isobenzan

H300: Fatal if swallowed [Danger Acute toxicity, oral]

H310: Fatal in contact with skin [Danger Acute toxicity, dermal]

H400: Very toxic to aquatic life [Warning Hazardous to the aquatic environment, acute hazard]

P262, P264, P270, P273, P280, P301+P316, P302+P352, P316, P321, P330, P361+P364, P391, P405, and P501 (click each P-code to see the statement)

H300+H310 (100%): Fatal if swallowed or in contact with skin [Danger Acute toxicity, oral; acute toxicity, dermal]

H300 (100%): Fatal if swallowed [Danger Acute toxicity, oral]

H310 (100%): Fatal in contact with skin [Danger Acute toxicity, dermal]

H400 (100%): Very toxic to aquatic life [Warning Hazardous to the aquatic environment, acute hazard]

H410 (97.4%): Very toxic to aquatic life with long lasting effects [Warning Hazardous to the aquatic environment, long-term hazard]

Aggregated GHS information provided per 39 reports by companies from 2 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown. For more detailed information, please visit ECHA C&L website.

H320: Causes eye irritation [Warning Serious eye damage/eye irritation]

H361: Suspected of damaging fertility or the unborn child [Warning Reproductive toxicity]

H370: Causes damage to organs [Danger Specific target organ toxicity, single exposure]

H372: Causes damage to organs through prolonged or repeated exposure [Danger Specific target organ toxicity, repeated exposure]

P203, P260, P262, P264, P264+P265, P270, P280, P301+P316, P302+P352, P305+P351+P338, P308+P316, P316, P318, P319, P321, P330, P337+P317, P361+P364, P405, and P501 (click each P-code to see the statement)

Caution: Symptoms may be long lasting because isobenzan is eliminated slowly. (Isobenzan has a half-life of

2.77 years in human blood.) Vital signs should be monitored closely. Caution is advised.

Signs and Symptoms of Isobenzan Exposure: Symptoms of acute isobenzan exposure include the following: headache, dizziness, vomiting, drowsiness, irritability, and numbness of the legs. Convulsions and seizures may occur.

Emergency Life-Support Procedures: Acute exposure to isobenzan may require decontamination and life support for the victims. Emergency personnel should wear protective clothing appropriate to the type and degree of contamination. Air-purifying or supplied-air respiratory equipment should also be worn, as necessary. Rescue vehicles should carry supplies such as plastic sheeting and disposable plastic bags to assist in preventing spread of contamination.

Inhalation Exposure:

1. Move victims to fresh air. Emergency personnel should avoid self-exposure to isobenzan.

2. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. If breathing is labored, administer 100% humidified oxygen or other respiratory support.

3. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.

4. Rush to a health care facility.

Dermal/Eye Exposure:

1. Remove victims from exposure. Emergency personnel should avoid self-exposure to isobenzan.

3. Remove and isolate contaminated clothing as soon as possible.

4. If eye exposure has occurred, eyes must be flushed with lukewarm water for at least 15 minutes.

5. Wash exposed skin areas thoroughly with water.

6. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.

7. Rush to a health care facility.

Ingestion Exposure:

1. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. If breathing is labored, administer 100% humidified oxygen or other respiratory support.

2. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.

3. Vomiting may be induced with syrup of Ipecac. If elapsed time since ingestion of isobenzan is unknown or suspected to be greater than 30 minutes, do not induce vomiting and proceed to Step

4. Ipecac should not be administered to children under 6 months of age. Warning: Ingestion of isobenzan may result in sudden onset of seizures or loss of consciousness. Syrup of Ipecac should be administered only if victims are alert, have an active gag-reflex, and show no signs of impending seizure or coma. If ANY uncertainty exists, proceed to Step

5. The following dosages of Ipecac are recommended: children up to 1 year old, 10 mL (1/3 oz); children 1 to 12 years old, 15 mL (1/2 oz); adults, 30 mL (1 oz). Ambulate (walk) the victims and give large quantities of water. If vomiting has not occurred after 15 minutes, Ipecac may be readministered. Continue to ambulate and give water to the victims. If vomiting has not occurred within 15 minutes after second administration of Ipecac, administer activated charcoal.

5. Activated charcoal may be administered if victims are conscious and alert. Use 15 to 30 g (1/2 to 1 oz) for children, 50 to 100 g (1-3/4 to 3-1/2 oz) for adults, with 125 to 250 mL (1/2 to 1 cup) of water.

6. Promote excretion by administering a saline cathartic or sorbitol to conscious and alert victims. Children require 15 to 3g (1/2 to 1 oz) of cathartic; 50 to 100 g (1-3/4 to 3-1/2 oz) is recommended for adults.

7. Rush to a health care facility. (EPA, 1998)

(Non-Specific -- Dry Insecticide) Avoid breathing dusts and fumes from burning material. Keep upwind. Avoid bodily contact with the material. Wear full protective clothing including boots, protective gloves, goggles, and wear self-contained breathing apparatus.

(Non-Specific -- Dry Insecticide) Use agent suitable for type of surrounding fire. Use water in flooding quantities as fog. Use alcohol foam, carbon dioxide, or dry chemical. (EPA, 1998)

Excerpt from ERG Guide 151 [Substances - Toxic (Non-Combustible)]:

IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids.

SPILL: Increase the immediate precautionary measure distance, in the downwind direction, as necessary.

FIRE: If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2024)

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal, aquatic, and plant life; and conformance with environmental and public health regulations.

(Non-Specific -- Dry Insecticide) Keep upwind. Avoid bodily contact with the material. (Non-Specific -- Insecticide, Dry, n.o.s.) Keep unnecessary people away; isolate hazard area and deny entry.

Small spills: absorb with sand or other noncombustible absorbent material and place into containers for later disposal.

Small dry spills: with clean shovel place material into clean, dry container and cover; move containers from spill area.

Large spills: dike far ahead of spill for later disposal. (EPA, 1998)

0.091 [mg/m3]

1.0 [mg/m3]

6.0 [mg/m3]

Intermediate Oral: 0.002 mg/kg/day (L134)

Chronic Oral: 0.0003 mg/kg/day (L134)

For emergency situations, wear a positive pressure, pressure-demand, full facepiece self-contained breathing apparatus (SCBA) or pressure- demand supplied air respirator with escape SCBA and a fully-encapsulating, chemical resistant suit. (EPA, 1998)

Personnel protection: ... Wear appropriate chemical protective gloves, boots and goggles. .... /Organochlorine pesticide, liquid; Organochlorine pesticide, solid, toxic/

Crystals. The technical product is a whitish to light-brown crystalline powder with a mild chemical odor. Used as an insecticide. Not registered as a pesticide in the U.S. (EPA, 1998)

White to light brown solid; [HSDB] Colorless crystals; [MSDSonline]

Whitish to light brown powder

Crystals from heptane

248 to 252 °F (EPA, 1998)

120-122 °C

Sol in ether, acetone, benzene, xylene, heavy aromatic naphtha

Greater than 1% in ethanol & kerosene

25 g/100 ml acetone at 25 °C, 38 g/100 ml benzene at 25 °C, 34 g/100 ml carbon tetrachloride at 25 °C, 2 g/100 ml fuel oil at 25 °C, 34 g/100 ml toluene at 25 °C, 29 g/100 ml xylene at 25 °C.

It is soluble in water to about 0.1 mg/L at 20 °C.

1.87 (EPA, 1998) - Denser than water; will sink

1.87 @25 °C

1e-05 mmHg at 77 °F (EPA, 1998)

0.00000292 [mmHg]

Vapor pressure = 3X10-6 mm Hg at 20 °C

2.92X10-6 mm Hg at 20 °C

0.00001 [mm Hg] @25 °C

log Kow = 4.51 /Estimated/

Henry's Law constant = 5.9X10-8 atm-cu m/mol at 25 °C /Estimated/

Relatively stable to acids; dehydrochlorination may occur under strong akaline conditions.

When heated to decomposition it emits toxic fumes of /hydrogen chloride/.

Hexane/acetonitrile partition coefficient -0.03 (log)

1-Octane/dimethyl formamide partition coefficient -0.69 (log)

1-Octane/85% dimethylformamide:15% water partition coefficient 0.23 (log)

Hexane/90% dimethyl sulfonoxide/10% water partition coefficient 0.27 (log)

For more Other Experimental Properties (Complete) data for ISOBENZAN (8 total), please visit the HSDB record page.

Potential endocrine disrupting compound

Pesticides -> Organochlorine Pesticides

Insoluble in water.

Halogenated Organic Compounds

Hydrocarbons, Aliphatic Unsaturated

Chlorine is evolved when ISOBENZAN is heated above 410F. Avoid acids, certain metal salts, and catalytically active carriers. [EPA, 1998].

It antagonizes the action of the neurotransmitter gamma-aminobutyric acid (GABA) acting at the GABA-A receptors, effectively blocking the GABA-induced uptake of chloride ions and causing hyperexcitability of the central nervous system. It also inhibits Na+ K+ ATPase and Ca2+ and Mg2+ ATPase which are essential for the transport of calcium across membranes. This results in the accumulation of intracellular free calcium ions, which promotes release of neurotransmitters from storage vesicles, the subsequent depolarization of adjacent neurons, and the propagation of stimuli throughout the central nervous system. It also causes increased lipid peroxidation, decreased membrane fluidity, and DNA damage in hepatocytes, but the exact mechanism is unknown. (T10, L112)

No indication of carcinogenicity (not listed by IARC). (L135)

Poisoning affects primarily the nerve system. Exposure causes various harmful effects including hyperexcitability, severe central nervous system damage, and death. It is also believed to cause birth defects. (T10, L112)

Oral (L111)

Symptoms that may result from endrin poisoning are headaches, dizziness, nervousness, confusion, nausea, vomiting, and convulsions. (L112)

Other Poison - Organochlorine

LD50: 3 mg/kg (Oral, Rat) (T14)

LD50: 12 mg/kg (Dermal, Rat) (T14)

LD50 Rat intravenous 1.8 mg/kg

LD50 Rat male (hooded) oral 11.1 mg/kg

LD50 Rat female (hooded) oral 8.9 mg/kg

LD50 Rat male (Sprague-Dawley) oral 6.6 mg/kg

For more Non-Human Toxicity Values (Complete) data for ISOBENZAN (19 total), please visit the HSDB record page.

Treatment is symptomatic, aimed at controlling convulsions, coma, and respiratory depression. If ingested, gastric lavage may be performed, followed by administering activated charcoal powder. (L150)

/SIGNS AND SYMPTOMS/ The neural excitation caused by the organochlorine insecticides leads to their primary toxic manifestations. The organochlorine insecticide toxicity syndrome includes disturbances of sensation, coordination, and mental status. Anorexia, malaise, headaches, myoclonic jerking, lethargy, tremor, hyperreflexia, motor hyperexcitability, oral paresthesia (after ingestion), and convulsions have been reported with acute organochlorine insecticide poisoning. High concentrations of organochlorine pesticides have been associated with increased myocardial irritability and cardiac arrhythmias. /Organochlorine insecticides/

/SIGNS AND SYMPTOMS/ Cases associated with isobenzan (with or without dieldrin) differed from those associated with dieldrin or endrin in that there were many complaints of headache, dizziness, drowsiness, irritability, and sometimes paresthesias, particularly in the legs.

/BIOMONITORING/ Isobenzan was initially manufactured and handled in the Netherlands between 1958 and 1965. ...In the 7 years of isobenzan production, 15 cases of clinical intoxication, including eight cases with convulsions, were reported. The mean concentration of isobenzan in the blood of nine workers at the time of intoxication was 23 ug/L, the range being 17-30 ug/L. Although these workers recovered fully, it took longer than with the related cyclodiene insecticides. In three cases, certain typical complaints, such as headache, dizziness, drowsiness, and irritability, persisted for 6 months, and the return to normal of the modified EEG pattern sometimes took more than a year. In one case of acute over-exposure, without signs of intoxication, the blood isobenzan concentration decreased from 8 ug/L to <2 ug/L within 3 days. The data from plant workers indicated a threshold level of isobenzan in blood below which no signs or symptoms of intoxication occur. This level was found to be 15 ug/L.

/BIOMONITORING/ The threshold blood level for isobenzan below which no signs or symptoms of intoxication occur is only 0.015 ppm. Blood levels as high as 0.030 ppm have been reported in connection with intoxications both with and without convulsions. The fatal level is not known.

/LABORATORY ANIMALS: Acute Exposure/ A 50% wettable powder formulation and a 15% emulsifiable concentrate (in mixed petroleum xylenes) were tested for their acute oral toxicity to rats, mice, rabbits, hamsters, cats, and dogs. The LD50 values, when expressed as active material, were comparable with those of isobenzan itself. The dermal LD50 value for the 15% emulsifiable concentrate was 25-35 mg isobenzan/kg bw for Hooded-Lister rats and 6 mg isobenzan/kg bw for New Zealand white rabbits, whereas in the case of the 50% wettable powder the LD50 was 41 mg isobenzan/kg bw for rabbits. Rabbits exposed dermally to the 15% emulsifiable concentrate formulation behaved differently /than/ rats similarly exposed. The rabbits generally lost weight due to anorexia and a failure to drink, and they would then convulse, even as much as 3 weeks after the exposure. However, if feeding and drinking were resumed quickly, the rabbits did not convulse. /Formulated products/

/LABORATORY ANIMALS: Acute Exposure/ The acute oral and intravenous toxicities of the metabolite isobenzan lactone for mice were 30 times lower than those of isobenzan. The oral and intravenous LD50 values were 306 mg/kg bw and >100 mg/kg bw, respectively. /Isobenzan lactone/

/LABORATORY ANIMALS: Acute Exposure/ Rats become lethargic and show an elevation of their fur in about 1 hr following a dose in the LD50 range. Soon tremors appear. The animals paw their faces, tend to carry their tails outstretched, and often gnaw the cage. Later there is frothing at the mouth, general twitching of the muscles, labored breathing, opisthotonus, and convulsions. During intervals between convulsions, the animals run around the cage. Most deaths occur within 20 hr. Recovery of survivors is rapid even in those that had violent convulsions.

/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ When groups of five female albino rabbits were given daily applications of isobenzan in corn oil (0, 5, 10, 20, 30, or 40 mg per rabbit) to the shaven skin for 3 weeks, mortality was high at all dose levels, reaching 100% after 2 weeks for rabbits given doses of 30 or 40 mg. Histopathological examination revealed necrosis of the heart muscle, non-dose-related lesions of the liver, and degenerative changes in cells of the central nervous system in a few animals.

For more Non-Human Toxicity Excerpts (Complete) data for ISOBENZAN (12 total), please visit the HSDB record page.

LD50 Mallard female, 5-7 month old, oral 4.15 mg/kg (95% confidence limit 2.47-6.97 mg/kg) /Sample purity 99%/

LD50 Coturnix quail (female) oral 4.2 mg/kg bw /from table/

LD50 Quiscalus quiscula (grackle) oral 1.3 mg/kg bw /from table/

LD50 Columba liva (pigeon) oral 10 mg/kg bw /from table/

For more Ecotoxicity Values (Complete) data for ISOBENZAN (10 total), please visit the HSDB record page.

/FIELD STUDIES/ Five sandy loam plots of pasture in New Zealand were treated with telodrin (15% emulsifiable concentrate) at a rate of 2 kg isobenzan/ha in June 1962. The populations of all recorded groups (grass grub, porina, collembola, diptera, hemiptera, coleoptera, mites, and earthworms), except nematodes, were drastically reduced. There was no recovery in the populations of any of the affected groups during the period of up to October 1965. In silt loam plots treated with isobenzan granules (1 kg/ha) in April 1964, the populations of coleoptera, collembola, diptera, mites, and earthworms were all reduced, but to a lesser extent than in the test using 2 kg/ha. Grass grub and hemiptera were not significantly affected,and nematode numbers were elevated 2 yr after treatment.

/FIELD STUDIES/ When loose sandy soil in New Zealand was treated with 2.25 kg isobenzan/ha as 5% granules, the population reduction, 1-18 wk after treatment, was 90-100% for larval coleoptera and lepidoptera and 75% for diptera and earthworms. The number of surface arthropods, 5-15 days after treatment, was reduced by 45%. Six months after treatment, little effect was found on nematodes (13% reduction), bacteria (18% reduction), and fungi (7% increase).

/AQUATIC SPECIES/ Groups of 5 adult Rasbora heteromorpha (Harlequin fish) were exposed for 2 hr at a temp of 20 °C to water (pH 7.2) containing isobenzan (99%), dissolved in DMSO at a concentration of 0.01, 0.1, or 1 mg/L. The fish were then /placed in/ clean water and observed for an additional 48 hr. The treatment with 1 mg/L caused disorientation and the fish became excited by external stimuli, lost ability to swim, and finally all died within 1 hr. In some cases, they appeared to be convulsive. Isobenzan at 0.1 mg/L caused similar symptoms; within 2 hr of exposure, all five fish died. No fish died at 0.01 mg/L, but slight changes in swimming behavior were observed. When guppies (Poecilia reticulata) were tested in the same way, the symptoms of intoxication and susceptibility were similar to those in Harlequin fish, but the guppies were slower to react.

/BIRDS and MAMMALS/ Sign of intoxication /for female mallard/: Ataxia, fasciculation, tenseness, swimming backwards, tail high and fanned, loss of righting reflex, circling, opisthotonos. Signs appeared as soon as 30 min and mortalities occurred about 2 hr after treatment. Survivors appeared normal by the next day, but lost moderate amount of body wt by the end of the 14-day observation period.

/BIRDS and MAMMALS/ When groups of five male and five female Japanese quail (Coturnix coturnix japonica) were fed diets containing 2 or 10 mg isobenzan/kg, the mean survival time in the high-dose group was 6.9 days (range, 2-20 days). The residues in the liver and brain averaged 3.4 mg/kg and 1.4 mg/kg, respectively. In the low-dose group, the mean survival time was 45.9 days (range, 19-65 days) and the average residues in liver and brain were 6 mg/kg and 1.6 mg/kg, respectively. The concentration of isobenzan in the liver of birds fed 2 mg/kg was significantly higher than that in the high-dose group, but the concentration in the brain showed no difference.

Isobenzan's former production and use as a insecticide resulted in its direct release to the environment through various waste streams. If released to air, a vapor pressure of 2.92X10-6 mm Hg at 25 °C indicates isobenzan will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase isobenzan will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 28 hours. The vapor-phase isobenzan will also react with ozone with an estimated half-life of 320 days. Particulate-phase isobenzan will be removed from the atmosphere by wet and dry deposition. Isobenzan may be susceptible to direct photolysis in the environmental UV spectrum. If released to soil, isobenzan is expected to have slight mobility based upon an estimated Koc of 4,700. Volatilization from moist soil surfaces is not expected to be an important fate process based upon an estimated Henry's Law constant of 5.9X10-8 atm-cu m/mole. Biodegradation of isobenzan may occur based on soil biodegradation half-lives of 20 to 26 weeks, however it is not expected to be an important environmental fate process. If released into water, isobenzan is expected to adsorb to suspended solids and sediment based upon the estimated Koc. Volatilization from water surfaces is not expected to be an important fate process based upon this compound's estimated Henry's Law constant. An estimated BCF of 600 suggests the potential for bioconcentration in aquatic organisms is high. Hydrolysis is not expected to be an important environmental fate process since similar organochlorine pesticides are not susceptible to hydrolysis. Occupational exposure and general population exposure should be low or non-existent since isobenzan is no longer produced or used. In the past, isobenzan was applied directly to crops as an insecticide and exposure to this compound was primarily during manufacture and application. (SRC)

Isobenzan's former production and use as a insecticide(1) resulted in its direct release to the environment through various waste streams(SRC).

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 4,700(SRC), determined from a structure estimation method(2), indicates that isobenzan is expected to have slight mobility in soil(SRC). Volatilization of isobenzan from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 5.9X10-8 atm-cu m/mole(3), using a fragment constant estimation method(3). Isobenzan is not expected to volatilize from dry soil surfaces(SRC) based on a vapor pressure of 2.92X10-6 mm Hg(4). Biodegradation in soil is not expected to be an important environmental fate process(SRC). The percentage of isobenzan in soil was shown to decrease with increasing clay content in the soil; no isobenzan was recovered after 4-8 days of exposure at 45 °C. On the other hand, moist soils showed a diminished ability to degrade isobenzan after 4 days at 45 °C with the exception of sandy soils(5). A soil half-life of 20-26 weeks depending on soil content has also been calculated(6).

Terrestrial Fate: The behavior of isobenzan in soil was investigated in laboratory tests. Eight types of soil were used ranging from sand to sandy clay, the percentage of sand varying from 93 to 56% and the percentage of clay from 4 to 35%. Following percolation with hexane, the percentage of isobenzan in the eluate fraction was shown to decrease with increasing content of clay in the soil (starting at about 30% clay). Except in the case of sand with a high organic matter content (6-19%), no isobenzan was recovered from the dry soils after 4-8 days of exposure at 45 °C. When the soils were moistened with water and exposed at 45 °C for 4 days, degradation was markedly diminished, with the exception of sand with high organic matter.

Terrestrial Fate: After isobenzan is applied to the soil, a rapid initial loss occurs, after which the remaining cmpd decays at a much slower rate. It persists in soil from 2-7 yr depending on type of soil.

Terrestrial Fate: 95% /telodrin/ disappearance from soils: 2-4 yr

For more Environmental Fate (Complete) data for ISOBENZAN (7 total), please visit the HSDB record page.

AEROBIC: Microbial degradation studies found no evidence of biodegradation of isobenzan in soil studies using 250 and 2500 ppm over 30 days(1), however, the method only observed carbon dioxide evolution ignoring the possibility of biological epoxidation. Biodegradation of isobenzan in 4 different soil samples at 45 °C for 4 days resulted in trace-74% of initial isobenzan concentration detected(2). Another study calculated a soil half-life of 20-26 weeks depending on soil content(3,4).

LD50 Mallard female, 5-7 month old, oral 4.15 mg/kg (95% confidence limit 2.47-6.97 mg/kg) /Sample purity 99%/

LD50 Coturnix quail (female) oral 4.2 mg/kg bw /from table/

LD50 Quiscalus quiscula (grackle) oral 1.3 mg/kg bw /from table/

LD50 Columba liva (pigeon) oral 10 mg/kg bw /from table/

For more Ecotoxicity Values (Complete) data for ISOBENZAN (10 total), please visit the HSDB record page.

/FIELD STUDIES/ Five sandy loam plots of pasture in New Zealand were treated with telodrin (15% emulsifiable concentrate) at a rate of 2 kg isobenzan/ha in June 1962. The populations of all recorded groups (grass grub, porina, collembola, diptera, hemiptera, coleoptera, mites, and earthworms), except nematodes, were drastically reduced. There was no recovery in the populations of any of the affected groups during the period of up to October 1965. In silt loam plots treated with isobenzan granules (1 kg/ha) in April 1964, the populations of coleoptera, collembola, diptera, mites, and earthworms were all reduced, but to a lesser extent than in the test using 2 kg/ha. Grass grub and hemiptera were not significantly affected,and nematode numbers were elevated 2 yr after treatment.

/FIELD STUDIES/ When loose sandy soil in New Zealand was treated with 2.25 kg isobenzan/ha as 5% granules, the population reduction, 1-18 wk after treatment, was 90-100% for larval coleoptera and lepidoptera and 75% for diptera and earthworms. The number of surface arthropods, 5-15 days after treatment, was reduced by 45%. Six months after treatment, little effect was found on nematodes (13% reduction), bacteria (18% reduction), and fungi (7% increase).

/AQUATIC SPECIES/ Groups of 5 adult Rasbora heteromorpha (Harlequin fish) were exposed for 2 hr at a temp of 20 °C to water (pH 7.2) containing isobenzan (99%), dissolved in DMSO at a concentration of 0.01, 0.1, or 1 mg/L. The fish were then /placed in/ clean water and observed for an additional 48 hr. The treatment with 1 mg/L caused disorientation and the fish became excited by external stimuli, lost ability to swim, and finally all died within 1 hr. In some cases, they appeared to be convulsive. Isobenzan at 0.1 mg/L caused similar symptoms; within 2 hr of exposure, all five fish died. No fish died at 0.01 mg/L, but slight changes in swimming behavior were observed. When guppies (Poecilia reticulata) were tested in the same way, the symptoms of intoxication and susceptibility were similar to those in Harlequin fish, but the guppies were slower to react.

/BIRDS and MAMMALS/ Sign of intoxication /for female mallard/: Ataxia, fasciculation, tenseness, swimming backwards, tail high and fanned, loss of righting reflex, circling, opisthotonos. Signs appeared as soon as 30 min and mortalities occurred about 2 hr after treatment. Survivors appeared normal by the next day, but lost moderate amount of body wt by the end of the 14-day observation period.

/BIRDS and MAMMALS/ When groups of five male and five female Japanese quail (Coturnix coturnix japonica) were fed diets containing 2 or 10 mg isobenzan/kg, the mean survival time in the high-dose group was 6.9 days (range, 2-20 days). The residues in the liver and brain averaged 3.4 mg/kg and 1.4 mg/kg, respectively. In the low-dose group, the mean survival time was 45.9 days (range, 19-65 days) and the average residues in liver and brain were 6 mg/kg and 1.6 mg/kg, respectively. The concentration of isobenzan in the liver of birds fed 2 mg/kg was significantly higher than that in the high-dose group, but the concentration in the brain showed no difference.

Isobenzan's former production and use as a insecticide resulted in its direct release to the environment through various waste streams. If released to air, a vapor pressure of 2.92X10-6 mm Hg at 25 °C indicates isobenzan will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase isobenzan will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 28 hours. The vapor-phase isobenzan will also react with ozone with an estimated half-life of 320 days. Particulate-phase isobenzan will be removed from the atmosphere by wet and dry deposition. Isobenzan may be susceptible to direct photolysis in the environmental UV spectrum. If released to soil, isobenzan is expected to have slight mobility based upon an estimated Koc of 4,700. Volatilization from moist soil surfaces is not expected to be an important fate process based upon an estimated Henry's Law constant of 5.9X10-8 atm-cu m/mole. Biodegradation of isobenzan may occur based on soil biodegradation half-lives of 20 to 26 weeks, however it is not expected to be an important environmental fate process. If released into water, isobenzan is expected to adsorb to suspended solids and sediment based upon the estimated Koc. Volatilization from water surfaces is not expected to be an important fate process based upon this compound's estimated Henry's Law constant. An estimated BCF of 600 suggests the potential for bioconcentration in aquatic organisms is high. Hydrolysis is not expected to be an important environmental fate process since similar organochlorine pesticides are not susceptible to hydrolysis. Occupational exposure and general population exposure should be low or non-existent since isobenzan is no longer produced or used. In the past, isobenzan was applied directly to crops as an insecticide and exposure to this compound was primarily during manufacture and application. (SRC)

Isobenzan's former production and use as a insecticide(1) resulted in its direct release to the environment through various waste streams(SRC).

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 4,700(SRC), determined from a structure estimation method(2), indicates that isobenzan is expected to have slight mobility in soil(SRC). Volatilization of isobenzan from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 5.9X10-8 atm-cu m/mole(3), using a fragment constant estimation method(3). Isobenzan is not expected to volatilize from dry soil surfaces(SRC) based on a vapor pressure of 2.92X10-6 mm Hg(4). Biodegradation in soil is not expected to be an important environmental fate process(SRC). The percentage of isobenzan in soil was shown to decrease with increasing clay content in the soil; no isobenzan was recovered after 4-8 days of exposure at 45 °C. On the other hand, moist soils showed a diminished ability to degrade isobenzan after 4 days at 45 °C with the exception of sandy soils(5). A soil half-life of 20-26 weeks depending on soil content has also been calculated(6).

Terrestrial Fate: The behavior of isobenzan in soil was investigated in laboratory tests. Eight types of soil were used ranging from sand to sandy clay, the percentage of sand varying from 93 to 56% and the percentage of clay from 4 to 35%. Following percolation with hexane, the percentage of isobenzan in the eluate fraction was shown to decrease with increasing content of clay in the soil (starting at about 30% clay). Except in the case of sand with a high organic matter content (6-19%), no isobenzan was recovered from the dry soils after 4-8 days of exposure at 45 °C. When the soils were moistened with water and exposed at 45 °C for 4 days, degradation was markedly diminished, with the exception of sand with high organic matter.

Terrestrial Fate: After isobenzan is applied to the soil, a rapid initial loss occurs, after which the remaining cmpd decays at a much slower rate. It persists in soil from 2-7 yr depending on type of soil.

Terrestrial Fate: 95% /telodrin/ disappearance from soils: 2-4 yr

For more Environmental Fate (Complete) data for ISOBENZAN (7 total), please visit the HSDB record page.

AEROBIC: Microbial degradation studies found no evidence of biodegradation of isobenzan in soil studies using 250 and 2500 ppm over 30 days(1), however, the method only observed carbon dioxide evolution ignoring the possibility of biological epoxidation. Biodegradation of isobenzan in 4 different soil samples at 45 °C for 4 days resulted in trace-74% of initial isobenzan concentration detected(2). Another study calculated a soil half-life of 20-26 weeks depending on soil content(3,4).

... persistence in river water in a sealed glass jar under sunlight and artificial fluorescent light-initial concn= 10 ug/l: after 1 hr, 100% of original cmpd found; after 1 wk, 25% of original cmpd found; after 2 wk, 10% of original cmpd found; after 4 & 8 wk, 0% of original cmpd found. /Telodrin/

The rate constant for the vapor-phase reaction of isobenzan with photochemically-produced hydroxyl radicals has been estimated as 4.7X10-12 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 28 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). The rate constant for the vapor-phase reaction of isobenzan with ozone has been estimated as 3.6X10-19 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(1). This corresponds to an atmospheric half-life of about 320 days at an atmospheric concentration of 7X10+11 ozone molecules per cu cm(2). Isobenzan is not expected to undergo hydrolysis in the environment since similar chlorine-containing pesticides are not susceptible to hydrolysis. However, isobenzan may be susceptible to direct photolysis in the environmental UV spectrum(3).

An estimated BCF of 600 was calculated for isobenzan(SRC), using an estimated log Kow of 4.51(1) and a regression-derived equation(2). According to a classification scheme(3), this BCF suggests the potential for bioconcentration in aquatic organisms is high(SRC).

Using a structure estimation method based on molecular connectivity indices(1), the Koc for isobenzan can be estimated to be 4,700(SRC). According to a classification scheme(2), this estimated Koc value suggests that isobenzan is expected to have slight mobility in soil.

The Henry's Law constant for isobenzan is estimated as 5.9X10-8 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that isobenzan is expected to be essentially nonvolatile from water surfaces(2). Isobenzan's Henry's Law constant indicates that volatilization from moist soil surfaces is not expected(SRC). Isobenzan is not expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 2.92X10-6 mm Hg(3).

SURFACE WATER: Isobenzan was not detected in water from the North Channel and Georgian Bay on Lake Huron(1).

Isobenzan was detected but concns not reported in the FDA program for monitoring pesticide residues in foods during 1978-1982; 49,877 samples of raw agricultural commodities were analyzed(1). Isobenzan was detected, concns not reported, in 3 fruit samples during 1970-1971(2).

Three Jersey cows were fed for 28 days at concentrations of technical isobenzan of 0, 0.005, or 0.02 mg/kg in their daily ration (average ration, 20 kg per cow). Residues found in the milk of the cow fed 0.005 mg/kg increased from 0.4 ug/L to 2 ug/L at the end of the feeding period and decreased rapidly thereafter. Higher residues of up to 7.7 ug/L were present in the milk from the cow fed 0.02 mg/kg, which decreased to 1.5 ug/L whole milk 10 weeks after the last day of dosing.

Occupational exposure and general population exposure should be low or non-existent since isobenzan is no longer produced or used(1). In the past, isobenzan was applied directly to crops as an insecticide and exposure to this compound was primarily during manufacture and application(SRC).

... Beagles developed convulsions when the concn of isobenzan in their blood ranged from 0.042 to 0.072 ppm.

When male and female rats were given a single iv injection of 14C-isobenzan (15 ug/kg bw), the radioactivity in the blood of males 48 hr later was 0.04% of the applied dose and in females was 0.37%. The radioactivity in the organs and tissues ranged between 0.01 and approximately 1.5% of the applied dose, concentrations being lower in females than in males. In abdominal fat, the concentrations were 19.2% in males and 26.6% in females and, in muscle, 12.3% and 9.3%, respectively.

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal, aquatic, and plant life; and conformance with environmental and public health regulations.

Marine pollutant