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In 1985, the American
Journal of Veterinary Research carried out an
investigation into the persistence of the
euthanasate sodium phenobarbital in the carcasses
of euthanized animals at a typical rendering
plant. They found that it survived a conventional
rendering process. This means that other chemical
contaminants (e.g., heavy metals, pesticides,
hormones, antibiotics, organophosphates etc) may
also survive the process largely unchanged.
Prion
Disease
BSE (Bovine
Spongiform Encaphalopathy) can be transmitted by
feeding ground up cattle to other cattle. It may
have originated from feed scrapie-infected sheep
to cattle though recent investigations suggest
that it is traceable to an imported antelope at a
zoo. Zoo animals also end up at rendering
facilities. A feline version of BSE, called FSE,
has already been reported in Europe. Some bovine
tissues are believed to pose a greater risk than
others. Bovine materials now banned from the food
chain (Specified Bovine Offals) includes the head,
spleen, thymus, tonsils, brain, spinal cord, small
and large intestines. These must be segregated and
incinerated. The materials are now called
Specified Risk Material and includes material from
sheep and goats as well as from cattle.
In Britain, the
PFMA policy towards Specified Bovine Offals was
ahead of the policies in the human food industry.
In June 1989, PFMA members adopted a voluntary ban
on the use of the specified bovine tissues. This
was a precautionary measure prior to the Ministry
of Agriculture, Fisheries and Food's introduction
of a ban on the use of these bovine materials for
human consumption in November 1989 and a
subsequent ban on their use in animal feed in
September 1990. In the US, it is believed that
transmissible spongiform encephalopathies (TSE)
carried in pig- and chicken-laden foods may
eventually eclipse the threat of BSE. The risk of
household pet exposure to TSE from contaminated
pet food is more than 3 times greater than the
risk for hamburger-eating humans. In the UK,
specified materials are not used in pet food.
There may be other diseases not yet seen in cats
and dogs because they do not routinely cannibalize
members of their own species.
Foreign
Bodies
Inedible items find
their way into the mix for various reasons. Some
are loaded into the grinder attached to carcasses,
some are part of the stomach contents or is inside
the animal e.g. shot from a gun. The British PFMA
recognizes that plant materials are often
accompanied by foreign bodies from the soil so its
members use cleaning systems such as screens,
magnets and metal detectors.
In the US and
Canada, non-food items apparently routinely end up
in the rendering pit - cattle insecticide patches,
carcasses full of antibiotics, ID tags and
surgical pins, spoiled supermarket meat still in
cardboard, styrofoam trays and shrink wrap and pet
body bags. It is simply to costly and time
consuming for staff to remove these items. Some
(e.g. metal objects) are filtered out, but other
melt into the mix and may form toxic compounds. A
Massachusetts Institute of Technology study,
titled "Lead in Animal Foods", found
that a nine-pound cat fed on commercial pet food
ingests more lead than the amount considered
potentially toxic for children.
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