Dithiopyr

401.42

401.42

619-297-9

2TXF17HAV1

DTXSID9032379

Pale, yellow, crystalline solid|Solid, crystalline; chemically pure: white, technical grade: yellow to burnt yellow

97.6

5.24290

1.332 g/cm3

65 °C

460.3ºC at 760 mmHg

1.505

3.49e-06 M|In water, 1.4 mg/L at 20 °C|In water, 1.38 mg/L at 20 °C|Solubility (g/100 mL at 25 °C): hexane <3.3, toluene >25, acetone >33.3, diethyl ether >50, ethanol >12, methylene chloride >50

0-6°C

4.0X10-6 mm Hg at 25 °C

LD50 orally in rats: >5000 mg/kg (Fujiyama, Yamane)

Faint sulfur-like odor|Sulfurous

Dithiopyr does not act as an acid (pKa not required for USEPA Registration)

Henry's Law constant = 1.53X10-6 atm-cu m/mole at 25 °C (estimated from vapor pressure and water solubility|Hydroxyl radical reaction rate constant = 7.1X10-12 cu-cm/molc sec at 25 °C (est)

P273, P391, P501

H400

SRP: 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 air, soil or water; effects on animal, aquatic and plant life; and conformance with environmental and public health regulations. If it is possible or reasonable use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity or environmental contamination.

|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 58 companies from 2 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.|H361: Suspected of damaging fertility or the unborn child [Warning Reproductive toxicity]|P201, P202, P260, P281, P308+P313, P314, P405, and P501

SRP: The scientific literature for the use of contact lenses by industrial workers is inconsistent. The benefits or detrimental effects of wearing contact lenses depend not only upon the substance, but also on factors including the form of the substance, characteristics and duration of the exposure, the uses of other eye protection equipment, and the hygiene of the lenses. However, there may be individual substances whose irritating or corrosive properties are such that the wearing of contact lenses would be harmful to the eye. In those specific cases, contact lenses should not be worn. In any event, the usual eye protection equipment should be worn even when contact lenses are in place.

Primary dermal irritation (rabbit): Slight erythema but no edema with 0.5 hours. No effects by 72 hours. /Technical, 90.9%/|Primary eye irritation (rabbit): No corneal opacity; irritation reversible within 24 hours. /Technical, 90.9%/|Primary dermal irritation (rabbit): Severe dermal irritation. Superficial (epidermis) necrosis, clearing with 14 days. /Dimension Turf Herbicide, 12.5% a.i./|Primary eye irritation (rabbit): Corneal corrosion reversible within 24 days, and possibly within 7 days; corneal opacity reversible within 7 days. /Dimension Turf Herbicide, 12.5% a.i./

IDENTIFICATION AND USE: Dithiopyr is a herbicide used preemergence and early postemergence for selective control of crabgrass and other susceptible annual grasses and broadleaf weeds in established lawns and ornamental turf. HUMAN STUDIES: Worker exposure is monitored by both passive dosimetry and biological monitoring techniques such as urinalysis. ANIMAL STUDIES: Severe dermal irritation has been noted in rabbits. In a 90 day subchronic study in rats the effect was an increase in organ weight and diffused hepatocellular swelling. In a rat and rabbit developmental toxicity study there were no developmental effects at 1000 mg/kg/day. Dithiopyr was not mutagenic in the Ames assays for mutagenicity with Ames (TA) strains of Salmonella typhimurium LT2 at limit of solubility (3,000 mg/plate) with or without activation.

LD50 Rat oral >5,000 mg/kg /Technical, 90.9%/|LD50 Mouse oral >5,000 mg/kg /Technical, 90.9%/|LD50 Rat dermal >5,000 mg/kg /Technical, 90.9%/|LD50 Rat (male) oral >4,100 mg/kg /Dimension Turf Herbicide, 12.5% a.i./|For more Non-Human Toxicity Values (Complete) data for Dithiopyr (6 total), please visit the HSDB record page.

Dithiopyr's production may result in its release to the environment through various waste streams; its use as a herbicide for pre-emergent and early post-emergent control of crabgrass and other annual grasses and weeds(1) will result in its direct release to the environment(SRC). Dithiopyr is used primarily in the professional turf, golf course and ornamental markets and is not currently registered for use in the US for foods or agricultural uses(1).

TERRESTRIAL FATE: Based on a classification scheme(1), a Koc range of 1141-3748(2), indicates that dithiopyr is expected to have low to slight mobility in soil(SRC). Research conducted to evaluate the movement of dithiopyr from golf courses found that most of the applied dithiopyr was detected in the top 0-12.5 cm of the rooting media(3). Volatilization of dithiopyr from moist soil surfaces may occur(SRC) given an estimated Henry's Law constant of 1.53X10-6 atm-cu m/mole(SRC), derived from its vapor pressure, 4.0X10-6 mm Hg(4), and water solubility, 1.38 mg/L(4). Despite having a low vapor pressure, dithiopyr belongs to a class of pesticides having important environmental volatility(5). Greenhouse studies found that volatilization can be a primary route of dithiopyr dissipation following herbicidal application with losses >50% after a few days(6-8). Dithiopyr dissipation in the soil environment occurs mostly through a combination of volatilization and biodegradation(4,8). Dithiopyr was found to degrade much faster in non-sterile media versus sterile media(8). Dithiopyr absorbs at wavelengths >290 nm(3) and, therefore, may be susceptible to direct photolysis by sunlight(SRC). One photodegradation study found minimal dithiopyr photolysis on soil (444.4 day half-life)(4), however, a distilled water study found a 1.7 day half-life(8). Field dissipation rates can vary widely depending on conditions. For example, rainstorms or irrigation following application can infiltrate the dithiopyr into the soil greatly decreasing volatilization and photodegradation losses(8). Reported field dissipation half-life rates are 17-61 days(4) and 4-49 days(9).|AQUATIC FATE: Based on a classification scheme(1), a Koc range of 1141-3748(2), indicates that dithiopyr is expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(3) based upon an estimated Henry's Law constant of 1.53X10-6 atm-cu m/mole(SRC), derived from its vapor pressure, 4.0X10-6 mm Hg(4), and water solubility, 1.38 mg/L(4). Using this Henry's Law constant and an estimation method(3), volatilization half-lives for a model river and model lake are 48 and 356 days, respectively(SRC). According to a classification scheme(5), an estimated BCF of 633(SRC), from its log Kow of 4.75(4) and a regression-derived equation(6), suggests the potential for bioconcentration in aquatic organisms is high(SRC). Dithiopyr was found to degrade much faster in non-sterile aqueous media versus sterile media(7) indicating biodegradation may be an important fate process(SRC). Hydrolysis studies indicated that hydrolysis is not an important route of degradation in the environment(4). An aqueous photolysis half-life of 17.6-20.6 days has been reported(4).|ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), dithiopyr, which has a vapor pressure of 4.0X10-6 mm Hg at 25 °C(2), will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase dithiopyr 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 54 hours(SRC), calculated from its rate constant of 7.1X10-12 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(2). Particulate-phase dithiopyr may be removed from the air by wet and dry deposition(SRC). Dithiopyr absorbs at wavelengths >290 nm(3) and, therefore, may be susceptible to direct photolysis by sunlight(SRC).

The rate constant for the vapor-phase reaction of dithiopyr with photochemically-produced hydroxyl radicals has been estimated as 7.1X10-12 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 54 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). Hydrolysis studies with dithiopyr in sterile water at pH 5 and pH 7 at 25 °C found no degradation after 30 days, and at pH 9, <2% degradation yielding an approximate half-life of 1053 days(2); the results indicated that ester hydrolysis was slowly occurring in alkaline conditions, and that hydrolysis was not an important route of degradation in the environment(2). Dithiopyr absorbs at wavelengths >290 nm(3) and, therefore, may be susceptible to direct photolysis by sunlight(SRC). Dithiopyr applied to soil and then exposed to UV (artificial sunlight) for an equivalent of 33.6 days yielded a direct photolysis half-life of 444.3 days suggesting this mechanism is not an important fate process in soil(2). However, irradiation tests using both distilled and natural waters (water containing humic acids photo-sensitizers) found sunlight equivalent half-lives of 17.6-20.6 days(2); it was concluded that dithiopyr in water exposed to sunlight is expected to degrade to a mixture of normal acid, reverse acid and lesser amounts of polar compounds(2). Dithiopyr UV irradiation tests using distilled water and nonsterile leachate water from a stimulated golf green found dithiopyr half-lives of 1.7 and 0.83 days respectively(3).

An estimated BCF of 633 was calculated in fish for dithiopyr(SRC), using a log Kow of 4.75(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), provided the compound is not metabolized by the organism(SRC).

Dithiopyr has a reported Koc range of 1141-3748(1) and a single reported Koc value of 1920(2). According to a classification scheme(3), this estimated Koc value suggests that dithiopyr is expected to have low to slight mobility in soil. Dithiopyr has a low potential for leaching into groundwater(4). Vertical mobility of dithiopyr through soil, even in conditions highly susceptible to herbicide leaching, was found not to exceed 24 inches and was often not more than 9 to 12 inches(4). Research conducted to evaluate the movement of dithiopyr from golf courses found that most of the applied dithiopyr was detected in the top 0-12.5 cm of the rooting media at the end of greenhouse experiments and that the highest concentration in runoff from simulated fairways did not exceed 40 ug/L (less than 2% of applied dithiopyr was transported)(5).

The Henry's Law constant for dithiopyr is estimated as 1.53X10-6 atm-cu m/mole(SRC) derived from its vapor pressure, 4.0X10-6 mm Hg(1), and water solubility, 1.38 mg/L(1). This Henry's Law constant indicates that dithiopyr is expected to volatilize 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 48 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 356 days(SRC). Dithiopyr's estimated Henry's Law constant indicates that volatilization from moist soil surfaces may occur(SRC). With respect to most compounds, dithiopyr would not be expected to volatilize from dry soil surfaces(SRC) based upon its vapor pressure. However, dithiopyr is included in select classes of pesticides that exhibit low to moderate volatility following field application despite having relatively low vapor pressures(3). In one greenhouse volatilization study, up to 70% of dithiopyr applied to crabgrass volatilized within 24 hours at 24 °C and volatilization losses were found to increase with temperature(4). In another greenhouse study, increased volatilization from smooth crabgrass resulted at temperatures of 25-30 °C compared to 10-15 °C(5). A study simulating dithiopyr application to golf course greens found that following application to the rooting media, dithiopyr was primarily lost by volatilization(6). A dissertation review of available literature and actual field testing of the efficacy of dithiopyr in turfgrass environments notes the potential importance of volatilization following field application as a herbicide(7). Volatilization rates of dithiopyr and other turfgrass herbicides can vary greatly under field conditions with dependency on temperature, surface conditions, soil or foliage type, moisture content, soil sorption, and irrigation/rain immediately following application (which reduces volatility)(7).

Occupational exposure to dithiopyr may occur through inhalation and dermal contact with this compound at workplaces where dithiopyr is produced or used. The general population may be exposed to dithiopyr via inhalation and dermal contact in localized areas where dithiopyr is being applied or recently applied as a herbicide. (SRC)

Based on urine sample residues of dicarbothioic acid, the equivalent dithiopyr exposure to ChemLawn lawn care workers applying dithiopyr was 1.45-13.7 ug body dose(1); the mean 72-hr body dose estimate was 4.60X10-5 mg/kg/lb applied(1).

1. Transformation of dithiopyr by rat liver enzymes in vitro produced the corresponding monoacids as the predominant metabolites. 2. Transformations of the methylthioester functional groups in dithiopyr to the monoacids were mediated via rat liver microsomal oxygenases, and not via esterases. 3. Based on the formation of a dithiopyr-glutathione conjugate, the mechanism of monoacid formation is believed to proceed through an initial sulfur oxidation of the methylthioester group and a subsequent nucleophilic displacement reaction.

Dithiopyr is a mitotic inhibitor of normal cell division of susceptible plants. The formation and function of microtubulin in inhibited. Susceptable plant roots and stunted and fail to function in the presence of dithiopyr.

/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 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 TKO /SRP: "To keep open", minimal flow rate/. Use 0.9% saline (NS) or lactated Ringer's (LR) 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 (Valium) or lorazepam (Ativan) ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Poisons A and B/

/BIOMONITORING/ ChemLawn lawn care specialists were monitored for worker exposure by both passive dosimetry and biological monitoring techniques in the performance of normal duties of mixing/loading and application of Dimension herbicide to turfgrass. Passive dosimetry was performed, utilizing cotton gauze patches, silica gel air sampling absorption media, and hand washes as per US Environmental Protection Agency Pesticide Assessment Guidelines. Biological monitoring was performed by analysis of all urine specimens collected from each specialist from initiation until 72 hr after application of dithiopyr. The mean body dose estimate from urinalysis of the specimens collected over the 72 hr period was 4.60 x 10(-5) mg/kg/lb applied. The passive dosimetry body dose estimates using dermal deposition measurements corrected for skin penetration and simulated inhalation measurements were calculated for the two clothing scenarios observed in the worker tests. The mean body dose estimate for a fully clothed specialist wearing a long-sleeved shirt was 8.09 x 10(-5) mg/kg/lb while for a specialist wearing a short-sleeved shirt the estimate was 3.62 x 10(-4) mg/kg/lb. The lower leg regions, which were protected by long pants and boots, had the highest exposure by passive dosimetry data.

dithiopyr

The National Pesticide Information Retrieval System (NPIRS) identifies 25 companies with active labels for products containing the chemical dithiopyr. To view the complete list of companies, product names and percent dithiopyr in formulated products click the following url and enter the CAS Registry number in the Active Ingredient field.|Alligare Dithiopyr 40 (Alligare, LLC): Active ingredient: dithiopyr 40.0%.|Chemsico Herbicide Concentrate 30-A (Chemsico): Active ingredient: dithiopyr 0.81%.|Dithiopyr 0.06% Plus Fertilizer (Control Solutions, Inc): Active ingredient: dithiopyr 0.06%.|For more Formulations/Preparations (Complete) data for Dithiopyr (28 total), please visit the HSDB record page.

Registration Notes: Outside USA: Dictran in Japan, Scoop in Egypt, Korea.

Agrochemicals -> Herbicides