Thioquinox

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 150(SRC), determined from a structure estimation method(2), indicates that thioquinox is expected to have moderate mobility in soil(SRC). Volatilization of thioquinox from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 7.8X10-8 atm-cu m/mole(SRC), using a fragment constant estimation method(3). Thioquinox is not expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 1X10-7 mm Hg(4). Biodegradation data were not available(SRC, 2005).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 150(SRC), determined from a structure estimation method(2), indicates that thioquinox is expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is not expected(3) based upon an estimated Henry's Law constant of 7.8X10-8 atm-cu m/mole(SRC), developed using a fragment constant estimation method(4). According to a classification scheme(5), an estimated BCF of 2(SRC), from an estimated log Kow of 1.3(6) and a regression-derived equation(7), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Biodegradation data were not available(SRC, 2005).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), thioquinox, which has a vapor pressure of 1X10-7 mm Hg at 25 °C(2), is expected to exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase thioquinox 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 2 days(SRC), calculated from its rate constant of 7.9X10-12 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Particulate-phase thioquinox may be removed from the air by wet and dry deposition(SRC). Thioquinox has been reported to be stable to light(4).

Using a structure estimation method based on molecular connectivity indices(1), the Koc for thioquinox can be estimated to be 150(SRC). According to a classification scheme(2), this estimated Koc value suggests that thioquinox is expected to have moderate mobility in soil.

An estimated BCF of 2 was calculated for thioquinox(SRC), using an estimated log Kow of 1.3(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).

The Henry's Law constant for thioquinox is estimated as 7.8X10-8 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that thioquinox is expected to be essentially nonvolatile from water surfaces(2). Thioquinox's Henry's Law constant indicates that volatilization from moist soil surfaces will not occur(SRC). Thioquinox is not expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 1X10-7 mm Hg(3).

/LABORATORY ANIMALS: Acute Exposure/ ...Dermal applications of 3,000 mg/kg did not affect rats...

/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ In rats fed at levels of ...100 mg/kg/day it produced weakness, wt loss, and 1 death after 2 weeks.

/GENOTOXICITY/ Rec-assay procedure (H17 rec+ & M45 rec- Bacillus subtilis strains) and reversion assays on plates (auxotrophic strains of Escherichia coli (WP2) & Salmonella typhimurium (Ames series)) showed no evidence of thioquinox mutagenicity.

The rate constant for the vapor-phase reaction of thioquinox with photochemically-produced hydroxyl radicals has been estimated as 7.9X10-12 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 2 days at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). Thioquinox has been shown to be resistant to hydrolysis(2). Thioquinox has been reported to be stable to light(2).

Occupational exposure and general population exposure should be low or non-existent since thioquinox is no longer produced or used. In the past, thioquinox was applied directly to crops as an acaricide and fungicide and exposure to this compound was primarily by dermal contact and inhalation. (SRC)

Thioquinox's former production and use as an acaricide and fungicde resulted in its direct release to the environment. If released to air, a vapor pressure of 1X10-7 mm Hg at 20 °C indicates thioquinox will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase thioquinox 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 2 days. Particulate-phase thioquinox will be removed from the atmosphere by wet and dry deposition. Thioquinox has been shown to be stable to light. If released to soil, thioquinox is expected to have moderate mobility based upon an estimated Koc of 150. Volatilization from water and moist soil surfaces is not expected to be an important fate process based upon an estimated Henry's Law constant of 7.8X10-8 atm-cu m/mole. Thioquinox is not expected to volatilize from dry soil surfaces based upon its vapor pressure. If released into water, thioquinox is expected to adsorb to suspended solids and sediment based upon the estimated Koc. An estimated BCF of 2 suggests the potential for bioconcentration in aquatic organisms is low. Thioquinox has been reported to be resistant to hydrolysis because of the lack of hydrolyzable functional groups. Currently occupational exposure and general population exposure should be low or non-existent since thioquinox is no longer produced or used. In the past, thioquinox was applied directly to crops as an acaricide and fungicide and exposure to this compound was primarily by dermal contact and inhalation. (SRC)

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/

LD50 Rat oral 3.4 g/kg

LD50 guinea pigs oral 1.0 g/kg