Imazethapyr

289.33

289.33

617-222-4

DTXSID3024287

White to off-white crystalline solid|Off-white to tan solid

29333990

91.6

1.49 (pH 7)

off-white to tan solid with a slightly pungent odor

1.10 to 1.12 at 21 deg C

172-175 °C

180 deg C (decomposes)

224ºC

In water, 1415 ppm at 25 deg C

0-6°C

2.3X10-11 mm Hg at 25 deg C (est)

Oral-Rat LD50: 5000 mg/kg; Oral-Mouse LD50: 5000 mg/kg

Combustion produces toxic nitrogen oxide gas

Henry's Law constant = 1.04X10-16 atm-cu m/mol at 25 °C (est)

pK1 = 2.1; pK2 = 3.9

Clear dark brown or green liquid; musty odor /Pursuit/

NONH for all modes of transport

1

US5682900

The warehouse is ventilated, low temperature and dry; stored and transported separately from food materials

Rapidly degraded in sunlight, DT50 about 2.1 days (pH 7, 22-24 deg C)

P273, P391, P501

H400

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity 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 and plant life; and conformance with environmental and public health regulations.|SRP: Wastewater from contaminant suppression, cleaning of protective clothing/equipment, or contaminated sites should be contained and evaluated for subject chemical or decomposition product concentrations. Concentrations shall be lower than applicable environmental discharge or disposal criteria. Alternatively, pretreatment and/or discharge to a permitted wastewater treatment facility is acceptable only after review by the governing authority and assurance that "pass through" violations will not occur. Due consideration shall be given to remediation worker exposure (inhalation, dermal and ingestion) as well as fate during treatment, transfer and disposal. If it is not practicable to manage the chemical in this fashion, it must be evaluated in accordance with EPA 40 CFR Part 261, specifically Subpart B, in order to determine the appropriate local, state and federal requirements for disposal.|Container disposal: triple rinse, then offer for recycling or reconditioning or puncture and dispose of in a sanitary landfill or incineration or, if allowed by state and local authorities, by burning. If burned, stay out of smoke.

|Warning|H400 (100%): Very toxic to aquatic life [Warning Hazardous to the aquatic environment, acute hazard]|P273, P391, and P501|Aggregated GHS information provided by 179 companies from 2 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

SRP: Contaminated protective clothing should be segregated in such a manner so that there is no direct personal contact by personnel who handle, dispose, or clean the clothing. The completeness of the cleaning procedures should be considered before the decontaminated protective clothing is returned for reuse by the workers. Contaminated clothing should not be taken home at the end of shift, but should remain at employee's place of work for cleaning.|Avoid skin, eye, clothing contact. Wash contaminated clothing with soap and hot water. Do not breathe spray mist.|For several good reasons, .... herbicides ... should be handled and applied only with full attention to safety measures that minimize personal contact. Many formulations contain adjuvants (stabilizers, penetrants, surfactants) that may have significant irritating and toxic effects. A number of premixed formulations contain two or more active ingredients; the companion pesticides may be more toxic than the principal herbicide. Good hygienic practice should not be disregarded just because a pesticide is reported to have a high LD50 in laboratory rodents. /Herbicides/

practically nontoxic

LD50 Rat oral >5000 mg/kg|LD50 Rabbit dermal >2000 mg/kg|LC50 Rat inhalation 3.27 mg/L /Duration not specified/

/AQUATIC SPECIES/ Cyprinus carpio was exposed to imazethapyr and imazapic at laboratory and at field conditions. The laboratory experiment was carried out for 7 days and at rice field for 7, 30 and 90 days. Oxidative stress parameters and antioxidant profile were studied as well as metabolic parameters. After 7 days, brain AChE activity increases in laboratory and field, but in muscle, reduction was observed only in laboratory. At the same period, brain and muscle TBARS and liver CAT increase in the laboratory. Metabolic parameters showed changes in both conditions and exposure periods. After 30 days in rice field, brain AChE activity decreases and in muscle it was enhanced. After 90 days in field, only muscle AChE activity was reduced. The disorders in oxidative stress parameters and metabolism remained, indicating mainly a protein catabolism.|/OTHER TERRESTRIAL SPECIES/ Imazethapyr is a member of the imidazolinone class of herbicides. These chemicals are active through inhibition of acetohydroxyacid synthase (AHAS) which is involved in amino acid synthesis (leucine, isoleucine, and valine). The inhibition causes a disruption in protein synthesis that leads to an interference in cell growth.

Imazethapyr's production may result in its release to the environment through various waste streams; its use as a herbicide(1) will result in its direct release to the environment(SRC).

TERRESTRIAL FATE: Based on a classification scheme(1), Koc values of 1.4 to 173(2-5), indicate that imazethapyr is expected to have very high to moderate mobility in soil(SRC). The pKa2 of imazethapyr is 3.9(6), indicating that this compound exists almost entirely in anion form in the environment and anions generally do not adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts(7). Volatilization of imazethapyr from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 1.0X10-16 atm-cu m/mole(SRC), using a fragment constant estimation method(8). Although low amounts of imazethapyr have evaporated from dry soil(9), volatilization is not expected based upon its very low estimated vapor pressure of 2.1X10-11 mm Hg at 25 °C(SRC), determined from a fragment constant method(10). Imazethapyr has been shown to biodegrade under aerobic conditions with biodegradation half-lives of 23.5 days(11) to 10.6 months(12). Photo decomposition of 14C-imazethapyr from Taloka silt loam, irradiated with sunlight between 8:00 am and 5:00 pm from June 26 thru July 5th was 8% for 43 hours, chain labeled degraded more than ring labeled imazethapyr(9).|TERRESTRIAL FATE: In a two year (1987-1988) field study, imazethapyr was applied to two soil types at pre-plant and pre-emergence times and plots were tilled with conventional and reduced conditions(1). Dissipation half-lives were 49 to 122 days, this included all environmental factors (volatilization, leaching, surface runoff, plant uptake and degradation)(1). Two test fields established in 1991 were treated with imazethapyr both pre-emergence and post-emergence(2). Pre-emergence and post-emergence half-lives were 47 and 19 days for Prince Edward Island site (60% sand, 29% silt, 11% clay, 2.9% organic matter, pH 5.8), and 63 and 34 days for Nova Scotia site (57% sand, 34% silt, 9% clay, 3.3% organic matter, pH 5.8), respectively(2).|AQUATIC FATE: Based on a classification scheme(1), Koc values of 1.4 to 173(2-5), indicate that imazethapyr is expected to adsorb to suspended solids and sediment(SRC). A pKa2 of 3.9(6) indicates imazethapyr will exist almost entirely in the anion form at pH values of 5 to 9 and therefore volatilization from water surfaces is not expected to be an important fate process(SRC). According to a classification scheme(7), an estimated BCF of 3(SRC), from an estimated log Kow of 1.49(6) and a regression-derived equation(8), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Imazethapyr has been reported to biodegrade in soil under aerobic conditions with half-lives of 23.5 days(9) to 10.6 months(10). Imazethapyr had measured aqueous photodegradation half-lives of 4.0 to 5.1 hours in 3 rice paddy waters collected from Beaumont and Eagle Lake, TX and Clarksdale, MS(11).|ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), imazethapyr, which has an estimated vapor pressure of 2.3X10-11 mm Hg at 25 °C(SRC), determined from a fragment constant method(2), is expected to exist solely in the particulate phase in the ambient atmosphere. Particulate-phase imazethapyr may be removed from the air by wet or dry deposition(SRC).

Imazethapyr is not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions(1). Exposure to UV light (using sunlamps, wavelengths >290 nm and <620 nm) in aqueous solutions caused complete degradation of imazethapyr in 48 hrs, with a half-life of 4 hrs reported(2). Imazethapyr had measured aqueous photodegradation half-lives of 4.0 to 5.1 hours in 3 rice paddy waters collected from Beaumont and Eagle Lake, TX and Clarksdale, MS(3). Photo decomposition of 14C-imazethapyr from Taloka silt loam, irradiated with sunlight between 8:00 am and 5:00 pm from June 26 thru July 5th was 8% for 43 hours, chain labeled degraded more than ring labeled imazethapyr(4).

An estimated BCF of 3 was calculated in fish for imazethapyr(SRC), using a log Kow of 1.49(1) and a regression-derived equation(2). According to a classification scheme(3), this BCF suggests the potential for bioconcentration in aquatic organisms is low(SRC).

7.08 L/kg|Imazethapyr had a reported mean Koc of 13.2 (range of 2 to 55) in 101 allophanic and non-allophanic surface soil samples collected throughout New Zealand(1). Imazethapyr had a reported Koc of 19 at pH 7.7 and an increased Koc of 163 as the pH was reduced to 5.4(2). Imazethapyr has a reported Koc range of 75 to 173(3). Koc values for Trani (55.1% sand, 22.0% silt, 22.9% clay, pH 7.5, organic carbon 1.46%) and Andria (69.1% sand, 18% silt, 12.9% clay, pH 7.8, organic carbon 0.62%) soils were 1.4 and 12.9, respectively(4). According to a classification scheme(5), these reported Koc values suggest that imazethapyr is expected to have very high to moderate mobility in soil. In an adsorption study using 2 humic acids, no measurable adsorption of imazethapyr occurred at pH 4.7, while at pH 3.6 and 3.7, the compound did adsorb(6). The pKa2, 3.9, indicates that at the lower pH values, about half of the amount of herbicide would exist in the molecular form and most of the carboxyl groups of humic acids are combined(6); at pH 4.7, the herbicide is mainly in the ionic form and most of the carboxyl groups of humic acids are also ionized(6). Using 10 soils, Kd values ranging from no detectable adsorption (pH 7.5, % organic carbon 0.86-1.39) to 14.74 (pH 4.5, % organic carbon 11.66) were obtained(6).

A pKa2 of 3.9(1) indicates imazethapyr will exist almost entirely in the anion form at pH values of 5 to 9 and therefore volatilization from water surfaces is not expected to be an important fate process(SRC). Volatilization of imazethapyr from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 1.0X10-16 atm-cu m/mole(SRC), calculated using a fragment constant estimation method(2). Volatilization of 14C radio-labeled imazethapyr (ring and chain labeled) from dry soil was 1.5% from Taloka silt loam (23% sand, 62% silt, 15% clay, 1.7% organic matter, pH 6.3) and 1.0% from Sharkey silty clay (9% sand, 40% silt, 51% clay, 2.4% organic matter, pH 6.7), soil was incubated at 49 °C for a maximum of 168 hours(3); these values are very low(SRC). Volatilization is not expected based upon its very low estimated vapor pressure of 2.1X10-11 mm Hg at 25 °C(SRC), determined from a fragment constant method(4).

GROUNDWATER: Imazethapyr was detected in 4 of 25 groundwater samples collected in the Midwestern United States from May to Aug 1998 at median and maximum concentrations of <0.01 and 0.059 ug/L, respectively, method reporting limit of 0.01 ug/L(1). Imazethapyr was detected at <0.02 ug/L in groundwater in Belle Plaine, IA and at 0.09 ug/L in Correctionville, IA, samples were collected June to Sept 1997(2).|DRINKING WATER: Imazethapyr was detected at a maximum concentration of 3 ng/L in 163 drinking water samples taken from 15 treatment facilities located in Manitoba, Saskatchewan and Alberta, Canada, samples were collected July 2004 and 2005(1).|SURFACE WATER: Imazethapyr was detected in 92 of 129 surface water samples collected from 75 surface water sites from the Upper Mississippi, Missouri, and Ohio River basins in the United States from May to Aug 1998 at median and maximum concentrations of 0.031 and 0.689 ug/L, respectively, method reporting limit of 0.01 ug/L(1). Imazethapyr was detected in 12 of 206 surface water samples at a maximum concentration of 11.0 ng/L taken from 15 drinking water reservoirs located in Manitoba, Saskatchewan and Alberta, Canada, samples were collected May to Aug 2003, Oct 2003, Jan 2004, and April 2004 and 2005(2). Imazethapyr was detected in 8% of samples taken from the Kisco river with a maximum concentration of 0.074 ug/L and in 25% of samples taken from the middle branch of the Croton River with a maximum concentration of 0.096 ug/L, samples were collected May 2000 to Feb 2001, rivers are part of New York City water supply system(3). Imazethapyr was not detected in the Tensas River near Tendal or the Illinois River near Valley City, IA(4). Imazethapyr was detected at 0.21, 0.05, 0.03 and 0.11 ug/L in the Iowa river near Rowan, IA, Mississippi River near Clinton, IA, Wabash River near New Harmony, IN and Illinois River near Ottawa, IL, samples were collected June to Sept 1997(4). Imazethapyr was detected at 0.10 ug/L in the Nishnabotna River near Hamburg, IA from samples collected Jun 17, 1998 after a 500 year flood(5).

Occupational exposure to imazethapyr may occur through inhalation of spray mists or aerosols and dermal contact with this herbicide during or after its application or at workplaces where imazethapyr is produced. (SRC)

Pesticides used to destroy unwanted vegetation, especially various types of weeds, grasses (POACEAE), and woody plants. Some plants develop HERBICIDE RESISTANCE. (See all compounds classified as Herbicides.)

In rats, following oral administration, 92% was excreted in the urine and 5% in the feces within 24 hr. Residue levels in blood, liver, kidney, muscle, and fat tissues were <0.01 ppm after 48 hr.

In a rat metabolism study, almost 100% of the administered radiolabeled test material /imazethapyr/ was recovered in the excreta within 96 hours (89-95% in the urine and 6-11% in the feces). Greater than 95% of the oral dose was excreted in the first 31 hours. The major residue in both urine and feces was the parent compound. Approximately 2% of the oral dose was metabolized and excreted as CL 288511 (1-hydroxy ethyl derivative of imazethapyr). A high percentage of the administered material was excreted in the urine as the unmodified parent compound (> 97%) and a very small amount as CL 288511. In the high dose group, the unmodified parent compound was the major fecal component in both sexes, particularly at 12 hours or less. CL 288511 was the major metabolite. One unknown metabolite was also found in significant quantities. In the low dose group, six components were found in the feces: parent compound, CL 288511, the unknown previously mentioned and three minor unknowns.|Rapidly metabolized in non-susceptible plants (50% loss in soyabeans in 1.6 days).

Absorbed by plant roots and foliage, being translocated to meristematic regions where it inhibits the biosynthesis of valine, leucine and isoleucine preventing cell division.|Imazapyr (IMZR), Imazapic (IMZC), Imazethapyr (IMZT), Imazamox (IMZX) and Imazaquin (IMZQ) ... are classified as imidazolinone (IMI) herbicides and their mode of action is to inhibit acetohydroxyacid synthase (AHAS), an enzyme involved in the biosynthesis of the amino acids leucine, isoleucine and valine. ...

/SRP:/ Immediate first aid: Ensure that adequate decontamination has been carried out. If patient is not breathing, start artificial respiration, preferably with a demand valve resuscitator, bag-valve-mask device, or pocket mask, as trained. Perform CPR if necessary. Immediately flush contaminated eyes with gently flowing water. Do not induce vomiting. If vomiting occurs, lean patient forward or place on the left side (head-down position, if possible) to maintain an open airway and prevent aspiration. Keep patient quiet and maintain normal body temperature. Obtain medical attention. /Poisons A and B/|/SRP:/ Basic treatment: Establish a patent airway (oropharyngeal or nasopharyngeal airway, if needed). Suction if necessary. Watch for signs of respiratory insufficiency and assist ventilations if needed. Administer oxygen by nonrebreather mask at 10 to 15 L/min. Monitor for pulmonary edema and treat if necessary ... . Monitor for shock and treat if necessary ... . Anticipate seizures and treat if necessary ... . For eye contamination, flush eyes immediately with water. Irrigate each eye continuously with 0.9% saline (NS) during transport ... . Do not use emetics. For ingestion, rinse mouth and administer 5 mL/kg up to 200 mL of water for dilution if the patient can swallow, has a strong gag reflex, and does not drool ... . Cover skin burns with dry sterile dressings after decontamination ... . /Poisons A and B/|/SRP:/ Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious, has severe pulmonary edema, or is in severe respiratory distress. Positive-pressure ventilation techniques with a bag valve mask device may be beneficial. Consider drug therapy for pulmonary edema ... . Consider administering a beta agonist such as albuterol for severe bronchospasm ... . Monitor cardiac rhythm and treat arrhythmias as necessary ... . Start IV administration of D5W /SRP: "To keep open", minimal flow rate/. Use 0.9% saline (NS) or lactated Ringer's if signs of hypovolemia are present. For hypotension with signs of hypovolemia, administer fluid cautiously. Watch for signs of fluid overload ... . Treat seizures with diazepam or lorazepam ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Poisons A and B/|Skin decontamination. Skin contamination should be treated promptly by washing with soap and water. Contamination of the eyes should be treated immediately by prolonged flushing of the eyes with large amounts of clean water. If dermal or ocular irritation persists, medical attention should be obtained without delay. /Herbicides/|For more Antidote and Emergency Treatment (Complete) data for IMAZETHAPYR (7 total), please visit the HSDB record page.

imazethapyr

Premix Partners: Atrazine; Dicamba; Glyphosate; Imazapyr; Imazaquin; Pendimethalin; Saflufenacil; Sulfentrazone; Trifluralin.|Aqueous concentrate|Pursuit Herbicide Technical (Basf Corporation) Imazethapyr 97.3%|Pursuit Plus EC Herbicide (Basf Corporation) Pendimethalin 30.24%, Imazethapyr 2.24%|For more Formulations/Preparations (Complete) data for IMAZETHAPYR (23 total), please visit the HSDB record page.

The WHO Recommended Classification of Pesticides by Hazard identifies imazethapyr as unlikely to present an acute hazard in normal use; Main Use: herbicide.

The enforcement method for use on rice grain and rice straw is Method M3120. This method measures the concentrations of imazethapyr and its metabolites CL 288511 and CL 182704. The method extracts residues with acidic aqueous methanol, and the extract is then eluted through C18, strong anion exchange, and strong cation exchange columns. Residues are quantified via capillary electrophoresis with a UV detector.|The enforcement method for use on crayfish is Method 3512. This method quantifies the residues for imazethapyr and its metabolite CL 299511. This method involves extraction of residues using acidic acetone, followed by elution through a C18 column, and residues are quantified using LC/MS analysis.|Method: USGS-NWQL O-2060-01; Procedure: high performance liquid chromatography-mass spectrometry; Analyte: imazethapyr; Matrix: water; Detection Limit: 0.0084 ug/L.|Residues of imazethapyr and metabolites in plants by capillary electrophoresis with UV, HPLC/MS or GC/NPD. In soil by capillary electrophoresis with UV or HPLC/UV.

Agrochemicals -> Herbicides, Plant Growth Regulators