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The information in this profile may be out-of-date.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 9/95.

FORMOTHION

REGULATORY STATUS: Formothion is a restricted use pesticide (RUP).

INTRODUCTION: Formothion is an organophosphate product. It is a systemic and contact insecticide used to control spider mites, aphids, psyllids, mealy bugs, whiteflies, jassids, leaf miners, ermine moths, and fruit flies (154). It is used on tree fruits, vines, olives, hops, cereals, sugar cane, rice (13). The U.S. EPA classifies formothion as toxicity class II - moderately toxic. Products containing formothion bear the Signal Word "Warning." Formothion is available as an emulsifiable concentrate and an ultra-low volume spray (112).

TOXICOLOGICAL EFFECTS

• Acute Toxicity: Formothion is a cholinesterase inhibitor which means it affects normal nervous system function. Early symptoms of formothion poisoning include nausea or vomiting, dizziness, and weakness. Tightness in the chest and difficulty breathing are common in inhalation exposure. As in other organophosphate poisonings, exposure may cause blurred vision, muscle spasms, or loss of coordination (131). The LD50, the dose of formothion which kills half of the test animals, is 365-500 mg/kg for rats; 410 - 420 mg/kg for rabbits; 102 mg/kg for mice; and 210 mg/kg for cats (126, 131). The LD50 is greater than 1,000 mg/kg for rats whose skin is exposed to formothion (154). The LC50 (4 hours), the concentration in air which kills half of the test animals, is 4.5 mg/l air for rats. Formothion is non-irritating to skin.
• Chronic Toxicity: No Information Available.
• Teratogenic Effects: No evidence of teratogenic or embryotoxic effects was seen in rabbits given formothion from days 6 to 18 of pregnancy at rates of 6 and 30 mg/kg/day.(131)
• Reproductive Effects: No information is currently available.
• Mutagenic Effects: A number of studies on salmonella bacteria indicate that formothion is not mutagenic (155).
• Carcinogenic Effects: Formothion is an organophosphate pesticide. Studies indicate that organophosphate compounds do not have structures resembling known carcinogens. Though no data is currently available on formothion, it is unlikely that it causes cancer.
• Organ Toxicity: Cholinesterase is an enzyme critical to proper function of the nervous system. Formothion has been found to inhibit the activity of cholinesterase, impairing normal nervous system functions (13, 131). Also, in rat feeding studies, 16 mg/kg/day of formothion caused growth impairment in males during the first year of a two year study. It also caused slight tremors and muscle spasms in individual rats during the same time period. Rats tended to recover during the second year (131).
• Fate in Humans and Animals: Formothion is rapidly absorbed by the stomach of rats. It passes through the liver, kidney, pancreas and thymus. Most (96%) of a dose of formothion is excreted within 24 hours. The majority of a dose (98-99%) is excreted in urine and 2% in feces (131).

ECOLOGICAL EFFECTS

• Effects on Birds: Formothion is slightly toxic to birds. The oral LD50 for pigeons was 630 mg/kg (13).
• Effects on Aquatic Organisms: Formothion is slightly toxic to fish. The LC50 (96 hours) for carp is greater than 50 mg/l (13).
• Effects on Other Animals (Nontarget species): Formothion is toxic to bees (138).

ENVIRONMENTAL FATE

• Breakdown of Chemical in Soil and Groundwater: Formothion is relatively non-persistent. The half-life of formothion in loamy soils is one to 14 days (13, 131). There is no danger of formothion residues accumulating in soil, even if plants are subject to repeated treatment (131).
• Breakdown of Chemical in Surface Water: No information is currently available.
• Breakdown of Chemical in Vegetation: In plants, formothion is metabolized rapidly and dissipates (13).

PHYSICAL PROPERTIES AND GUIDELINES

Physical Properties:

• Appearance: pale yellow, viscous liquid or crystalline mass. It is extremely stable to acids but decomposes on distillation. It is incompatible with alkaline pesticides (131).
• Chemical Name: O,O-dimethyl dithiophos- phorylacetic acid N-methyl-N-formylamide
• CAS Number: 2540-82-1
• Molecular Weight: 257.3
• Water Solubility: 2.6 g / l
• Solubility in Other Solvents: Soluble in alcohols, ether, chloroform, ketones, and xylene (131)
• Melting Point: 25-26 degrees C (13).
• Vapor Pressure: 0.113 mPa (20 degrees C)
• Partition Coefficient:(octanol/water) ca. 30 (13)
• Adsorption Coefficient:Not Available

Exposure Guidelines:

• ADI: 0.2 mg/kg (131)
• MCL: Not Available
• RfD: Not Available
• PEL: Not Available
• HA: Not Available
• TLV: Not Available

BASIC MANUFACTURER:

Sandoz Ltd.
1300 E. Touhy Avenue
Des Plaines, IL 60018

• Fax: 708-390-3940
• Telephone: 708-699-1616

REFERENCES

References for the information in this PIP can be found in Reference List Number 5