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The information in this profile may be out-of-date. It was last revised in 1996. EXTOXNET no longer updates this information, but it may be useful as a reference or resource.

Please visit the National Pesticide Information Center (NPIC) to find updated pesticide fact sheets. If you don't find a fact sheet related to your question, feel free to call 1-800-858-7378. NPIC is open five days a week from 8:00am to 12:00pm Pacific Time.

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E X T O X N E T

Extension Toxicology Network

Pesticide Information Profiles

A Pesticide Information Project of Cooperative Extension Offices of Cornell University, Oregon State University, the University of Idaho, and the University of California at Davis and the Institute for Environmental Toxicology, Michigan State University. Major support and funding was provided by the USDA/Extension Service/National Agricultural Pesticide Impact Assessment Program.

EXTOXNET primary files maintained and archived at Oregon State University

Revised June 1996

Pronamide

Trade and Other Names: Pronamide is also known as propyzamide. Trade names include Benzamide, Clanex, Kerb, Propyzamide, RH-315 Rapier, and Ronamid.

Regulatory Status: 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 tumor growth.

Chemical Class: Not Available

Introduction: 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.

Toxicological Effects:

• 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 [8]. Pronamide is slightly toxic by skin exposure, with a dermal LD50 of greater than 3160 mg/kg [1]. 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 [58].
• 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 [58]. In a study in rats over 3 months, similar effects were seen at doses of over 10 mg/kg/day [58], and changes in thyroid, adrenal, and pituitary function were observed at 50 mg/kg/day [58]. 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 tested [5].
• 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 [58]. In a three-generation rat reproduction study, no effects on reproduction were observed at 300 ppm (15 mg/kg/day), the highest dose tested [121]. 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 [121]. It appears pronamide is not mutagenic.
• Carcinogenic effects: Pronamide caused liver tumors in mice after 2 years at doses of 10 mg/kg/day and above [58]. 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 [58]. 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 [121]. Traces of pronamide were found in the milk of cows given feed that contained 5 ppm doses of a pronamide formulation [8]. Pronamide has a low potential for bioaccumulation in animal tissues.

Ecological Effects:

• 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 [123].
• 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 [58]. Pronamide may be moderately toxic to aquatic invertebrates [122].
• Effects on other organisms: Pronamide is nontoxic to honey bees [8].

Environmental Fate:

• Breakdown in soil and groundwater: Pronamide is moderately persistent in most soils, with a reported average field half-life of 60 days [11]. It is readily bound, or adsorbed, to most soils [11]. Increasing soil temperature, and to a lesser extent, soil moisture and pH increase the rate of pronamide degradation in soil [121]. In most soil types, there is very little movement, or leaching, of pronamide into groundwater as it is nearly insoluble in water [58]. Leaching of pronamide residues in soil is most likely in soils with low organic matter content, such as loamy sands or silt loams [8]. Pronamide is inactivated by soil organic matter and will not be effective on muck, peat, or other very high-organic content soils [124]. 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 [120]. 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 [6].
• 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 [8]. It is stable to hydrolysis between pH 4.7 and 8.8 [122].
• 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 [58].

Physical Properties:

• Appearance: Pronamide is a white or off-white crystalline solid with no odor [1].
• Chemical Name: 3,5-dichloro-N-(1,1-dimethylpropynyl) benzamide [1]
• CAS Number: 23950-58-5
• Molecular Weight: 256.13
• Water Solubility: 15 mg/L @ 25 C [1]
• Solubility in Other Solvents: (@ 25 C): v.s. in simethyl sulfoxide and methanol; s. in benzene, xylene, and carbon tetrachloride [1]
• Melting Point: 155-156 C [1]
• Vapor Pressure: 11.3 mPa @ 25 C [1]
• Partition Coefficient: 3.1959 [58]
• Adsorption Coefficient: 800 [11]

Exposure Guidelines:

• ADI: Not Available
• MCL: Not Available
• RfD: 0.075 mg/kg/day [13]
• PEL: Not Available
• HA: 0.05 mg/L (lifetime) [121]
• TLV: Not Available

Basic Manufacturer:

Rohm and Haas Co.
Agricultural Chemicals
100 Independence Mall West
Philadelphia, PA 19106

• Phone: 215-592-3000
• Emergency: Not Available
  

References:

References for the information in this PIP can be found in Reference List Number 10

DISCLAIMER: The 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 product labeling.