---

The information in this profile may be out-of-date.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

---

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

Oxamyl

Trade and Other Names: Trade names include Blade, DPX 1410, Oxamil, Oxamimidic Acid, Pratt, Thioxamil, and Vydate.

Regulatory Status: Oxamyl is a highly toxic compound in EPA toxicity class I. The U.S. Environmental Protection Agency (EPA) has classified most products containing oxamyl as Restricted Use Pesticides (RUPs) due to oxamyl's acute toxicity to humans and its toxicity to birds and mammals. Restricted Use Pesticides may be purchased and used only by certified applicators. Granular formulations of oxamyl are banned in the United States. Labels on containers of oxamyl and/or its formulated products must bear the Signal Words DANGER - POISON.

Chemical Class: carbamate

Introduction: Oxamyl is a carbamate insecticide/acaricide/nematicide that controls a broad spectrum of insects, mites, ticks, and roundworms. It may work both through systemic distribution in the target pest and on contact. Oxamyl is used on field crops, vegetables, fruits, and ornamental plants and may be applied directly onto plants or the soil surface. It is available in both liquid and granular form, but as is stated above, the granular form is banned in the U.S.

Formulation: It is available in both liquid and granular form, but as is stated above, the granular form is banned in the U.S.

Toxicological Effects:

• Acute toxicity: Oxamyl is highly toxic via the oral route, with a reported oral LD50 of 5.4 mg/kg in rats [10]. Exposure to oxamyl will cause similar effects to the other carbamate compounds, and as with other carbamates the cholinesterase-inhibiting effects are short-term and reversible [5]. These effects include headache, nausea, sweating, tearing, tremors, and blurred vision. It is slightly toxic via the dermal route, with a reported dermal LD50 for technical oxamyl of 2960 mg/kg in rabbits [10]. Skin and eye exposure may cause poisoning, although absorption through the skin and eye is slower than through the gastrointestinal tract [5]. Exposure of rabbit's eyes to technical oxamyl caused mild irritation [5]. Oxamyl is highly toxic via the inhalation route as well with a reported 4-hour LC50 of 0.12 to 0.17 mg/L in rats [10].
• Chronic toxicity: Prolonged or repeated exposure to oxamyl may cause symptoms similar to those caused by acute exposure. In a 2-year mouse feeding study, no effects were observed at a dose of 1.25 mg/kg/day, although at the very high doses of 2.5 and 3.75 mg/kg/day there was decreased body weight and changed nutritional performance [41]. Liver impairment was suggested by a slight biochemical change seen in dogs that were fed 3.75 mg/kg/day as a part of a 2-year feeding study [5]. Male rats fed the very high dose of 7.5 mg/kg/day oxamyl for 2 years had decreased organ weight of the heart, testes, and adrenals. In females, there was an increase in the relative weights of the brain, heart, lungs, and adrenals at these doses [42].
• Reproductive effects: When pregnant rats were fed oxamyl, no effects were observed (relative to unexposed animals) on the number of implantation sites, resorptions, and live fetuses in rats fed doses of 2.5, 5, 7.5, or 15 mg/kg/day on days 6 through 15 of pregnancy. There were, however, dose-related decreases in maternal body weights and in food consumption rates [42]. Litter size, viability, lactation and body weights of offspring were decreased in a three-generation (two litters per generation) reproduction study in rats fed very high doses, approximately 5 and 7.5 mg/kg/day technical oxamyl [42]. Based on these studies, oxamyl is unlikely to cause reproductive effects in humans at expected exposure levels.
• Teratogenic effects: No teratogenic effects were observed in the offspring of rabbits fed 2 and 4 mg/kg/day during days 6 to 19 of gestation [42]. Oxamyl was not teratogenic or embryotoxic in the offspring of pregnant rats fed up to 15 mg/kg/day of the insecticide [3,42]. No teratogenic effects were observed in rabbits given oxamyl levels at doses of approximately 4 mg/kg/day in the diet [5]. Thus, it appears that oxamyl does not cause teratogenic effects.
• Mutagenic effects: Oxamyl was not mutagenic in several test systems [5,42].
• Carcinogenic effects: In a study of mice fed up to 9 mg/kg/day, no carcinogenic effects were seen [5]. In addition, no evidence of carcinogenic potential was seen following long-term dietary exposure of rats [42]. This indicates that oxamyl is not carcinogenic.
• Organ toxicity: Effects noted in animal studies include changes in liver function, and changes in organ weights of the brain, heart, lungs, testes, and adrenals [42].

• Fate in humans and animals: When oxamyl was administered to rats, most of the dose was rapidly eliminated in the urine and feces as breakdown by-products, or metabolites [5]. Carbamates generally are excreted rapidly and do not accumulate in mammalian tissue [5].

Ecological Effects:

• Effects on birds: Oxamyl is very highly toxic to birds [10]. The acute oral LD50 for oxamyl in quail is 4.18 mg/kg [10]. Hens given single oral doses of oxamyl at 20 to 40 mg/kg of body weight followed by intramuscular injections of 0.5 mg of atropine, an antidote, exhibited early symptoms of cholinesterase inhibition with full recovery after 12 hours. No signs of delayed neurotoxicity were observed in these same hens [42]. The oral LD50 for oxamyl is 2.6 mg/kg in mallard ducks and 9.4 mg/kg in bobwhite quail [17].
• Effects on aquatic organisms: Oxamyl is moderately to slightly toxic to fish [10]. The reported 96-hour LC50 values for technical oxamyl are 5.6 mg/L in bluegill sunfish, 27.5 mg/L in goldfish, 4.2 mg/L in rainbow trout and 17.5 mg/L in channel catfish [10]. Concentrations of 0.5 to 5.0 mg/L may have an effect on Daphnia magna, an aquatic invertebrate [43].
• Effects on other organisms: Oxamyl is highly toxic to bees [10].

Environmental Fate:

• Breakdown in soil and groundwater: Oxamyl is of low persistence in soil with reported field half-lives of 4 to 20 days [13]. Loss is due to decomposition by aerobic and anaerobic bacteria (44). Oxamyl is hydrolyzed rapidly in neutral and alkaline soils and more slowly in acid soils [42]. It does not readily bind, or "adsorb," to soil or sediments and it has been shown to leach in soil [13,42]. Its adsorption is strongest in soils of high organic matter, and on sandy loam is fairly weak. An increase in temperature causes a decrease in adsorption [44]. Since oxamyl degrades relatively quickly in the presence of bacteria, it is more likely to be found in groundwater than in surface water. It has been found in very small amounts in the states of New York (1 to 60 ug/L) and Rhode Island (1 ug/L) [45]. Wherever conditions favor very rapid movement of leachate, oxamyl may reach the groundwater.
• Breakdown in water: In a river water study, oxamyl had a half-life of 1 to 2 days [42].
• Breakdown in vegetation: Oxamyl has a residual period in plants of approximately 1 to 2 weeks. It is considered non-toxic to plants [10]. Plants take oxamyl up through both leaves and roots; it is translocated in treated plants [10]. Oxamyl is metabolized rapidly by plants [42].

Physical Properties:

• Appearance: Oxamyl is a colorless or white crystalline solid with a garlic-like odor.
• Chemical Name: N,N-dimethyl-2-methylcarbamoyloxyimino-2-(methylthio)-acetamide [10]
• CAS Number: 23135-22-0
• Molecular Weight: 219.36
• Water Solubility: 280 g/L @ 25 C [10]
• Solubility in Other Solvents: v.s. in acetone, ethanol, 2-propanol, and methanol; s. in toluene [10]
• Melting Point: 100-102 C [10], at which point it changes to a different crystalline structure that melts at 108-110 C [10]
• Vapor Pressure: 31 mPa @ 25 C [10]
• Partition Coefficient: Not Available
• Adsorption Coefficient: 25 [13]

Exposure Guidelines:

• ADI: 0.03 mg/kg/day [10]
• MCL: 0.2 mg/L [19]
• RfD: 0.025 mg/kg/day [20]
• PEL: Not Available
• HA: Not Available
• TLV: Not Available

Basic Manufacturer:

DuPont Agricultural Products
Walker's Mill, Barley Mill Plaza
P.O. Box 80038
Wilmington, DE 19880-0038

• Phone: 800-441-7515
• Emergency: 800-441-3637
  

References:

References for the information in this PIP can be found in Reference List Number 3

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.