Rat poison
Encyclopedia
Rodenticides are a category of pest control
chemicals intended to kill rodent
s.
Single feed baits are chemicals sufficiently dangerous that the first dose is sufficient to kill.
Rodents are difficult to kill with poisons because their feeding habits reflect their place as scavenger
s. They will eat a small bit of something and wait, and if they don't get sick, they continue. An effective rodenticide must be tasteless and odorless in lethal concentrations, and have a delayed effect.
In addition to this specific metabolic disruption, massive toxic doses of 4-hydroxycoumarin or 4-hydroxythiacoumarin and indandione anticoagulants cause damage to tiny blood vessels (capillaries
), increasing their permeability, causing diffuse internal bleedings (haemorrhagias). These effects are gradual, developing over several days, but claims that they are painless are unfounded: in humans both warfarin
poisoning and haemophilia
commonly cause moderate to severe pain from bleeding into muscles and joints. In the final phase of the intoxication, the exhausted rodent collapses in hypovolemic circulatory shock or severe anemia
and dies calmly. However, because of the duration of discomfort and pain before death it has been suggested that the use of rodenticides can be considered as inhumane.
The main benefit of anticoagulants over other poisons is that the time taken for the poison to induce death means that the rats do not associate the damage with their feeding habits.
Vitamin K1
has been suggested, and successfully used, as antidote for pet
s or humans accidentally or intentionally (poison assaults on pets, suicidal attempts) exposed to anticoagulant poisons. Some of these poisons act by inhibiting liver
functions and in advanced stages of poisoning, several blood-clotting factors are absent, and the volume of circulating blood is diminished, so that a blood transfusion (optionally with the clotting factors present) can save a person who has been poisoned, an advantage over some older poisons.
Clinical signs for canine rodenticide toxicosis include lethargy, epistaxis, melena, bruising, acute blindness, seizures, dyspnea, depression, weakness, pallor, paresis or paralysis, gingival bleeding, profuse bleeding from wounds, hematemesis and hematuria. The vet may notice prolonged bleeding from venipuncture sites, hematomas and hemorrhaging into body cavities. If any of these signs are noticed and rodenticide ingestion is a probable cause, the pet should be taken to an animal hospital immediately.
This drug works by inhibiting an enzyme that uptakes and reuses vitamin K. Vitamin K is critical in the production of coagulation factors and thus when ceased it reduces the production of vitamin K dependent factors 2,7, 9 and 10. The body is then unable to activate vitamin K. Coagulation pathways are affected and can lead to coagulopathy. This is why external and internal bleeding are major signs that the patient has been exposed to rodenticide. It can take up to 5-7 days for signs to develop depending on the half-life of the active ingredient. The half-life of Warfarin is only 14.5 hours while others like second generation hydroxycoumarins and indanediones are between 4-6 days.
To diagnose rodenticide toxicosis, veterinarians use blood testing to find abnormal values to assess the patient’s clotting time and other related issues. Baseline testing includes pack cell volume (PVC), total protein (TP), complete blood count (CBC), platelet estimate and activated clotting time (ACT). From these values the veterinarian will be able to know if the patient is anemic, if the platelet count is within normal limits and if the clotting time is delayed. Further testing if time allows would include a coagulation screen (PT, PTT, fibrinogen, and FDP’s), PIVKA (proteins induced by vitamin K absence), complete serum biochemical profile, urinalysis, fecal exam, blood gas analysis and chemical analysis of heparinized plasma.
Treatment begins with identifying the specific toxic agent. This will significantly affect the depth and length of treatment needed for the patient and the prognosis. If the product was ingested within 1 hour upon presentation to the hospital then emesis will be utilized by administering an IV medication called apomorphine. If it has been between 2-4 hours of ingestion, gastric lavage will be performed. Activated charcoal should then be given by mouth every 3-4 hours and continued depending on the time of ingestion. Finally the antidote, vitamin K should be administered and repeated again depending on the time of exposure.
The prognosis of the patient all depends on what kind of rodenticide was ingested, the amount, the time lapse between ingestion and treatment, the severity of the symptoms, underlying diseases that may bring about further complications and the correct treatment and diagnosis. It is very important to bring your pet into a veterinarian as soon as you suspect ingestion and don’t wait for clinical signs. You will be saving their life the quicker you act upon it.
) is left where the rodents can eat it. The acid in the digestive system of the rodent reacts with the phosphide to generate the toxic phosphine
gas. This method of vermin control has possible use in places where rodents are resistant to some of the anticoagulants, particularly for control of house and field mice; zinc phosphide baits are also cheaper than most second-generation anticoagulants, so that sometimes, in the case of large infestation by rodents, their population is initially reduced by copious amounts of zinc phosphide bait applied, and the rest of population that survived the initial fast-acting poison is then eradicated by prolonged feeding on anticoagulant bait. Inversely, the individual rodents, that survived anticoagulant bait poisoning (rest population) can be eradicated by pre-baiting them with nontoxic bait for a week or two (this is important to overcome bait shyness, and to get rodents used to feeding in specific areas by specific food, especially in eradicating rats) and subsequently applying poisoned bait of the same sort as used for pre-baiting until all consumption of the bait ceases (usually within 2-4 days). These methods of alternating rodenticides with different modes of action gives actual or almost 100% eradications of the rodent population in the area, if the acceptance/palatability of baits are good (i.e., rodents feed on it readily).
Zinc phosphide is typically added to rodent baits in a concentration of 0.75% to 2.0%. The baits have strong, pungent garlic-like odor characteristic for phosphine
liberated by hydrolysis
. The odor attracts (or, at least, does not repulse) rodents, but has repulsive effect on other mammals. Birds, notably wild turkey
s, are not sensitive to the smell, and will feed on the bait, and thus become collateral damage.
The tablets or pellets (usually aluminium, calcium or magnesium phosphide for fumigation/gassing) may also contain other chemicals which evolve ammonia
, which helps to reduce the potential for spontaneous ignition
or explosion
of the phosphine gas.
Phosphides do not accumulate in the tissues of poisoned animals, so the risk of secondary poisoning
is low.
Before the advent of anticoagulants, phosphides were the favored kind of rat poison. During World War II, they came into use in United States because of shortage of strychnine
due to the Japanese occupation of the territories where strychnine-producing plants are grown (Strychnos nux-vomica, in southeast Asia). Phosphides are rather fast-acting rat poisons, resulting in the rats dying usually in open areas, instead of in the affected buildings.
Phosphides used as rodenticides are:
(vitamin D3) and ergocalciferol
(vitamin D2) are used as rodenticides. They are toxic to rodents for the same reason they are important to humans: they affect calcium and phosphate homeostasis
in the body. Vitamins D are essential in minute quantities (few IU
s per kilogram body weight daily, only a fraction of a milligram), and like most fat soluble vitamin
s, they are toxic in larger doses, causing hypervitaminosis. If the poisoning is severe enough (that is, if the dose of the toxin is high enough), it leads to death. In rodents that consume the rodenticidal bait, it causes hypercalcemia, raising the calcium level, mainly by increasing calcium absorption from food, mobilising bone-matrix-fixed calcium into ionised form (mainly monohydrogencarbonate calcium cation, partially bound to plasma proteins, [CaHCO3]+), which circulates dissolved in the blood plasma
. After ingestion of a lethal dose, the free calcium levels are raised sufficiently that blood vessel
s, kidney
s, the stomach
wall and lung
s are mineralised/calcificated (formation of calcificates, crystals of calcium salts/complexes in the tissues, damaging them), leading further to heart problems (myocardial tissue is sensitive to variations of free calcium levels, affecting both myocardial contractibility and excitation propagation between atrias and ventriculas), bleeding (due to capillary damage) and possibly kidney failure. It is considered to be single-dose, cumulative (depending on concentration used; the common 0.075% bait concentration is lethal to most rodents after a single intake of larger portions of the bait) or sub-chronic (death occurring usually within days to one week after ingestion of the bait). Applied concentrations are 0.075% cholecalciferol and 0.1% ergocalciferol when used alone.
There is an important feature of calciferols toxicology, that they are synergist
ic with anticoagulant
toxicants, that means, that mixtures of anticoagulants and calciferols in same bait are more toxic than a sum of toxicities of the anticoagulant and the calciferol in the bait, so that a massive hypercalcemic effect can be achieved by a substantially lower calciferol content in the bait, and vice-versa, a more pronounced anticoagulant/hemorrhagic effects are observed if the calciferol is present. This synergism is mostly used in calciferol low concentration baits, because effective concentrations of calciferols are more expensive than effective concentrations of most anticoagulants.
The first application of a calciferol in rodenticidal bait was in the Sorex product Sorexa D (with a different formula than today's Sorexa D), back in early 1970s, which contained 0.025% warfarin and 0.1% ergocalciferol. Today, Sorexa CD contains a 0.0025% difenacoum and 0.075% cholecalciferol combination. Numerous other brand products containing either 0.075-0.1% calciferols (e.g. Quintox) alone or alongside an anticoagulant are marketed.
The Merck Veterinary Manual states the following:
Additional anticoagulant renders the bait more toxic to pets as well as human. Upon single ingestion, solely calciferol-based baits are considered generally safer to birds than second generation anticoagulants or acute toxicants. A specific antidote for calciferol intoxication is calcitonin
, a hormone that lowers the blood levels of calcium. The therapy with commercially available calcitonin preparations is, however, expensive.
Other chemical poison
s include:
Pest control
Pest control refers to the regulation or management of a species defined as a pest, usually because it is perceived to be detrimental to a person's health, the ecology or the economy.-History:...
chemicals intended to kill rodent
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
s.
Single feed baits are chemicals sufficiently dangerous that the first dose is sufficient to kill.
Rodents are difficult to kill with poisons because their feeding habits reflect their place as scavenger
Scavenger
Scavenging is both a carnivorous and herbivorous feeding behavior in which individual scavengers search out dead animal and dead plant biomass on which to feed. The eating of carrion from the same species is referred to as cannibalism. Scavengers play an important role in the ecosystem by...
s. They will eat a small bit of something and wait, and if they don't get sick, they continue. An effective rodenticide must be tasteless and odorless in lethal concentrations, and have a delayed effect.
Anticoagulants
Anticoagulants are defined as chronic (death occurs after one to two weeks after ingestion of the lethal dose, rarely sooner), single-dose (second generation) or multiple-dose (first generation) rodenticides, acting by effective blocking of the vitamin K cycle, resulting in inability to produce essential blood-clotting factors — mainly coagulation factors II (prothrombin), VII (proconvertin), IX (Christmas factor) and X (Stuart factor).In addition to this specific metabolic disruption, massive toxic doses of 4-hydroxycoumarin or 4-hydroxythiacoumarin and indandione anticoagulants cause damage to tiny blood vessels (capillaries
Capillary
Capillaries are the smallest of a body's blood vessels and are parts of the microcirculation. They are only 1 cell thick. These microvessels, measuring 5-10 μm in diameter, connect arterioles and venules, and enable the exchange of water, oxygen, carbon dioxide, and many other nutrient and waste...
), increasing their permeability, causing diffuse internal bleedings (haemorrhagias). These effects are gradual, developing over several days, but claims that they are painless are unfounded: in humans both warfarin
Warfarin
Warfarin is an anticoagulant. It is most likely to be the drug popularly referred to as a "blood thinner," yet this is a misnomer, since it does not affect the thickness or viscosity of blood...
poisoning and haemophilia
Haemophilia
Haemophilia is a group of hereditary genetic disorders that impair the body's ability to control blood clotting or coagulation, which is used to stop bleeding when a blood vessel is broken. Haemophilia A is the most common form of the disorder, present in about 1 in 5,000–10,000 male births...
commonly cause moderate to severe pain from bleeding into muscles and joints. In the final phase of the intoxication, the exhausted rodent collapses in hypovolemic circulatory shock or severe anemia
Anemia
Anemia is a decrease in number of red blood cells or less than the normal quantity of hemoglobin in the blood. However, it can include decreased oxygen-binding ability of each hemoglobin molecule due to deformity or lack in numerical development as in some other types of hemoglobin...
and dies calmly. However, because of the duration of discomfort and pain before death it has been suggested that the use of rodenticides can be considered as inhumane.
The main benefit of anticoagulants over other poisons is that the time taken for the poison to induce death means that the rats do not associate the damage with their feeding habits.
- First generation rodenticidal anticoagulants generally have shorter elimination half-lives, require higher concentrations (usually between 0.005% and 0.1%) and consecutive intake over days in order to accumulate the lethal dose, and less toxic than second generation agents.
- Second generation agents are far more toxic than first generation. They are generally applied in lower concentrations in baits — usually on the order of 0.001% to 0.005% — are lethal after a single ingestion of bait and are also effective against strains of rodents that became resistant to first generation anticoagulants; thus, the second generation anticoagulants are sometimes referred to as "superwarfarins".
| Class | Examples |
|---|---|
| Coumarin Coumarin Coumarin is a fragrant chemical compound in the benzopyrone chemical class, found in many plants, notably in high concentration in the tonka bean , vanilla grass , sweet woodruff , mullein , sweet grass , cassia cinnamon and sweet clover... s/4-hydroxycoumarins |
|
| 1,3-indandione 1,3-Indandione 1,3-indandione is an aromatic trans-fixed β-diketone, in standard conditions it is referred to in different sources as colourless or yellowish, green or yellow solid... s |
diphacinone, chlorophacinone Chlorophacinone Chlorophacinone is an anticoagulant used as a rodenticide.... , pindone Pindone Pindone is an anticoagulant drug for agricultural use. It is commonly used as a rodenticide in the management of rat and rabbit populations.It is pharmacologically analogous to warfarin and inhibits the synthesis of Vitamin K-dependent clotting factors.... These are harder to group by generation. According to some sources, the indandiones are considered second generation. However, according to the U.S. Environmental Protection Agency, examples of first generation agents include chlorophacinone Chlorophacinone Chlorophacinone is an anticoagulant used as a rodenticide.... and diphacinone. |
| Other | Difethialone Difethialone Difethialone is an anticoagulant used as a rodenticide.It is considered a second generation agent.In May 2008 the United States Environmental Protection Agency promulgated a decision that would ban the use of difethialone in consumer-use rodenticide products.... is considered a second generation anticoagulant rodenticide . |
| Indirect | Sometimes, anticoagulant rodenticides are potentiated by an antibiotic Antibiotic An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of... or bacteriostatic agent Bacteriostatic agent A bacteriostatic agent or bacteriostat, abbreviated Bstatic, is a biological or chemical agent that stops bacteria from reproducing, while not necessarily harming them otherwise. Depending on their application, bacteriostatic antibiotics, disinfectants, antiseptics and preservatives can be... , most commonly sulfaquinoxaline Sulfaquinoxaline Sulfaquinoxaline is a veterinary medicine which can be given to cattle and sheep to treat coccidiosis.... . The aim of this association is that the antibiotic suppresses intestinal symbiotic Symbiosis Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens... microflora, which are a source of vitamin K. Diminished production of vitamin K by the intestinal microflora contributes to the action of anticoagulants. Added vitamin D Vitamin D Vitamin D is a group of fat-soluble secosteroids. In humans, vitamin D is unique both because it functions as a prohormone and because the body can synthesize it when sun exposure is adequate .... also has a synergistic effect with anticoagulants. |
Vitamin K1
Vitamin K
Vitamin K is a group of structurally similar, fat soluble vitamins that are needed for the posttranslational modification of certain proteins required for blood coagulation and in metabolic pathways in bone and other tissue. They are 2-methyl-1,4-naphthoquinone derivatives...
has been suggested, and successfully used, as antidote for pet
Pet
A pet is a household animal kept for companionship and a person's enjoyment, as opposed to wild animals or to livestock, laboratory animals, working animals or sport animals, which are kept for economic or productive reasons. The most popular pets are noted for their loyal or playful...
s or humans accidentally or intentionally (poison assaults on pets, suicidal attempts) exposed to anticoagulant poisons. Some of these poisons act by inhibiting liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
functions and in advanced stages of poisoning, several blood-clotting factors are absent, and the volume of circulating blood is diminished, so that a blood transfusion (optionally with the clotting factors present) can save a person who has been poisoned, an advantage over some older poisons.
Rodenticide in dogs
Rodenticide, also known as rat bait, is an anticoagulant used to kill rodents. This product is also lethal to many other species, specifically, dogs. Even in small doses this pest control substance can be fatal if not treated immediately.Clinical signs for canine rodenticide toxicosis include lethargy, epistaxis, melena, bruising, acute blindness, seizures, dyspnea, depression, weakness, pallor, paresis or paralysis, gingival bleeding, profuse bleeding from wounds, hematemesis and hematuria. The vet may notice prolonged bleeding from venipuncture sites, hematomas and hemorrhaging into body cavities. If any of these signs are noticed and rodenticide ingestion is a probable cause, the pet should be taken to an animal hospital immediately.
This drug works by inhibiting an enzyme that uptakes and reuses vitamin K. Vitamin K is critical in the production of coagulation factors and thus when ceased it reduces the production of vitamin K dependent factors 2,7, 9 and 10. The body is then unable to activate vitamin K. Coagulation pathways are affected and can lead to coagulopathy. This is why external and internal bleeding are major signs that the patient has been exposed to rodenticide. It can take up to 5-7 days for signs to develop depending on the half-life of the active ingredient. The half-life of Warfarin is only 14.5 hours while others like second generation hydroxycoumarins and indanediones are between 4-6 days.
To diagnose rodenticide toxicosis, veterinarians use blood testing to find abnormal values to assess the patient’s clotting time and other related issues. Baseline testing includes pack cell volume (PVC), total protein (TP), complete blood count (CBC), platelet estimate and activated clotting time (ACT). From these values the veterinarian will be able to know if the patient is anemic, if the platelet count is within normal limits and if the clotting time is delayed. Further testing if time allows would include a coagulation screen (PT, PTT, fibrinogen, and FDP’s), PIVKA (proteins induced by vitamin K absence), complete serum biochemical profile, urinalysis, fecal exam, blood gas analysis and chemical analysis of heparinized plasma.
Treatment begins with identifying the specific toxic agent. This will significantly affect the depth and length of treatment needed for the patient and the prognosis. If the product was ingested within 1 hour upon presentation to the hospital then emesis will be utilized by administering an IV medication called apomorphine. If it has been between 2-4 hours of ingestion, gastric lavage will be performed. Activated charcoal should then be given by mouth every 3-4 hours and continued depending on the time of ingestion. Finally the antidote, vitamin K should be administered and repeated again depending on the time of exposure.
The prognosis of the patient all depends on what kind of rodenticide was ingested, the amount, the time lapse between ingestion and treatment, the severity of the symptoms, underlying diseases that may bring about further complications and the correct treatment and diagnosis. It is very important to bring your pet into a veterinarian as soon as you suspect ingestion and don’t wait for clinical signs. You will be saving their life the quicker you act upon it.
Metal phosphides
Metal phosphides have been used as a means of killing rodents and are considered single-dose fast acting rodenticides (death occurs commonly within 1-3 days after single bait ingestion). A bait consisting of food and a phosphide (usually zinc phosphideZinc phosphide
Zinc phosphide is an inorganic chemical compound.- Reactions :Zinc phosphide can be prepared by the reaction of zinc with phosphorus:Zinc phosphide will react with water to produce phosphine and zinc hydroxide :-Rodenticide:...
) is left where the rodents can eat it. The acid in the digestive system of the rodent reacts with the phosphide to generate the toxic phosphine
Phosphine
Phosphine is the compound with the chemical formula PH3. It is a colorless, flammable, toxic gas. Pure phosphine is odourless, but technical grade samples have a highly unpleasant odor like garlic or rotting fish, due to the presence of substituted phosphine and diphosphine...
gas. This method of vermin control has possible use in places where rodents are resistant to some of the anticoagulants, particularly for control of house and field mice; zinc phosphide baits are also cheaper than most second-generation anticoagulants, so that sometimes, in the case of large infestation by rodents, their population is initially reduced by copious amounts of zinc phosphide bait applied, and the rest of population that survived the initial fast-acting poison is then eradicated by prolonged feeding on anticoagulant bait. Inversely, the individual rodents, that survived anticoagulant bait poisoning (rest population) can be eradicated by pre-baiting them with nontoxic bait for a week or two (this is important to overcome bait shyness, and to get rodents used to feeding in specific areas by specific food, especially in eradicating rats) and subsequently applying poisoned bait of the same sort as used for pre-baiting until all consumption of the bait ceases (usually within 2-4 days). These methods of alternating rodenticides with different modes of action gives actual or almost 100% eradications of the rodent population in the area, if the acceptance/palatability of baits are good (i.e., rodents feed on it readily).
Zinc phosphide is typically added to rodent baits in a concentration of 0.75% to 2.0%. The baits have strong, pungent garlic-like odor characteristic for phosphine
Phosphine
Phosphine is the compound with the chemical formula PH3. It is a colorless, flammable, toxic gas. Pure phosphine is odourless, but technical grade samples have a highly unpleasant odor like garlic or rotting fish, due to the presence of substituted phosphine and diphosphine...
liberated by hydrolysis
Hydrolysis
Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...
. The odor attracts (or, at least, does not repulse) rodents, but has repulsive effect on other mammals. Birds, notably wild turkey
Wild Turkey
The Wild Turkey is native to North America and is the heaviest member of the Galliformes. It is the same species as the domestic turkey, which derives from the South Mexican subspecies of wild turkey .Adult wild turkeys have long reddish-yellow to grayish-green...
s, are not sensitive to the smell, and will feed on the bait, and thus become collateral damage.
The tablets or pellets (usually aluminium, calcium or magnesium phosphide for fumigation/gassing) may also contain other chemicals which evolve ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
, which helps to reduce the potential for spontaneous ignition
Combustion
Combustion or burning is the sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat and conversion of chemical species. The release of heat can result in the production of light in the form of either glowing or a flame...
or explosion
Explosion
An explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases. An explosion creates a shock wave. If the shock wave is a supersonic detonation, then the source of the blast is called a "high explosive"...
of the phosphine gas.
Phosphides do not accumulate in the tissues of poisoned animals, so the risk of secondary poisoning
Secondary poisoning
Secondary poisoning is poisoning that can result when one organism comes into contact with or ingests another organism that has poison in its system. It typically occurs when a predator eats an animal, such as a mouse, rat, or insect, that has previously been poisoned by a commercial pesticide...
is low.
Before the advent of anticoagulants, phosphides were the favored kind of rat poison. During World War II, they came into use in United States because of shortage of strychnine
Strychnine
Strychnine is a highly toxic , colorless crystalline alkaloid used as a pesticide, particularly for killing small vertebrates such as birds and rodents. Strychnine causes muscular convulsions and eventually death through asphyxia or sheer exhaustion...
due to the Japanese occupation of the territories where strychnine-producing plants are grown (Strychnos nux-vomica, in southeast Asia). Phosphides are rather fast-acting rat poisons, resulting in the rats dying usually in open areas, instead of in the affected buildings.
Phosphides used as rodenticides are:
- aluminium phosphideAluminium phosphideAluminium phosphide is an inorganic compound used as a wide band gap semiconductor and a fumigant. This colourless solid is generally sold as a grey-green-yellow powder due to the presence of impurities arising from hydrolysis and oxidation.-Properties:...
(fumigant only) - calcium phosphideCalcium phosphideCalcium phosphide is a chemical is used in incendiary bombs. It has the appearance of red-brown crystalline powder or grey lumps, with melting point of 1600 °C. Its trade name is Photophor for the incendiary use or Polythanol for the use as rodenticide.It may be formed by reaction of the elements...
(fumigant only) - magnesium phosphide (fumigant only)
- zinc phosphideZinc phosphideZinc phosphide is an inorganic chemical compound.- Reactions :Zinc phosphide can be prepared by the reaction of zinc with phosphorus:Zinc phosphide will react with water to produce phosphine and zinc hydroxide :-Rodenticide:...
(in baits)
Hypercalcemia
Calciferols (vitamins D), cholecalciferolCholecalciferol
Cholecalciferol is a form of vitamin D, also called vitamin D3 or calciol.It is structurally similar to steroids such as testosterone, cholesterol, and cortisol .-Forms:Vitamin D3 has several forms:...
(vitamin D3) and ergocalciferol
Ergocalciferol
Ergocalciferol is a form of vitamin D, also called vitamin D2. It is marketed under various names including Deltalin , Drisdol and Calcidol...
(vitamin D2) are used as rodenticides. They are toxic to rodents for the same reason they are important to humans: they affect calcium and phosphate homeostasis
Homeostasis
Homeostasis is the property of a system that regulates its internal environment and tends to maintain a stable, constant condition of properties like temperature or pH...
in the body. Vitamins D are essential in minute quantities (few IU
International unit
In pharmacology, the International Unit is a unit of measurement for the amount of a substance, based on biological activity or effect. It is abbreviated as IU, as UI , or as IE...
s per kilogram body weight daily, only a fraction of a milligram), and like most fat soluble vitamin
Vitamin
A vitamin is an organic compound required as a nutrient in tiny amounts by an organism. In other words, an organic chemical compound is called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet. Thus, the term is conditional both on...
s, they are toxic in larger doses, causing hypervitaminosis. If the poisoning is severe enough (that is, if the dose of the toxin is high enough), it leads to death. In rodents that consume the rodenticidal bait, it causes hypercalcemia, raising the calcium level, mainly by increasing calcium absorption from food, mobilising bone-matrix-fixed calcium into ionised form (mainly monohydrogencarbonate calcium cation, partially bound to plasma proteins, [CaHCO3]+), which circulates dissolved in the blood plasma
Blood plasma
Blood plasma is the straw-colored liquid component of blood in which the blood cells in whole blood are normally suspended. It makes up about 55% of the total blood volume. It is the intravascular fluid part of extracellular fluid...
. After ingestion of a lethal dose, the free calcium levels are raised sufficiently that blood vessel
Blood vessel
The blood vessels are the part of the circulatory system that transports blood throughout the body. There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and...
s, kidney
Kidney
The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...
s, the stomach
Stomach
The stomach is a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract in some animals, including vertebrates, echinoderms, insects , and molluscs. It is involved in the second phase of digestion, following mastication .The stomach is...
wall and lung
Lung
The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...
s are mineralised/calcificated (formation of calcificates, crystals of calcium salts/complexes in the tissues, damaging them), leading further to heart problems (myocardial tissue is sensitive to variations of free calcium levels, affecting both myocardial contractibility and excitation propagation between atrias and ventriculas), bleeding (due to capillary damage) and possibly kidney failure. It is considered to be single-dose, cumulative (depending on concentration used; the common 0.075% bait concentration is lethal to most rodents after a single intake of larger portions of the bait) or sub-chronic (death occurring usually within days to one week after ingestion of the bait). Applied concentrations are 0.075% cholecalciferol and 0.1% ergocalciferol when used alone.
There is an important feature of calciferols toxicology, that they are synergist
Synergist
A Synergist is a kind of muscle that performs, or helps perform, the same set of joint motion as the agonists. Synergists muscles act on movable joints. Synergists are sometimes called as "neutralizers" because they help cancel out, or neutralize, extra motion from the agonists to make sure that...
ic with anticoagulant
Anticoagulant
An anticoagulant is a substance that prevents coagulation of blood. A group of pharmaceuticals called anticoagulants can be used in vivo as a medication for thrombotic disorders. Some anticoagulants are used in medical equipment, such as test tubes, blood transfusion bags, and renal dialysis...
toxicants, that means, that mixtures of anticoagulants and calciferols in same bait are more toxic than a sum of toxicities of the anticoagulant and the calciferol in the bait, so that a massive hypercalcemic effect can be achieved by a substantially lower calciferol content in the bait, and vice-versa, a more pronounced anticoagulant/hemorrhagic effects are observed if the calciferol is present. This synergism is mostly used in calciferol low concentration baits, because effective concentrations of calciferols are more expensive than effective concentrations of most anticoagulants.
The first application of a calciferol in rodenticidal bait was in the Sorex product Sorexa D (with a different formula than today's Sorexa D), back in early 1970s, which contained 0.025% warfarin and 0.1% ergocalciferol. Today, Sorexa CD contains a 0.0025% difenacoum and 0.075% cholecalciferol combination. Numerous other brand products containing either 0.075-0.1% calciferols (e.g. Quintox) alone or alongside an anticoagulant are marketed.
The Merck Veterinary Manual states the following:
Although this rodenticide [cholecalciferol] was introduced with claims that it was less toxic to nontarget species than to rodents, clinical experience has shown that rodenticides containing cholecalciferol are a significant health threat to dogs and cats. Cholecalciferol produces hypercalcemia, which results in systemic calcification of soft tissue, leading to renal failure, cardiac abnormalities, hypertension, CNS depression and GI upset. Signs generally develop within 18-36 hours of ingestion and can include depression, anorexia, polyuria and polydipsia. As serum calcium concentrations increase, clinical signs become more severe. ... GI smooth muscle excitability decreases and is manifest by anorexia, vomiting and constipation. ... Loss of renal concentrating ability is a direct result of hypercalcemia. As hypercalcemia persists, mineralization of the kidneys results in progressive renal insufficiency."
Additional anticoagulant renders the bait more toxic to pets as well as human. Upon single ingestion, solely calciferol-based baits are considered generally safer to birds than second generation anticoagulants or acute toxicants. A specific antidote for calciferol intoxication is calcitonin
Calcitonin
Calcitonin is a 32-amino acid linear polypeptide hormone that is producedin humans primarily by the parafollicular cells of the thyroid, and in many other animals in the ultimobranchial body. It acts to reduce blood calcium , opposing the effects of parathyroid hormone . Calcitonin has been found...
, a hormone that lowers the blood levels of calcium. The therapy with commercially available calcitonin preparations is, however, expensive.
Other
Poison
In the context of biology, poisons are substances that can cause disturbances to organisms, usually by chemical reaction or other activity on the molecular scale, when a sufficient quantity is absorbed by an organism....
s include:
- ANTUAntuIn Akkadian mythology, Antu or Antum is a Babylonian goddess, derived from the older Sumerian Ki, though the cosmogony has been altered to suit a separate tradition. She was the first consort of Anu, and the pair were the parents of the Anunnaki and the Utukki...
(α-naphthylthiourea; specific against Brown ratBrown RatThe brown rat, common rat, sewer rat, Hanover rat, Norway rat, Brown Norway rat, Norwegian rat, or wharf rat is one of the best known and most common rats....
, Rattus norvegicus) - ArsenicArsenicArsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...
- BariumBariumBarium is a chemical element with the symbol Ba and atomic number 56. It is the fifth element in Group 2, a soft silvery metallic alkaline earth metal. Barium is never found in nature in its pure form due to its reactivity with air. Its oxide is historically known as baryta but it reacts with...
(a toxic metal) compound- Barium carbonateBarium carbonateBarium carbonate , also known as witherite, is a chemical compound used in rat poison, bricks, ceramic glazes and cement.Witherite crystallizes in the orthorhombic system...
- Barium carbonate
- BromethalinBromethalinBromethalin is a rodenticide which poisons the central nervous system by uncoupling mitochondrial oxidative phosphorylation, which causes a decrease in adenosine triphosphate synthesis. Decreased ATP ultimately results in increased intracranial pressure, which damages neuronal axons...
(which affects the nervous systemNervous systemThe nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body. In most animals the nervous system consists of two parts, central and peripheral. The central nervous...
, no antidoteAntidoteAn antidote is a substance which can counteract a form of poisoning. The term ultimately derives from the Greek αντιδιδοναι antididonai, "given against"....
) - ChloraloseChloraloseChloralose is an avicide, rodenticide used to kill mice in temperatures below 15 °C. It is also widely used in neuroscience and veterinary medicine as an anesthetic and sedative.Chemically, it is a chlorinated acetal derivative of glucose....
(narcotic acting condensation product of chloral and glucose) - CrimidineCrimidineCrimidine is a convulsant poison used as a rodenticide....
(2-chloro-N, N,6-trimethylpyrimidin-4-amine; a synthetic convulsant poison, antivitamin B6) - 1,3-Difluoro-2-propanol1,3-Difluoro-2-propanol1,3-Difluoro-2-propanol is a metabolic poison which disrupts the citric acid cycle and is used as a rodenticide, similar to sodium fluoroacetate. It is the main ingredient in the rodenticide product Gliftor which was widely used in the former USSR....
("Gliftor" in the former USSR) - EndrinEndrinEndrin is an organochloride that was primarily used as an insecticide. It is a colourless odorless solid, although commercial samples are often off-white. It is also a rodenticide. This compound became infamous as persistent organic pollutant and for this reason is banned in many...
(organochlorine cyclodiene insecticide, used in the past for extermination of voles in fields during winter by aircraft spraying) - FluoroacetamideFluoroacetamideFluoroacetamide is an organic compound based on acetamide with one fluorine atom replacing hydrogen on the methyl group. it is a metabolic poison which disrupts the citric acid cycle and was used as a rodenticide....
("1081") - PhosacetimPhosacetimPhosacetim is a toxic organophosphate compound which acts as an acetylcholinesterase inhibitor and is used as a rodenticide....
(a delayed-action organophosphorous rodenticide) - White phosphorusPhosphorusPhosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...
- PyrinuronPyrinuronPyrinuron is a chemical compound used as a rodenticide....
(an ureaUreaUrea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....
derivative) - ScillirosideScillirosideScilliroside is a toxic compound derived from the plant Drimia maritima , which is sometimes used as a rodenticide....
- Sodium fluoroacetate ("1080")
- StrychnineStrychnineStrychnine is a highly toxic , colorless crystalline alkaloid used as a pesticide, particularly for killing small vertebrates such as birds and rodents. Strychnine causes muscular convulsions and eventually death through asphyxia or sheer exhaustion...
- TetramethylenedisulfotetramineTetramethylenedisulfotetramineTetramethylenedisulfotetramine is an organic compound that is used as a rodenticide . It is an odorless, tasteless white powder that is slightly soluble in water, DMSO and acetone, and insoluble in methanol and ethanol. It is a sulfamide derivative...
("tetramine") - ThalliumThalliumThallium is a chemical element with the symbol Tl and atomic number 81. This soft gray poor metal resembles tin but discolors when exposed to air. The two chemists William Crookes and Claude-Auguste Lamy discovered thallium independently in 1861 by the newly developed method of flame spectroscopy...
(a toxic heavy metal) compounds - Zyklon BZyklon BZyklon B was the trade name of a cyanide-based pesticide infamous for its use by Nazi Germany to kill human beings in gas chambers of extermination camps during the Holocaust. The "B" designation indicates one of two types of Zyklon...
(hydrogen cyanide absorbed in an inert carrier)
Combinations
In some countries, fixed three-component rodenticides, i.e., anticoagulant + antibiotic + vitamin D, are used. Associations of a second-generation anticoagulant with an antibiotic and/or vitamin D are considered to be effective even against most resistant strains of rodents, though some second generation anticoagulants (namely brodifacoum and difethialone), in bait concentrations of 0.0025% to 0.005% are so toxic that resistance is unknown, and even rodents resistant to other rodenticides are reliably exterminated by application of these most toxic anticoagulants.List of rat eradications
- Campbell Island, New ZealandCampbell Island, New ZealandCampbell Island is a remote, subantarctic island of New Zealand and the main island of the Campbell Island group. It covers of the group's , and is surrounded by numerous stacks, rocks and islets like Dent Island, Folly Island , Isle de Jeanette Marie, and Jacquemart Island, the latter being the...
, largest ever. - Alberta, Canada
- Rat Island (Alaska)Rat Island (Alaska)Rat Island is an island in the Rat Islands archipelago of the western Aleutian Islands in the U.S. state of Alaska. The island has a land area of 10.3126 sq mi and no permanent population...
- Mokapu Island, MolokaiMolokaiMolokai or Molokai is an island in the Hawaiian archipelago. It is 38 by 10 miles in size with a land area of , making it the fifth largest of the main Hawaiian Islands and the 27th largest island in the United States. It lies east of Oahu across the 25-mile wide Kaiwi Channel and north of...
- Falkland IslandsFalkland IslandsThe Falkland Islands are an archipelago in the South Atlantic Ocean, located about from the coast of mainland South America. The archipelago consists of East Falkland, West Falkland and 776 lesser islands. The capital, Stanley, is on East Falkland...
- San Jorge IslandSan Jorge IslandSan Jorge Island is the second largest island in the Isabel Province, Solomon Islands. The island lies at the southern end of Santa Isabel Island and borders Thousand Ships Bay. San Jorge has an area of 184 km² and has less than 1000 inhabitants living in four villages....
s, Mexico - Canna, ScotlandCanna, ScotlandCanna is the westernmost of the Small Isles archipelago, in the Scottish Inner Hebrides. It is linked to the neighbouring island of Sanday by a road and sandbanks at low tide. The island is long and wide...