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Propetamphos

Publication Date: 9/93

TRADE OR OTHER NAMES

Trade names for products containing propetamphos include Blotic, Safrotin and Seraphos. Commercial products include aerosols, emulsified concentrates, liquids, and powders.

INTRODUCTION

Propetamphos is an organophosphate, household and public health insecticide designed to control cockroaches, flies, ants, ticks, moths, fleas and mosquitoes on contact. Propetamphos works internally in the insect where it promotes stomach activity. Its veterinary use is for skin parasites such as cattle ticks and skin lice.

Propetamphos is a General Use Pesticide. Safrotin, an emulsified concentrate (50% propetamphos), is a Restricted Use Pesticide (RUP). Restricted Use Pesticides may be purchased and applied only by a certified applicator.

TOXICOLOGICAL EFFECTS

ACUTE TOXICITY

Propetamphos is a moderately toxic compound that carries the signal word WARNING on its label. Typical of other organophosphates, the compound inhibits the family of enzymes called cholinesterases that are found throughout living organisms. A common cholinesterase enzyme, acetylcholinesterase, is found at the ends of nerve junctions. Others are found in the brain and in the blood stream. See the TIB "Cholinesterase Inhibition" for more information.

The oral LD50 for propetamphos in male rats ranges from 75 to 119 mg/kg. The acute dermal LD50 for the compound is 2,300 mg/kg. The acute dermal LD50 for rats is 825 mg/kg (5). The LD50 of propetamphos indicates that the compound is moderately toxic (ranging from 50 to 500 mg/kg), but the trade products are labeled as slightly toxic because they contain relatively small amounts of the compound.

CHRONIC TOXICITY

Rats fed propetamphos for 13 weeks exhibited no effects below the very low dose of 0.2 mg/kg/day. Over a 77 week study the rats exhibited no adverse effects at or below the very low dose of 0.05 mg/kg/day (9). In two year feeding studies with rats, there were no effects noted at or below a dose of 6 mg/kg in their diets. Dogs fed the compound for six months showed no adverse effects at the dose of 0.05 mg/kg/day.

Reproductive Effects

A three-generation rat study, for which only an interim report is available, produced no significant effects in litters at the low dose of 1 mg/kg/day (9).

Teratogenic Effects

A teratology study in rabbits was negative (9). No additional information was available on the potential of the compound to produce birth defects.

Mutagenic Effects

In studies with the fruit fly Drosophila and with mouse tissue, propetamphos did not cause any chromosome damage. However, in mouse tissue, the high dosage of the compound caused some mild chromosome damage. The insecticide is a weak mutagen, but only at high concentrations (10).

Carcinogenic Effects

According to the Environmental Protection Agency, carcinogenicity tests on rats and mice have been negative. Both studies were conducted over relatively long periods of time (one with rats for two years and one with mice for the lifetime of the animals). The top dose administered to the rats was 6 mg/kg and the top dose administered to the mice was 21 mg/kg (15).

Organ Toxicity

A limited amount of information indicates that low doses of propetamphos administered to mice over their lifetime can cause changes in the kidneys in males and females (15). Rats fed low doses of the compound for two years experienced hair loss.

Fate in Humans and Animals

Dogs sprayed with a very low concentration solution (0.05% active ingredient) of propetamphos showed a moderate reduction in the cholinesterase activity in the blood (about 20% reduction) after twenty-four hours. After forty-eight hours, cholinesterase activity was reduced by the greatest extent (nearly 30%). These levels are near or exceed the World Health Organization level of 20% inhibition for enzyme activity reductions at which no further exposure is recommended (11). The dogs suffered no clinical signs of toxicity (7). Normal concentrations of the compound in trade products range from 1 to 2 percent.

The house fly, cockroach and mouse liver all demonstrated the ability to breakdown the compound in the presence of water (hydrolysis) within the organism (8).

ECOLOGICAL EFFECTS

Tests on mallard ducks and on bobwhite quail indicate that the compound is moderately toxic to wild birds. The acute oral LD50 for propetamphos in the mallard ranges from 45 mg/kg to nearly 200 mg/kg. The dietary LC50 for the compound in the mallard ranges from about 700 ppm to greater than 1,780 ppm. Both of these sets of values indicate the moderately toxic nature of the compound to these species. The dietary LC50 of the compound in quail is somewhat lower indicating that it is slightly more toxic. The LC50 for propetamphos in the quail ranges from 138 ppm to 250 ppm. The EPA has indicated that birds and mammals may be exposed to the compound near where it has been applied. They state, however, that additional information on application rates and its behavior after application are needed to assess its potential to adversely affect wildlife (14).

The compound is highly toxic to bluegill sunfish and rainbow trout. The LC50 values range from 0.13 mg/l for bluegill to 0.36 for rainbow trout to 3.7 mg/l for carp (moderately toxic range for carp). Aquatic invertebrates may be quite susceptible to low concentrations of the compound. The water flea, Daphnia magna, has an LC50 ranging between 0.68 ppb (14) and 14.5 ppb (15). A study conducted in 1990 found a 48 hour LC50 of 3.3 ppb for this invertebrate (15).

The EPA has indicated that the use of the product Safrotin (an emulsified concentrate) would not be likely to cause harm to endangered species if used as specified on the label.

ENVIRONMENTAL DATA

No data was available on the fate of propetamphos in soil or on plants. In water, half of the initial amount of the compound disappeared within eleven days at 24{C under strongly acidic conditions (pH 3). In a weakly acidic solution (pH 6.0), half of the initial amount of the compound remained after a year. In neutral water, the half-life was 47 days while in a basic solution (pH 9.0) the half-life was 37 to 41 days (3). At cooler temperatures, the half-life of the compound is expected to increase significantly (greater than five years at 20 degrees C) (4). The toxic effects of a 1 g/m2 spray persisted on a whitewashed wall for 32 weeks while the toxic effects of a 0.1 g/m2 spray persisted for four weeks (6).

Exposure Guidelines:

NOEL: rat - 0.05 mg/kg/day
LEL: rat - 1.0 mg/kg/day
RfD: 0.005 mg/kg (OPP)

Physical Properties:

Common name: propetamphos
CAS #: 31218-83-4
Chemical name: (E)-1-methylethyl 3-[{(ethylamino)methoxyphosphinothioly}oxy]-2-butenoate
Chemical class: organophosphate
Chemical use: insecticide
Solubility in water: 110 mg/l
Solubility in solvent: acetone, chloroform, ethanol, hexane, miscible
Melting point: colorless oil at room temperature
Vapor pressure: 1.9 mPa at 20 degrees C

BASIC MANUFACTURER

Sandoz Agro, Inc.
1300 E. Touhy Ave.
Des Plaines, IL 60018
Telephone: 708-699-1616

Review by Basic Manufacturer - Sandoz Agro Inc.:

Comments solicited: April, 1993
Comments received: May, 1993

Zoecon Corporation
12005 Ford Road
Suite 800
Dallas, Texas 75234
Telephone: 214-243-2321
FAX: 214-243-8527

Review by Basic Manufacturer - Zoecon:

Comments solicited: April, 1993
Comments received: May, 1993

REFERENCES

  1. Scientific and Technical Information Network. 1988. CAS Online, Chemical Abstracts Service, Columbus, OH.
  2. National Institute for Occupational Safety and Health. 1985-86. Registry of Toxic Effects of Chemical Substances, U.S. Department of Health and Human Services, Centers for Disease Control.
  3. Meister, R.T. (ed.) 1992. Farm Chemicals Handbook, Meister Publishing Co., Willoughby, OH.
  4. Spencer, E.Y. 1981. Guide to the Chemicals Used in Crop Protection. Research Branch, Agriculture Canada, Canadian Government Publishing Centre, Ottawa, Canada.
  5. Worthing, C.R. (ed.) 1983. The Pesticide Manual, A World Compendium. The British Crop Protection Council, The Ravenham Press Limited, Ravenham, Suffolk, England.
  6. Rettich, F. 1980. Residual Toxicity of Wall-Sprayed Organophosphates, Carbamates, and Pyrethroids to Mosquito Culex pipiens molestus Forskal, J. of Hygiene, Epidemiology, Microbiology and Immunology 24:110-117.
  7. Sabnis, A.M., S. Jagadish, H.V. Jahagirdar and K. Jayakumar. 1982. Evaluation of the Safety of Propetamphos as an Acaricidal Spray in Dogs, Indian Vet. J. 59:510-514.
  8. Wells, D.S., L.M. Afifi, N. Motoyama and W.C. Dauterman. 1986. In Vitro Metabolism of Propetamphos by House fly, Cockroach, and Mouse Liver Preparations, J. Agric. Food Chem. 34:79-86.
  9. Federal Register. 1981. Tolerance for Pesticides in Food, Propetamphos 46:170:43964-5.
  10. Kumari, J. and N.B. Krishnamurthy. 1986. Mutagenicity Studies with Safrotin in Drosophila melanogaster and Mice, Envir. Research 41:44-52.
  11. Garcia-Lopez, J.A. and M. Monteoliva. 1988. Geographic and Environmental Changes in Human Erythrocyte AChE and Their Possible Relationship with Environmental Pollution Caused by Organophosphate Pesticides, Chemosphere 17:6:1237-1240.
  12. Smith, G.J. 1993. Toxicology and Pesticide Use in Relation to Wildlife: Organophosphates and Carbamate Compounds. C.K. Smoley. Boca Raton, FL.
  13. The Agrochemicals Handbook. 1991. the Royal Society of Chemistry. Cambridge, England.
  14. Environmental Effects Branch. 1981. United States Environmental Protection Agency. Washington, DC.
  15. Personal Communication. Zoecon Corporation. April 1, 1993.