Chemical Fact Sheet

Chemical Abstract Number (CAS #) 122145
CASRN 122-14-5
Phosphorothioic acid, O,O-dimethyl O-(3-methyl-4-nitrophenyl) ester
Dimethyl 4-nitro-m-tolyl phosphorothionate
Analytical Methods EPA Method 622.1
EPA Method 8141
Molecular FormulaC9H12NO5PS

Link to the National Library of Medicine's Hazardous Substances
Database for more details on this compound.

Boiling Point 118 DEG C @ 0.05 MM HG
Molecular Weight 277.25
Density 1.32 to 1.34 @ 25 deg C/25 deg C
Environmental Impact The release of fenitrothion in the environment is expected to occur during the manufacture and particularly during the application of the insecticide against a wide range of pests and insects. Abiotic hydrolysis of fenitrothion in soil and water should not be important. The photolysis of fenitrothion in clear water and soil surfaces should be important and the photolysis half-life has been estimated to be about 1 day. The biodegradation of fenitrothion may be important in water and in soil and biodegradation is expected to be faster under anaerobic than aerobic conditions. The volatilization loss of fenitrothion from soil and water should not be important, but the volatilization from surface slicks following application has been reported to be very fast. Based on experimentally determined soil sorption coefficients, fenitrothion should show medium to low mobility in soil and it should moderately to strongly adsorb to suspended solids and sediments in water. The experimentally determined BCF values suggest that fenitrothion should moderately bioconcentrate in aquatic organisms. Based on an estimated rate constant, fenitrothion vapor should react with photochemically produced hydroxyl radicals with a half-life of 6.2 days. The removal of atmospheric vapor phase fenitrothion by direct photolysis may also be important, but the photolysis rates under sunlight irradiation is not known. Partial removal from the atmosphere by dry deposition of spray droplets or particulate fenitrothion is also possible. The most likely routes of exposure to fenitrothion is by inhalation and dermal absorption and applicators of the pesticide are most susceptible of exposure to fenitrothion.
Environmental Fate SUMITHION HAS BEEN USED OVER A PERIOD OF YEARS FOR SPRUCE BUDWORM CONTROL. SOME STUDIES HAVE SHOWN THAT, ALTHOUGH 70-85% OF THE INITIAL DOSE DEPOSITED ON TREES WAS LOST WITHIN 2 WK ABOUT 10% PERSISTS FOR @ LEAST 10 MO. IN VIEW OF THESE FINDINGS A SURVEY WAS MADE TO CHECK RESIDUE ACCUMULATIONS IN AREAS OF NB, CANADA WHICH HAD BEEN TREATED FOR UP TO 5 CONSECUTIVE YR. NO MEASURABLE AMT OF SUMITHION OR KNOWN BREAKDOWN PRODUCTS WERE FOUND IN ANY TESTED SOILS. AFTER TREATMENT OF COASTAL BERMUDAGRASS & CORN WITH ACCOTHION THE PARENT COMPD DISAPPEARED RAPIDLY. RESIDUES OF OXYGEN ANALOG WERE LOW & NONE WERE DETECTED 21 DAYS POSTTREATMENT. RESIDUES OF THE NITROCRESOL WERE HIGHEST FROM 1-7 DAYS POSTTREATMENT. IN THE FOREST ENVIRONMENT, ABOUT HALF THE INITIAL ACCOTHION DEPOSIT WAS LOST BY FOLIAGE WITHIN 4 DAYS & 70-85% WITHIN ABOUT 2 WK AFTER SPRAYING. LOSS FROM SPRUCE WAS AT A FASTER RATE THAN FROM FIR. THE REMAINDER WAS MORE STABLE THAN ANTICIPATED. ONLY TRACES OF THE OXON & NITROCRESOL WERE FOUND AT ANY STAGE. TERRESTRIAL FATE: Metabolism studies were carried out on fenitrothion, methyl parathion, and parathion in acid-sulfate and low-sulfate soils under flooded conditions. In the soils reduced by flooding, the major product obtained from fenitrothion was aminofenitrothion. Also detected in anaerobic acid sulfate soils was desethyl aminofenitrothion. No degradation of the insecticides occurred in aerobic soils. The presence of sulfate was necessary for the occurrence of dealkylation. Terrestrial Fate: The relative stability of formulated emulsifiable concentrates of fenitrothion, methyl parathion, and parathion in an anaerobic soil was studied. When fenitrothion was applied to 10-day preflooded soil, followed by continued incubation of soil samples under static flooded conditions, degradation of fenitrothion proceeded by hydrolysis. Fenitrothion was degraded by nitro group reduction to its amino analogue when it was directly equilibrated with the soil prereduced by flooding for different periods. Of the two pathways implicated in the degradation of the organophosphorus insecticides used in this study, hydrolysis can be both chemical and microbiological while nitro group reduction is essentially microbiological. In a Piedmont site, New Hope Forest near Research Triangle Park, North Carolina, an aqueous solution of 2% fenitrothion was sprayed uniformly to the soil and litter of a loblolly pine forest. Trees were not sprayed. Less than 2% of the fenitrothion applied was found in the soil at day 1, and by day 107, this had decreased to 0.3%. Soil sorption constants based on the organic carbon content of 15 pesticides were measured using 2 soils (clay loam and high clay) at 0.01, 0.1 and 1.0 ppm pesticide. The soil sorption coefficients ((ug pesticide/g soil)/(ug pesticide/g water)) for fenitrothion were 25.1 or - 10.7 in clay loam and 3.5 or - 0.2 in high clay soil. The soil sorption constants were 593 and 254 respectively, with a mean of 424. Significant correlations were found between organic carbon content and water solubility, octanol/water partition coefficient, retention time in reversed phase high pressure liquid chromatography and molecular wt. TERRESTRIAL FATE: Based on hydrolysis studies in water(3,9), abiotic hydrolysis of fenitrothion in soil at the pH normally available should not be important, although the importance of abiotic hydrolysis should increase as the pH of soil becomes more basic. The photolysis of fenitrothion on soil surface should be rapid(4-5), and the half-life as a result of irradiation with sunlight on two soil thin layer plates was determined to be 1 day . Fenitrothion is biodegraded in soil by cometabolism , and biodegradation is faster under anaerobic conditions than aerobic conditions . The biodegradation half-life of fenitrothion in a variety of soils range from 4.4-153.7 days in non-flooded and 3.9-10.9 days in the same flooded soils . Based on studies of evaporation loss from water surface(6), some loss of fenitrothion should occur due to volatilization. The half-life for volatilization loss from two soil thin layer plates was determined to be greater than 12 days . Based on the determined log Koc values in the range 2.40-3.19(7-8), fenitrothion should show medium to low mobility in soil(10). AQUATIC FATE: Hydrolysis of fenitrothion in water in the pH range 5-9 normally available in water should not be important, although the rate of hydrolysis should increase as the pH is increased(1-2). Photodecomposition of fenitrothion in water should be important(3-5). When irradiated with sunlight, the photolysis half-life in a river and sea water was determined to be about 1 day . The biodegradation of fenitrothion in water should be important and the relative importance of biodegradation compared to photolysis should increase as light transparency of water decreases and the availability of microorganisms increases(6-8). AQUATIC FATE: Volatilization of fenitrothion from water should be a slow process as indicated by a volatilization half-life of 64 days in still water . The volatilization was further retarded by dissolved fulvic acid in water . However, volatilization from surface slicks following spray application may be very fast as indicated by a half-life of 18 mins at 20 deg C . Based on log Koc value of 2.40-3.19, fenitrothion should moderately to strongly adsorb to suspended solids and sediments in water(2-3,SRC). This is confirmed by the presence of a large portion of fenitrothion in suspended solids and sediments following application to a stream . Experimentally determined log BCF of 2.35-2.66 in fish muscle tissues(5-7) suggests that fenitrothion should moderately bioconcentrate in aquatic organisms. ATMOSPHERIC FATE: Based on an estimation method, the rate constant for the reaction of fenitrothion with photochemically produced hydroxyl radicals has been estimated to be 6.21X10-11 cu cm/molecule-sec(1,SRC). If it is assumed that the average concentration of hydroxyl radicals in the atmosphere is 5X10 5/cu cm , the half-life for the reaction can be estimated to be 6.2 days. The direct photolysis of fenitrothion vapor in the atmosphere may also be important(3-4). The photolysis half-life of fenitrothion vapor due to irradiation with a Xenon lamp of up to 2 watts of UV(200-400 nm) output was 61 mins . Partial removal of atmospheric fenitrothion by dry deposition of spray droplets or particulate fenitrothion is also possible.
Drinking Water Impact DRINKING WATER: No fenitrothion was detected in Ottawa, Canada tap water at a detection limit of 1 ng/L . SURFACE WATER: Fenitrothion was detected in 1 of 58 Swedish stream water collected in June and 1 of 56 waters collected in July during 1985-1987 at a maximum concn of 0.1 ug/L . The concentration of fenitrothion in a Spanish Lake water ranged from less than 0.05-2.02 ug/L during 1983-1985 . During the summer of 1974, no fenitrothion was detected in water from the upper Great Lakes at a detection limit of 0.005 ug/L . RAIN/SNOW: The fenitrothion concn of rain water collected in New Brunswick, Canada in 1978 was less than 0.01-0.86 ug/L . EFFL: The concn of fenitrothion in unsprayed stream and pond water within 200 m from a conifer forest in New Brunswick, Canada which was sprayed with fenitrothion ranged 0.01-1.48 ug/L . However, the concn range in the same waters was less than 0.01-0.07 ug/L a year later suggesting the lack of persistence of fenitrothion in water . Following an accidental pesticide storehouse fire in Switzerland, the estimated concn of fenitrothion in Rhine River water at Village Neuf was 15-65 ug/L .

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