Biology 110 - Lab 4
 

Chemicals in the Environment
 

1. Resmethrin
   
   Found in Products: Chryson, Crossfire, Derringer, FMC 17370, Isathrine, NRDC 104, Pynosect, Raid Flying Insect Killer, Respond, Scourge, Sun-Bugger #4, SPB-1382, Synthrin, Syntox, Vectrin, and Whitmire PT-110.

Beneficial/Intended Use: It is a pyrethroid insecticide. While it is among the least toxic of insecticides, it is a nerve poison that affects the sodium ion channels in nerve cell membranes. It is used to kill most any kind of insect, though the range of insects targeted depends on the particular product it is found in. Gardeners and farmers spray it on their plants and crops; the average homeowner uses a product containing Resmethrin to kill household pests.

Environmental/Health Side Effects: For the most part, it is one of the least toxic chemicals. It is highly toxic to bees and fish. Small animals (such as rodents) also are affected by it, though not fatally. In soil, it has a half-life of about 30 days; in water, it is 36.5 days. To birds, it is essentially harmless. For humans, inhaling pyrethroid insecticides can cause coughing, wheezing, shortness of breath, runny or stuffy nose, chest pain or difficulty breathing. No adverse effects on plants or other vegetation have been found, and it seems to be quite harmless in both soil and water.

Availability: Most of the products can be found at almost any home-improvement or hardware store, as well as some grocery stores, plant nurseries, and flower shops.

2. Carbaryl

Found in Products: A controversial insecticide called Sevin. Also known as/found in: Adios, Bugmaster, Carbamec, Carbamine, Crunch, Denapon, Dicarbam, Hexavin, Karbaspray, Nac, Rayvon, Septene, Tercyl, Torndao, Thinsec, Tricarnam and Union Carbide 7744.

Beneficial/Intended Use: It is a carbamate introduced in 1958. It is a toxic insect killer used in commercial agriculture, forest and rangeland protection, and in home and garden pest control products. It is used to kill over 100 species of insects on citrus, fruit, cotton, forests, lawns, shade trees and other crops. It is also used on poultry, livestock and pets. It is also used as a molluscicide and an acaricide.

Environmental/Health Side Effects: Carbaryl can be moderately to highly toxic, depending on the product. Skin contact can cause burns. Toxic to the respiratory and nervous systems, it can cause sweating, blurring of vision, convulsions, nausea and stomach cramps. It is not generally considered fatal to humans. While some reports had alleged side effects to mammals (birth defects, mutations, cell damage, et cetera), the reports proved to be false. In very high doses Carbaryl can be toxic to rats and a few animals such as pigs. It is not toxic to birds, but can be to numerous species of fish. In soil, it has a half life of seven to 14 days, where it is considered harmless as well as to crops. In water, it has a half-life of about 10 days, and the toxicity is determined by the pH level of the water.

Availability: It is available as bait, dusts, wettable powders, granules, dispersions and suspensions. It can be found in many products in most home / garden stores.

3. Lindane

Found in Products: Among others, Agrocide, Ambrocide, Aparasin, Aphitiria, Benesan, Benexane, BoreKil, Borer-Tox, Exagama, Gallogama, Gamaphex, gamma-BHC, Gamma-Col, gamma-HCH, Gammex, Gammexane, Gamasan, Gexane, Isotox, Jacutin, Kwell, Lindafor, Lindagronox, Lindaterra, Quellada, Steward, Streunex, and Tri-6.

Beneficial/Intended Use: It is a chlorinated hydrocarbon poison. It was used as an insecticidal poison treatment for lumber, grains, and livestock, and in dog dips, pet and human (baby) shampoos for treatment of fleas, ticks, lice and similar problems. Lindane was used to kill fungicides as well.

Environmental/Health Side Effects: Extremely toxic to the point that most registered uses were banned in 1983. One teaspoon taken orally would most likely kill a man. Other long-term effects on human health include aplastic anemia, liver, testicular, bone marrow and kidney damages. It has been associated with causing leukemia as well. Small to moderate doses are enough to cause health problems—too numerous to list—in many animals, and some animals with long-term exposure to the chemical (such as dogs) died. It is toxic to some species of birds and very toxic to almost all species of fish. In soil it has a half-life of about 15 months and poses a risk to groundwater contamination. It will only disappear from water via secondary mechanisms such as absorption in fish.

Availability: With a few exceptions, almost nowhere for nearly 20 years, though it is sometimes imported. It is banned in 18 countries mainly because the risk to humans is so high.

4.   Dichlorvos

Found in Products: Apavap, Benfos, Cekusan, Cypona, Derriban, Derribante, Devikol, Didivane, Duo-Kill, Duravos, Elastrel, Fly-Bate, Fly-Die, Fly-Fighter, Herkol, Marvex, No-Pest, Prentox, Vaponite, Vapona, Verdican, Verdipor, and Verdisol.

Beneficial/Intended Use: An organophosphate compound, it is an agricultural insecticide used to treat crops, stored products, and animals. It is also used as an insecticide for slow release on pest-strips for pest control in homes. Dichlorvos is used as a worming agent for dogs, swine, and for horses. It is also as an agent that kills fly larvae for horses, and in flea collars for dogs.

Environmental/Health Side Effects: Considered highly toxic to humans, it can cause cancer. Symptoms can be relatively mild (headaches, nausea, et cetera) to severe, such as paralysis and respiratory failure. In animals such as lab rats, some died within an hour and others never showed any adverse effects at all. male rats, repeated high doses caused abnormalities in the tissues of the lungs, heart, thyroid, liver, and kidneys. Some dogs showed adverse liver effects and lung hemorrhages. To birds, including pheasants and waterfowl, dichlorvos is highly toxic. In fish, a few varities of shrimp and crab are mildly toxic—ultraviolet light intensifies the toxicity of the chemical by as much as 150 times, however. It has a half-life of 20 to 80 hours, depending on the pH level, and dissolves through hydrolysis. In soil, this chemical has a half-life of about 5 to 7 days and there is a threat that groundwater may become poisoned; most plants, however, will not be affected by the chemical except in larger amounts.

Availability: Dichlorvos is considered a Restricted-Use Pesticide, and may only be purchased and used only by certified applicators.

5.   2,4-Dichlorophenoxyacetic acid ["2,4-D"]

Found in Products: Aqua-Kleen, Barrage, Lawn-Keep, Malerbane, Planotox, Plantgard, Savage, Salvo, Weedone, and Weedtrine-II.

Beneficial/Intended Use: It is a chlorinated phenoxy compound that functions as a systemic herbicide and is used to control many types of weeds. It is used in cultivated agriculture, in pasture and rangeland applications, forest management, home, garden, and to control aquatic vegetation.

Environmental/Health Side Effects: Considered somewhat toxic to humans. In humans, it can cause liver damage, damage to the kidney and central nervous system; also, vomiting, diarrhea, anorexia, and ulcers of the mouth and pharynx. In small animals such as lab rats, most displayed no adverse effects even after long-term exposure, though some younger ones showed decreased bone development, and in very high doses, it was fatal. Some dogs given lesser amounts of the chemical died within two years, but this is mainly because they do not efficiently expel organic acids. To birds, 2,4-D is slightly to moderately toxic; to fish, some formulations can be highly toxic but others are relatively harmless. While it has a half-life of less than 7 days in soil, the chemical has been found in groundwater and is considered toxic to many crops, mostly cotton and various fruits. It interferes with the normal growth process of the plants. In water it has a half-life of one week to many weeks; the breakdown of the chemical is proportional to the number of microorganisms in the water.

Availability: A General Use Pesticide, it is (relatively) readily available to those who use it, but it is not a product to be found in most home and garden stores.

6.   Glyphosate

Found in Products: Gallup, Landmaster, Pondmaster, Ranger, Roundup, Rodeo, and Touchdown.

Beneficial/Intended Use: An organophosphate herbicide used for control of annual and perennial plants including grasses, sedges, broad-leaved weeds, and woody plants. It can be used on non-cropland as well as on a wide variety of crops.

Environmental/Health Side Effects: It is practically nontoxic to humans, though mild symptoms have occasionally been reported in agricultural workers. The symptoms that have been reported (due to long-term exposure) are irritaion of the eyes, skin, and respiratory tract. In both rats and dogs alike, no symptoms or other health problems were found, even in long-term exposure and high dosage levels. Glyphosate is slightly toxic to birds; to fish, it is almost completely harmless. However, the effect it has on flora can have a damaging effect on mammals and birds through habitat destruction. The EPA concluded that many endangered species of plants may be at risk from glyphosate use. In the soil, it has a half-life averaging 47 days but little to no runoff into groundwater has been reported. While many wild plants can be killed by very small amounts of the chemical, most crops are either unaffected by it or, in the case of some, have been genetically engineered to be resistant to such herbicides. In the water it has a half-life of anywhere from ten days to twelve weeks; again, this is determined mostly by the amount of microorganisms in the water that break down the compound.

Availability: It is a General Use Pesticide that is most frequently distributed as a salt, powder, or concentrate. It seems to sell in great quantity and has very high yearly product sales figures, used mostly on plantations and in vineyards, but it is unknown how easy to find or readily available it is.

7.   Endosulfin

Found in Products: Afidan, Beosit, Cyclodan, Devisulfan, Endocel, Endocide, Endosol, FMC 5462, Hexasulfan, Hildan, Hoe 2671, Insectophene, Malix, Phaser, Thiodan, Thimul, Thifor, and Thionex.

Beneficial/Intended Use: A chlorinated hydrocarbon insecticide and acaricide, and acts as a contact poison in a wide variety of insects and mites. Sometimes used as a wood preservative, it is used on many crops such as coffee, fruits, vegetables, and a number of various grains such as rice. It kills the wide variety of insects that destroy the crops.

Environmental/Health Side Effects: In humans it can be highly dangerous, and a person working with it has to wear many articles of protective clothing to prevent poisoning. A condition known as ‘acute toxicity stimulation of the central nervous system’ is the first sign of exposure to the chemical. Coming into contact with the chemical can cause conditions such as vomiting, diarrhea, agitation, convulsions and loss of consciousness. Also toxic to many animals, it has been known to cause blindness in pigs, sheep, and cows. In lab rats and mice, many deaths occurred, in addition to others suffering seizures, damage to reproductive organs, and in some, has even caused mutagenic side effects, leading scientists to believe that humans could be at the same risk if they come into contact with a significant amount of the chemical. The toxicity level to birds is moderately to very high depending on the particular bird; at least four species of fish are at a very high poisoning risk should they encounter the compound. In soil this chemical has a half-life averaging 50 days, though there is not much risk of it contaminating groundwater. On the crops themselves, endosulfin shows a half-life of three to seven days—the pH level of the soil determines how quickly it will break down. In water the half-life can be anywhere form four weeks to five months, again depending on the acidity of the water.

Availability: It is a Restricted-Use Pesticide because of the danger it poses to both humans and numerous animals. A number of countries have banned it altogether, and while it is still legal to use in the U.S., it is very limited in availability and even then it is not recommended. Campaigns have started in recent years attempting to have it barred in favor of safer insecticides.

8.   Methoxychlor

Found in Products: Chemform, Dimethoxy-DT, DMDT, ENT 1716, Higalmetox, Methoxychlore, Marlate, Methoxy-DDT, OMS 466 and Prentox.

Beneficial/Intended Use: An organochlorine insecticide used both agriculturally and in households, it is considered a much safer replacement for DDT. It has a variety of uses; in addition to being effective on a wide variety of insects, it can be safely sprayed on fruits, vegetables, forage crops, and large forested areas. Additionally, veterinarians use it as an ectoparasiticide, which kills parasites. Methoxychlor has even been used in helping to prevent an ailment known as Dutch elm disease.

Environmental/Health Side Effects: Almost completely harmless to humans, one of the only known effects it has been known to cause is mild irritation of the skin if a person comes into contact with it dermally. Rats and mice showed weight loss, but only at very high levels of dosage; lower doses were often found to be fatal when administered to rabbits. Dogs generally showed no adverse reactions, though some monkeys and pigs showed damage to certain internal organs. Some reactions in animals given larger quantities of the chemical included convulsions, weakness/energy loss, diarrhea, and occasionally death. The chemical is slightly toxic to birds, though it is considered highly toxic to fish. In soil, methoxychlor has a half-life of as long as 120 days, but if the soil has a significant supply of oxygen, the half-life could be reduced to but a week. The risk of groundwater pollution is generally very slight; crops are also essentially unharmed by it, studies showing that less than 1% of the chemical residue remains on the vegetation. In water, the pesticide is not very soluble in water and the half-life is about 37 to 46 days. It also evaporates very slowly.

Availability: A General Use Pesticide, it is one of the most harmless chemicals in use. Since the ban of DDT thirty years ago, it is one of the few organochlorine chemicals that has increased in availability and usage. It is available in a variety of forms such as powders and aerosol sprays, though the actual products it is most commonly found in are not commonly seen in most stores.

9.     Bacillus thuringiensis

Found in Products: Acrobe, Bactospeine, Berliner, Certan, Dipel, Javelin, Leptox, Novabac, Teknar, Thuricide, and Victory. Also known as B.t.

Beneficial/Intended Use: A naturally occurring, live microorganism used to kill unwanted insects in forests, agriculture, and urban areas. There are different strains of this bacterium, each of which has a “target group” of insects; certain varieties kill certain types of insects. It is mostly used to control insects that destroy farming crops; it is estimated that over 150 different types of insects are vulnerable to one of the forms of this natural pesticide.

Environmental/Health Side Effects: Humans are almost completely unaffected by B.t.; while it does have a potential to cause irritation of the eyes or skin if someone comes into direct contact with it, it poses no actual health risk. Birds, rats, mice, dogs, humans, and other animals have been given significant quantities of the chemical, and other than the skin and eye irritation, no side effects have been seen. There appears to be no risk of toxicity whatsoever except in crops. B.t. is completely non-toxic to birds, and fish also appear to not be affected; the only potential exception to this is shrimp and mussels. In soil, the naturally occurring pathogen breaks down in the environment over time and has a half-life of about four months or less. It poses no threat to groundwater contamination. It is not poisonous to plants and, on foliage, has a half-life of less than six hours because the ultraviolet light emitted by the sun destroys it very quickly. In water, the specific half-life has not been determined, but it is estimated that it is effective for about two days before usually settling out. However, it is considered unwise to use it excessively on food crops or similar vegetation because it has the potential to cause mutagenic effects in plant life if used extensively.

Availability: A General Use Pesticide, it is available mostly to agricultural or farm workers. It does not appear to be banned anywhere, though the alarmist attitude of some environmentalist extremists seems to sometimes limit the availability in some areas. It has been registered as a pesticide for over forty years, however, and remains a popular and effective choice.

10.    Methoprene

Found in Products: Altosid, Apex, Diacan, Dianex, Kabat, Minex, Pharorid, Precor, and ZR-515.

Beneficial/Intended Use: A synthetic insect growth hormone, it is a compound that mimics the action of an insect growth-regulation hormone. It is used as an insecticide because it interferes with the normal maturation process. It artificially stunts the insects' development, making it impossible for insects to mature to the adult stages, preventing them from being able to reproduce. It is used in the production of a number of foods as well as in aquatic areas to control the population of such insects as mosquitoes.

Environmental/Health Side Effects: It appears to be completely non-toxic to humans, with no side effects or conditions arising from accidental exposure to the compound. It is not poisonous and poses no health risk, though people are of course still discouraged from experimenting with it. In lab animals mainly comprised of rats, mice, and rabbits, no poisoning or other serious health risks were found. The only symptom seen in some lab rats was increased liver weight after long-term exposure. For birds, methoprene is slightly toxic and mostly results in energy loss, lack (or loss) of coordination, and reluctance to move; these conditions last about two days. In fish, the chemical ranges from slightly to moderately toxic, except in some types of freshwater fish, in which case it can be very highly toxic. Methoprene, in soil, has a half-life of ten days, though it degrades faster in sunlight. It has chemical properties that make it unlikely to be very mobile and is considered essentially no risk of groundwater pollution. It is a chemical that biodegrades easily, and on plant life, can have a half-life from less than two days to seven weeks, depending largely on the plant’s moisture level. It appears to be of little risk to actual crops and most plants do not seem to have any residue of the chemical at all. In water, methoprene degrades rapidly as well, with a half-life between 30 and 40 hours. It is mostly degraded by sunlight and underwater microorganisms.

Availability: A General Use Pesticide, it is essentially harmless and generally popular among people working in the agriculture industry. Relatively readily available to such people, it comes in a few different forms. Other than this, however, there is not much information regarding where it is available or how frequently it has been used in recent years. Considering the safe nature of the chemical, however, it would be safe to guess that it is a common compound to find in pesticides used by farmers and other such people.

Bibliography

            Kamrin, Michael A. Pesticide Profiles: Toxicity, Environmental Impact and Fate.
            New York: Lewis Publishers, 1997.

            Miller, Terry L. (Ed.) EXTOXNET: The Extension Toxicology Network.
            November 2002. National Pesticide Information Center. 6 December 2002.
            <http://ace.orst.edu/info/extoxnet>.

            Safe 2 Use: Nontoxic Natural Products and Services. 2002. Safe 2 Use. 6 December
            2002. <http://www.safe2use.com>.