Pesticide profiles : Toxicity, environmental impact and fate - Chapter 5 docx

© 2000 CRC Press LLC chapter five Organophosphates 5.1Class overview and general description Background Organophosphates are the most commonly used insecticides. They are also employed as herbicides and fungicides. Although developed in the early 19th cen- tury, it was not until 1932 that the effects of these compounds on insects were discovered (1). Organophosphates (OPs) are characterized by a central phosphorus atom and numerous side chains. Most of the OPs used as insecticides are dimethoxy and diethoxy compounds. These broad groups of pesticides contain the well-known insecticides malathion and diazinon. The generalized structure of the organophos- phate compounds is shown in Figure 5.1 (2). One feature of the OPs that has led to their wide usage in agriculture and in the home is that they are much less persistent in the environment than the organochlo- rines, such as DDT. The compounds in the latter group were the pesticides of choice before the development of the OPs. The OPs are considerably more acutely toxic to vertebrates than the organochlorines (3). The OPs are being replaced in some appli- cations by the carbamate insecticides, which have lower toxicities to humans and wildlife. The commonly used OPs are listed in Table 5.1. Organophosphate usage Organophosphate insecticides can be effective whether they are ingested by the pest or are absorbed through the cuticle (skin) of the insect. However, some of the OPs are specifically formulated as stomach poisons or as contact poisons. The OPs are used against a wide array of insects and mites. OPs are used extensively on cotton, corn, wheat, and a variety of other agricul- tural crops. They are also used for domestic pest control. Some of the OPs, such as dichlorvos (DDVP), are administered orally to livestock to control internal parasites like the bot larva. Several others are used externally on livestock to control parasites on the animal’s skin. Figure 5.1 Generic organophosphate structure. L1190 CH05 pgs Page 135 Friday, July 2, 1999 4:46 PM © 2000 CRC Press LLC In 1982, OPs accounted for 67% of all insecticides used in the U.S. (4). This represented nearly 50 million pounds applied annually in the U.S. Also in that year, OP production in the U.S. was greater than 143 million pounds. Exports to the international community accounted for over 50% of the total U.S. organophosphate production. In 1990, OPs accounted for 33% of all pesticidal poisoning reports in the U.S. Diazinon and chlorpyrifos led the list, accounting for over 50% of the reports (5). Mechanism of action and toxicology The toxic mechanism of action of OP compounds is the same for insects and mammals. The OP compounds cause the enzyme acetylcholinesterase (AChE) to become inactivated. This enzyme speeds the breakdown of acetylcholine (ACh) which is produced in the nerve cells. ACh allows the transfer of a nerve impulse from one nerve cell to a receptor cell, such as from a muscle cell or another nerve cell. The nerve impulse continues until AChE breaks down ACh by chemical inac- tivation. Without this regulation of ACh by the enzyme, the nerve transmission continues indefinitely, causing a wide variety of symptoms in mammals such as weakness or paralysis of the muscles (2). In humans, OP insecticides can be absorbed through the skin, can be inhaled, or can enter the body through direct ingestion. Skin absorption is a slow process, so significant absorption occurs only after prolonged contact with the pesticide (5). Absorption is considerably faster when the skin is inflamed; thus, dermatitis could lead to much more serious poisoning than would normally occur. Acute toxicity Members of this group of pesticides are cholinesterase inhibitors and among the most acutely toxic of all the pesticides in current use (1). They are highly toxic by all routes of exposure. When inhaled, the first effects are usually respiratory and Table 5.1 Organophosphates Acephate Formothion Azinphos-methyl* Isofenphos* Bensulide* Malathion* Carbophenothion Methidathion* Chlorpyrifos* Methyl-parathion* Coumaphos* Mevinphos* Demeton-S-methyl Monocrotophos Diazinon* Naled* Dichlorvos/DDVP* Parathion Dicrotophos Phorate* Dimethoate* Phosalone Disulfoton* Phosmet* Endothion Phosphamidon Ethion* Phoxim Fenamiphos* Propetamphos* Fenitrothion Temephos* Fenthion* Terbufos* Fonofos* Trichlorfon* Note: * indicates that a profile for this compound is included in this chapter. L1190 CH05 pgs Page 136 Friday, July 2, 1999 4:46 PM © 2000 CRC Press LLC may include bloody or runny nose, coughing, chest discomfort, difficulty in breath- ing, and wheezing due to constriction or excess fluid in the bronchial tubes. Skin contact with organophosphates may cause localized sweating and involuntary mus- cle contractions. Eye contact will cause pain, bleeding, tears, pupil constriction, and blurred vision. Following exposure by any route, other systemic effects may begin within a few minutes or be delayed for up to 12 hours. These may include pallor, nausea, vomiting, diarrhea, abdominal cramps, headache, dizziness, eye pain, blurred vision, contraction or dilation of the pupils, tears, salivation, sweating, and confusion. Severe poisoning will affect the central nervous system and the peripheral ner- vous system (6). The central nervous system includes the spinal cord and the brain, while the peripheral nervous system includes all of the nerves and fibers that are not associated with the central nervous system. Typically, the signs of acute exposure become noticeable when the normal activity of AChE is reduced by about one half. Symptoms may include some of the following: incoordination, slurred speech, loss of reflexes, weakness, fatigue, involuntary muscle contractions, twitching, trem- ors of the tongue or eyelids, and eventually paralysis of the body extremities and the respiratory muscles. In severe cases, there may also be involuntary defecation or urination, psychosis, irregular heart beats, unconsciousness, convulsions, and coma. Death may occur when enzyme activity falls to between 10 and 20% of normal functioning levels (7) and be caused by respiratory failure or cardiac arrest (8). Acetylcholine is also found in red blood cells and in blood plasma and, thus, levels of cholinesterase in the bloodstream provide a good indicator of organophosphate and carbamate exposure (6). All of these symptoms may vary with the dose and the specific type of nerve cells that are affected. Generally, the toxic effects can be broken down into three broad categories: 1) effects on smooth muscles, including the heart and endocrine glands (muscarinic receptors); 2) effects on motor nerve endings in skeletal muscles and autonomic nervous system (nicotinic signs); and 3) central nervous system effects (7). In addition, it has been suggested that the organophosphates may have syner- gistic effects with pyrethroid insecticides (3); i.e., the combined toxicity is greater than the sum of the individual toxicities. Chronic toxicity Effects of repeated low-dose exposure to organophosphates have been shown in pesticide workers and applicators. Repeated or prolonged exposure to OPs may result in the same effects as acute exposure including the delayed symptoms. Other effects reported in workers repeatedly exposed include impaired memory and con- centration, disorientation, severe depression, irritability, confusion, headache, speech difficulties, delayed reaction times, nightmares, sleepwalking, drowsiness, and insomnia. An influenza-like condition with headache, nausea, weakness, loss of appetite, and malaise has also been reported (2,8). Reproductive effects When coumaphos or malathion was administered at high doses, it caused a decrease in the number of pregnancies, litter size, and surviving offspring and also depressed cholinesterase activity of the fetus (2,8). However, other OP compounds at lower doses (such as azinphos-methyl at 0.25 mg/kg/day and DDVP at 5 mg/kg/day) have not produced any reproductive effects (2). It appears that OP compounds will be unlikely to cause reproductive effects in humans at expected exposure levels. L1190 CH05 pgs Page 137 Friday, July 2, 1999 4:46 PM © 2000 CRC Press LLC Teratogenic effects Some experiments have shown that some OPs have crossed the placental barrier. However, in rat and rabbit experiments with various OP compounds, no teratogenic effects were detected (2,8,9). Therefore, organophosphate compounds appear unlikely to cause teratogenic effects. Mutagenic effects The overwhelming majority of OP compounds are not mutagenic (2,8,9). How- ever, there may be some exceptions. It has been suggested that diazinon has some potential to cause mutagenic effects, though there is no conclusive evidence. Malathion has produced detectable mutations in three different types of human cells, but mutagenic risks to humans are unlikely at expected exposure levels (2). Carcinogenic effects When OP compounds were fed to animals in laboratory experiments, there were no noticeable tumor growths (2,8). However, there is one exception. Dichlorvos has been classified as a possible human carcinogen by the U.S. EPA because in an experiment with female rats, there was an increase in benign tumors of the mammary glands (10,11). The overwhelming majority of the evidence suggests that OP compounds will be unlikely to cause carcinogenic effects in humans. Organ toxicity As previously mentioned in the acute toxicity section, OP compounds are cho- linesterase inhibitors and their effects occur throughout the body in many organs such as the brain, nervous system, adrenal glands, and liver. Fate in humans and animals Organophosphate compounds are metabolized and excreted rapidly in animals. The half-life for diazinon is approximately 12 hours (2). The metabolites are elimi- nated rapidly in the urine and feces and there is no evidence of bioaccumulation in body tissues (2,12). Ecological effects Effects on birds The avian toxicity of organophosphate compounds (OPs) varies from slightly toxic to highly toxic. However, a majority of OPs such as coumaphos, dichlorvos, fonofos, methidathion, and parathion are highly toxic to wild birds, mallard ducks, and pheasants (8,13–15). Effects on aquatic organisms OPs are moderately to highly toxic to fish. For example, the 96-hour LC 50 of azinphos-methyl in rainbow trout is 0.003 mg/L; the LC 50 of dichlorvos is 0.9 mg/L in bluegills; and the LC 50 of bensulide is 0.7 mg/L in rainbow trout (8,13,16). Studies also show that OPs are highly toxic to aquatic invertebrates. For example, the LC 50 for azinphos-methyl ranged from 0.13 to 56 mg/L in these species (17), and for coumaphos was 0.015 µ g/L in amphipods (18). L1190 CH05 pgs Page 138 Friday, July 2, 1999 4:46 PM © 2000 CRC Press LLC Effects on other organisms (non-target species) Organophosphate compounds are moderately toxic to highly toxic to bees (8,13). Environmental fate Breakdown in soil and groundwater The behavior and fate of organophosphates in the soil environment is largely governed by soil moisture, soil organic matter, acidity, temperature, and the mineral content of the soil (19,20). Generally, though, OPs (along with the carbamates) are much less persistent in soils than most other pesticides. They are categorized as low to moderately persistent compounds that persist in soil at the application site from a few hours through several weeks to months (21). Although generalizations are difficult to make with such a large and diverse group of compounds, the OPs are less mobile in soils with high organic content and a high inorganic metal concentration. One notable exception is an increase in deg- radation of diazinon and chlorpyrifos when in contact with inorganic copper (21). Generally, the pesticides are more stable under acidic conditions than under alkaline conditions. Due to the relatively short half-lives under many field conditions, the OPs do not represent a great threat to surface or groundwater over the long term. However, lakes and streams may be susceptible to pesticide runoff if application occurs prior to rainfall (21). Breakdown in water The temperature effects on degradation of OPs in surface water are striking. For example, methyl parathion has a half-life of 8 days during the summer and 38 days in winter (12). A similar response is shown for a variety of other organophosphate compounds (12,21). Also, pH affects the rate of degradation. The breakdown rates increase substan- tially with increasing alkalinity (21). Breakdown in vegetation The effects of organophosphate compounds in plants depend on several factors such as the rate and frequency of application, the nature of the plant surface, and the weather conditions. Plants absorb OPs mainly through the roots and translocate them to other parts of the plant, although leafy vegetables will also absorb OPs through the foliage (8). OPs do not usually bioaccumulate. For example, residues of azinphos-methyl, chlorpyrifos, and diazinon remain in plants only between 1 and 3 weeks (13,22). 5.2Individual profiles 5.2.1 Azinphos-methyl Trade or other names Common names include azinphos-methyl and metiltriazotion. Trade names include Azimil, Bay 9027, Bay 17147, Carfene, Cotnion-methyl, Gusathion, Gusathion-M, Guthion, and Methyl-Guthion. L1190 CH05 pgs Page 139 Friday, July 2, 1999 4:46 PM © 2000 CRC Press LLC Regulatory status All azinphos-methyl liquids with a concentration greater than 13.5% are classi- fied as Restricted Use Pesticides (RUPs) by the U.S. Environmental Protection Agency (EPA) because of the inhalation hazard and acute toxicity they present, as well as their potential adverse effects on mammalian species, birds, and aquatic organisms. RUPs may be purchased and used only by certified applicators. The EPA has imposed a 24-hour reentry interval for this material. It is toxicity class I — highly toxic. Products containing azinphos-methyl bear the Signal Words DANGER — POISON. Introduction Azinphos-methyl is a highly persistent, broad-spectrum insecticide. It is also toxic to mites and ticks, and poisonous to snails and slugs. It is a member of the organophosphate class of chemicals. It is nonsystemic, meaning that it is not trans- ported from one plant part to another. It is used primarily as a foliar application against leaf-feeding insects. It works as both a contact insecticide and a stomach poison. Azinphos-methyl is registered for use in the control of many insect pests on a wide variety of fruit, vegetable, nut, and field crops, as well as on ornamentals, tobacco, and forest and shade trees. Outside the U.S., azinphos-methyl is used in lowland rice production. Azinphos-methyl is available in emulsifiable liquid, liquid flowable, ULV liquid, and wettable powder formulations. Toxicological effects Acute toxicity Azinphos-methyl is one of the most toxic of the OP insecticides (2,23). It is highly toxic by inhalation, dermal absorption, ingestion, and eye contact (2). Like all orga- nophosphate chemicals, azinphos-methyl is a cholinesterase inhibitor. It damages normal functioning of cholinesterase, an enzyme essential to proper nervous system function. Individuals with a history of reduced lung function, convulsive disorders, or recent exposure to other cholinesterase inhibitors are at increased risk from expo- sure to azinphos-methyl (2,8). There is wide variation in the recorded LD 50 values for azinphos-methyl, depend- ing on the route of exposure and the test animal. The oral LD 50 for azinphos-methyl is 4.4 to 16 mg/kg in rats, 80 mg/kg in guinea pigs, and 8 to 20 mg/kg in mice (2,8,13). The dermal LD 50 is 88 to 220 mg/kg in rats, and 65 mg/kg in mice (2,8,13). The 1-hour inhalation LC 50 for azinphos-methyl in rats is 0.4 mg/L (13). Figure 5.2 Azinphos-methyl. L1190 CH05 pgs Page 140 Friday, July 2, 1999 4:46 PM © 2000 CRC Press LLC For humans, ingestion of azinphos-methyl in amounts above 1.5 mg/day can cause severe poisoning with symptoms such as dimness of vision, salivation, exces- sive sweating, stomach pain, vomiting, diarrhea, unconsciousness, and death (2,23). Inhalation of the dust or aerosol preparation of azinphos-methyl may cause wheez- ing, tightness in the chest, blurred vision, and tearing of the eyes. Complete symp- tomatic recovery may occur within 1 week after sublethal poisoning; i.e., poisoning from an exposure that is just below the amount necessary to be fatal (23). Pure azinphos-methyl is easily absorbed by the skin, and lethal amounts can build up in the body after dermal exposure. Symptoms of illness caused by this type of exposure include nausea, vomiting, blurred vision, and muscle cramps (2,23). Eye contact with concentrated solutions of azinphos-methyl can be life-threat- ening. Within a few minutes of eye exposure, azinphos-methyl may cause pain, blurring of distant vision, tearing, and other problems. Symptoms of cholinesterase inhibition may also occur, such as respiratory difficulties, gastrointestinal problems, and central nervous system disturbances (23). Some organophosphates may cause delayed symptoms beginning 1 to 4 weeks after an acute exposure that may or may not have produced immediate symptoms. In such cases, numbness, tingling, weakness, and cramping may appear in the lower limbs and progress to incoordination and paralysis. Improvement may occur over months or years, and in some cases residual impairment will remain (2,23). Chronic toxicity Long-term exposure to azinphos-methyl, above the average 8-hour standard set by the Occupational Safety and Health Administration (OSHA), can impair concen- tration and memory, and cause headache, irritability, nausea, vomiting, muscle cramps, and dizziness (23). Cholinesterase inhibition from exposure to azinphos-methyl may persist for 2 to 6 weeks (1). Repeated exposure to small amounts may result in an unexpected inhibition of cholinesterase, causing symptoms that resemble other flu-like illnesses, including general discomfort, weakness, and lack of appetite (1,2). The effects of azinphos-methyl exposure may be greater in a previously exposed person than in an individual with no previous exposure. Rats tolerated dietary doses of 0.25 mg/kg/day for 60 days without cholinesterase inhibition, 1 mg/kg/day resulted in questionable growth effects and a slight inhibition of brain and red blood cell cho- linesterase. In chronic oral toxicity studies, rats and dogs were fed doses of 0.125, 0.5, 1, or 2.5 mg/kg/day. The 2.5-mg/kg/day dose was increased to 5 mg/kg/day after 47 weeks. At 0.125 mg/kg/day, cholinesterase was not affected in rats and dogs. At 1 mg/kg/day, the plasma and red blood cell cholinesterases in the rat were initially inhibited, but returned to normal after 65 weeks. The 5-mg/kg/day doses produced convulsions in some animals. In dogs, 0.5 mg/kg/day produced a slight, irregular decrease in red blood cell cholinesterase (24,25). Rats fed about 5 to 10 mg/kg/day azinphos-methyl for 2 years had depressed red blood cell counts and brain cholinesterase activity. Dietary levels of about 0.5 mg/kg/day or less had no negative effects (2). Reproductive effects In a two-generation reproduction study, there were no observed reproductive or maternal effects in rats at 0.25 mg/kg/day (25). However, at oral doses of 20 mg/kg to 8-day pregnant mice, Guthion was toxic to the fetus (25). These data indicate that reproductive effects in humans are unlikely at expected exposure levels. L1190 CH05 pgs Page 141 Friday, July 2, 1999 4:46 PM © 2000 CRC Press LLC Teratogenic effects In a teratology study, no maternal or developmental effects were observed in rats at doses of 2 mg/kg/day (25). A 16-mg/kg oral dose to 8-day pregnant rats caused specific development abnormalities in the muscles and bones. It appears that teratogenic effects are not likely in humans under expected exposure conditions. Mutagenic effects No mutagenic effects were observed in the Ames test on bacteria and a test on human cell cultures (25). These data suggest that azinphos-methyl is not mutagenic. Carcinogenic effects Although one carcinogenicity study on rats suggested that tumors of the pan- creas and selected thyroid cells may have been associated with azinphos-methyl (2), two other studies at doses up to 10 mg/kg/day did not show an increase in the incidence of tumors in mice from azinphos-methyl (2,17). The carcinogenicity of azinphos-methyl is not clear from current evidence. Organ toxicity Toxicity from azinphos-methyl is primarily manifested in cholinesterase inhibi- tion, which affects the nervous system. Dogs fed 9 mg/kg/day showed tremors, weakness, abnormal quietness, and some weight loss (2). Fate in humans and animals One study suggests that Guthion is rapidly broken down into nonpoisonous forms in the body (24). Azinphos-methyl is eliminated in the feces and urine of mammals within 2 days of administration. Ecological effects Effects on birds Azinphos-methyl is slightly to moderately toxic to birds. Acute symptoms of azinphos-methyl poisoning include regurgitation, wing drop, wing spasms, diarrhea, and lack of movement (26). Chickens fed azinphos-methyl at doses of 40 mg/kg developed leg weakness. The oral LD 50 for azinphos-methyl is 136 mg/kg in young mallards, 74.9 mg/kg in young pheasants, 84.2 mg/kg in young chukar partridges, 262.0 mg/kg in chick- ens, and 32.2 mg/kg in bobwhite quail (13,17,27). The dietary LC 50 for azinphos- methyl is 639 ppm in Japanese quail, 1821 ppm in ring-necked pheasant, and 1940 ppm in mallard duck (13,17). Effects on aquatic organisms Azinphos-methyl is moderately to very highly toxic to freshwater fish. For most species, the LC 50 values are less than 1 mg/L. The 96-hour LC 50 for azinphos-methyl in rainbow trout is 0.003 mg/L (8,13). Guthion-poisoned fish exhibit central nervous system impairment, including erratic swimming accompanied by uncontrolled convulsions. Rapid gill movements, paralysis, and death follow in rapid succession (8). Azinphos-methyl is highly toxic to aquatic invertebrates, shellfish, frogs, and toads (8). The LC 50 values are below 1 µ g/L for many of the species (8,17). L1190 CH05 pgs Page 142 Friday, July 2, 1999 4:46 PM © 2000 CRC Press LLC Effects on other organisms (non-target species) Several studies have indicated that azinphos-methyl causes adverse effects in wildlife. Wild mammals and aquatic organisms appear to be more vulnerable than birds to hazards created by this material (29). The EPA requires endangered species labeling for certain azinphos-methyl uses (17). Azinphos-methyl is toxic to honeybees and other beneficial insects (8,24). It will cause severe bee losses if used when bees are present at treatment time or within a day thereafter (30). A 90% mortality rate is seen in pollinating leaf-cutting bees after a 9-day exposure to greenhouse alfalfa treated with azinphos-methyl (27). Environmental fate Breakdown in soil and groundwater Persistence of azinphos-methyl in soil is quite variable, but is generally low under field conditions (19,31). The half-life in sandy loam soil is 5 days. Its half-life in nonsterile soil is 21 days when oxygen is present, or 68 days under oxygen-free conditions. In sterile soil, the half-life is reported to be 355 days. Azinphos-methyl is fairly immobile in soil because it adsorbs strongly to soil particles and has low water solubility. It has low leaching potential and is unlikely to contaminate groundwater (19,31). It was not detected in 54 groundwater samples collected in New York state (32). Azinphos-methyl is one of 118 synthetic organic chemicals that the state of Florida has designated for groundwater monitoring (33). It was detected in only 5 out of 1628 wells sampled in ten states from 1983 to 1991 (34). The disappearance of azinphos-methyl from soil is more rapid in the surface layers (0 to 2.5 cm deep) than it is in the next deeper layer (2.4 to 7.5 cm). Biodeg- radation and evaporation are the primary routes of disappearance for azinphos- methyl. Azinphos-methyl is also subject to degradation by ultraviolet (UV) light from the sun and hydrolytic decomposition. Photodecomposition is particularly rapid at high levels of soil moisture and in the presence of UV light (31). Rapid degradation of Gusathion was observed at temperatures higher than 37 ° C (29). Breakdown in water In general, organophosphates such as azinphos-methyl are dissipated rapidly in water (35). In pond water, it is subject to degradation by sunlight and microorgan- isms, with a half-life of up to 2 days. Volatilization from water is unlikely. Chemical hydrolysis is important in alkaline waters (12). Azinphos-methyl is very stable in water below pH 10.0. Above pH 11.0, it is rapidly hydrolyzed to anthranilic acid, benzamide, and other metabolites. Azinphos-methyl has a low to medium tendency to adsorb to sediments or suspended solids (12). Breakdown in vegetation Residue levels of azinphos-methyl in crops are dependent on the rate and fre- quency of application, nature of the plant surface, and weather conditions such as rainfall, temperature, sunlight, humidity, and wind (24). The half-life on vegetable and forage crops is 3 to 5 days under field conditions (24). It gives effective protection for 2 or more weeks (36). On treated apple trees, the half-life of this pesticide was about 2.6 to 6.3 days (28). Hawthorn and American Linden trees have been injured by this material. It has also caused russeting on certain varieties of fruit (24). L1190 CH05 pgs Page 143 Friday, July 2, 1999 4:46 PM © 2000 CRC Press LLC Physical properties Pure azinphos-methyl is a white crystalline solid. Technical azinphos-methyl is a brown waxy solid (13,37). Chemical name: S-(3,4-dihydro-4-oxobenzo[d]-[1,2,3]-triazin-3-ylmethyl) O,O- dimethyl phosphorodithioate (13) CAS #: 86-50-0 Molecular weight: 317.33 (13) Water solubility: 30 mg/L @ 25 ° C (13) Solubility in other solvents: dichloromethane v.s.; toluene v.s. (13) Melting point: 65–68 ° C (technical) (13); 73–74 ° C (pure form) (13) Vapor pressure: <1 mPa @ 20 ° C (13) Partition coefficient (octanol/water): Not available Adsorption coefficient: 1000 (19) Exposure guidelines ADI: 0.005 mg/kg/day (38) HA: Not available RfD: Not available PEL: 0.2 mg/m 3 (8-hour) (skin) (39) Basic manufacturer Miles, Inc. P.O. Box 4913 8400 Hawthorn Road Kansas City, MO 64120 Telephone:816-242-2429 Emergency:816-242-2582 5.2.2 Bensulide Trade or other names Trade names for bensulide include Betamec, Betasan, Bensumec, Benzulfide, Disan, Exporsan, Prefar, Pre-San, and R-4461. It is used in combination with other pesticides such as thiobencarb and molinate. Figure 5.3 Bensulide. L1190 CH05 pgs Page 144 Friday, July 2, 1999 4:46 PM [...]... point: 41 .5 44°C (13) Vapor pressure: 2 .5 mPa @ 25 C (13) Partition coefficient (octanol/water ): 50 ,000 (13) Adsorption coefficient: 6070 (19) Exposure guidelines ADI: 0.01 mg/kg/day (38) HA: 0.02 mg/L (lifetime) (53 ) RfD: 0.003 mg/kg/day (53 ) PEL: 0.2 mg/m3 (8-hour) (skin) (47) Basic manufacturer DowElanco 9330 Zionsville Rd Indianapolis, IN 4626 8-1 054 Telephone: 31 7-3 3 7-7 344 Emergency: 80 0-2 5 8-3 033 5. 2.4... (13) CAS #: 74 1 -5 8-2 Molecular weight: 397 .54 (13) Solubility in water: 25 mg/L @ 20°C (13) Solubility in other solvents: kerosene s.; acetone v.s, ethanol v.s., xylene v.s (13) Melting point: 34.4°C (13) Vapor pressure: 0.133 mPa @ 25 C (13) Partition coefficient (octanol/water ): 16 ,50 0 (13) Adsorption coeffient: 1000 (estimated) (19) Exposure guidelines ADI: Not available MCL: Not available RfD: Not available... when applied to the soil and translocated to other parts of the plant (13) Physical properties Diazinon is a colorless to dark brown liquid It has a flashpoint of 180°F (13) Chemical name: O,O-diethyl 0-2 -isopropyl-6-methyl(pyrimidine-4-yl) phosphorothioate (13) CAS #: 33 3-4 1 -5 Molecular weight: 304. 35 (13) Solubility in water: 40 mg/L @ 20°C (13) Solubility in other solvents: petroleum ether v.s.; alcohol... insoluble in water, and is stable over a wide pH range (8) © 2000 CRC Press LLC L1190 CH 05 pgs Page 156 Friday, July 2, 1999 4:4 6 PM Breakdown in vegetation No data are currently available Physical properties Technical coumaphos is a tan crystalline solid with a slight sulfur odor (13) Chemical name: 3-chloro-7-diethoxyphosphinothioyloxy-4-methylcoumarin (13) CAS #: 5 6-7 2-4 Molecular weight: 362 .5 (13) Water... that this insecticide and its soil metabolites can accumulate in certain crops (8) Physical properties Technical chlorpyrifos is an amber to white crystalline solid with a mild sulfur odor (13) Chemical name: O,O-diethyl O-3 ,5, 6-trichloro-2-pyridyl phosphorothioate (13) CAS #: 292 1-8 8-2 Molecular weight: 350 .62 (13) Water solubility: 2 mg/L @ 25 C (13) Solubility in other solvents: benzene s.; acetone... point: 43– 45 C (technical) (13) Vapor pressure: 1.1 mPa @ 25 C (13) Partition coefficient: (octanol/water ): 5 (13) Adsorption coefficient: 20 (19) Exposure guidelines: ADI: 0.01 mg/kg/day (38) HA: Not available RfD: 0.0002 mg/kg/day (53 ) PEL: Not available © 2000 CRC Press LLC L1190 CH 05 pgs Page 169 Friday, July 2, 1999 4:4 6 PM Basic manufacturer BASF Corp Agricultural Products Group P.O Box 1 352 8 Research... Blvd Los Angeles, CA 90023 Telephone: 21 3-2 6 4-3 910 Emergency: 80 0-2 2 8 -5 6 35, ext 169 © 2000 CRC Press LLC L1190 CH 05 pgs Page 1 65 Friday, July 2, 1999 4:4 6 PM 5. 2.7 Dimethoate Figure 5. 8 Dimethoate Trade or other names Trade names for dimethoate include Cekuthoate, Chimigor 40, Cygon 400, Daphene, De-Fend, Demos NF, Devigon, Dicap, Dimate 267, Dimet, Dimethoat Tech 95% , Dimethopgen, Ferkethion, Fostion... point: Decomposes @ >120°C (8) Vapor pressure: 0.097 mPa @ 20°C (13) Partition coefficient (octanol/water ): not available (8) Adsorption coefficient: 1000 (estimated) (19) Exposure guidelines ADI: 0.002 mg/kg/day (38) HA: 6 × 10–4 mg/L (lifetime) (8) RfD: 9 × 10 5 mg/kg/day (53 ) TLV: 0.1 mg/m3 (8-hour) (47) © 2000 CRC Press LLC L1190 CH 05 pgs Page 160 Friday, July 2, 1999 4:4 6 PM Basic manufacturer Ciba-Geigy... NC 2741 9-8 300 Telephone: 80 0-3 3 4-9 481 Emergency: 80 0-8 8 8-8 372 5. 2.6 Dichlorvos (DDVP) Figure 5. 7 Dichlorvos(DDVP) Trade or other names Dichlorvos is also called DDVP Trade names include Apavap, Benfos, Cekusan, Cypona, Derriban, Derribante, Devikol, Didivane, Duo-Kill, Duravos, Elastrel, FlyBate, Fly-Die, Fly-Fighter, Herkol, Marvex, No-Pest, Prentox, Vaponite, Vapona, Verdican, Verdipor, and Verdisol... NC 2770 9-3 52 8 Telephone: 80 0-6 6 9-2 273 Emergency: 80 0-8 3 2-4 357 5. 2.8 Disulfoton Figure 5. 9 Disulfoton Trade or other names Trade names for disulfoton include Bay S276, Disyston, Disystox, Dithiodemeton, Dithiosystox, Frumin AL, Solvigram, and Solvirex Regulatory status All products formulated at greater than 2% disulfoton are classified as Restricted Use Pesticides (RUPs) RUPs may be purchased and used . Zionsville Rd. Indianapolis, IN 4626 8-1 054 Telephone:31 7-3 3 7-7 344 Emergency:80 0-2 5 8-3 033 5. 2.4 Coumaphos Figure 5. 5 Coumaphos. L1190 CH 05 pgs Page 152 Friday, July 2, 1999 4:4 6 PM © 2000 CRC Press LLC Trade. (13). Chemical name: O,O-diethyl O-3 ,5, 6-trichloro-2-pyridyl phosphorothioate (13) CAS #: 292 1-8 8-2 Molecular weight: 350 .62 (13) Water solubility: 2 mg/L @ 25 C (13) Solubility in other solvents: benzene. solid (13). Chemical name: O,O-diisopropyl S-2-phenylsulfonylaminoethyl phospho- rodithioate (13) CAS #: 74 1 -5 8-2 Molecular weight: 397 .54 (13) Solubility in water: 25 mg/L @ 20 ° C (13) Solubility