal cooking temperatures are not high enough to kill the BSE
agent.  The teenage boy in the original group of 10 who died was actually a
vegetarian for about 4 years at his death, but before that he had consumed
beef routinely.  This factoid led scientists to conclude that it takes some
time for v-CJD to develop.  And in that poor boy's case, the cessation of
meat-eating had not occurred far enough back in time to keep him from being
exposed to beef from cattle fed the improperly processed meal.

No one can prove that there is no BSE in the United States.  It is
impossible to prove a negative.  However, the law requires slaughtering
establishments to send my agency the entire head of any cow that arrives at
the plant exhibiting BSE-like symptoms.  And we are required to analyze
those heads for BSE.  Again, these analyses have disclosed not one case of
BSE in American livestock.  And we have not permitted British beef (either
live cows or meat) to come into this country since 1989.

Now then, what if anything does all this have to do with gardening?

At the end of the TV program, the guest speaker (author of a new book called
"Deadly Feasts") summarized a conversation he recently had with Dr.
Gadjusek.  The doctor asked the speaker if he ever used bonemeal on his
roses.  The speaker said, "Yes, I do."  Then Dr. G. said, "I recommend you
stop doing that."

It turns out that among the 30 current victims of v-CJD being studied in
Europe, three were rose growers and all three had been routinely applying
British-made bonemeal to their roses.

But they hadn't been eating it, OR the roses.  So what's the connection?
The answer lies in what happens when you dump part of a bag of bonemeal into
a rose-plant hole:  some of the dust blows back up into your face.  It may
be possible to introduce into your own lungs the agent that causes v-CJD by
aerosolization--the process of inhaling dust motes, in this case dust from
ground-up bones from animals that were infected with BSE when alive.

This is a scary concept for sure.  The British Royal Horticutural Society
recommended recently that bonemeal users apply bonemeal only while wearing a
facemask.

I believe American gardeners are very unlikely to have exposed themselves to
the BSE agent via bonemeal because (1) American bonemeal is processed using
solvent extraction, and (2) American cattle are not known to harbor BSE.

Nevertheless, it is now time to err on the side of caution.  I will be
omitting bonemeal from all my gardening routines, mask or no mask.

If you would like to read up on how your government is helping to prevent
the incursion of BSE into this country, please point your Web browser to the
USDA-APHIS homepage at

http://www.aphis.usda.gov

and under Hot Issues, select BSE.

--Janet Wintermute
Adelphi, MD



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Janet Wintermute             jwintermute@ids2.idsonline.com
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