Primisulfuron-methyl

468.34

468.34

617-814-2

3TN6B6S8JP

DTXSID8032463

Colorless crystals|Fine white powder

154

0.06 @ 25 deg C, unstated pH

1.61 g/cm³ @ Temp: 20 °C

194.8-197.4 °C (decomp)

203 °C

1.535

Solubility in water: 3.3 (pH 5), 243 (pH 7), 5280 (pH 9) (all in mg/l)

2-8°C

<5X10-3 mPa (<3.75X10-8 mm Hg) @ 25 deg C

LD50 in rats (mg/kg): >4000 orally; >2000 dermally (Maurer)

pKa = 5.1

On hydrolysis (50 °C): DT50 10 hrs (pH 3 and pH 5), >300 hrs (pH 7 and pH 9), 120 hrs (pH 10); stable up to 100 °C.

UN 3077 9 / PGIII

3

50/53

60-61

DG4436000

N

Compatible in tank mixtures with atrazine, bromoxynil, cyanazine, dicamba & 2,4-D.

P273

H400

USEPA/Office of Pesticide Programs; Report of the Food Quality Protection Act (FQPA) Tolerance Reassessment Progress and Risk Management Decision (TRED) for Primisulfuron-Methyl. EPA issues a TRED for a pesticide that requires tolerance reassessment decisions, but does not require a reregistration eligibility decision at present because: the pesticide was initially registered after November 1, 1984, and by law is not included within the scope of the reregistration program; EPA completed a RED for the pesticide before FQPA was enacted on August 3, 1996; or the pesticide is not registered for use in the U.S. but tolerances are established that allow crops treated with the pesticide to be imported from other countries.[Available from, as of May 8, 2003: http://www.epa.gov/pesticides/reregistration/status.htm]

Weakly adsorbed by soil components and accordingly leaching can occur in soils. Short-to-moderate soil persistence.

LD50 Rat oral >5050 mg/kg|LD50 Rat percutaneous >2010 mg/kg|LC50 Rat inhalation >4.8 mg/L air/4 hr

/BIRDS and MAMMALS/ Effects on birds: Primisulfuron-methyl is practically nontoxic to wildfowl. Both bobwhite quail and mallard ducks show a high tolerance for the compound. The 5-day dietary LC50 for primisulfuron-methyl in both these species was in excess of 2150 ppm. In addition, mallards fed moderate amounts of the compound showed no adverse effects on reproduction at the highest dose tested (500 ppm) in their diet.|/AQUATIC SPECIES/ Primisulfuron-methyl is only slightly toxic to freshwater fish, aquatic organisms, and marine (estuarine) shrimp. The reported 96-hr LC50 values are >48 mg/L in bluegill, and >13 mg/L in rainbow trout. The compound is practically nontoxic to the freshwater invertebrate Daphnia magna.|/OTHER TERRESTRIAL SPECIES/ Primisulfuron-methyl is nontoxic to honey bees.

Primisulfuron-methyl'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: Primisulfuron-methyl has a pKa of 5.1(8) indicating that this compound will exist primarily as the anion under environmental conditions(SRC). Koc values of 11 to 675 were measured in six soils with differing organic carbon content and at different pH values(1). In general, Koc values were less than 100 and sorption was shown to decrease with increasing pH(1). Based on a classification scheme(2), these values indicate that primisulfuron-methyl is expected to have moderate to very high mobility in soil(SRC). As primisulfuron-methyl exists almost entirely as an anion at pH values of 5 to 9, volatilization from moist soil surfaces is not expected to be an important fate process(SRC). Volatilization of the neutral species from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 1.4X10-12 atm-cu m/mole(SRC), using a fragment constant estimation method(3). Primisulfuron-methyl is not expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of <3.75X10-8 mm Hg(4). Hydrolysis, particularly in acidic soils, may be an important fate process(SRC); half-lives of 0.32, 41, and 95 days were reported for primisulfuron-methyl at pH values of 4, 7, and 9, respectively(5). Field dissipation half-lives of 3.8 to 14 days were measured at eight different sites(6). In laboratory studies, primisulfuron-methyl was found to biodegrade fairly rapidly in soil with aerobic half-lives of 25.6 and 26.8 days(7); under anaerobic conditions, half-lives of 198 and 365 days were observed(5).|AQUATIC FATE: Based on a classification scheme(1), Koc values generally less than 100(2) indicate that primisulfuron-methyl is not expected to adsorb to suspended solids and sediment(SRC). Sorption was shown to decrease with increasing pH in six different soils(2). A pKa of 5.1(3) indicates primisulfuron-methyl will exist almost entirely as an anion 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 the neutral species from water surfaces is not expected(4) based upon an estimated Henry's Law constant of 1.4X10-12 atm-cu m/mole(SRC), developed using a fragment constant estimation method(5). According to a classification scheme(6), an estimated BCF of 14(SRC), from an estimated log Kow(7) and a regression-derived equation(8), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Hydrolysis, particularly in acidic water, may be an important fate process(SRC); half-lives of 0.32, 41, and 95 days were reported for primisulfuron-methyl at pH values of 4, 7, and 9, respectively(9). Biodegradation data in anaerobic sediment/water microcosms indicate that primisulfuron-methyl will biodegrade slowly (half-lives of 198 and 365 days)(9). Data for aerobic conditions in water were not available; however, in soil studies, biodegradation was fairly rapid with half-lives of 25.6 and 26.8 days(10).|ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), primisulfuron-methyl, which has a vapor pressure of <3X10-10 mm Hg at 20 °C(2), is expected to exist solely in the particulate phase in the ambient atmosphere. Particulate-phase primisulfuron-methyl may be removed from the air by wet and dry deposition(SRC).

The hydrolysis of primisulfuron-methyl was measured in buffer solution at pH 4, 7, and 10 following Organization for Economic Cooperation and Development (OECD) guidelines(1). Hydrolysis occurs at the sulfonylurea bridge; saccharin was detected as a hydrolysis product(1). Pseudo-first order hydrolysis rate constants of 2.14 (half-life of 0.32 days), 0.017(half-life of 41 days), and 0.0073 days-1 (half-life of 95 days) were reported at pH 4, 7, and 10, respectively, following incubation at 40 °C(1). At pH 4 and an incubation temperature of 22 °C, a pseudo first-order hydrolysis rate constant of 0.1238 (half-life of 5.6 days) was measured(1). Hydrolysis half-lives of 2.34, 1.41, 1.06, and 0.65 days were reported for primisulfuron-methyl at 15, 20, 25, and 30 °C and at pH 4(2). At pH 2, 3, 4, 5, 6.5, 7.5, and 8.5 half-lives of 0.90, 0.97, 1.06, 12.34, 48.88, 298.81 days, respectively, were measured in aqueous solution(2). Primisulfuron-methyl is not expected to photolyze directly at environmental wavelengths (>290 nm); data for a structurally-similar compound, primisulfuron, shows only very weak absorption at wavelengths above 300 nm(3). A pKa value of 5.1(4) indicates that this compound will be present as the anion at the majority of environmental pH values(SRC).

An estimated BCF of 14 was calculated for primisulfuron-methyl(SRC), using an estimated log Kow of 2.41(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).

12.02 L/kg|Primisulfuron-methyl is a moderately weak acid (pKa of 5.1) with a low, pH-dependent water solubility(1). Sorption of this compound is dependent on the affinity of both the neutral species (when pH < pKa) and the anionic species, found when the pH is greater than the pKa, to the soil matrix. The sorption and desorption of primisulfuron-methyl was measured in six soils with different organic carbon content, iron oxide, and clay contents(1). Sorption coefficients (in L/kg) of 15.47 (Koc of 32) and 5.43 (Koc of 11) were measured at pH 4.5 and 5.8, respectively, in a Medisaprist (muck) soil(47.7% organic carbon). Sorption coefficients (in L/kg) of 2.71, 1.56, 1.24, 1.17, and 0.18 were measured at pH 4.1, 4.5, 4.8, 4.9, and 6.5, respectively (Koc of 162, 93, 74, 70, 11, respectively), in a Haplaquept soil(1.67% organic carbon). Sorption coefficients (in L/kg) of 0.55, 0.29, and 0.23 were measured at pH 4.5, 5.0, and 5.6, respectively (Koc of 83, 44, 35, respectively), in a Hapludalf (A horizon) soil(0.66% organic carbon). Sorption coefficients (in L/kg) of 1.62, 0.90, 0.67, and 0.39 were measured at pH 3.9, 4.3, 4.4, and 5.0, respectively (Koc of 675, 375, 279, and 163, respectively), in a Hapludalf (B Horizon) soil(0.24% organic carbon)(1). Sorption of primisulfuron-methyl decreased in each of these soils with increasing pH. Koc values of 13, 0.00, 4, and 20 were reported in clay (4.8% OM), sand (0.9% OM), sandy loam (1.9% OM) and loam (0.8% OM) soils, respectively(2). According to a classification scheme(), these Koc values suggest that primisulfuron-methyl is expected to have moderate to very high mobility in soil.|In a one year field lysimeter study using undisturbed Dothan soils (90 cm length soil columns), an average Rf value of 0.16 was measured for primisulfuron-methyl. After 90 days, the 14C from the initially applied primisulfuron-methyl was 14% in the 4 cm section, 16% in the 11 cm section and 4% in the 19 cm section; loss of radioactivity was mainly attributed to escape of CO2 although further data were not given(1). A Koc of 20 was reported for primisulfuron-methyl(2). Multivariate regression analysis was used to determine the importance of various soil characteristics on the Kd value of primisulfuron-methyl; the Kd value was determined on a Ravenna silt loam soil. In this study, clay content had a strong effect (90% of r2) on the adsorption of this pesticide while total organic content had a lesser effect (10% of r2)(2).

A pKa of 5.1 indicates primisulfuron-methyl will exist almost entirely as an anion at pH values of 5 to 9 and therefore volatilization from both moist soil and water surfaces is not expected to be an important fate process. The Henry's Law constant for the neutral species is estimated as 1.4X10-12 atm-cu m/mole(SRC) using a fragment constant estimation method(1); this indicates that this species is expected to be essentially nonvolatile from both moist soil and water surfaces(2). Primisulfuron-methyl is not expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of <3.75X10-8 mm Hg(3).

GROUNDWATER: Primisulfuron-methyl was not detected above the method reporting limit (MRL) in 25 groundwater samples collected from municipal wells in Iowa and from 5 observation wells in the Lower Illinois in 1998 (median <0.01 ug/l; maximum <0.01 ug/l)(1).|SURFACE WATER: 130 surface water samples from 75 streams, large rivers, and reservoir outflows in the Upper Mississippi, Missouri, and Ohio River basins were collected in 1998; 0% of the samples contained detections of primisulfuron-methyl above the method reporting limit (MRL) (median is <0.01 ug/l; maximum is <0.01 ug/l)(1).

Occupational exposure to primisulfuron-methyl may occur through dermal contact with this compound at workplaces where primisulfuron-methyl is produced or used. (SRC)

The major pathway in the metabolism of primisulfuron-methyl in the rat and other large animals involves hydroxylation of the pyrimidine ring, followed by hydrolysis and/or glucuronic acid conjugation.|In maize, a major metabolite is the O-glucoside of 5-hydroxy-primisulfuron. At harvest time, no residues >0.05 mg/kg are detectable in the grain and fodder of maize.

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/

75% wettable granules in water soluble packets.|USEPA/OPP Pesticide Code 128973; Trade Names: CGA-136872.