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The information in this profile may be out-of-date.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

Mevinphos

Trade and Other Names: Trade names include Apavinphos, CMDP, ENT 22374, Fosdrin, Gesfid, Meniphos, Menite, Mevinox, Mevinphos, OS-2046, PD5, Phosdrin and Phosfene.

Regulatory Status: Mevinphos is a highly toxic compound in EPA toxicity class I. All emulsifiable and liquid concentrates of mevinphos are classified as Restricted Use Pesticides (RUPs) by the U.S. Environmental Protection Agency (EPA), due to their acute oral and dermal toxicity and residue effects on mammalian, aquatic and bird species. RUPs may be purchased and used only by certified applicators. Products containing mevinphos must bear the Signal Words DANGER - POISON.

Chemical Class: organophosphate

Introduction: Mevinphos is an organophosphate insecticide used to control a broad spectrum of insects, including aphids, grasshoppers, leafhoppers, cutworms, caterpillars, and many other insects on a wide range of field, forage, vegetable, and fruit crops. It is also an acaricide that kills or controls mites and ticks. It acts quickly both as a contact insecticide, acting through direct contact with target pests, and as a systemic insecticide which becomes absorbed by plants on which insects feed. It is available in concentrate or liquid formulations.

Formulation: It is available in concentrate and liquid formulations.

Toxicological Effects:

• Acute toxicity: Mevinphos is highly toxic via the oral route, with reported oral LD50 values of 3 to 12 mg/kg in rats, and 4 to 18 mg/kg in mice [2,13]. Via the dermal route it is highly toxic as well, with reported dermal LD50 values for mevinphos of 4.2 mg/kg in rats, and 40 mg/kg in mice [2,13]. The 1-hour LC50 for mevinphos in rats is 0.125 mg/L, indicating high toxicity by inhalation as well [2]. Acute pulmonary edema, or the filling up of lungs with fluid, and changes in the structure or function of salivary glands, were seen in rats that exposed to this concentration for 1 hour. Effects of acute exposure to mevinphos are similar to those due to exposure to other organophosphates, except that these may occur at lower doses than with other organophosphates. Symptoms of acute exposure to organophosphate or cholinesterase-inhibiting compounds may include the following: numbness, tingling sensations, incoordination, headache, dizziness, tremor, nausea, abdominal cramps, sweating, blurred vision, difficulty breathing or respiratory depression, and slow heartbeat. Very high doses may result in unconsciousness, incontinence, and convulsions or fatality. In humans, symptoms of poisoning have appeared within as little as 15 minutes to 2 hours after exposure to mevinphos, but onset of symptoms has been delayed for as long as 2 days [2]. Several children were made ill by unknowingly wearing clothing which had been contaminated with mevinphos. Cholinesterase inhibition resulting from acute exposure is reversible, but it can persist for 2 to 6 weeks.
• Chronic toxicity: The lowest oral dose of mevinphos that produced toxic effects (peripheral nervous system effects) in humans was 690 ug/kg when it was given intermittently over 28 days [2,8]. Repeated low-level exposure to mevinphos may cause similar effects to those observed with acute exposures [2,8]. Severe symptoms of cholinesterase-inhibition may be produced in a previously exposed person, whereas symptoms of cholinesterase-inhibition may not occur in someone who has not been previously exposed to mevinphos [2,8]. In a 2-year feeding study with rats, no observable effects occurred at 0.025 mg/kg/day. A similar result was found in a 2-year feeding study with dogs [8]. No effects on general health and no poisoning symptoms were seen in a 2-year study with rats fed 4 mg/kg/day, nor in dogs given dietary doses of 5 mg/kg/day [8]. However, rats were killed by doses of 20 mg/kg/day mevinphos in their diets for 13 weeks. Dietary doses of 10 mg/kg/day for 14 weeks were lethal for dogs [8]. Rats given dietary doses of 10 or 20 mg/kg/day for 13 weeks exhibited degeneration of the liver, kidneys and cells lining the salivary, tear, and other glands [13].
• Reproductive effects: In a three-generation reproduction study with rats, there were no reproductive effects at 1.2 mg/kg/day [85], indicating that mevinphos is unlikely to cause reproductive toxicity.
• Teratogenic effects: No teratogenic effects were seen in rabbits given doses of 1.0 mg/kg/day [85], suggesting that this pesticide is not teratogenic.
• Mutagenic effects: No data are currently available.
• Carcinogenic effects: A 2-year study with rats fed dietary doses of up to 0.75 mg/kg/day mevinphos produced no evidence of tumor formation [85]. This evidence suggests that mevinphos is not carcinogenic.
• Organ toxicity: Target organs affected by mevinphos include the nervous system, liver, kidneys, and cells lining the salivary, tear, and other glands.

• Fate in humans and animals: Mevinphos is rapidly degraded by the liver. Samples taken by autopsy from a man who had died within 45 minutes of drinking mevinphos showed the following bodily concentrations of the compound: 3400 ppm in the stomach wall, 360 ppm in blood, 240 ppm in the liver, 86 ppm in skeletal muscle, 20 ppm in the kidneys, 8 ppm in urine, and 3 ppm in the brain [2,8]. In a case of moderate poisoning associated with occupational exposure to mevinphos, the concentration of metabolites of mevinphos in the urine collected during the first 12 hours after onset of symptoms was 0.4 ppm. The concentration declined rapidly until 36 hours after onset, and excretion was nearly complete within 50 hours [2].

Ecological Effects:

• Effects on birds: Mevinphos is highly toxic to birds. The acute symptoms of mevinphos poisoning in birds include lack of muscle coordination, curled toes, salivation, diarrhea, trembling, and wing beating. Pheasant deaths all occurred 8 to 18 minutes after treatment; deaths of mallards and grouse occurred 5 to 40 minutes post-treatment [26]. The oral LD50 for mevinphos is 7.52 mg/kg in chickens, 3 mg/kg in wild bird species, 4.63 mg/kg in female mallards, 1.37 mg/kg in male pheasants, and 0.75 to 1.50 mg/kg in male grouse. Its dermal LD50 in ducks is 11 mg/kg [41].
• Effects on aquatic organisms: Mevinphos is very highly toxic to fish. The 96-hour LC50 for technical mevinphos is 0.012 mg/L in rainbow trout, and 0.022 mg/L in bluegill sunfish [13]. The 48-hour LC50 for mevinphos is 0.017 mg/L in rainbow trout; the 24-hour LC50 is 0.034 mg/L in rainbow trout, 0.041 mg/L in bluegills, and 0.8 mg/L in mosquito fish [27].
• Effects on other organisms: Mevinphos is highly toxic to bees, especially when they are exposed to direct treatment or residues on crops [30].

Environmental Fate:

• Breakdown in soil and groundwater: Mevinphos is of low persistence in the soil environment, with reported half-lives of 2 to 3 days [19]. One study indicated that this material lost its insecticidal capability in 2 to 4 weeks [85]. It is poorly adsorbed to soil particles, and thus may be mobile [19]. Its capacity to contaminate groundwater may be limited by its short half-life. No harmful effects to soil microorganisms have been observed from applications of mevinphos formulations [86].
• Breakdown in water: Mevinphos dissolves and is readily broken down by water (hydrolyzed), losing its insecticidal activity within 2 to 4 weeks [31]. In aqueous solution, mevinphos is hydrolyzed with half-lives of 1.4 hours at pH 11, 3 days at pH 9, 35 days at pH 7, and 120 days at pH 6 [8].
• Breakdown in vegetation: When mevinphos is used as directed, it is not phytotoxic (toxic to plants). Plants rapidly degrade it to less toxic products [13]. However, some crops may be sensitive to solvents in which the active ingredient is formulated, as well as to excessive dosages [86].

Physical Properties:

• Appearance: Pure mevinphos is a colorless liquid; technical grade mevinphos is a pale yellow liquid that has a very mild odor or is odorless [13].
• Chemical Name: 2-methoxycarbonyl-1-methylvinyl dimethyl phosphate [13]
• CAS Number: 7786-34-7
• Molecular Weight: 224.15
• Water Solubility: >10 mg/L [13]; completely miscible with H2O
• Solubility in Other Solvents: Technical mevinphos is v.s. in alcohols, ketones, chlorinated hydrocarbons, aromatic hydrocarbons and most organic solvents; s.s in aliphatic hydrocarbons and petroleum ether [13]
• Melting Point: 21 C (E-isomer); 6.9 C (Z-isomer) [13]
• Vapor Pressure: 17 mPa @ 20 C [13]
• Partition Coefficient: Not Available
• Adsorption Coefficient: 44 [19]

Exposure Guidelines:

• ADI: 0.0015 mg/kg/day [38]
• MCL: Not Available
• RfD: Not Available
• PEL: Not Available
• HA: Not Available
• TLV: 0.092 mg/m3 (8-hour) [47]

Basic Manufacturer:

Amvac Chemical Corp.
4100 E. Washington Blvd.
Los Angeles, CA 90023

• Phone: 213-264-3910
• Emergency: 800-228-5635, ext. 169
  

References:

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

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.