Introduction have banned the use of 1080

Introduction
to Compound 1080:

1080 is an
organofluorine chemical compound and can be stored in its dry form as
crystalline powder. It is called as sodium monofluoroacetate (CH2FCOONa)
in its sodium salt form.

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It is
naturally present in the plants as an anti-herbivore metabolite but it can be
produced synthetically. Compound 1080 is sold as a metabolic poison by its use
on the baits that are designed for the consumption of possums and rats.

The toxin
1080 is manufactured in Alabama in the United States. In New Zealand, the only
manufacturer of 1080 baits is based in Wanganui which converts the raw material
imported from Alabama. Another company, located in Canterbury has announced
that it intends to produce 1080 baits in a factory in Rolleston.

 

First
Use of 1080:

Compound
1080 was first registered as pesticide in new Zealand by Department of
Conservation in order to control vertebrate pets in 1964 under the ‘Pesticides
Act’. The toxicity of this chemical was well known at that time which is why it
was classified as ‘controlled pesticide’. Controlled pesticide means it is only
available to licensed operators for use. 1080 was first used in Australia in
the early 1950’s in rabbit control programmes.

 

Use
of 1080:

Manufactured
1080 is very popular toxin to create bait products in order to control the
populations of possums, bats and stoats. This is done because these predators
have an enormous impact on the native animal and plant species of New Zealand.
It is also used to control the expansion of disease called bovine tuberculosis.
This disease is carried by possums and can infect deers and cattles which play
a huge role in the New Zealand’s prime export markets. The population of these
predators is controlled through the use of pre-feeding of baits and secondary
poisoning.

 

 

According to
one of the report published by an Environmental Protection Agency (EPA) in
2008, New Zealand accounts for about 80% of the global use of 1080. The
Department of Conservation and TBfree NZ are largest users of 1080 followed by
regional councils. New Zealand use 1080 because it does not have native land
mammals except bats which are limited to small-scale geographical areas.
Countries such as USA have banned the use of 1080 toxin to protect coyotes
which would be affected by toxins. Aerial 1080 is one of the most
cost-effective mechanism to control pests over large and inaccessible areas.

Biodegradable 1080 naturally breaks down in the
environment without leaving any residue in soil, plants, animals and water or
building up in the food chain. Its use is strictly controlled and monitored to
protect environment and people. Over the past 50 years, studies show
that
sub-lethal dose of 1080 in mammals such as sheeps, goats and rabbits is very
likely to be metabolised and excreted with no detectable amount in tissues
within seven days.                                                                                                                      Compound
1080 is safe to use in relations with public safety. An adult would have to
consume about seven cereal baits for it to be lethal.

 

 

Ministry of Health has set a drinking water
standard of two parts of 1080 per billion parts of water. According to this
level, an adult would have to drink about 60,000 litres of water in one sitting
to consume a lethal dose of toxin. Along with above, an adult would need to
consume about 37 kg of meat from animal that died in 1980 to consume a fatal
dose of toxin. No traces of 1080 has been detected in commercially -produced
foods by the New Zealand food safety Authority.

Manufacture of Compound 1080:                                                                             
                      Sodium monofluoroacetate is an organic carbon
compound. Carbon has four electrons in its valence shell which determines what
compounds can carbon form. Carbon does not form ions but shares the four
valence electrons with elements it combines with. Element it combines in turn
contributes one electron each. In the structure of sodium monofluoroacetate
carbon atom (Labelled as carbon 1) forms single bonds with one fluorine atom ,
two hydrogen atoms and adjacent carbon atom (Labelled as carbon 2) in the
figure shown below. Second carbon atom forms one single bond with one oxygen
atom and one double bond with other oxygen atom. Oxygen has 6 electrons in its
valence shell therefore for stable octet it either needs to form double bond
with carbon atom or join with an inorganic element in a weak ionic bond. In the
structure of sodium fluoroacetate, oxygen forms a weak ionic bond with sodium
as shown below. The weak ionic bond is represented as dotted line in the
structure drawn.

1080 is a derivative of fluoroacetic acid. When
fluoroacetic acid combines with sodium hydroxide under the chemical conditions
of low pressure and high temperature it results in the production of sodium
fluoroacetate along with water.

Word Equation: Fluoroacetic acid + Sodium
Hydroxide ? Sodium fluoroacetate + Water

Symbol Equation: CH2FCOOH + NaOH ? CH2FCOONa
+ H2O

Working of Poison 1080:                                                                                                      Monofluoroacetate is the toxic component of
chemical 1080 found in the native species of Australia, Africa and Brazil. The
salt form of fluoroacetate ion i.e. sodium monofluoroacetate is used as pest
control because it is water-soluble and the white powder can be easily
developed into bait products. Microorganisms involved in the defluorination
utilise fluoroacetate as sole carbon source when 1080 is dissolved in water.
These microorganisms have enzymes that are involved in catalysing the
hydrolysis of monofluoroacetate to glycolate and fluoride.           FCH2CO2-
+ OH- ?HOCH2CO2- +F-

The whole
biological process behind the manufacture of monofluoroacetate has not been
understood completely. One model suggests that leaves of the plants obtain the
raw materials from soil to produce monofluoroacetate. These plants grown in
soils which are relatively low in fluoro-minerals. Other studies also show that
site of the toxin production can differ from species to species such as fruits,
roots, shoots and leaves which has probably been evolved in response to how
animals harvest the plant products.

 

According to
the different studies, it is the monofluoroacetate part of the compound that is
responsible for the overall toxicity of the chemical 1080.

Different
living organisms utilise acetate ion in order to convert it into carbon dioxide
in the Kreb’s cycle. This whole process results in the production of energy.
The chemical structure of the monofluoroacetate ion closely resemble the
structure of acetate ion. Living organisms which absorb and utilise acetate ion
for energy production also tend to absorb monofluoroacetate ion, mistaking it
to be acetate ion. Acetate ion is generally converted to citrate ion in Kreb’s
cycle as seen in step 1 to 2 (Refer to figure below)  but because of the
absorption of wrong ion, monofluoroacetate ion is converted to
monofluorocitrate ion which is highly toxic in nature. Monofluorocitrate ion
results in the immobilisation of enzyme which is required for the next step of
the Kreb’s cycle. As a result of this cycle stops resulting in the accumulation
of monofluorocitrate ion in the organism along with the loss of energy
ultimately leading to death.

 

 

Therefore
the toxicity of the monofluoroacetate ion either in the natural 1080 or the
manufactured ion is due to the unique ability of fluoroacetate ion to enter the
metabolic pathway of cell and immobilising the enzymes aconitase and succinate
dehydrogenase in the Kreb’s Cycle. This obstruction in the energy production
along with the accumulation of citrate ion results in the cell damage and
death. Herbivores die of heart failure whereas carnivores die mostly due to
respiratory failure.

 

 

Breaking of
1080:                                                                                                                 
                                    In the chemical structure of compound 1080,
carbon-carbon bond is weaker than the carbon-fluoride bond. Over the period of
time, factors such as sunlight and addition of water results in the degradation
of the molecules into compounds such as sodium bicarbonate and methyl fluoride.
Compound 1080 can also disintegrate if its lying on the surface water in sunlight
for prolonged period of time. However, if the molecules have reached the
groundwater or streams it does not decompose via sunlight.

Methyl
Fluoride (CH3F) is a fluoro-hydrocarbon which is volatile and is
responsible for ozone hole and depletion of ozone layer. Sodium bicarbonate
(NaHCO3) is a metal salt. Metal salt is composed of positively
charged metal ion and negatively charged ion of element or radicle.

 

Word
Equation: Sodium Fluoroacetate + Water ? Sodium
Bicarbonate + Methyl Fluoride

Symbol Equation: CH2FCO2Na + H2O ? NaHCO3
+ CH3F

 

 

Biodegradation
of compound 1080 occurs very rapidly in water. At high temperatures such as 21?, compound
1080 is degraded within two to six days. At low temperatures such as 7 ? degradation
takes upto one to two weeks due to slow microbial action. At high temperatures
such as 21?
concentration of microorganisms involved in the biodegradation of 1080 is more
as compared to low temperatures such as 7? which leads to faster degradation in them.
Therefore the diluting effect of running waterways and temperature is crucial
to decrease the concentration of 1080 to insignificant level.

 

According to
the different studies, compound 1080 is also degraded in the New Zealand soil
by microorganisms through the process of microbial de-fluoronitation. Microbial
defluoroniation is defined as the biological process in which fungi and certain
soil bacteria are able to cleave the fluoro-carbon bond present in the structure
of compound 1080. According to the work that has been done so far on Australian
soils and in controlled laboratory conditions of New Zealand, species such as
Pseudomanus, P. acidovorans, P.fluorescens, Fusarium oxysporum, Penicillium
purpurescens, P.restrictum,Moraxella species strain B are the most commonly
occurring microorganisms that have the ability to de-fluorinate 1080.

 

This
deforming ability of organisms is determined in aqueous solution or the
autoclaved soil by observing the concentration of fluoride ions (F-)
using the fluoride electrode in the culture broth.The resulting fluoride ions
from the microbial process of de-flouoronitation can associate with other
hydrocarbons present in the upper layers of soil, can attach to plant roots
through mycorrhizal fungi or can be present in the litter layers on the soil
surface. On the other hand, rain can dissolve the fluoroacetate ions present in
nature and it can be leached down into streams and rivers at below detection
level. As a result of above, the products of de-fluorination can initially be
present in the upper or litter layers of soil surface which can then be imbibed
by bacteria onto plant cellulose followed by its presence in the plants or
algae in the rivers and streams. Therefore, different factors such as
temperature, concentration of carbon-dioxide in the soil, moisture content of
soil, availability of microorganisms, rainfall, efficiency of organisms in
de-flouoronitation plays an important role in controlling the microbial
activity of de-fluoronitaion in compound 1080.

 

Problems
posed by 1080:

According to
the report published in 2008 by the Parliamentary Commissioner for the
environment, Dr. Jan Wright, 1080 leaves residues in the environment for small
durations of time but it can remain in the carcasses of poisoned organisms in
the cold and dry conditions for months. In these cases, 1080 poses a huge risk
to dogs if they feed on carcases. Dog deaths are generally due to the
scavenging on dead possums mainly the stomach of carcass.

Use of 1080
also poses a threat to the native birds of New Zealand such as kea on the West
coast of South Island. However, most of the bird deaths were recorded from the
operation that was performed 35 years ago with the use of poor quality carrot
baits which had number of tiny fragments. These days hard cereal baits are used
for operations.

Feral deers
are sometimes killed by the use of 1080. This is mainly in the areas where high
deer populations have eaten the forest underground herbs and shrubs making it
easier to locate 1080 baits. In order to control this, deer repellent is used
in baits in the popular hunting areas.

Along with
above, all the quoted success stories of microbial defluorination has been
reported in the controlled laboratory environment of New Zealand. These stories
cannot be anticipated in the real outside environment conditions of New Zealand
without carefully directed research and testing. Different effects of microbial
de-fluoronitation needs to be examined such as:

Effect on the biodiversity of micro-fauna as they go through the
DNA transformation to respond to the increased concentration of fluoride
ions.
Effect of this environment on the invertebrates.

 

Alternatives
to the use of 1080:

There are
different alternatives to the pest control but they are not as effective as
1080. Cyanide has been found to kill rodents and possums, but not stoats. 1080
can kill stoats because they are carnivores and hence feed on poisoned carcases.
Brodifacoum is used in the form of Talon in households on smaller-scale. As
compared to 1080, it stays in the environment for longer duration of time and cause
more unwanted by-kill. Different biological options for pest control have been
interrupted due to lack of progress.