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EXTOXNET primary files maintained and archived at Oregon State
Revised June 1996
Trade and Other Names:
Pronamide is also known as propyzamide. Trade names include
Benzamide, Clanex, Kerb, Propyzamide, RH-315 Rapier, and Ronamid.
Pronamide is a Restricted Use Pesticide (RUP). It is EPA toxicity
class III - slightly toxic. Products containing pronamid bear the
Signal Word CAUTION. It may be purchased and used only by
certified applicators. The U.S. Environmental Protection Agency
(EPA) restricts the use of all pronamide formulations, except
those in water-soluble packets, due to their potential to cause
Chemical Class: Not
Pronamide is a selective herbicide used either before weeds
emerge (pre-emergence), and/or after weeds come up
(post-emergence). It controls a wide range of annual and
perennial grasses, as well as certain annual broadleaf weeds. It
is used primarily on lettuce and alfalfa crops, as well as on
blueberries, ornamentals, fruit trees, forage legumes, and on
fallow lands. Pronamide is usually incorporated into the soil by
cultivation, irrigation, or rain immediately following
application. It is available in wettable powder and granular
formulations. Information presented here pertains to the
technical product unless otherwise noted.
Formulation: It is
available in wettable powder and granular formulations.
- Acute toxicity: Pronamide is practically
nontoxic via ingestion. The reported oral LD50 values for
pronamide range from 5620 mg/kg in female rats to 8350
mg/kg in male rats, respectively, and 10,000 mg/kg in
dogs . Pronamide is slightly toxic by skin exposure,
with a dermal LD50 of greater than 3160 mg/kg . When
applied to the skin of rabbits, it produced slight local
irritation, but no systemic intoxication. The 4-hour
inhalation LC50 for pronamide is greater than 5.0 mg/L,
indicating slight toxicity by this route .
- Chronic toxicity: When dogs were fed a
diet containing pronamide for 3 months, decreases in
weight gain and food consumption, changes in blood
chemistry, and increased liver weights were observed at
doses of 15 mg/kg/day . In a study in rats over 3
months, similar effects were seen at doses of over 10
mg/kg/day , and changes in thyroid, adrenal, and
pituitary function were observed at 50 mg/kg/day . In
a 2-year feeding study in dogs, the addition of pronamide
to the diet at doses of 0.75, 2.5, or 7.5 mg/kg/day
caused no adverse health effects at any of the doses
- Reproductive effects: When pregnant
rabbits were given doses of 5, 20, or 80 mg/kg/day during
days 7 to 19 of gestation (18 rabbits per dose), no
effects on development or reproduction were observed at
or below the 20 mg/kg dose. At 80 mg/kg, there was an
increased incidence of liver lesions, one maternal death,
five abortions, and a decrease in maternal and offspring
weight gain . In a three-generation rat reproduction
study, no effects on reproduction were observed at 300
ppm (15 mg/kg/day), the highest dose tested . It is
unlikely that pronamide will have reproductive effects
except at doses high enough to cause maternal toxicity.
- Teratogenic effects: No teratogenic
effects were found when doses as high as 15 mg/kg/day
were administered to pregnant rabbits [58,121]. This
evidence suggests pronamide is not teratogenic.
- Mutagenic effects: Mutagenicity tests on
bacteria, mammalian cell cultures, and live animals have
been negative . It appears pronamide is not
- Carcinogenic effects: Pronamide caused
liver tumors in mice after 2 years at doses of 10
mg/kg/day and above . In rats, doses of 50 mg/kg/day
and above produced changes in ovary and liver structure
and function, as well as thyroid and testicular effects
. These data suggest that pronamide may have
carcinogenic activity at sufficient doses.
- Organ toxicity: Target organs identified
in animal studies include the liver, thyroid, and adrenal
and pituitary glands.
- Fate in humans and animals: Pronamide is
not readily absorbed into the bloodstream from the
gastrointestinal tracts of rats and cows. After oral
doses of Kerb to rats, 54% and 0.6% of the unmetabolized
Kerb was recovered in feces and urine, respectively.
Unmetabolized Kerb did not appear in the urine of a cow
treated orally with Kerb . Traces of pronamide were
found in the milk of cows given feed that contained 5 ppm
doses of a pronamide formulation . Pronamide has a low
potential for bioaccumulation in animal tissues.
- Effects on birds: Pronamide is
practically nontoxic to birds. The oral LD50 for
pronamide in Japanese quail is 8700 mg/kg, and greater
than 14,000 mg/kg in mallard ducks [58,122]. The 8-day
dietary LC50 for Kerb Technical Herbicide in bobwhite
quail and mallard ducks is greater than 10,000 ppm .
- Effects on aquatic organisms: Pronamide
is practically nontoxic to warmwater fish and slightly
toxic to coldwater fish. The 96-hour LC50 for pronamide
is 100 mg/L in bluegill sunfish, 72 mg/L in rainbow
trout, 350 mg/L in goldfish, 204 mg/L in harlequin fish,
and 150 mg/L in guppies [8,58]. The 48-hour LC50 for
Daphnia magna, a small freshwater crustacean, is greater
than 5.6 mg/L . Pronamide may be moderately toxic to
aquatic invertebrates .
- Effects on other organisms: Pronamide is
nontoxic to honey bees .
- Breakdown in soil and groundwater:
Pronamide is moderately persistent in most soils, with a
reported average field half-life of 60 days . It is
readily bound, or adsorbed, to most soils .
Increasing soil temperature, and to a lesser extent, soil
moisture and pH increase the rate of pronamide
degradation in soil . In most soil types, there is
very little movement, or leaching, of pronamide into
groundwater as it is nearly insoluble in water .
Leaching of pronamide residues in soil is most likely in
soils with low organic matter content, such as loamy
sands or silt loams . Pronamide is inactivated by soil
organic matter and will not be effective on muck, peat,
or other very high-organic content soils . Depending
upon soil type and climatic conditions, persistence of
pronamide may be higher. Accumulation of the herbicide
from repeated annual applications to the same soil does
not appear problematic. Chemical degradation may be the
main route of disappearance from the soil.
Photodecomposition at the soil surface can also occur
. A moderate amount of pronamide breakdown is
carried out by soil microorganisms. The herbicide is not
active against common soil microorganisms. Volatilization
loss may be high under hot, dry conditions .
- Breakdown in water: In water bodies,
pronamide is stable at a neutral pH. It is slowly
degraded chemically, by light, and by aquatic and
microorganisms. Loss from volatilization is not
significant [58,8]. Pronamide is thought to be stable
because less than 10% was hydrolyzed, or broken down in
water, over a 4-week period . It is stable to
hydrolysis between pH 4.7 and 8.8 .
- Breakdown in vegetation: Pronamide is
readily translocated from the roots to other plant parts.
Absorption of pronamide through plant leaves is minimal.
Pronamide is metabolized slowly by both tolerant and
sensitive plants .
- Appearance: Pronamide is a white or
off-white crystalline solid with no odor .
- Chemical Name:
3,5-dichloro-N-(1,1-dimethylpropynyl) benzamide 
- CAS Number: 23950-58-5
- Molecular Weight: 256.13
- Water Solubility: 15 mg/L @ 25 C 
- Solubility in Other Solvents: (@ 25 C):
v.s. in simethyl sulfoxide and methanol; s. in benzene,
xylene, and carbon tetrachloride 
- Melting Point: 155-156 C 
- Vapor Pressure: 11.3 mPa @ 25 C 
- Partition Coefficient: 3.1959 
- Adsorption Coefficient: 800 
- ADI: Not Available
- MCL: Not Available
- RfD: 0.075 mg/kg/day 
- PEL: Not Available
- HA: 0.05 mg/L (lifetime) 
- TLV: Not Available
Rohm and Haas Co.
100 Independence Mall West
Philadelphia, PA 19106
- Phone: 215-592-3000
- Emergency: Not Available
References for the information in this PIP can be found in
Reference List Number 10
information in this profile does not in any way replace or
supersede the information on the pesticide product labeling or
other regulatory requirements. Please refer to the pesticide