Thiazopyr

396.37500

396.38

601-493-0

AEQ9R142XI

DTXSID1032488

Light tan granular solid|Light tan crystalline solid

76.85000

3.95210

1.3777 g/cm³ @ Temp: 25 °C

77.3-79.1 °C

448.9ºC

225.3ºC

1.535

6.31e-06 M|In organic solvents at 20 °C (g/100 ml): methanol = 28.7; hexane = 3.06|In water, 2.5 mg/l @ 20 °C

0-6ºC

2.98E-08mmHg at 25°C

Sulfurous

Photostable in dry soil. Aqueous photolysis DT50 15 days.|Compatible with many products in tank mix.

SRP: At the time of review, criteria for land treatment or burial (sanitary landfill) disposal practices are subject to significant revision. Prior to implementing land disposal of waste residue (including waste sludge), consult with environmental regulatory agencies for guidance on acceptable disposal practices.

LD50 Rat oral >5000 mg/kg|LD50 Rabbit percutaneous >5000 mg/kg|LD50 Rat dermal >5000 mg/kg

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

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc of 542,000(SRC), determined from a structure estimation method(2), indicates that thiazopyr is expected to be immobile in soil(SRC). In 14 field dissipation studies across the U.S.(3), the vertical movement of thiazopyr, even in sandy soils with low organic carbon content, did not exceed 12 inches, and thiazopyr was usually only detectable in the 0-6 inch layer of soil. Volatilization from moist soil surfaces is not expected to be an important fate process based on an estimated Henry's Law constant of 4.7X10-7 atm-cu m/mole(SRC), derived from its vapor pressure, 2.25X10-6 mm Hg at 25 °C(4), and water solubility, 2.5 mg/l(4). The photolysis half-life on soil is very slow with an extrapolated half-life of 1,373 days(3). Thiazopyr has an average field dissipation half-life of 85 days, based on 14 field dissipation studies(3).|AQUATIC FATE: Based on a classification scheme(1), an estimated Koc of 542,000(SRC), determined from a structure estimation method(2), indicates that thiazopyr is expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected to be slow(3) based upon an estimated Henry's Law constant of 4.7X10-7 atm-cu m/mole(SRC), derived from its vapor pressure, 2.25X10-6 mm Hg at 25 °C(4), and water solubility, 2.5 mg/l(4). Based on this Henry's Law constant, the volatilization half-life from a model river (1 m deep, flowing 1 m/sec, wind velocity of 3 m/sec)(3) is estimated as 156 days(SRC). The volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec)(3) is estimated as 1138 days(SRC). According to a classification scheme(5), bioconcentration factors ranging from 11 to 400 for different fish tissue(6) suggest that bioconcentration in aquatic organisms is low to high(SRC). Thiazopyr is stable to hydrolysis in sterile aqueous buffered solutions at pH 4 and pH 5(6); hydrolysis was observed at pH 7 and pH 9, with predicted half-lives of 3,394 days and 64 days, respectively(6). Thiazopyr photodegradation half-lives of 7.8 and 20.8 days, respectively, were observed in unsensitized and humic sensitized sterile aqueous pH 5 buffer solutions using artificial sunlight at 25 °C(6).|ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), thiazopyr, which has a vapor pressure of 2.25X10-6 mm Hg at 25 °C (2), will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase thiazopyr is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 31 hours(SRC), calculated from its rate constant of 1.2X10-11 cu cm/molecule-sec at 25 °C(SRC), that was derived using a structure estimation method(3). Particulate-phase thiazopyr may be removed from the air by wet and dry deposition(SRC).

Thiazopyr is stable to hydrolysis in sterile aqueous buffered solutions at pH 4 and pH 5(1); hydrolysis was observed at pH 7 and pH 9, with predicted half-lives of 3,394 days and 64 days, respectively(1); in both cases, the product of the hydrolysis was thiazopyr monoacid(1). Thiazopyr photodegradation half-lives of 7.8 and 20.8 days, respectively, were observed in unsensitized and humic sensitized sterile aqueous pH 5 buffer solutions using artificial sunlight at 25 °C(1). Thiazopyr was observed to photodegrade very slowly on soil, with an extrapolated half-life of 1,373 days(1).|The rate constant for the vapor-phase reaction of thiazopyr with photochemically-produced hydroxyl radicals has been estimated as 1.2X10-11 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 31 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1).

A dynamic fish bioaccumulation study showed that thiazopyr should not bioconcentrate, with bioconcentration factors ranging from 11 to 400 for different fish tissue(1). According to a classification scheme(2), BCF values less than 30 are low and from 100 to 1,000 are high.

In 14 field dissipation studies across the country(1), the vertical movement of thiazopyr, even in sandy soils with low organic carbon content, did not exceed 12 inches, and thiazopyr was usually only detectable in the 0-6 inch layer of soil. The major soil metabolite (monoacid) was detected only in very low amount in the top soils(1).|Thiazopyr was observed to have low mobility in soil column leaching studies using sandy soils from a citrus region in central Florida(1).|Using a structure estimation method based on molecular connectivity indices(1), the Koc for thiazopyr can be estimated to be 542,000(SRC). According to a classification scheme(2), this estimated Koc value suggests that thiazopyr is expected to be immobile in soil.

The Henry's Law constant for thiazopyr is estimated as 4.7X10-7 atm-cu m/mole(SRC) derived from its vapor pressure, 2.250X10-6 mm Hg at 25 °C(1), and water solubility, 2.5 mg/l(1). This Henry's Law constant indicates that thiazopyr is expected to volatilize slowly from water surfaces(2). Based on this Henry's Law constant, the volatilization half-life from a model river (1 m deep, flowing 1 m/sec, wind velocity of 3 m/sec)(2) is estimated as 156 days(SRC). The volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec)(2) is estimated as 1,138 days(SRC).

Occupational exposure to thiazopyr may occur through inhalation of dust and dermal contact with this compound at workplaces where thiazopyr is produced or used. (SRC)

Two metabolism studies were conducted in rats with radio- labeled thiazopyr. One with the 14C at the 4 position of the pyridine ring & one with the 14C at the 4' & 5' positions of the thiazole ring. The absorption of an orally admin dose was about 90%. The overall radiolabel recovery for all study groups was 88.9, plus or minus 0.65%. No significant sex-related differences were observed in the total % recovery. However, the distribution of recovery was sex-related. There was little radiolabel detected in tissues at study termination. Preferential sites for localization of the radiolabel included liver, adipose tissue, muscle & bone. The metabolic pathway is essentially an oxidative pathway. Vulnerable sites of the molecule are the thiazoline ring, the isobutyric side chain & the pyridine rings. Thiazapyr appears to be rapidly & extensively eliminated with low amounts of residues remaining in the tissues & carcasses. The % of radiolabel remaining in the carcasses following feeding thiazoline labeled thiazopyr was beween 6.9 & 10.8%.

1. Thiazopyr was hydrolysed in vitro to its corresponding acid by rabbit & porcine liver esterases. 2. A wide range of thiazopyr esterase activity was observed in extracts from liver acetone powders from 15 animal species with bovine, rabbit & pigeon showing the highest activities. 3. Using soybean tissue culture cells & Arabidopsis seedlings, the acidic metabolite was shown to possess < 1% of the herbicidal activity of thiazopyr. 4. We propose that biotransformation of thiazopyr to the acid is a critical pathway of metab in animals & plants.

Mode of action: Inhibits cell division by disrupting spindle microtubule formation.

Basic treatment: Establish a patent airway. 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 normal saline 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 ... . /Poison A and B/|Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious, has severe pulmonary edema, or is in respiratory arrest. Positive pressure ventilation techniques with a bag valve mask device may be beneficial. Monitor cardiac rhythm and treat arrhythmias as necessary ... . Start an IV with D5W /SRP: "To keep open", minimal flow rate/. Use lactated Ringer's if signs of hypovolemia are present. Watch for signs of fluid overload. Consider drug therapy for pulmonary edema ... . For hypotension with signs of hypovolemia, administer fluid cautiously. Watch for signs of fluid overload ... . Treat seizures with diazepam (Valium) ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Poison A and B/

thiazopyr

USEPA/OPP Pesticide Code 129100; Trade Names: MON 13200, MON 13211, MON 13211-A, MON 13211-B.|95.1% active ingredient Technical; EC formulation containing 22.3% thiazopyr|Emulsifiable concentrate; granules; wettable powder

Agrochemicals -> Herbicides