UKTC Archive

Re: Chipping Cherry Laurel or Bird Cherry ?

Subject: Re: Chipping Cherry Laurel or Bird Cherry ?
From: Alan Reeves
Date: Jul 14 2001 19:21:30
 --- billkowalczyk <> wrote: > I
am aware of the presence of Potassium Cyanide in
Cherry Laurel (Prunus
laurocerasus), but not in Bird Cherry (Prunus
padus).  Is this the case?

The following notes are from my Scrapbook of Toxic
Trivia - apologies if too much chemistry has been left
in/out. (Please delete as appropriate)

Good Luck Bill!

Cyanide Sources

Members of the rose family, Rosaceae, often contain
compounds called cyanogenic glycosides. These
compounds, when broken down in the body, liberate
cyanide, one of the most toxic substances known to
man. It's lethal dose is only 1 mg/kg body weight.
Fortunately, the concentration in these plants is
usually far below the toxic dose, and the breakdown of
the cyanogenic glycosides is often not complete.
However, several species in common cultivation do have
high concentrations of the glycosides in their seeds,
and eating these seeds can (and has been) fatal. 
Hydrocyanic acid (also called prussic acid), is one of
the decomposition products said to be formed by the
action of enzymes on the glycoside amygdalin. Many
factors appear to contribute to the formation of the
acid, but it is most commonly found when the leaves
are partially wilted. When fresh leaves are eaten,
they release hydrogen cyanide (HCN) in the stomach or
rumen after mastication. 
Leaves, twigs, bark, or seeds will also contain
cyanogenic principles. Discarded fruit pits should not
be available to dogs or caged birds
Other plants with toxic seeds include apple seeds,
cultivated cherries, peach and apricot pits, almonds,
and pears, which are all members of the rose family.
The leaves of wild cherries will also contain such
Cyanogenic glycosides are not exclusive to the
Rosaceae. More than 2050 species of higher plants
contain them. Some other common plants which can
generate cyanide include hydrangeas, tropical lima
beans (not the white american ones), bamboo sprouts,
sorghum shoots, and cassava tubers. Cassava, in
particular, is very toxic, and cannot be eaten raw. 
Roses themselves don't contain the cyanide-producing

The major threat of cyanide poisoning is to livestock
and terrestrial mammalian wildlife through ingestion
of plants containing high levels of cyanogenic

Plants implicated in cyanide poisoning of animals

        elderberry (Sambucus spp.),
         wild cherry (Prunus spp.),
and the pits of several common fruits

Upon ingestion these plants and their fruit pits have
the potential of releasing cyanide. 
Domestic goats (Capra spp.) died of cyanide poisoning
after eating leaves and fruit of the crab apple (Malus
Crab apple contains cyanogenic glycosides in its
leaves and fruit. 
Cattle appear to be more vulnerable to cyanide
poisoning than are sheep (Ovis aries), horses (Equus
cabalus), and pigs (Sus spp.).

Branches / twigs of many such spp are unsuitable for
use as perches in aviaries.

Prunus serotina
ANIMALS AFFECTED: All animals may be affected.
Ruminants (cattle, sheep, goats, deer) are more at
risk than monogastric animals (dogs, cats, pigs,
horses) and birds. 
DANGEROUS PARTS OF PLANT: Damaged leaves pose the
greatest risk. All parts are potentially toxic. 
SIGNS: Anxiety, breathing problems, staggering,
convulsions, collapse, death (which may be sudden).

Prunus laurocerasus 
Where Found Landscape as cultivated woody shrub. 
Mode Ingestion. 
        Wilted leaves, twigs (stems), seeds. 
        Gasping, weakness, excitement, pupil            
        dilation, spasms, convulsions, coma, 
        respiratory failure. 
TOXIC PRINCIPLE  Cyanogenic glycoside, amygdalin. 

At least in principle, it would be possible for
workers exposed to material which has been throught
the chipper to put themselves at risk by accidental
transfer of sap, or ingestion of vegetation fragments.
Probably the greater hazard is posed to the client?s
pets / farm livestock.

The greatest threat would be posed in spring (young
shoots and leaves) f, from wilted material, and
possibly in autumn.

Perhaps working practices in and around pits or
landfill where large quantities of cyanide-containing
green wastes may be ?dumped? should be reviewed.

Some more on cyanide . . 
Cyanide has relatively low persistence in surface
waters under normal conditions but may persist for
extended periods in ground water.
Volatilization is the dominant mechanism for removal
of free cyanide from concentrated solutions and is
effective under conditions of high temperatures, high
dissolved oxygen levels, and at increased
of atmospheric carbon dioxide. Loss of simple cyanides
from the water column is primarily through
sedimentation, microbial degradation, and
volatilization. Water-soluble strong complexes, such
as ferricyanides and ferrocyanides, do not release
free cyanide unless exposed to ultraviolet light.
Thus, sunlight may lead to cyanide formation in wastes
containing iron-cyanide complexes.
Cyanide seldom remains biologically available in soils
because it is either complexed by trace metals,
metabolized by various microorganisms, or lost through
volatilization. Cyanide ions are not strongly adsorbed
or retained on soils, and leaching into the
surrounding ground water will probably occur.
The danger of poison effects to aquatic wildlife is significant.

Alan Reeves
27 Garstang Road North
01772 XXXXXX   07811 XXXXXX

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