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Multiple sodium fluoroacetate molecules arranged in a crystal. Fluorines are shown in green, sodium in purple, oxygen in red.
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| Names | |
|---|---|
| IUPAC name
Sodium 2-fluoroacetate
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| Other names
1080; SFA; Sodium monofluoroacetate; Compound 1080
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| Identifiers | |
3D model (JSmol)
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| ChEBI | |
| ChEMBL | |
| ChemSpider | |
| ECHA InfoCard | 100.000.499 |
| KEGG | |
PubChem CID
|
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| RTECS number | AH9100000 |
CompTox Dashboard (EPA)
|
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| Properties | |
| NaFC2H2O2 | |
| Molar mass | 100.0 g/mol |
| Appearance | Fluffy, colorless-to-white powder |
| Odor | odorless |
| Melting point | 200 °C (392 °F; 473 K) |
| Boiling point | Decomposes |
| soluble | |
| Hazards | |
| Main hazards | Toxic, Flammable |
| R/S statement (outdated) | R26 R27 R28 |
| Flash point | ? |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose)
|
1.7 mg/kg (rat, oral) 0.34 mg/kg (rabbit, oral) 0.1 mg/kg (rat, oral) 0.3 mg/kg (guinea pig, oral) 0.1 mg/kg (mouse, oral) |
| US health exposure limits (NIOSH): | |
PEL (Permissible)
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TWA 0.05 mg/m3 [skin] |
REL (Recommended)
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TWA 0.05 mg/m3 ST 0.15 mg/m3 [skin] |
IDLH (Immediate danger)
|
2.5 mg/m3 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Sodium fluoroacetate is the organofluorine chemical compound with the formula FCH2CO2Na. This colourless salt has a taste similar to that of sodium chloride and is used as a metabolic poison. Sodium fluoroacetate is a synthetic chemical compound, and does not occur naturally. Potassium fluoroacetate is a different compound, and does occur naturally as an anti-herbivore metabolite in various plants. Like sodium fluoroacetate, potassium fluoroacetate can also be produced synthetically. Both are derivatives of fluoroacetic acid, a carboxylic acid. The more common fluorinated acetic acid (trifluoroacetic acid) and its derivatives are far less toxic.
History and production
The effectiveness of sodium fluoroacetate as a rodenticide was reported in 1942. The name "1080" refers to the catalogue number of the poison, which became its brand name.
The salt is synthesized by treating sodium chloroacetate with potassium fluoride.
Occurrence
Dichapetalum cymosum
Potassium fluoroacetate, (as opposed to the commercially manufactured synthetic compound sodium fluoroacetate) occurs naturally in at least 40 plant species in Australia, New Zealand, Brazil, and Africa. It was first identified in Dichapetalum cymosum, commonly known as gifblaar (Afrikaans) or poison leaf, by Marais in 1944. As early as 1904, colonists in Sierra Leone used extracts of Chailletia toxicaria, which also contains fluoroacetic acid or its salts, to poison rats. Several native Australian plant genera contain the toxin, including Gastrolobium, Gompholobium, Oxylobium, Nemcia, and Acacia. New Zealand's native Puha contains 1080 in very low concentrations.
Potassium fluoroacetate occurrence in Gastrolobium species
Gastrolobium is a genus of flowering plants in the family Fabaceae.
There are over 100 species in this genus, and all but two are native to
the south west region of Western Australia, where they are known as
"poison peas". Gastrolobium growing in south western Australia are unique in their ability to concentrate fluoroacetate from low fluorine soils.
Brush-tailed possums, bush rats, and western grey kangaroos native to
this region are capable of safely eating plants containing
fluoroacetate, but livestock and introduced species from elsewhere in
Australia are highly susceptible to the poison, as are species introduced from outside Australia, such as the red fox. The fact that many Gastrolobium
species also have high secondary toxicity to non-native carnivores is
thought to have limited the ability of cats to establish populations in
locations where the plants form a major part of the understorey
vegetation.
The presence of Gastrolobium species in the fields of farmers in Western Australia
has often forced these farmers to 'scalp' their land — that is, remove
the top soil and any poison pea seed which it may contain, and replace
it with a new poison pea-free top soil sourced from elsewhere in which
to sow crops. Similarly, following bushfires in north-western Queensland cattlemen have to move livestock before the poisonous Gastrolobium grandiflorum emerges from the ashes.
Toxicology
Sodium fluoroacetate is toxic to all obligate aerobic organisms, and highly toxic to mammals and insects. The oral dose of sodium fluoroacetate sufficient to be lethal in humans is 2–10 mg/kg.
The toxicity varies with species. The New Zealand Food Safety Authority established lethal doses for a number of species. Dogs, cats, and pigs appear to be most susceptible to poisoning.
The enzyme fluoroacetate dehalogenase has been discovered in a soil bacterium, which can detoxify fluoroacetate in the surrounding medium.
Mechanism of action
Fluoroacetate is similar to acetate, which has a pivotal role in cellular metabolism. Fluoroacetate disrupts the citric acid cycle (also known as the Krebs cycle) by combining with coenzyme A to form fluoroacetyl CoA, which reacts with citrate synthase to produce fluorocitrate which binds very tightly to aconitase,
thereby halting the citric acid cycle. This inhibition results in an
accumulation of citrate in the blood. Citrate and fluorocitrate are
allosteric inhibitors of phosphofructokinase-1 (PFK-1), a key enzyme in glycolysis. When PFK-1 is inhibited, cells are no longer able to metabolize carbohydrates, depriving them of energy.
Symptoms
In humans, the symptoms of poisoning normally appear between 30 minutes and three hours after exposure. Initial symptoms typically include nausea, vomiting, and abdominal pain; sweating, confusion, and agitation follow. In significant poisoning, cardiac abnormalities including tachycardia or bradycardia, hypotension, and ECG changes develop. Neurological effects include muscle twitching and seizures; consciousness becomes progressively impaired after a few hours leading to coma. Death is normally due to ventricular arrhythmias, progressive hypotension unresponsive to treatment, and secondary lung infections.
Symptoms in domestic animals vary: dogs tend to show nervous
system signs such as convulsions, vocalization, and uncontrollable
running, whilst large herbivores such as cattle and sheep more
predominantly show cardiac signs.
Sub-lethal doses of sodium fluoroacetate may cause damage to tissues with high energy needs — in particular, the brain, gonads, heart, lungs, and fetus. Sub-lethal doses are typically completely metabolised and excreted within four days.
Treatment
Effective antidotes are unknown. Research in monkeys has shown that the use of glyceryl monoacetate
can prevent problems if given after ingestion of sodium fluoroacetate,
and this therapy has been tested in domestic animals with some positive
results. In theory, glyceryl monoacetate supplies acetate ions to allow
continuation of cellular respiration which the sodium fluoroacetate had
disrupted.
Experiments of Dr. Goncharov and co-workers resulted in
development of a successful therapeutic complex, containing a
phenothiazine compound, a dioic acid compound, and a pharmaceutically
acceptable carrier. In another aspect the pharmaceutical composition can
include a phenothiazine compound, a nitroester compound, ethanol, and a
pharmaceutically acceptable carrier.
In clinical cases, use of muscle relaxants, anti-convulsants, mechanical ventilation,
and other supportive measures may all be required. Few animals or
people have been treated successfully after significant sodium
fluoroacetate ingestions.
In one study, sheep gut bacteria were genetically engineered
to contain the fluoroacetate dehalogenase enzyme that inactivates
sodium fluoroacetate. The bacteria were administered to sheep, who then
showed reduced signs of toxicity after sodium fluoroacetate ingestion.
Pesticide use
Common brushtail possum, an invasive pest in New Zealand whose population is controlled with sodium fluoroacetate
Sodium fluoroacetate is used as a pesticide, especially for mammalian pest species. Farmers and graziers use the poison to protect pastures and crops from various herbivorous mammals. In New Zealand and Australia it is also used to control invasive non-native mammals that prey on or compete with native wildlife and vegetation.
Australia
In Australia,
sodium fluoroacetate was first used in rabbit control programmes in the
early 1950s, where it is regarded as having "a long history of proven
effectiveness and safety". It is seen as a critical component of the integrated pest-control programmes for rabbits, foxes, wild dogs, and feral pigs. Since 1994, broad-scale fox control using 1080 meat baits in Western Australia
has significantly improved the population numbers of several native
species and led, for the first time, to three species of mammals being
taken off the state's endangered species list. In Australia, minor
direct mortality of native animal populations from 1080 baits is
regarded as acceptable, compared to the predatory and competitive
effects of those introduced species being managed using 1080.
Western Shield is a project to boost populations of endangered mammals in south-west Australia conducted by the DEC. The project entails distributing fluoroacetate-baited meat from the air to kill predators. Wild dogs and foxes will readily eat the baited meat. Cats pose a greater difficulty as they are generally not interested in scavenging. However, an Australian RSPCA-commissioned study criticized 1080, calling it an inhumane killer. Some Western Australian herbivores (notably, the local subspecies of the tammar wallaby, Macropus eugenii derbianus, but not the subspecies M. e. eugenii of southern Australia and M. e. decres on Kangaroo Island) have, by natural selection, developed partial immunity to the effects of fluoroacetate, so that its use as a poison may reduce collateral damage to some native herbivores specific to that area.
In 2011, over 3,750 toxic baits containing 3 ml of 1080 were laid across 520 properties over 48,000 hectares between the Tasmanian settlements of Southport and Hobart as part of an ongoing attempt at the world's biggest invasive animal eradication operation – the eradication of red foxes
from the island state. The baits were spread at the rate of one per 10
hectares and were buried, to mitigate the risk to non-target wildlife
species like Tasmanian devils. Native animals are also targeted with 1080. During May 2005 up to 200,000 Bennett's wallabies on King Island were intentionally killed in one of the largest coordinated 1080 poisonings seen in Tasmania.
In 2016 PAPP
(para-amino propiophenone) became available for use, which the RSPCA
has endorsed as a more humane alternative to 1080 due in part to its
ability to kill faster, as well as having an antidote, which 1080 does
not, though as of July 2018, 1080 was still being used in attempts to reduce feral cat populations.
New Zealand
Sign warning of poisonous sodium fluoroacetate baits on the West Coast of New Zealand
Worldwide, New Zealand is the largest user of sodium fluoroacetate. This high usage is attributable to the fact that, apart from two species of bat,
New Zealand has no native land mammals, and some of those that have
been introduced have had devastating effects on vegetation and native
species.
1080 is used to control possums, rats, stoats, deer, and rabbits. The largest users, despite some vehement opposition, are OSPRI New Zealand and the Department of Conservation.
United States
Sodium fluoroacetate is used in the United States to kill coyotes. Prior to 1972 when the EPA cancelled all uses, sodium fluoroacetate was used much more widely as a cheap predacide and rodenticide; in 1985, the restricted-use "toxic collar" approval was finalized.
Other countries
Environmental impacts
Water
Because
1080 is highly water-soluble, it will be dispersed and diluted in the
environment by rain, stream water and ground water. Sodium fluoroacetate
at the concentrations found in the environment after standard baiting
operations will break down in natural water containing living organisms,
such as aquatic plants or micro-organisms. Water-monitoring surveys,
conducted during the 1990s, have confirmed that significant
contamination of waterways following aerial application of 1080 bait is
possible, but unlikely. Research by NIWA showed that 1080 deliberately placed in small streams for testing was undetectable after 8 hours, as it washed downstream.
In New Zealand, surface water is routinely monitored after aerial
application of 1080, and water samples are collected immediately after
application, when there is the highest possibility of detecting
contamination.
Of 2442 water samples tested in New Zealand between 1990 and 2010,
following aerial 1080 operations: 96.5% had no detectable 1080 at all
and, of all the samples, only six were equal to, or above the Ministry of Health level for drinking water, and none of these came from drinking water supplies.
Of 592 samples taken from human or stock drinking supplies, only four
contained detectable 1080 residues at 0.1ppb (1 sample) and 0.2 ppb (3
samples) – all well below the Ministry of Health level of 2 ppb.
In an experiment funded by the Animal Health Board and conducted
by NIWA simulating the effects of rainfall on 1080 on a steep
soil-covered hillside a few meters from a stream, it was found that
99.9% of the water containing 1080 leached straight into the soil
and did not flow over the ground to the stream as had been expected.
The experiment also measured contamination of soil water, which was
described as the water carried through the soil underground at short
horizontal distances (0.5-3m), downhill towards the stream. The
experiment did not measure contamination of deeper soil and ground water
immediately beneath the site of application.
Soil
The fate of
1080 in the soil has been established by research defining the
degradation of naturally occurring fluoroacetate (Oliver, 1977). Sodium
fluoroacetate is water-soluble, and residues from uneaten baits leach
into the soil where they are degraded to non-toxic metabolites by soil
microorganisms, including bacteria (Pseudomonas) and the common soil fungus (Fusarium solani) (David and Gardiner, 1966; Bong, Cole and Walker, 1979; Walker and Bong, 1981).
Birds
Although it is now infrequent, individual aerial 1080 operations can still sometimes affect local bird populations if not carried out with sufficient care. In New Zealand,
individuals from 19 species of native birds and 13 species of
introduced birds have been found dead after aerial 1080 drops. Most of
these recorded bird deaths were associated with only four operations in
the 1970s that used poor-quality carrot baits with many small fragments.
On the other hand, many native New Zealand bird populations have been
successfully protected by reducing predator numbers through aerial 1080
operations. Kokako, blue duck, New Zealand pigeon, kiwi, kaka, New Zealand falcon, tomtit, South Island robin, North Island robin, New Zealand parakeets (kakariki), and yellowhead
have all responded well to pest control programmes using aerial 1080
operations, with increased chick and adult survival, and increases in
population size. In contrast, seven of 38 tagged kea, the endemic alpine parrot, were killed during an aerial possum control operation in Okarito
Forest conducted by DOC and AHB in August 2011. Because of their
omnivorous feeding habits and inquisitive behaviour, kea are known to be
particularly susceptible to 1080 poison baits, as well as other
environmental poisons like the zinc and lead used in the flashings of
backcountry huts and farm buildings.
Recent research found that proximity to human-occupied sites where kea
scrounge human food is inversely related to survival; the odds of
survival increased by a factor of 6.9 for remote kea compared to those
that lived near scrounging sites. High survival in remote areas is
explained by innate neophobia and a short field-life of prefeed baits,
which together preclude acceptance of poison baits as familiar food.
Reptiles and amphibians
Reptiles and amphibians are susceptible to 1080, although much less sensitive than mammals.
Amphibian and reptile species that have been tested in Australia are
generally more tolerant to 1080 poison than are most other animals.
McIlroy (1992) calculated that even if lizards fed entirely on insects
or other animals poisoned with 1080, they could never ingest enough
poison to receive a lethal dose. Laboratory trials in New Zealand simulating worst-case scenarios indicate that both Leiopelma archeyi (Archey's frog) and L. hochstetteri (Hochstetter's frog)
can absorb 1080 from contaminated water, substrate, or prey. The chance
of this occurring in the wild is ameliorated by a variety of factors,
including frog ecology. Captive maintenance and contamination problems
rendered parts of this study inconclusive. Further population monitoring
is recommended to provide more conclusive evidence than provided by
this single study.
In New Zealand, the secondary poisoning of feral cats and stoats
following 1080 operations is likely to have a positive effect on the
recovery of native skink and gecko populations. Killing rabbits and possums, which compete for food with skinks and geckos, may also have benefits.
Fish
Fish generally have very low sensitivity to 1080. Toxicity tests have been conducted in the US on bluegill sunfish, rainbow trout, and the freshwater invertebrate Daphnia magna. Tests at different 1080 concentrations on sunfish (for four days) and Daphnia
(two days) showed that 1080 is "practically non-toxic" (a US EPA
classification) to both these species. Rainbow trout were also tested
over four days at four concentrations ranging from 39 to 170 mg 1080 per
litre. From these results an LC50
(the concentration of 1080 per litre of water which theoretically kills
50% of the test fish) can be calculated. The LC50 for rainbow trout was
calculated to be 54 mg 1080/litre – far in excess of any known
concentration of 1080 found in water samples following 1080 aerial
operations. Thus 1080 is unlikely to cause mortality in freshwater fish.
Invertebrates
Insects are susceptible to 1080 poisoning. Some field trials in New Zealand
have shown that insect numbers can be temporarily reduced within 20 cm
of toxic baits, but numbers return to normal levels within six days of
the bait being removed. Other trials have found no evidence that insect communities are negatively affected. Another New Zealand study showed that weta, native ants, and freshwater crayfish excrete 1080 within one to two weeks. There is also evidence that 1080 aerial operations in New Zealand can benefit invertebrate species. Both possums and rats are a serious threat to endemic
invertebrates in New Zealand, where around 90 per cent of spiders and
insects are endemic and have evolved without predatory mammals.
In a study on the diet of brushtail possums, 47.5 per cent of possum
faeces examined between January 1979 and June 1983 contained
invertebrates, mostly insects. One possum can eat up to 60 endangered native land snails (Powelliphanta spp.) in one night.
