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Propanil

Publication Date: 9/93

TRADE OR OTHER NAMES

Some trade names include Bay 30130, Cekupropanil, Prop-Job, Chem-Rice, DPA, Strel, S 10145, Vertac, Dropaven, Propanilo, Supernox, Erban, FW-734, Herbax, Propanex, Riselect, Stampede, Stam-F-34, Stam M-4, Surcopur, Surpur and Wham EZ.

REGULATORY STATUS

Products containing propanil must bear the signal word "Warning" (4).

INTRODUCTION

Propanil is an acetanilide postemergence herbicide with no residual effect. It is used against numerous grasses and broad-leaved weeds in rice (1, 4). It is available as emulsifiable concentrates, liquid and dry flowable, low volume, and ultra low volume (ULV) formulations (4).

TOXICOLOGICAL EFFECTS

ACUTE TOXICITY

Propanil is toxic by ingestion and slightly toxic by dermal absorption (7). It is readily absorbed into the body through ingestion, inhalation or dermal exposure. It may cause central nervous system (CNS) depression. CNS effects include headache, dizziness, drowsiness, and confusion. Other symptoms include dark urine and blood (from the formation of methemoglobin), acetanilide in the urine, chills, cyanosis (also from methemoglobin), and jaundice. Death from respiratory failure may occur. Eating propanil may result in a burning sensation and irritation of the mouth, throat and gut, accompanied by gagging, coughing, nausea or vomiting. Ingestion may also cause stupor, dizziness, fever, drowsiness and blue lips and fingernails (2). Inhalation of vapors can irritate the nose and throat and cause drowsiness, slurred speech, headache, nausea, dizziness, stupor and unconsciousness (2). Cardiac patients are especially susceptible to the toxic effects of the acetanilide group of herbicides (11).

Propanil has caused chloracne and hyperkeratinosis (thickening and roughening of the skin) in unprotected factory workers. Sensitization, irritation and dermatitis are possible (3, 11). Repeated contact can cause irritation with drying, splitting or cracking of the skin (2).

Propanil is very irritating to the eyes (2). It will cause irritation, conjunctivitis, photophobia (bright light is painful) and even severe lesions if splashed in the eye (12).

A person who attempted to commit suicide by drinking a 35% solution of propanil became disoriented, vomited repeatedly and had a sore, swollen stomach. Their conjunctiva (the tender membrane under the eyelids) became yellowed (jaundice) (JPN. J. Accident. Med. Assoc. 28(1):37-41. 1980).

The amount of a chemical that is lethal to one-half (50%) of experimental animals fed the material is referred to as its acute oral lethal dose fifty, or LD50. The oral LD50 for propanil in rats is 367 to 2500 mg/kg, 360 mg/kg in mice, and 1,217 mg/kg in dogs. The dermal LD50 in rabbits is greater than 5,000 mg/kg (3, 4). The lethal concentration fifty, or LC50, is that concentration of a chemical in air or water that kills half of the experimental animals exposed to it for a set time period. The inhalation LC50 for propanil in rats is greater than 1120 mg/m3 (7).

CHRONIC TOXICITY

In a 2-year study, a dietary level of 1600 ppm caused a decrease in growth and a relative increase in the weight of the spleen and liver in female rats and of the testes in males. The NOEL for this study was 400 ppm (19 mg/kg/day). In a 2-year study with dogs, a dietary level of 4,000 ppm depressed growth in spite of increased food intake. The only other change detected was a slight increase in the relative weight of the heart. The NOEL for this study was 600 ppm (12.6 mg/kg/day) (3).

Repeated overexposure to propanil can cause liver damage and blood changes (2).

Reproductive Effects

In a 3-generation study, male and female rats were fed propanil for 11 weeks before the parent generation was mated. Dietary levels as high as 1,000 ppm had no effect on fertility, gestation, viability or lactation (3).

Teratogenic Effects

No evidence of teratogenic effects was observed in studies with rats and mice (9).

Mutagenic Effects

In vitro tests (with isolated cells in culture and bacterial cells) show propanil and some of its breakdown products to be mutagens (11). The Ames test, tests on mammalian cell cultures, and a cytogenetic assay on mice failed to show mutagenic effects (9).

Carcinogenic Effects

No evidence of carcinogenicity was observed in long-term studies of mice and rats (9).

Organ Toxicity

Several organs are affected by propanil and its metabolites. Liver and kidney damage are likely after long-term exposure. Dermatitis (rashes) and sensitization (allergies) are possible. High doses may produce anemia because of the formation of methemoglobin.

In a 2-year feeding study with rats, high doses of propanil caused a decrease in growth and a relative increase in the weight of the spleen and liver in females and of the testes in males. In a 2-year study with dogs high doses caused a slight increase in the relative weight of the heart (3). Repeated overexposure to propanil can cause liver damage and blood changes (2).

Fate in Humans and Animals

When propanil was fed to a cow for 4 days, 1.4% of the total dose was recovered in the feces, but none was detected in the urine or milk (3). This suggests that propanil is absorbed into the bloodstream through the gastrointestinal tract and, that once in the bloodstream, propanil is metabolized by the body. Propanil is lipid (fat) soluble. The liver breaks down propanil to aniline derivatives. These metabolites are responsible for the methemoglobin formation (11). Excretion is through the urine.

ECOLOGICAL EFFECTS

Effects on Birds

Propanil is slightly to moderately toxic birds. The oral LD50 for technical propanil (88% active ingredient) in bobwhite quail is 196 mg/kg. The 8-day dietary LC50 for technical propanil in bobwhite quail is 2,861 ppm, and in mallard ducks is 5,627 ppm (9).

Effects on Aquatic Organisms

Propanil is toxic to aquatic invertebrates such as crayfish, worms and snails, and to fish (2, 5). The 96-hour LC50 for technical propanil (88% active ingredient) in bluegill sunfish is 3.7 to 5.36 ppm, and 2.3 ppm in rainbow trout (4, 9). The 48-hour LC50 for technical propanil in Daphnia magna, a small freshwater crustacean, is 0.14 mg/l (9). All contamination of streams and lakes with propanil should be avoided.

Effects on Other Animals (Nontarget species)

Propanil appears to have very low toxicity to mammals. Only information on lab animals such as rabbits, rats and dogs was found.

ENVIRONMENTAL FATE

Breakdown of Chemical in Soil and Groundwater

Although propanil is soluble in water and it absorbs only weakly to soil particles (Koc = 188 g/ml), its rapid breakdown in soil practically eliminates the potential for groundwater contamination (6). Propanil is rapidly broken down in the soil by micro-organisms (Menzie. Metab. Pesticides 1969). Its half-life in the soil is from 1-3 days under warm, moist conditions (2, 6). Fungi use it as a carbon source. Bacteria produce highly colored by-products such as tetrachloroazobenzene.

Breakdown of Chemical in Water

Propanil will break down in water. Streams and lakes should not be contaminated with propanil.

Breakdown of Chemical in Vegetation

Within a plant, propanil is moved from the leaves to the growing shoots, then back to other leaves. It is a contact herbicide. Crop plants such as rice completely metabolize propanil (2). Carry over of herbicidal activity to subsequent crops is not likely. The use of propanil with other pesticides such as the organophosphorous compounds can kill even desirable plants because these plants can no longer metabolize the propanil (10).

PHYSICAL PROPERTIES AND GUIDELINES

Propanil is a white to brown crystalline solid with a mild offensive odor (7). The technical product is brownish, crystalline solid or a dark, oily liquid, with a melting point of 88 to 91 degrees C. It is stable in emulsion concentrates, but is hydrolyzed in extremely acid or basic conditions (3, 4). Propanil is stable under normal temperatures and pressures, but it may pose a slight fire hazard if exposed to heat or flame. It poses a fire and explosion hazard in the presence of strong oxidizers. Thermal decomposition of propanil will release toxic oxides of nitrogen and carbon and toxic and corrosive fumes of chlorides (7).

Propanil is incompatible with a number of pesticides. Combination of propanil with carbamates or organophosphates will kill most plants. At least two weeks should pass between the application of either of these two classes of pesticides and the application of propanil (8). The toxic effects of propanil to mammals and fish are also increased by these combinations (11). Propanil should not be applied with liquid fertilizers.

Occupational Exposure Limits:

No occupational exposure limits have been established for propanil by OSHA, NIOSH or ACGIH. Rohm and Haas Company recommends a TWA of 5 mg/m3 and an STEL of 10 mg/m3 (7).

Physical Properties:

CAS #: 709-98-8
Specific gravity: 1.25 at 25 degrees C (2)
Solubility in water: 225 ppm at 25 degrees C
  • Solubility in other solvents: Propanil is soluble in benzene and highly soluble in methanol (14).
    At 25 degrees C, it is more than 25% soluble in hexalene glycol, isopropyl alcohol, methyl ethyl ketone, toluene and xylene (2).
    Melting point: 91 - 93 degrees C (196 - 199 degrees F) (13).
    Flash point: 100 degrees C (4)
    Vapor pressure: negligible (7); 9 x 10 to the minus 5 mm Hg at 60 degrees C (5); 2.6 x 10 to the minus 7 mbar (4)
    Koc: 188 g/ml (6)
    Density: 1.054 at 25 degrees C/15.6 degrees C (Spencer. guide to chem. in crop prot. 1982)
    Chemical class/use: amide herbicide; aniline derivative

    BASIC MANUFACTURER

    Rohm and Haas Co.
    Agricultural Chemicals
    Independence Mall West
    Philadelphia, PA 19105

    Review by Basic Manufacturer:

    Comments solicited: October, 1992
    Comments received:

    REFERENCES

    1. Meister, R.T. (ed.) 1987. Farm Chemicals Handbook. Willoughby, OH: Meister Publishing Co.
    2. WSSA Herbicide Handbook Committee. 1989. Herbicide Handbook of the Weed Science Society of America. 6th Ed. WSSA, Champaign, IL.
    3. Hayes, W.J. and E.R. Laws (ed.). 1990. Handbook of pesticide toxicology, Vol. 3, Classes of Pesticides. Academic Press, Inc., NY.
    4. Meister, R.T. (ed.). 1992. Farm Chemicals Handbook '92. Meister Publishing Company, Willoughby, OH.
    5. Worthing, C.R. (ed.). 1987. The pesticide manual: A world compendium. 8th Ed. The British Crop Protection Council. Croydon, England.
    6. U.S. Department of Agriculture, Soil Conservation Service. 1990 (Nov.). SCS/ARS/CES Pesticide Properties Database: Version 2.0 (Summary). USDA - Soil Conservation Service, Syracuse, NY.
    7. Occupational Health Services, Inc. 1991 (Feb. 21). MSDS for Propanil. OHS Inc., Secaucus, NJ.
    8. Hartley, D. and H. Kidd, (eds.) 1983. The agrochemicals handbook. Nottingham, England: Royal Society of Chemistry.
    9. Rohm and Haas. 1991 (Nov. 7). Product: STAM Tech 98% DCA Herbicide (Key: 904399-2). Rohm and Haas Company, Philadelphia, PA.
    10. Casarett, L.J. 1980. Casarett & Doull's Toxicology: the basic science of poisons. 2nd Ed. New York: Macmillan.
    11. Hallenbeck, W.H. & K.M. Cunningham-Burns. 1985. Pesticides and human health. New York: Springer-Verlag.
    12. Lef'evre, M.J. 1980. First aid manual for chemical accidents. New York: Van Nostrand Reinhold.
    13. Windholz, M. (ed.) 1976. The Merck Index: an encyclopedia of chemicals and drugs. 9th Ed. Rahway, NJ: Merck.
    14. Sunshine, Irving. 1969. Handbook of analytical toxicology. Cleveland, OH: Chemical Rubber Co.