| Chemical Abstract Number (CAS #) |
709988
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| Synonyms | Propanil |
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Propanamide, N-(3,4-dichlorophenyl)- | Apronox | Chem-Rice | Prostar | Prop-Job |
| Analytical Method |
EPA Method 632.1 |
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| Molecular Formula | C9H9Cl2NO |
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| Use | HERBICIDE (CONTACT TYPE); POSTEMERGENCE WITH NO RESIDUAL EFFECT
AGAINST NUMEROUS GRASSES AND BROADLEAVED WEEDS IN RICE.
IN NEMATOCIDE FORMULATIONS
It is used as a herbicide in rice and potato fields
Control of many grasses and broad-leaved weeds in potatoes and wheat.
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| Apparent Color | WHITE CRYSTALLINE SOLID ; Colorless solid ; Light brown solid ; Dark oily liquid ;
Gray-black solid
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| Melting Point | 85-89 deg C Pure propanil
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| Molecular Weight | 218.09
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| Density | 1.054 AT 25 DEG C/15.6 DEG C
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| Environmental Impact | Propanil is released directly to the environment through its use and application as an
agricultural herbicide. If released to soil, microbial degradation is expected to be the major
removal process. Propanil will biodegrade to 3,4-dichloroaniline which metabolizes to
3,3',4,4'-tetrachloroazobenzene. Neither leaching nor adsorption (Kocs of 149 and 220) should be
important for propanil in relation to biodegradation; its metabolites, however, may chemically
bind to soil. The half-life in soil typically ranges from 1 to 3 days; the US Dept of Agriculture's
Pesticide Properties Database lists a soil half-life of 1 day. Photolysis may be important on soil
surfaces and in near-surface waters based on a half-life of 4 hrs when irradiated with 300 nm
sunlight lamps in an acetonitrile and water solvent system. If released to water, propanil will also
degrade through microbial degradation (half-lives of 17 and 154 hrs in amended and unamended
environmental waters). Hydrolysis, volatilization and bioconcentration in fish will not be
important. If released to the atmosphere, propanil will exist in the vapor and particulate phases;
vapor phase propanil degrades rapidly by reaction with photochemically produced hydroxyl
radicals (estimated half-life of 24 hours). Physical removal from the atmosphere occurs through
wet and dry deposition. Photolysis will be important in air. Worker exposure to propanil occurs
through dermal contact and inhalation of dust.
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| Environmental Fate | TERRESTRIAL FATE: AT 1 TO 4 KG/HA ITS PERSISTENCE IN SOILS IS
BRIEF.
When used in flooded rice culture, propanil applied as a foliar spray dissipated within 24 hr after
flooding of the rice. 3,4-Dichloroaniline concentration in the flood waters corresponded to the
decrease in propanil.
Red Rice (Oryza sativa L.) seedlings were the source of an aryl amidase. Studiesshowed that this
enzyme was able to hydrolyze propanil, as well as some analogs. Although active between pH 7.4
to 8.7, the optimum was 8.2. Calculations showed the Km = 2.5X10-5 and that the activity was in
the order propanil >3'Cl > propionanilide > 4'-Cl greater than or equal to 3'5'-dichloro > 2'-Cl.
Propanil was hydrolyzed by Corynebacterium pseudodiphtheriticum NCIB 10803. A strain of
Fusarium solani used propanil as a sole source of carbon and energy for growths and the primary
product of degradation was 3,4-DCA. This acylamidase did not catalyze hydrolysis of dicryl,
karsil, fenuron, monuron or IPC. It seems to be different than acylamidases isolated from rice, rat
liver and chick kidney. Studies with rice have shown that diazinon and carbaryl, absorbed from
soil and translocated could inhibit propanil hydrolysis.
In studies with propanil and 3,4-dichloroaniline, it was observed that in different soils there were
differences in the amount of tetrachloroazobenzene formed. Formation of tetrachloroazobenzene
did not correlate with soil pH. With five soils of pH 4.5 to 5.5, tetrachloroazobenzene was formed
from both compounds; pH 5.8 and 7.4 tetrachloroazobenzene formed from 3,4-dichloroaniline
only; pH 3.4 and 6.4, no tetrachloroazobenzene from either substrate. In soil, the conversion of
3,4-dichloroaniline to tetrachloroazobenzene increased with an increase in peroxidase activity.
Terrestrial fate: Duration of activity in soil in warm, moist conditions in approximately 1-3
days.
TERRESTRIAL FATE: Volatilization and hydrolysis will not be important in soils. Kocs of
149 and 220 suggest weak adsorption may take place. Field tests indicate that
leaching to groundwater is not an important transport process in soil(6). Photolysis may be
important on terrestrial surfaces based on a half-life of 4 hrs when irradiated with 300 nm sunlight
lamps in an acetonitrile and water solvent system(7,SRC). Microbial degradation to
3,4-dichloroaniline and 3,3',4,4'-tetrachloroazobenzene should be the primary fate process of
propanil in soil. Propanil's half-life in a soil grab sample at 28 deg C was determined to be
0.1-2.3 days at initial concns of 10-250 ppm, respectively . According to the US Dept of
Agriculture's Pesticide Properties Database, the soil half-life of propanil is 1 day . Propanil will
persist 1-3 days in or on soil under warm, moist conditions typical of application . Field tests
indicate that propanil does not appear to be a threat to groundwater from rice paddy
application(8).
Volatilization (estimated Henry's Law constant of 4.5X10-9 atm-cu m/mole at 25 deg C(1,SRC)),
hydrolysis and bioconcentration in fish (measured BCF of 1.6 ) will not be important in
aquatic environments. Kocs of 149 and 220 suggest weak adsorption to sediment and
suspended solids. Photolysis may be important in near-surface water based on a half-life of
4 hrs when irradiated with 300 nm sunlight lamps in an acetonitrile and water solvent
system(6,SRC). Microbial degradation to 3,4-dichloroaniline should be the primary removal
process in water; average aerobic biodegradation half-lives of 17 and 154 hrs were
determined for propanil (1 ppm initial concn) in amended and unamended environmental
waters(7).
Based upon a reported vapor pressure of 4X10-5 mm Hg at 20-25 deg C , propanil can exist in
both the vapor and particulate phases in the ambient atmosphere(2,SRC). It will degrade rapidly
in the vapor phase by reaction with photochemically produced hydroxyl radicals with an estimated
half-life of about 24 hrs(3,SRC). Physical removal from air by wet deposition (dissolution in
clouds, rainfall, etc) and dry deposition (particulate settling, etc) will also occur. Photolysis
may be important in air based on a half-life of 4 hrs when irradiated with 300 nm sunlight lamps in
an acetonitrile and water solvent system(7,SRC).
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| Drinking Water Impact | GROUNDWATER: On July 27, 1988, during heavy use, propanil was detected in 1 of
12 rice paddy groundwater wells (20 m deep maximum) at a concn of 0.04 ug/l in the provinces
of Vercelli and Novara, Italy; in December, no propanil was detected in this well . In the same
study, propanil was not detected during June, July and December in 12 groundwater wells at least
70 m deep .
SURFACE WATER: On July 27,1988, during heavy use, propanil was detected in 5 of 12 river
samples at a concn range of 0.1-0.228 ug/l in an area of rice cultivation in the provinces of
Vercelli and Novara, Italy. In December, no propanil was detected in these surface waters .
EFFL: Draining ditches of rice paddies were remarkably polluted with propanil (no quantification
given) during heavy propanil use in June and July of 1988; no propanil was detected in the ditches
in December of 1988 .
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