化合物详情

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), isazofos, which has a vapor pressure of 8.7X10-5 mm Hg at 25 °C(2), will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase isazofos 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 3.8 hours(SRC), calculated from its rate constant of 9.4X10-11 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Particulate-phase isazofos may be removed from the air by wet and dry deposition(SRC). While isazofos is susceptible to photolysis in water and on soil(4), no data were found regarding the direct ph...

Persistence of isazophos, as either an emulsifiable concentrate or as granules, was measured in field lysimeters packed with Plainfield sand (1.5% organic matter) and receiving either natural rainfall or supplementary watering(3). Neither isazophos or its metabolite, CGA 17193 (5-chloro-1-isopropyl-3-triazolol), were found in the effluent of lysimeters receiving only rainfall over the 21 week period (223 mm rain fell)(1). Isazophos, applied as an emulsifiable concentrate, was eluted on 22 occasions from the lysimeters; however, when applied as granules, only 4 instances of isazophos elution were reported (total water input of 811 mm)(1).

AEROBIC: Average time for 50% dissipation in a turf-soil profile was 7 days for isazofos(1). It was also reported that the pesticides examined in this study, which included isazofos, appeared to degrade more rapidly in the turfgrass environment than what is typically reported for other agronomic cropping systems (1). Field half-lives of 34 days(2) and 2.5 to 48.4 days(4) have been reported for isazofos. Isazofos was reported to have a half-life in soil of 10 days in laboratory studies(3). An aerobic an anaerobic half-life of 40.5 and 14 days were reported for isazofos in soil, respectively(4).

An estimated BCF of 170 was calculated for isazofos(SRC), using a log Kow of 3.82(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).

The Henry's Law constant for isazofos is 5.21X10-7 atm-cu m/mole(SRC) derived from its vapor pressure, 8.7X10-5 mm Hg(1), and water solubility, 69 mg/l(1). This Henry's Law constant indicates that isazofos 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 270 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 2000 days(SRC). Isaozofos' Henry's Law constant indicates that volatilization from moist soil surfaces is expected(SRC). Isazofos is not expected to volatilize from dry soil surfaces(SRC) based upon its vapor pressure(1). Pesticides were...

The rate constant for the vapor-phase reaction of isazofos with photochemically-produced hydroxyl radicals has been estimated as 9.4X10-11 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 3.8 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). Isazofos is hydrolyzed more rapidly in alkali than in acids; half-lives were calculated at 20 °C as 85 days (pH 5), 48 days (pH 7), and 19 days (pH 9)(2). Half-lives of 4 and 40 days at 25 deg have been reported for photolysis of isazofos in water (pH 7.5) and soil (pH 5), respectively(3).

/PLANTS/ Phytotoxic to potatoes and tobacco.

Isazofos' former production may have resulted in its release to the environment through various waste streams; its use as a nematicide and insecticide(1) resulted in its direct release to the environment(SRC).

Secondary exposure of children through contact with their parents' contaminated clothing can also occur. /Organophosphorus pesticides/

Isazofos' former production may have resulted in its release to the environment through various waste streams; its use as a nematicide and insecticide resulted in its direct release to the environment. If released to air, a vapor pressure of 8.7X10-5 mm Hg at 25 °C indicates isazofos will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase isazofos 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 3.8 hours. Particulate-phase isazofos will be removed from the atmosphere by wet and dry deposition. While isazofos is susceptible to photolysis in water and on soil, no data were found regarding the direct photolysis in air by sunlight. If released to soil,...

Symptoms of low dose exposure include excessive salivation and eye-watering. Acute dose symptoms include severe nausea/vomiting, salivation, sweating, bradycardia, hypotension, collapse, and convulsions. Increasing muscle weakness is a possibility and may result in death if respiratory muscles are involved. Hypertension, hypoglycemia, anxiety, headache, tremor and ataxia may also result.

If the compound has been ingested, rapid gastric lavage should be performed using 5% sodium bicarbonate. For skin contact, the skin should be washed with soap and water. If the compound has entered the eyes, they should be washed with large quantities of isotonic saline or water. In serious cases, atropine and/or pralidoxime should be administered. Anti-cholinergic drugs work to counteract the effects of excess acetylcholine and reactivate AChE. Atropine can be used as an antidote in conjunction with pralidoxime or other pyridinium oximes (such as trimedoxime or obidoxime), though the use of '-oximes' has been found to be of no benefit, or possibly harmful, in at least two meta-analyses. Atropine is a muscarinic antagonist, and thus blocks the action of acetylcholine peripherally.

The combination of certain herbicides with insecticides can inhibit crop growth. Greenhouse studies were conducted to evaluated interaction effects of herbicides and insecticides with/without protectant, on corn and weed species. 'Northrup King 9283' hybrid corn showed greater sensitivity to acetanilide herbicides than 'Cargill 7567'. Neither the insecticides terbufos nor isazofos appeared to enhance this sensitivity....

LC50 (rat) = 103 mg/m3

Acute exposure to cholinesterase inhibitors can cause a cholinergic crisis characterized by severe nausea/vomiting, salivation, sweating, bradycardia, hypotension, collapse, and convulsions. Increasing muscle weakness is a possibility and may result in death if respiratory muscles are involved. Accumulation of ACh at motor nerves causes overstimulation of nicotinic expression at the neuromuscular junction. When this occurs symptoms such as muscle weakness, fatigue, muscle cramps, fasciculation, and paralysis can be seen. When there is an accumulation of ACh at autonomic ganglia this causes overstimulation of nicotinic expression in the sympathetic system. Symptoms associated with this are hypertension, and hypoglycemia. Overstimulation of nicotinic acetylcholine receptors in the central...

Other Poison - Organophosphate

Isazofos is a cholinesterase or acetylcholinesterase (AChE) inhibitor. A cholinesterase inhibitor (or 'anticholinesterase') suppresses the action of acetylcholinesterase. Because of its essential function, chemicals that interfere with the action of acetylcholinesterase are potent neurotoxins, causing excessive salivation and eye-watering in low doses, followed by muscle spasms and ultimately death. Nerve gases and many substances used in insecticides have been shown to act by binding a serine in the active site of acetylcholine esterase, inhibiting the enzyme completely. Acetylcholine esterase breaks down the neurotransmitter acetylcholine, which is released at nerve and muscle junctions, in order to allow the muscle or organ to relax. The result of acetylcholine esterase inhibition is...

/SIGNS AND SYMPTOMS/ Principal effects /of anticholinesterases as toxic components of insecticides/ on eye, whether from local contact or systemic poisoning, are miosis and spasm of accommodation for near vision. /Anticholinesterases/

No indication of carcinogenicity to humans (not listed by IARC).

LD50 Rat (male) dermal >3100 mg/kg.