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The information in this profile may be out-of-date. It was last revised in 1996. EXTOXNET no longer updates this information, but it may be useful as a reference or resource.

Please visit the National Pesticide Information Center (NPIC) to find updated pesticide fact sheets. If you don't find a fact sheet related to your question, feel free to call 1-800-858-7378. NPIC is open five days a week from 8:00am to 12:00pm Pacific Time.

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E X T O X N E T

Extension Toxicology Network

Pesticide Information Profiles

A Pesticide Information Project of Cooperative Extension Offices of Cornell University, Oregon State University, the University of Idaho, and the University of California at Davis and the Institute for Environmental Toxicology, Michigan State University. Major support and funding was provided by the USDA/Extension Service/National Agricultural Pesticide Impact Assessment Program.

EXTOXNET primary files maintained and archived at Oregon State University

Revised June 1996

Endosulfan

Trade and Other Names: Trade or other names for the product include Afidan, Beosit, Cyclodan, Devisulfan, Endocel, Endocide, Endosol, FMC 5462, Hexasulfan, Hildan, Hoe 2671, Insectophene, Malix, Phaser, Thiodan, Thimul, Thifor, and Thionex.

Regulatory Status: Endosulfan is a highly toxic pesticide in EPA toxicity class I. It is a Restricted Use Pesticide (RUP). Labels for products containing endosulfan must bear the Signal Words DANGER - POISON, depending on formulation.

Chemical Class: chlorinated hydrocarbon

Introduction: Endosulfan is a chlorinated hydrocarbon insecticide and acaricide of the cyclodiene subgroup which acts as a poison to a wide variety of insects and mites on contact. Although it may also be used as a wood preservative, it is used primarily on a wide variety of food crops including tea, coffee, fruits, and vegetables, as well as on rice, cereals, maize, sorghum, or other grains. Formulations of endosulfan include emsulsifiable concentrate, wettable powder, ultra-low volume (ULV) liquid, and smoke tablets. It is compatible with many other pesticides and may be found in formulations with dimethoate, malathion, methomyl, monocrotophos, pirimicarb, triazophos, fenoprop, parathion, petroleum oils, and oxine-copper. It is not compatible with alkaline materials. Technical endosulfan is made up of a mixture of two molecular forms (isomers) of endosulfan, the alpha- and beta-isomers. Information presented in this profile refers to this technical product unless otherwise stated.

Formulation: Formulations of endosulfan include emulsifiable concentrate, wettable powder, ultra-low volume (ULV) liquid, and smoke tablets.

Toxicological Effects:

• Acute toxicity: Endosulfan is highly toxic via the oral route, with reported oral LD50 values ranging from 18 to 160 mg/kg in rats, 7.36 mg/kg in mice, and 77 mg/kg in dogs [2,9]. It is also highly toxic via the dermal route, with reported dermal LD50 values in rats ranging from 78 to 359 mg/kg [2,9]. Endosulfan may be only slightly toxic via inhalation, with a reported inhalation LC50 of 21 mg/L for 1 hour, and 8.0 mg/L for 4 hours [2]. It is reported not to cause skin or eye irritation in animals [2]. The alpha-isomer is considered to be more toxic than the beta-isomer [2]. Animal data indicate that toxicity may also be influenced by species and by level of protein in the diet; rats which have been been deprived of protein are nearly twice as susceptible to the toxic effects of endosulfan [2]. Solvents and/or emulsifiers used with endosulfan in formulated products may influence its absorption into the system via all routes; technical endosulfan is slowly and incompletely absorbed into the body whereas absorption is more rapid in the presence of alcohols, oils, and emulsifiers [2]. Stimulation of the central nervous system is the major characteristic of endosulfan poisoning [51]. Symptoms noted in acutely exposed humans include those common to the other cyclodienes, e.g., incoordination, imbalance, difficulty breathing, gagging, vomiting, diarrhea, agitation, convulsions, and loss of consciousness [2]. Reversible blindness has been documented for cows that grazed in a field sprayed with the compound. The animals completely recovered after a month following the exposure [2]. In an accidental exposure, sheep and pigs grazing on a sprayed field suffered a lack of muscle coordination and blindness [2].
• Chronic toxicity: In rats, oral doses of 10 mg/kg/day caused high rates of mortality within 15 days, but doses of 5 mg/kg/day caused liver enlargement and some other effects over the same period [2]. This dose level also caused seizures commencing 25 to 30 minutes following dose adiministration that persisted for approximately 60 minutes [2]. There is evidence that administration of this dose over 2 years in rats also caused reduced growth and survival, changes in kidney structure, and changes in blood chemistry [2,51].
• Reproductive effects: Rats fed doses of endosulfan of 2.5 mg/kg/day for three generations showed no observable reproductive effects, but 5.0 mg/kg/day caused increased dam mortality and resorption [2,51]. Female mice fed the compound for 78 weeks at 0.1 mg/kg/day had damage to their reproductive organs [52]. Oral dosage for 15 days at 10 mg/kg/day in male rats caused damage to the semeniferous tubules and lowered testes weights [2,5]. It is unlikely that endosulfan will cause reproductive effects in humans at expected exposure levels.
• Teratogenic effects: An oral dose of 2.5 mg/kg/day resulted in normal reproduction in rats in a three-generational study, but 5 and 10 mg/kg/day resulted in abnormalities in bone development in the offspring [2,51]. Teratogenic effects in humans are unlikely at expected exposure levels.
• Mutagenic effects: Endosulfan is mutagenic to bacterial and yeast cells [51]. The metabolites of endosulfan have also shown the ability to cause cellular changes [2,51]. This compound has also caused mutagenic effects in two different mammalian species [51]. Thus, evidence suggests that exposure to endosulfan may cause mutagenic effects in humans if exposure is great enough.
• Carcinogenic effects: In a long-term study done with both mice and rats, the males of both groups experienced such a high mortality rate that no conclusions could be drawn [52]. However, the females of both species failed to develop any carcinogenic conditions 78 weeks after being fed diets containing up to about 23 mg/kg/day. The highest tolerated dose of endosulfan did not cause increased incidence of tumors in mice over 18 months, and a later study also showed no evidence of carcinogenic activity in mice or rats [2,52]. It appears that endosulfan is not carcinogenic.
• Organ toxicity: Data from animal studies reveal the organs most likely to be affected include kidneys, liver, blood, and the parathyroid gland [51].

• Fate in humans and animals: Endosulfan is rapidly degraded into mainly water-soluble compounds and eliminated in mammals with very little absorption in the gastrointestinal tract [2]. In rabbits, the beta-isomer is cleared from blood plasma more quickly than the alpha-isomer, with reported blood half-lives of approximately 6 hours and 10 days, respectively [2], which may account in part for the observed differences in toxicity. The metabolites are dependent on the mixture of isomers and the route of exposure [2]. Most of the endosulfan seems to leave the body within a few days to a few weeks.

Ecological Effects:

• Effects on birds: Endosulfan is highly to moderately toxic to bird species, with reported oral LD50 values in mallards ranging from 31 to 243 mg/kg [9,53], and in pheasants ranging from 80 to greater than 320 mg/kg [53]. The reported 5-day dietary LC50 is 2906 ppm in Japanese quail [54]. Male mallards from 3 to 4 months old exhibited wings crossed high over their back, tremors, falling, and other symptoms as soon as 10 minutes after an acute, oral dose. The symptoms persisted for up to a month in a few animals [53].
• Effects on aquatic organisms: Endosulfan is very highly toxic to four fish species and both of the aquatic invertebrates studied; in fish species, the reported 96-hour LC50 values were (in ug/L): rainbow trout, 1.5; fathead minnow, 1.4; channel catfish, 1.5; and bluegill sunfish, 1.2. In two aquatic invertebrates, scuds (G. lacustris) and stoneflies (Pteronarcys), the reported 96-hour LC50 values were, respectively, 5.8 ug/L and 3.3 ug/L [55]. The bioaccumulation for the compound may be significant; in the mussel (Mytelus edulis) the compound accumulated to 600 times the ambient water concentration [17].
• Effects on other organisms: It is moderately toxic to bees and is relatively nontoxic to beneficial insects such as parasitic wasps, lady bird beetles, and some mites [9,17].

Environmental Fate:

• Breakdown in soil and groundwater: Endosulfan is moderately persistent in the soil environment with a reported average field half-life of 50 days [14]. The two isomers have different degradation times in soil. The half-life for the alpha -somer is 35 days, and is 150 days for the beta-isomer under neutral conditions. These two isomers will persist longer under more acidic conditions. The compound is broken down in soil by fungi and bacteria [9]. Endosulfan does not easily dissolve in water, and has a very low solubility [9,14]. It has a moderate capacity to adhere or adsorb to soils [14]. Transport of this pesticide is most likely to occur if endosulfan is adsorbed to soil particles in surface runoff. It is not likely to be very mobile or to pose a threat to groundwater. It has, however, been detected in California well water [12].
• Breakdown in water: In raw river water at room temperature and exposed to light, both isomers disappeared in 4 weeks [12]. A breakdown product first appeared within the first week. The breakdown in water is faster (5 weeks) under neutral conditions than at more acidic conditions or basic conditions (5 months) [12]. Under strongly alkaline conditions the half-life of the compound is 1 day. Large amounts of endosulfan can be found in surface water near areas of application [51]. It has also been found in surface water throughout the country at very low concentrations [12].
• Breakdown in vegetation: In plants, endosulfan is rapidly broken down to the corresponding sulfate [9]. On most fruits and vegetables, 50% of the parent residue is lost within 3 to 7 days [9]. Endosulfan and its breakdown products have been detected in vegetables (0.0005-0.013 ppm), in tobacco, in various seafoods (0.2 ppt-1.7 ppb), and in milk [12].

Physical Properties:

• Appearance: Pure endosulfan is a colorless crystal. Technical grade is a yellow-brown color [9].
• Chemical Name: 6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzadioxathiepin 3-oxide [9]
• CAS Number: 115-29-7 (alpha-isomer, 959-98-8; beta-isomer, 33213-65-9)
• Molecular Weight: 406.96
• Water Solubility: 0.32 mg/L @ 22 C [9]
• Solubility in Other Solvents: s. in toluene and hexane [9]
• Melting Point: Technical material, 70-100 C [9]
• Vapor Pressure: 1200 mPa @ 80 C [9]
• Partition Coefficient: Not Available
• Adsorption Coefficient: 12,400 [14]

Exposure Guidelines:

• ADI: 0.006 mg/kg/day [27]
• MCL: Not Available
• RfD: 0.00005 mg/kg/day [8]
• PEL: Not Available
• HA: Not Available
• TLV: 0.1 mg/m3 (8-hour) [56]

Basic Manufacturer:

FMC Corporation
Agricultural Chemicals Group
1735 Market Street
Philadelphia, PA 19103

• Phone: 215-299-6661
• Emergency: 800-331-3148
  

References:

References for the information in this PIP can be found in Reference List Number 6

DISCLAIMER: The information in this profile does not in any way replace or supersede the information on the pesticide product labeling or other regulatory requirements. Please refer to the pesticide product labeling.