| Chemical Abstract Number (CAS #) |
114261
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| Synonyms | Propoxur |
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Phenol, 2-(1-methylethoxy)-, methylcarbamate | Baygon |
| Analytical Methods |
EPA Method 531.1 |
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EPA Method 632 |
| Molecular Formula | C11H15NO3 |
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| Use | Insecticide; Molluscicide
BAYGON: EFFECTIVE AGAINST COCKROACHES, FLIES, MOSQUITOES . ALSO
FOR CONTROL OF WOOLY APHIDS, BUGS, & LEAF HOPPERS.
VET: EFFECTIVE AGAINST FLEAS & TICKS ON CATTLE, HORSE, CATS, & DOGS &
SARCOPTIC MANGE OF CATTLE PROTECTION AGAINST TICKS APPEARS TO
WANE AFTER 1 WK.
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| Consumption Patterns | OVER 50% AS AN INSECTICIDE FOR MOSQUITOES IN OUTDOOR AREAS;
UNDER 50% IN ALL OTHER APPLICATIONS AS AN INSECTICIDE (FOR FLIES ON
AGRICULTURAL PREMISES, FOR FLEAS & TICKS ON PETS, ON LAWNS & TURF, FOR
ANTS ON FLOWERING PLANTS, & IN DWELLINGS & PUBLIC FACILITIES) (1974)
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| Apparent Color | MINUTE CRYSTALS ; WHITE TO TAN CRYSTALLINE SOLID
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| Melting Point | 91.5 DEG C
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| Molecular Weight | 209.24
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| Environmental Impact | Propoxur, known chemically by o-isopropoxyphenyl N-methylcarbamate or
2-(1-methylethoxy)phenol methylcarbamate, is an insecticide and molluscide characterized by a
fast knockdown and long residual effect. It will be released to the environment when it is applied
as a spray or dust or used in bait to control household pests as well as lawn and garden insects. If
released on soil it would not adsorb strongly to the soil. In one field study, 75% of propoxur
disappeared from sandy soil in 100 days but levels were virtually unchanged in muck and silt loam
soils. However, the rate of biodegradation is markedly increased when the soil has been
previously exposed to methylcarbamate pesticides. Additionally, abiotic hydrolysis should be
important in alkaline soils. Propoxur is readily degradable in water (half-life from 1 day to 1
week). In surface layers of water it will photolyze relatively rapidly, especially when humic
material is present (half-life 13 - 88 hr). Degradability increases with temperature, high microbial
populations, the presence of mud and biota, and increasing pH. Volatilization, adsorption to
sediment and bioconcentration in fish should not be important fate processes. Propoxur would be
released into the atmosphere primarily as a dust or aerosol and be subject to gravitational settling.
The vapor phase chemical should react with photochemically produced hydroxyl radicals and have
a half-life of about 4 hr. People will primarily be exposed to propoxur where it is used to control
insects, both indoors and outdoors.
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| Environmental Fate | TERRESTRIAL FATE: 25% OF APPLIED BAYGON WAS LOST FROM SAND IN
100 DAYS, BUT PRACTICALLY NO DECLINE IN SILT-LOAM SOIL DURING 6 MO
PERIOD
TERRESTRIAL FATE: Propoxur is not strongly adsorbed to soil and is highly persistent in
neutral and acid soils. While 75% of the insecticide degraded in 100 days in a sandy soil, in a
muck and silt loam soil, virtually no loss occurred during the same period and the propoxur
persisted in these soils beyond six months . Other studies show that when the resident
microorganisms are acclimated to methylcarbamate pesticides, biodegradation is markedly
enhanced and in one study propoxur had largely disappeared in one day. Since propoxur
hydrolyzes in basic media (half-life 16 days at pH 8), this process would be expected to contribute
to propoxur loss in alkaline soil.
AQUATIC FATE: Propoxur was found to be readily degradable in water. It was degraded in a
model aquatic ecosystem containing the standard food chain members, algae, daphnia, mosquito
larvae, snails, and fish , and highly biodegradable in components of a model terrestrial-aquatic
ecosystem containing the same food chain members in the aqueous compartment . After 1
month, observed concentrations of propoxur were: 0.2 ppb in water, 15 ppb in snails, 50 ppb in
fish, and traces in mosquito larvae . It was the second most labile of 9 pesticides dosed in
lighted, agitated river water. The half-lives of the 9 pesticides ranged from 0.42 for carbaryl to
11.91 for lindane; the specific half-life of propoxur was not reported . The degradation rates
were temperature dependent and altered by the presence of mud, aquatic plants and
invertebrates . Propoxur has also been shown to photolyze in waters (half-life 88 hr), and this
photolysis is enhanced by the presence of humic material (half-life 13 - 41 hr) . Therefore
photolysis may be a major factor affecting propoxur disappearance in surface water as exemplified
by a 1 week half-life in water from the Little Miami River .
ATMOSPHERIC FATE: Propoxur would be primarily released to the atmosphere in the form of
a dust or aerosol during its use as an insecticide and would be subject to gravitational settling.
However propoxur also has been shown to volatilize from baits. Vapor phase propoxur resulting
from this volatilization is estimated to have a half-life of 4.3 hr with an average ambient hydroxyl
radical concentration of 5X10 5 radicals/cc . However indoors, the half-life should be much
longer because the concentration of hydroxyl radicals is lower.
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| Drinking Water Impact | SURFACE WATER: After propoxur was aerially applied around Winnipeg, Manitoba
for mosquito control, half of the samples collected from surface water in and around the city was
positive for the insecticide . The highest level was 36.4 ppb, in a creek 12 hr after spraying.
Four other samples were in excess of 17.5 ppb.
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