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The information in this profile may be out-of-date.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

Carboxin

Trade and Other Names: Trade names for products containing carboxin include Cadan, Kisvax, Kemikar, Oxalin, Padan, Sanvex, Thiobel, Vegetox, and Vitavax. It is often used in combination with other fungicides such as thiram or captan.

Regulatory Status: Carboxin is classified as a General Use Pesticide (GUP) by the U.S. Environmental Protection Agency. It is in toxicity class III - slightly toxic, and products containing it carry the Signal Word CAUTION on the label.

Chemical Class: anilide

Introduction: Carboxin is a systemic anilide fungicide. It is used as a seed treatment for control of smut, rot, and blight on barley, oats, rice, cotton, vegetables, corn, and wheat. It is also used to control fairy rings on turf grass. Carboxin may be used to prevent the formation of these diseases or may be used to cure existing plant diseases.

Formulation: Not Available

Toxicological Effects:

• Acute toxicity: Carboxin is slightly toxic. Symptoms of poisoning can include vomiting and headache. Recovery is very rapid if the exposed individual is treated quickly. The oral LD50 is 3820 mg/kg in rats and 3550 mg/kg in mice [18]. The compound produces very little skin irritation; however, it can seriously irritate the eyes. Acute dermal exposure results in an LD50 of greater than 8000 mg/kg in rabbits. The inhalation LC50 (1-hour) is greater than 20 mg/L in rats [18].
• Chronic toxicity: Rats fed doses up to 311 mg/kg/day for 28 days showed some fluid accumulation in the liver, even at low doses [18]. Another rat study showed kidney changes at somewhat higher doses (1000 mg/kg) fed for 90 days [18]. A 2-year rat study with levels of up to 30 mg/kg produced no compound related effects in physical appearance, behavior, blood chemistry, or urinalysis [18]. However, there were changes in organ weights. Male and female mice also showed liver effects after being fed high doses (912 mg/kg) of carboxin for 1 1/2 years [18]. Beagle dogs showed no effects at the highest dose tested, 15 mg/kg for 2 years [18].
• Reproductive effects: A three-generation study with rats showed treatment related effects on reproductive performance at levels from 5 to 30 mg/kg/day. However, at the highest dose, there was only moderate growth suppression in nursing pups [18]. It is unlikely that the compound would produce reproductive effects in humans at expected exposure levels.
• Teratogenic effects: At the highest dose tested (40 mg/kg) administered to pregnant rats on days 6 to 15, there were no birth defects in the offspring [18]. Pregnant rabbits treated with very high doses on days 6 to 27 of gestation had increased abortions but no fetal malformations [18]. These data indicate that carboxin is not teratogenic.
• Mutagenic effects: Carboxin is either a non-mutagen or is a very weak mutagen, based on information from several studies on bacteria and mammalian cells [18].
• Carcinogenic effects: A 2-year study with rats fed up to 30 mg/kg/day showed no evidence of increased tumor frequency [18]. Mice fed up to 900 mg/kg/day for 84 weeks had no apparent compound related increase in tumor formation. Carboxin does not appear to cause cancer.
• Organ toxicity: Animal studies have demonstrated effects in the liver and kidneys.

• Fate in humans and animals: Rats excreted almost all of a carboxin dose in 24 hours, with most excreted in urine and some in feces [15]. Rabbits showed a similar excretion pattern. Carboxin is incompletely absorbed in the gut, especially in rats [18]. The compound does not acumulate in animal tissues. Only trace amounts of carboxin were found in rat tissues 48 hours after dosing [18]. In milk cows fed up to 5 ppm for 10 days, less than 2% of the administered dose was found in tissues. However, significant levels were found in milk a few days after exposure. The main breakdown product is carboxin sulfoxide, for which the rat oral LD50 is 2000 mg/kg. Carboxin sulfoxide is sold as a pesticide also and is known as oxycarboxin [19].

Ecological Effects:

• Effects on birds: The oral LD50 of carboxin in chickens is very high, at 24 g/kg, indicating that it has a very low acute toxicity [8]. In chronic, low exposure experiments over 5 1/2 months, changes were noted in the digestive tract, cardiovascular system, and blood of chickens [20].
• Effects on aquatic organisms: Carboxin is highly toxic to fish. The 96-hour LC50 in rainbow trout is greater than 0.1 mg/L [8]. Carboxin is practically nontoxic to freshwater invertebrates. The LC50 is 217 mg/L in juvenile crayfish [20].
• Effects on other organisms: The compound is nontoxic to bees [8].

Environmental Fate:

• Breakdown in soil and groundwater: Carboxin is rapidly degraded to carboxin sulfoxide in soil. It has a low persistence, with a half-life of about 3 days in soil [11]. In one study after 7 days, 95% of the parent was gone and the sulfoxide, a breakdown product, represented 31 to 45% of the amount applied [8]. Minor products formed were carboxin sulfone, hydroxy carboxin, and CO2. Carboxin does not readily adsorb to soil. Both parent and sulfoxide are very mobile and could possibly leach to groundwater [18].
• Breakdown in water: In water, carboxin oxidizes to the sulfoxide and sulfone within 7 days [18]. This happens both under ultraviolet light and in the dark. Blue-green algae like Anabaena and Nostoc degrade the pesticide extensively. Other algae can also break down carboxin, but not to the same extent [8].
• Breakdown in vegetation: Although the distribution pattern of the parent and sulfoxide metabolite vary, carboxin is found systemically (throughout the plant) in all species of plants studied. Plants grown from treated seed had no carboxin present 6 weeks after emergence. Carboxin sulfoxide found in plants can come either from the soil or through oxidation within the plant [8].

Physical Properties:

• Appearance: Carboxin is a colorless crystal [1].
• Chemical Name: A 5,6-dihydro-2-methyl-N-phenyl-1,4-oxathiin-3-carboxamide [1]
• CAS Number: 5234-68-4
• Molecular Weight: 235.31
• Water Solubility: 170 mg/L @ 25 C [1]
• Solubility in Other Solvents: acetone v.s.; benzene s.s.; methanol s.s. [1]
• Melting Point: Two crystal structures: 91.5-92.5 C and 98-100 C [1]
• Vapor Pressure: <0.025 mPa @ 25 C [1]
• Partition Coefficient: 2.1703 [1]
• Adsorption Coefficient: 260 [11]

Exposure Guidelines:

• ADI: Not Available
• MCL: Not Available
• RfD: 0.1 mg/kg/day [13]
• PEL: Not Available
• HA: 0.7 mg/L (lifetime) [18]
• TLV: Not Available

Basic Manufacturer:

Uniroyal Chemical Co., Inc.

Benson Road

Middlebury, CT 06749

• Phone: 203-573-2000
• Emergency: 203-723-3670
  

References:

References for the information in this PIP can be found in Reference List Number 10

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.