Category: Comm CORE, Priv CORE
It is estimated that annually in the U.S there are between 10,000 to 20,000 cases of work-related pesticide poisonings. Of these, insecticides are most often implicated. Two thirds of these poisonings occur in children under the age of 6. These do not reflect suicide/homicide cases and focus on symptom producing poisonings.
In about 90 percent of pesticide poisoning cases, only minor symptoms occur and are typically treated at home. However, carbamates, organophosphates, pyrethrin/pyrethroids, organochlorines, and anticoagulant rodenticides are much more likely to require medical attention.
Route of Entery of Pesticide into Body. A major factor that greatly influences the risk of a pesticide product is its route of entry into the body. Pesticides can enter the human body a number of ways, including through the skin (dermal), the eyes (conjunctival), the mouth (oral), and by breathing (inhalation).
Dermal/Conjunctival Exposure. Pesticides can easily enter through the skin and eyes. Entry through the eye is generally the most rapid means, with other dermal entry rates varying quite drastically, depending on the particular area of the skin (Figure 1).
Figure 1. The relative rate of absorption of pesticides through the skin over various areas of the body. These rates are comparatively based on absorption through the forearms equaling one.
These relative rates are calculated by comparing them to the rate determined on the forearm. For example, a pesticide can enter the body 11.8 times faster through the groin than through the forearm. As can be seen in the above diagram, pesticides are absorbed much more rapidly through the skin on the head (forehead, ear canal skin, and scalp) and groin than through the skin on the forearms, balls of the feet and palms. This is significant as pesticide residues can be easily transferred from one area of the body to another. If this occurs, the applicator increases the potential for poisoning of pesticides moved from a hand (1.3) to a sweaty forehead (4.2) or to the genital area (11.8). At the very highest rate (groin), the absorption of a pesticide through the skin may be more dangerous than if swallowed!
Oral exposure. Generally speaking, pesticides are absorbed more rapidly when ingested than when exposed to most areas of the skin and when ingested can result in serious injury or death. This is even true for some of the “relatively nontoxic pesticides”. In some cases the solvents used in formulating a product are more toxic than the so-called toxicants. The most common accidental oral exposures occur when pesticides have been removed from their original containers and placed into an unlabeled bottle, jar or food container. Children under ten are victims of at least 1/2 of the accidental pesticide poisoning deaths in the United States. It is considered a serious violation to store a pesticide in a food or similar container.
Respiratory exposure. Inhalation of pesticide particles is especially hazardous as they are rapidly absorbed by the lungs into the bloodstream. Besides acute or chronic poisoning, they can cause serious damage to nose, throat and lungs. Vapors and very small particles pose the most serious risks.
The hazard from inhaling pesticide spray droplets is fairly low when dilute sprays are applied with low-pressure application equipment. With this type of application, most droplets are too large to remain airborne long enough to be inhaled. However, when high pressure, ultra low volume (ULV), or fogging equipment is used, the potential for respiratory exposure is increased. The droplets produced during these operations are relatively small and can be carried on air currents for considerable distances.
Product Labels, Signal Words and Warning Statements
Nearly all pesticides are toxic, differing only in degree. The product label is a valuable tool in detecting the relative toxicity of a given pesticide. Relative toxicity can quickly be determined by referring to signal words on the labels. The labels of the most toxic pesticides are marked with the signal words“Danger”, which indicate that it contains a toxicant with a LD50 that falls between 1 and 50. Similarly those pesticides with the signal words “Warning” and “Caution” contain a toxicant with LD50s that fall between 51 and 500 and 501 and 5,000, respectively. LD50 refers to that dose of a toxicant that will kill 50% of a test population.
It should be noted that these signal words are somewhat misleading as there is quite a range of toxicity represented by each. For example Pesticide A could contain a toxicant (active ingredient) that has an LD50 of 2 and Pesticide B could contain a toxicant that has an LD50 of 50. Both would have the same signal word on the label but Pesticide A would potentially be 25 time more toxic than Pesticide B, assuming both had the same amount of active ingredient and were formulated similarly. With this in mind it is to the applicators advantage to know the precise LD50 of a given pesticide rather than rely on the signal words alone.
Measuring Toxicity. The toxicity of a pesticide is determined by laboratory testing on animals such as rats, mice and rabbits. The measuring method, LD50 (lethal dose, 50 percent), describes the dose of a pesticide that will kill half of a group of test animals from a single exposure (dose) by either the dermal, oral or inhalation routes. A pesticide with a lower LD50is more toxic than a pesticide with a higher number because it takes less of the pesticide to kill half of the test animals. The toxicity of fumigant pesticides is described in terms of the concentration of the pesticide in the air, LC50 (lethal concentration, 50 percent). A similar system is used to test the potential effects of pesticides against aquatic organisms in water.
As discussed above all labels have signal words that indicate the degree of potential risk to a user. The three signal words that are used are indicated below (Table 2) along with their related toxicity and amount that is potentially deadly to hum
Table 2. Signal Words and Related Potential Dose that is Potentially Deadly. Oral Lethal Toxicity Base on 15O Pound HuMAN
Few drops to 1 teaspoon
1 teaspoon to 1tablespoon
1 ounce to more than a pint
aThe skull and crossbones symbol and the word "Poison" are often printed with the "Danger" signal word.
The pesticide label also has precautionary statements that relate to the potential hazard.
Table 3. Typical Precautionary Statements on Pesticide Labels
Fatal if swallowed,
Can kill you if
Harmful or Fatal if
swallowed, or May be
fatal if swallowed.
Harmful if swallowed, or May be harmful if
Poisonous if inhaled, or Can kill you if breathed, or Do not breathe dusts, vapors, or spray mist.
Harmful or fatal if inhaled, or May be fatal if breathed, and a statement such as, Do not breathe dusts, vapors, or spray mist.
Harmful if inhaled, or May be harmful if breathed, and Avoid breathing dusts, vapors, or spray mist.
Fatal if absorbed through the skin, or Can kill you by skin contact, and Do not get on skin or clothing.
Harmful or fatal if absorbed through the skin, or May be fatal by skin contact, and a statement such as Do not get on skin or clothing.
Harmful if absorbed through skin, or May be harmful by skin contact, and Avoid contact with skin or clothing.
Corrosive causes severe skin burns," and "Do not get on skin."
Causes skin irritation, or Causes skin burns, followed by a statement such as Do not get on skin."
May irritate skin, and Avoid contact with skin."
Corrosive — causes irreversible eye damage," or Causes severe eye burns or blindness," and Do not get in eyes.
Causes eye irritation," or Causes eye burns, and a statement such as Do not get in eyes."
May irritate eyes," and Avoid contact with eyes.
Two additional terms are commonly used when measuring pesticide toxicity, namely acute and chronic toxicity. Acute toxicity refers to the effects from a single exposure or repeated exposure over a short time, such as an accident during mixing or applying pesticides. This term is frequently used in conjunction the previously described terms. For example if a pesticide had an acute oral LD50 of 20 it would require a dose of 20 milligrams (per kilogram of body weight) to kill 50% of a test animal population when administer via one dose through the mouth.
Chronic toxicity refers to the effects of long-term or repeated lower level exposures to a toxic substance. The effects of chronic exposure do not appear immediately after first exposure and may take years to produce signs and symptoms. Examples of chronic poisoning effects may include: Carcinogenicity—exposure may result in cancer; mutagenicity—exposure may result in genetic changes; teratogenicity—exposure may result in birth defects; oncogenicity—exposure may result in the development of tumors (not necessarily cancers); liver damage—exposure may result in destruction of liver cells, jaundice (yellowing of the skin), fibrosis and cirrhosis; reproductive disorders—exposure may result in or produce reduced sperm count, sterility, and miscarriage; nerve damage--including accumulative effects on cholinesterase depression associated with organophosphate insecticides;allergenic sensitization--development of allergies to pesticides or chemicals used in formulating pesticides.
The effects of chronic toxicity, as with acute toxicity, are dose-related. In other words, low-level exposure to chemicals that have potential to cause long-term effects may not cause immediate injury, but repeated exposures through careless handling or misuse can greatly increase the risk of chronic adverse effects.
Formulation and Potential Risks.
It is worthwhile to remember that the toxicity of the active ingredient in a product does not always correlate directly to potential hazard of that product. The hazard may vary considerably depending on the formulation of the product, concentration of the toxicant in the product, method of application and other factors. For example pesticide A when formulated as a granule presents a totally different hazard (much less) than when formulated as an emulsifiable concentrate. The granular formulation would not likely present much of a dermal hazard (as it may be coated with a nontoxic material) and the same chemical when formulated as an emulsifiable concentrate may present a high dermal hazard. These potential hazards are indicated in the precautionary statements on the labels. It is worthwhile to discuss the various types of formulation available and the potential risk from each.
A pesticide product consists of two parts, namely the active ingredient and the inert ingredient. The active ingredient is the toxicant that kills the targeted pest. The inert ingredients are solvents and carriers that help deliver the active ingredient to the pest. Inert ingredients maybe liquids into which the active ingredient is dissolved chemicals that keep the product from separating or settling, and even compounds that help secure the pesticide to its target after application. The combination of an active ingredient with a compatible inert ingredient is referred to as a formulation.
Solid formulations can be divided into two types: ready-to-use, and concentrates which must be mixed with water to be applied as a spray. Three of the solid formulations (dusts, granules, and pellets) are ready-to-use, and three (wettable powders, dry flowables, and soluble powders) are intended to be mixed with water.
Dusts. Dusts are manufactured by the sorption of an active ingredient onto a finely-ground, solid inert such as talc, clay, or chalk. They are relatively easy to use because no mixing is required and the application equipment (e.g., hand bellows and bulb dusters) is lightweight and simple. Dusts can provide excellent coverage, but the small particle size that allows for this advantage also creates an inhalation and drift hazard. In general, dust formulations are no longer used in large scale outdoor. Commercial pest control operators use dusts effectively in residential and institutional settings for control of various insect pests. Indoors, this type of formulation permits the delivery of an insecticide into cracks and crevices, behind baseboards and cabinets, etc. Thus, the insecticide is placed into the pest’s habitat and away from contact by people and pets.
Granules. The manufacture of granular formulations is similar to that of dusts except that the active ingredient is absorbed onto a larger particle. The inert solid may beclay, sand, or ground plant materials. Granules are applied dry and usually are intended for soil applications where they have the advantage of weight to carry them through foliage to the ground below. The larger particle size of granules, relative to dusts, minimizes the potential for drift. There is also a reduced inhalation hazard, but finer particles (inhalation hazard) are frequently associated with the formulation—especially when a bag is being emptied. In addition granules have a low dermal hazard.
Pellets. Pellets are very similar to granules, but their manufacture is different. The active ingredient is combined with inert materials to form a slurry (a thick liquid mixture). This slurry is then extruded under pressure through a die and cut at desired lengths to produce a particle that is relatively uniform in size and shape. Pellets are typically used in spot applications. Pelleted formulations provide a high degree of safety to the applicator. They do have the potential to roll on steep or frozen slopes and thereby harm nontarget vegetation or contaminate surface water.
Wettable Powders. Wettable powders are finely divided solids, typically mineral clays, to which an active ingredient is absorbed. This formulation is diluted with water and applied as a liquid spray. Upon dilution, a suspension is formed in the spray tank. Wettable powders will likely contain wetting and dispersing agents as part of the formulation. These are chemicals used to help wet the powder and disperse it throughout the tank. Wettable powders are a very common type of formulation. They provide an ideal way to apply an active ingredient in spray form that is not readily soluble in water. Wettable powders tend to pose a lower dermal hazard in comparison to liquid formulations, and they do not burn vegetation as readily as many oil-based formulations. This formulation does present an inhalation hazard to the applicator during mixing and loading because of the powdery nature of the particles.
Dry Flowables. Dry flowerless—or water dispersible granules, as they are sometimes called—are manufactured in the same way as wettable powders except that the powderis aggregated into granular particles. They are diluted with water and applied in a spray exactly as if they were a wettable powder. During the mixing and loading process, dry flowables pour more easily from the container and because of their larger particle size, reduce inhalation hazard to the applicator.
Soluble Powders. Soluble powders, although not particularly common, are worth mentioning for purposes of contrast with the wettable powders and dry flowables. Their lack of availability is due to the fact that not many solid active ingredients are soluble in water. Those that do exist and are formulated in this fashion are mixed with water prior to spraying, dissolve in the spray tank, and form a true solution. Soluble powders, like any finely divided particle, can present an inhalation hazard to applicators during mixing and loading.
Liquid Flowables. The manufacture of liquid flowables (or flowables) mirrors that of wettable powders—with the additional step of mixing the powder, dispersing agents, wetting agents, etc., with water before packaging. The result is a suspension that is further diluted with water before use. The product is applied as a spray with all the advantages of a wettable powder. The benefit of this formulation is that there is no inhalation hazard to the applicator during mixing and loading since the powder already is suspended in water, permitting it to be poured. One further problem noted with this formulation is the difficulty in removing all of the product from the container during mixing, loading, and container rinsing.
Microencapsulates. Microencapsulates consist of a solid or liquid inert (containing an active ingredient) surrounded by a plastic or starch coating. The resulting capsules can be aggregated to form dispersible granules (see dry flowables), or they can be suspended in water and the product sold as a liquid formulation. Encapsulation enhances applicator safety while providing timed release of the active ingredient. Sine the toxicant is encapsulated it inherent toxicity is greatly reduced. In many case oral toxicity is greatly reduced since if consumed much of the toxicant pass through the gut of the nontarget organism and is eliminated. Liquid forms of microencapsulates are further diluted with water and applied as sprays.
Emulsifiable Concentrates. Emulsifiable concentrates consist of an oil-soluble active ingredient dissolved in an appropriate oil-based solvent to which is added an emulsifying agent. Emulsifiable concentrates are mixed with water and applied as a spray. As their name implies, they form an emulsion in the spray tank. The emulsifying agents are long chainchemicals that orient themselves around the droplets of oil and bind the oil-water surfaces together to prevent the oil and water from separating. Emulsifiable concentrates allow oil-soluble active ingredients to be sprayed in water as a carrier. Emulsifiable concentrates have several disadvantages. There is a dermal hazard associated with this formulation. Emulsifiable concentrates readily penetrate oily barriers like human skin.
Solutions. Solutions (water-soluble concentrates) consist of water-soluble active ingredients dissolved in water for sale to the applicator for further dilution prior to fieldapplication. They will, obviously, form a true solution in the spray tank and require no agitation after they are thoroughly dissolved. Although not a particularly common formulation, several major herbicides with wide-scale use are formulated in this way. They include products containing paraquat, glyphosate and 2,4-D. Aside from lack of availability, solutions have few disadvantages; however, some that are produced as dissolved salts can be caustic to human skin.
Miscellaneous Liquid Formulations. Low and ultra low volume concentrates used in specialty situations (e.g., space spraying and fogging are
frequently applied undiluted. Dermal hazards are a problem during mixing and loading of these products because of the high concentration of active ingredient. Low and ultra low volume concentrated formulations utilize special equipment to deliver the product in the form of very tiny droplets. Consequently, while they provide excellent coverage, drift potential and inhalation problems during application can be quite high.
Recognizing Signs and Symptoms of Poisoning
Anyone who may become exposed to pesticides should be aware of the signs and symptoms of pesticide poisoning. Prompt action during pesticide overexposure can prevent serious consequences.
The following is important when dealing with pesticides: Recognize the signs and symptoms of pesticide poisoning for those pesticides you commonly use or to which you may be exposed. If poisoning occurs, quickly contact a local hospital, physician, or the nearest poison control center and identify the pesticide to which the victim was exposed. Provide this information to medical authorities. A copy of the label should be available. This provides information that will be useful in treating a pesticide poisoning victim. First aid and medical treatment procedures for pesticide poisoning are listed on the product label.
All toxicants in a given chemical group generally affect the human body in the same way; however, severity of the effects vary depending on the formulation, concentration, toxicity of each and route of exposure of the pesticide. It is important, therefore, to know both the type of pesticide you are using and the signs and symptoms associated with poisoning from it.
Organophosphate and Carbamate Insecticides
Most pesticide poisoning cases involve either organophosphate or carbamate insecticides. Many of these chemicals have been commonly used in the past but in recent years their use has been greatly curtailed and many are no longer available. Both chemical groups affect humans by inhibiting acetyl cholinesterase, an enzyme essential to proper functioning of the nervous system. Poisoning from these chemicals can be accumulative in effect. As a result repeated exposure to low levels of these chemicals may have no apparent effect until a critical level is reached. However once that level is reached the effects of these materials quickly unveil, particularly organophosphate insecticides. In the case of heavy exposure, symptoms begin shortly after or even during the exposure.
Blood tests can be used to determine whether these chemicals have accumulated in a person's body. One such test uses cholinesterase, an enzyme that occurs naturally in the blood at levels that vary from one person to another. "Baseline" levels of cholinesterase for an individual can be determined at a time of the year when pesticide handling is minimal. The baseline helps determine the normal level of cholinesterase in the body. Other tests throughout the year indicate if there is a reduction in the baseline level. If a reduction has occurred, the individual should not apply organophosphate insecticides. The body normally produces new cholinesterase continuously, and levels return to normal after several weeks.
Signs and symptoms of mild exposures include:
- headache, fatigue, dizziness, nausea, mild stomach cramps and diarrhea.
- blurred vision and increase secretions such as tearing, salivation, sweating and respiratory secretions.
- dilation of the pupils
- slowed heartbeat, often fewer than 50 per minute;
- rippling of surface muscles just under the skin.
Signs and Symptoms of moderate exposure include all of the above and the following:
- inability to walk;
- discomfort and tightness of the chest;
- marked constriction of the pupils (pinpoint pupils);
- muscle twitching;
- involuntary urination and bowel movement.
Sign and symptoms of severe poisoning include incontinence, unconsciousness and seizures.
Fortunately, good antidotes are available for victims of organophosphate or carbamate poisoning at emergency treatment centers, hospitals, and many physicians' offices. As with all pesticide poisonings, time is extremely critical.
The use of these chemicals has been greatly curtailed due persistence in the environment and other side effects. Two organochlorine insecticides, lindane and methoxychlor, still have limited use. Nausea and vomiting commonly occur soon after ingesting organochlorines. Other early signs and symptoms include: apprehension, excitability, dizziness, headache, disorientation, weakness, a tingling or pricking sensation on the skin, and muscle twitching. This is followed by loss of coordination, convulsions similar to epileptic seizures, and unconsciousness. When chemicals are absorbed through the skin, apprehension, twitching, tremors, confusion, and convulsions may be the first symptoms.
Synthetic Pyrethroid Insecticides
These chemicals are commonly used in agriculture and structural pest control and to a large extent are replacing the use of the more toxic organophosphrous and carbamate insecticides. Common examples include cyfluthrin, cypermethrin and permethrin. Most have very high LD50s and are relatively safe, if there is such a thing as a safe insecticide. There have been very few systemic poisonings of humans by pyrethroids. Inflammatory reaction usually occurs within one to two hours. Dermal contact may result in skin irritation such as stinging, burning, itching, and tingling progressing to numbness.
Some may be toxic orally, but usually ingestion of pyrethroid insecticide presents relatively little risk. Very large doses may rarely cause lose of coordination, tremors, salivation, vomiting, diarrhea, and irritability to sound and touch. The kidney promptly excretes most pyrethroids. .
Crude pyrethrum is derived from Chrysanthemum flower heads and is used in structural pest control and reportedly can be a dermal and respiratory allergen with exposure resulting in skin irritation and asthma. Exposure to the more refined forms (pyrethrins) can cause similar but typically relatively milder symptoms. The synergist piperonyl butoxide is frequently used with pyrethin to enhance its insecticidal activity and presents little if any toxic potential in humans.
Rotenone, another plant derivative, is used in gardens and on food crops. Although rotenone is toxic to the nervous systems of insects, fish, and birds, commercial rotenone products have presented little hazard to humans.
Bacillus thuringiensis (Bt). There are no reported work-related cases of poisoning (any form) from products containing this bacterium.
DEET, diethyltoluamide is the main ingredient in repellents used against mosquitoes and other blood feeding arthropods. Products such as OFF and MGK are effective and generally well- tolerated when applied to human skin. Tingling and mild irritation has been reported with repeated applications. In some cases, DEET has caused skin irritation and intensification of preexisting skin conditions. It is very irritating to the eyes. Serious adverse effects have occurred especially under hot, humid conditions or if applied to skin areas that are in direct contact during sleep. If so the skin can become red, tender and blistered, often leaving painful sweeping bare areas that heal slowly. Permanent scarring can result in severe cases. Due to the tender nature of their skin and smaller size products containing DEET should only be used sparingly on children. If used it should only be applied to clothing and products containing lower concentrations are advisable.
Various types of fumigants produce differing physiologic effects. Headache, dizziness, nausea and vomiting are common early signs and symptoms of excessive exposure.
Sulfuryl fluoride (product Vikane) is the most commonly used fumigant for control of drywood termites. It is a clear, tasteless, odorless gas with poisoning symptoms including depression, slowed gait, slurred speech, nausea, vomiting, stomach pain, drunkenness, itching, numbness, twitching, and seizures. Inhalation may be fatal due to respiratory failure. Inhalation of high, concentrations may cause respiratory tract irritation. Skin contact with sulfuryl fluoride normally poses no hazard, but contact with liquid sulfuryl fluoride can cause pain and frostbite due to rapid evaporation.
Aluminum phosphide (Phostoxin, Gastoxin, Fumitoxin) is commonly used for grain fumigation and control of burrowing rodents. It can affect cell function, liver and lungs. A sensation of cold, chest pains, diarrhea and vomiting has been reported with mild exposure. More serious cases may result in cough, chest tightness, difficult breathing, weakness, thirst and anxiety. Extreme exposure is indicated by stomach pain, loss of coordination, blue skin color, limb pain, enlarged pupils, choking, fluid in the lungs and stupor. Severe poisonings lead to seizures, coma and death.
Chloropicrin and methyl bromide affect the central nervous systems, lungs, heart and liver. Methyl bromide has been used in large quantities in the past for soil fumigation and tent fumigation for drywood termites. Its use has been greatly curtailed due to environmental complications. Chloropicrin (tear gas) is used to mark the otherwise odorless Vikane when used in tent fumigation. Persons poisoned by these types of fumigant experience the common signs and symptoms of fumigant poisoning along with abdominal pain, weakness, slurred speech, mental confusion, tremors, and convulsions similar to epileptic seizures.
To treat victims of fumigant exposure, remove them to fresh air immediately, keep them quiet and in a semi-reclining position. Mouth- to-mouth resuscitation or cardiopulmonary resuscitation (CPR) should be applied if breathing or pulse stops. Anyone attempting to rescue a person suffering from fumigant exposure should be properly equipped with self-contained breathing apparatus. Minimum physical activity limits the likelihood of pulmonary edema, a medical emergency characterized by the accumulation of abnormally large amounts of fluid in the lungs. If skin is contaminated, flush with water for at least 15 minutes. Seek medical attention immediately. Time is particularly critical in fumigant poisonings; victims must receive prompt medical attention.
Rodenticides pose particular risks for accidental poisonings for several reasons. Since they are designed specifically to kill mammals, usually rodents, their toxicity is similar for humans. Also, because many rodents (rats and mice) frequently share our habitats, these chemicals may come in close contact with us, especially children. Finally, as rodents have developed resistance to existing rodenticides, there is a continuous need to develop new and potentially more toxic chemicals. The coumarins are frequently referred to as the first generation anticoagulants. Common products include Havoc, Talon, Weather Blok (active ingredient brodifacoum), Contrac and Maki (active ingredient bromadiolone), and warfarin. These are also known as multiple dose anticoagulants. Multiple daily feedings (several) are typically required to produce symptoms. Their primary mode of action is to prevent blood from coagulating. When taken in lethal amounts they also cause capillaries to rupture and the victim bleeds to death. Since these materials are typically formulated as bait there are little problems from dermal exposure. Intestinal tract absorption of these toxicants is efficient. The main signs and symptoms are nosebleed, bleeding gums, blood in the urine, tar feces, and large irregular blue-black to greenish-brown spots or patches on the skin.
The indandiones are commonly referred to as the second-generation anticoagulants and include products such as Rozol (active ingredient chlorophacinine) and Diphacin and Ramik (active ingredient diphacinone). Unlike the coumarin compounds, some indandiones cause signs and symptoms of nerve, heart and circulatory system damage in laboratory rats leading to death before hemorrhage occurs. None of these signs and symptoms has been reported in human poisonings. The antidote for first and second-generation anticoagulants is vitamin K, which enhances the clotting ability of blood.
Zinc phosphide reacts with atmospheric moisture to slowly release phosphine (not phosgene), a toxic and flammable gas with an odor similar to garlic or onions. When formulated as grain bait and exposed to normal atmospheric conditions the gas that is produced presents little hazard. However when exposed to acidic conditions (as in the stomach) the gas is released quickly accounting for the toxic nature of the chemical. Although zinc phosphide baits have a strong pungent odor this seems to attract rodents, especially rats, and apparently makes the bait unattractive to some other animals Animals that consume lethal amounts of zinc phosphide typically die within 30 hours. Early symptoms include nausea, tightness of the chest, excitement and an overall feeling of cold and vomiting of a black colored stomach contents and the garlic smell of phosphine gas. Advanced symptoms include convulsions, paralysis, coma and death due to respiratory failure. If symptoms extend for several days intoxication occurs with resultant heavy liver damage. Typically if an individual lives for 3-days recovery is complete. The dust at the bottom of zinc phosphide container creates a potential hazard and every precaution should be maintained to inhaling this material when pouring from the original packaging. Zinc phosphide bait should not be handled without gloves. Oils and other liquid are used in the preparation of some bait. As a result repeated handling can result in small amounts being absorbed through the skin. Repeated absorption to phosphine gas can result in symptoms at a later date. Zinc phosphide causes severe irritation if ingested. It reacts with water and stomach juices to release phosphine gas which can enter the blood stream and affect the lungs, liver, kidneys, heart and central nervous system. Zinc phosphide is easily absorbed through the skin or inhaled from fumes. With repeated exposure, it accumulates in the body to dangerous levels. Signs and symptoms of mild zinc phosphide poisoning include diarrhea and stomach pains. In more severe cases, nausea, vomiting, chest tightness, excitement, coldness, unconsciousness, coma and death can occur from pulmonary edema and liver damage. There is no antidote for zinc phosphide poisoning. It is a slow-acting material, which gives a victim time to get medical help. It is also a natural emetic frequently inducing vomiting. This is advantageous in accidental poisoning since it is quickly removed from the body.
Strychnine is mainly used as gopher bait. It is an extremely toxic material to mammals with an AOLD50 of around 4 to 6. A lethal dose of this natural toxin is as little as 15 mg in children. This is especially bothersome since the public can purchase it in any nursery or garden shop. It is not easily absorbed through the skin nor does it accumulate in the human body. When ingested, it acts on the central nervous system (mainly the spinal cord) within 10 to 30 minutes. Violent convulsions occur, causing breathing to stop. This material has an extremely bitter taste when ingested even in very small amounts. There is no antidote for strychnine poisoning. Treatment is geared toward eliminating outside stimuli that can trigger convulsions. If strychnine poisoning occurs, it is important to place the victim in a warm, dark room, which reduces outside stimuli. In addition it is advisable to bring medical help to the victim rather than transporting the victim to a medical center because movement may trigger convulsions.
What To Do When Pesticide Poisoning Occurs
The key to surviving and recovering from a pesticide poisoning is rapid treatment. Take emergency action immediately when you suspect a pesticide poisoning. As time continues to elapse after exposure, recovery is hindered and the toxic effects are heightened. If the common emergency telephone number is available in your area, immediately call 911 whenever a pesticide poisoning is suspected. An advanced life support team will be dispatched to provide assistance. If the common emergency telephone number is not available in your community, contact in the following order:
1. The Poison Center, 1-800-955-9119. The poison center will be able to provide specific directions on procedures to follow until a life support team arrives. 2. The nearest hospital. 3. A physician. Another source of medical information related to pesticides during non-emergencies is the National Pesticide Telecommunications Network, 1-800-858-7378.Medical and consumer information on pesticides is available through this hotline.
What a victim might think is a cold or the flu could be a fatal pesticide poisoning. Whenever possible, find out the following critical information: 1. Has the victim been exposed to a pesticide? 2. If so which one and how did the exposure occur? 3. What emergency actions are on the pesticide label?
Many labels direct that vomiting be induced. Vomiting can be induced by giving the patient ipecac and water or by inserting the finger into the throat of the victim. Do not induce vomiting when: 1.The label says not to. 2. Convulsions have occurred. 3. the victim is unconscious. 4. The pesticide contains petroleum products such as xylene.
Always wash the victim's exposed skin with a detergent and plenty of water. Skin irritation can result from continuous exposure if not treated. If skin exposure occurs, obtain medical treatment. If the victim's clothing has been contaminated by a pesticide that is readily absorbed dermally, remove the clothing and decontaminate the victim's skin.
Even though careful pesticide application is normal, accidents can happen. Be prepared. Keep the number for the Poison Center readily available either in your telephone directory or near your telephone. Do not hesitate to contact medical authorities if any symptoms of pesticide poisoning occur. It is better to be safe than sorry. Any pesticide can cause exposure problems. Use all pesticides safely. Read the pesticide label completely and comply with all directions. Failure to do so may subject you to sanctions or penalties provided by federal and/or state laws.
Pesticide Poisoning Questions
True-False. Accreditation Credit. Call or Email in False answers
1. It is estimated that approximately 2/3 of all pesticide poisoning cases occur with children under the age of six.
2. In about 90 percent of pesticide poisoning cases, only minor symptoms occur and are typically treated at home.
3. A major factor that greatly influences the risk of a pesticide product is its route of entry into the body.
4. Pesticides can easily enter through the skin and eyes. Entry through the eyes is generally the most rapid means, with other dermal entry rates varying quite drastically, depending on the particular area of the skin.
5. A pesticide can enter dermally into the body approximately 12 times faster than through the skin on the forearms.
6. Generally speaking, pesticides are absorbed more rapidly when ingested than when exposed to most areas of the skin and when ingested can result in serious injury or death.
7. The hazard from inhaling pesticide spray droplets is fairly low when dilute sprays are applied with low-pressure application equipment.
8. Inhalation of pesticide particles is especially hazardous as they are rapidly absorbed by the lungs into the bloodstream. Besides acute or chronic poisoning, they can cause serious damage to nose, throat and lungs.
9. Acute toxicity refers to the effects from a single exposure or repeated exposure over a short time, such as an accident during mixing or applying pesticides.
10. Generally speaking insecticides can enter into the body more rapidly via the mouth than through most areas of the skin.
11. Repeated exposure to low levels of organophosphrous insecticides may have no apparent effect until a critical level is reached.
12. Application of pesticides via low pressure equipment presents more of a hazard from the standpoint of respiratory intoxication than it does high pressure equipment.
13. A pesticide having an acute oral LD50 of 20 would require a dose of 20 milligrams (per kilogram of body weight) to kill 50% of a test
animal population when administer via one dose through the mouth.
14. The toxicity of fumigant pesticides is described in terms of the concentration of the pesticide in the air.
15. The term mutagenicity refers to cancer causing.
16. The term teratogenicity refers to birth defects causing.
17. There is a dermal hazard associated with emulsifiable concentrates as they readily penetrate oily barriers like human skin.
18. Pelleted formulations provide a relatively high degree of safety to the applicator.
19. Pinpoint pupils and tightness of the chest are key symptoms of pyrethroid poisoning.
20. Dilated pupils and tightness of the chest are key symptoms of organophosphrous insecticide poisoning.
21. Most synthetic pyrethroids have very high LD50s and are relatively safe, if there is such a thing as a safe insecticide.
22. There are no reported work-related cases of poisoning (any form) from products containing this Bacillus thuringiensis.
23. A key antidote for anticoagulant rodenticides is vitamin K.
24. With DEET serious adverse effects have occurred especially under hot, humid conditions or if applied to skin areas that are in direct contact during sleep.
25. Boric acid is moderately irritating to skin and if inhaled causes irritation of the respiratory tract and shortness of breath.
26. Rodenticides pose particular risks for accidental poisonings for several reasons. Since they are designed specifically to kill mammals, usually rodents, their toxicity is similar for humans.
27. Zinc phosphide is easily absorbed through the skin or inhaled from fumes. With repeated exposure, it accumulates in the body to dangerous levels.
28. There have been very few systemic poisonings of humans by pyrethroids.
29. Vikane is a clear, tasteless, odorless gas with poisoning symptoms including depression, slowed gait, slurred speech, nausea, vomiting, stomach pain, drunkenness, itching, numbness, twitching, and seizures. Inhalation may be fatal due to respiratory failure.
30. Animals that consume lethal amounts of zinc phosphide typically die within 1 hour.
31. Strychnine is an extremely toxic material to mammals with an AOLD50 of around 4 to 6. A lethal dose of this natural toxin is as little as 15 mg in children.
32. There is no antidote for strychnine poisoning. Treatment is geared toward eliminating outside stimuli that can trigger convulsions
33. DEET, diethyltoluamide, is the main ingredient in repellents used against mosquitoes and other blood feeding arthropods.
34. Strychnine is very fast acting and readily absorbed through the skin.
35. The key to surviving and recovering from a pesticide poisoning is rapid treatment.
36. Do not induce vomiting when a victim is unconscious.
38. Do not induce vomiting when the pesticide contains petroleum products such as xylene.
39. If strychnine poisoning occurs, it is important to place the victim in a warm, dark room which reduces outside stimuli.