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The information in this profile may be out-of-date.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

Dinoseb

Trade and Other Names: Product names for pesticides containing dinoseb include Basanite, Caldon, Chemox, Chemsect DNBP, Dinitro, Dynamyte, Elgetol, Gebutox, Hel-Fire, Kiloseb, Nitropone, Premerge, Sinox General, Subitex, and Vertac Weed Killer.

Regulatory Status: The use of dinoseb was cancelled in the U.S. in 1986. This action was based on the potential risk of birth defects and other adverse health effects for applicators and other persons with substantial dinoseb exposure. This pesticide is not commercially available in the U.S.

Dinoseb is a highly toxic compound. Prior to its ban, it was a Restricted Use Pesticide (RUP), and products containing dinoseb were required to be labeled with a DANGER Signal Word.

Chemical Class: phenolic compound

Introduction: Dinoseb is a phenolic herbicide used in soybeans, vegetables, fruits and nuts, citrus, and other field crops for the selective control of grass and broadleaf weeds (e.g., in corn). It is also used as an insecticide in grapes, and as a seed crop drying agent. It is produced in emuslifiable concentrates or as water soluble ammonium or amine salts. The information presented here pertains to the technical grade of dinoseb unless otherwise specified.

Formulation: It is produced in emuslifiable concentrates or as water soluble ammonium or amine salts.

Toxicological Effects:

• Acute toxicity: Dinoseb is highly toxic by ingestion, with reported oral LD50 values of 25 to 58 mg/kg in rats and 25 mg/kg in guinea pigs [1,29]. It is highly toxic by skin exposure, with a reported dermal LD50 of 80 to 200 mg/kg in rabbits and 200 to 300 mg/kg in guinea pigs [1,29]. Dinoseb did not cause skin irritation in rabbits [29]. Inhalation of dusts and sprays may be irritating to the lungs and eyes, and may cause serious illness; direct skin contact may cause irritation, yellow stains, burns, and dermatitis, and more serious effects in humans [29]. In one fatal incident, a farm worker was using a backpack hand-held sprayer that leaked dinoseb onto his body and penetrated his skin [29]. Symptoms in persons receiving accidental exposure include fatigue, thirst, sweating, insomnia, weight loss, headache, flushing of the face, nausea, abdominal pain, and occasional diarrhea [29]. In one case, some of these persisted for several months following exposure [29].
• Chronic toxicity: Dinoseb interferes with cellular conversion of food molecules (such as glucose) into useable energy for the body [83]. Specifically, it disturbs the production of adenosine triphosphate (ATP) in the mitochondria of the cells, ATP being the molecule that provides energy for all cellular activities [83]. This may account for many of the toxic effects caused by dinoseb. Dietary levels of about 25 mg/kg/day caused marked food refusal and some deaths after five or more doses [29]. Lower doses (5 to 20 mg/kg/day) caused statistically significant decreases in growth [29]. Some formulations of dinoseb may cause anemia-like effects, jaundice, and increased excretion of hemoglobin-related compounds (coproporphyrinuria) [29].
• Reproductive effects: Dinoseb is reported to adversely affect reproduction in rats and mice at levels that are commonly found among occupational workers. Decreased sperm count and abnormal sperm shape were observed in male rats and mice after 3 weeks at low exposure levels (about 10 mg/kg/day) for 30 days [84]. In a separate study, rats were exposed to relatively small quantities of dinoseb through their diet for a total of 22 weeks. Effects such as decreased fertility, slow weight gain, and poor survival of newborns appeared to be related to this pesticide [85]. Because of the adverse effects observed in laboratory animals at low chronic exposure levels, it is believed that dinoseb may cause decreased fertility or sterility in humans [83].
• Teratogenic effects: Low levels of dinoseb fed to rats and rabbits caused birth defects in the fetuses of exposed females [8]. When dinoseb was administered to pregnant mice, its breakdown products were found in the embryos. However, no teratogenic effects were noted. Various tests of mice and rats fed or injected with small amounts of dinoseb (around 10 mg/kg/day) have shown maternal toxicity, decreased fetal body weights and changes in fetal development [29]. In some studies of mice, oral doses to pregnant mothers caused an increased death rate in the exposed animals but caused no fetal damage [8]. Other studies indicate that dinoseb is a stronger teratogen when injected than when ingested. At low feeding levels the compound was responsible for skeletal deformities and neurological problems in newborn rats [83]. Based on the data, dinoseb may produce teratogenic effects in humans.
• Mutagenic effects: Dinoseb was not mutagenic or genotoxic in laboratory studies performed using eukaryotic cells (the type found in mammals and other higher order species) [29,83]. This evidence suggests that mutagenic effects in humans due to dinoseb exposure are unlikely.
• Carcinogenic effects: Dinoseb didn't cause significant increases in tumors when administered to two strains of mice at the maximum tolerated dose over a period of 18 months [29]. While not carcinogenic to male mice, it was found to be carcinogenic to female mice in another study [83]. The compound caused liver cancer in these animals at moderate to high doses [83]. The evidence regarding the carcinogenic potential of dinoseb is currently inconclusive.
• Organ toxicity: Dinoseb has the potential to damage the eye. It may also affect the immune system, liver, kidneys, and spleen [29].

• Fate in humans and animals: Dinoseb is readily absorbed through the skin, gastrointestinal tract, and lung surface [29]. Esters of dinoseb are rapidly transformed into dinoseb, which is the active toxicant [29]. The chemical is excreted in the urine and feces and is metabolized in the liver. Breakdown products are found in the liver, kidneys, spleen, blood, and urine [29]. Dinoseb can also pass through the placenta into the fetus of experimental animals.

Ecological Effects:

• Effects on birds: The compound is very highly toxic to birds, with reported acute oral LD50 values between 7 and 9 mg/kg [8]; its reported 5- to 8-day dietary LC50 ranges from 409 ppm in quail to 515 ppm in pheasants [8]. It thus has the potential to negatively impact local pheasant and songbird populations.
• Effects on aquatic organisms: Dinoseb is highly toxic to fish, with reported 96-hour LC50 values ranging from 44 ug/L in lake trout to 118 ug/L in catfish [8]. Other 96-hour LC50 values are 100 ug/L in coho salmon and 67 ug/L in cutthroat trout [8,37]. It is more toxic to fish in acidic water than in neutral or alkaline water [37]. Dinoseb has caused fish kills in small Scottish streams when washed from fields by rain [88]. The bioconcentration factor is 135 (86). Dinoseb is rapidly taken up by fish, but is is rapidly eliminated from exposed fish if placed in clean water. Dinoseb, thus, does not pose a significant risk for bioaccumulation [84].
• Effects on other organisms: Dinoseb is toxic to bees [1].

Environmental Fate:

• Breakdown in soil and groundwater: Dinoseb is of low persistence regardless of the form (phenolic or salt). Reported field half-lives for both types of dinoseb range from 5 to 31 days [53]. An overall representative value is estimated to be 20 tp 30 days in most circumstances, although persistence may be much longer in the vadose zone [9]. Photodegradation and microbial breakdown may play roles in the breakdown of dinoseb in the soil environment, but volatilization should not be a significant route of loss [9]. The phenolic form of dinoseb is slightly soluble in water and moderately sorbed by most soils [53]. Studies have shown soil sorption capacity to be much greater at lower pH values [9]. It thus should present only a moderate risk to groundwater. On the other hand, the ammonium and amine salt forms of dinoseb are much more water-soluble and much less strongly bound to soils [8]. These may pose a significant risk to groundwater. Over a 10-year period, dinoseb was found to be one of three particularly persistent contaminants in Ontario wells [8]. Entry to the wells was due to spills of concentrated and dilute herbicide, drift during spraying, and from storm runoff. Well water concentrations ranged from 0.05 to 5000 ug/L in these wells, and removal of dinoseb proved to be very difficult [9].
• Breakdown in water: Photodegradation may occur in surface waters, but hydrolysis is essentially negligible [9]. Dinoseb has been found in streams at about 5 ug/L [8].
• Breakdown in vegetation: Dinoseb persists on treated crop soils for 2 to 4 weeks, under average conditions of use [8].

Physical Properties:

• Appearance: Dinoseb is a dark reddish-brown solid or dark orange viscous liquid, depending on the temperature [1].
• Chemical Name: 2-(sec-butyl)-4,6-dinitrophenol [1]
• CAS Number: 88-85-7
• Molecular Weight: 240.22
• Water Solubility: 52 mg/L @ 20 C [1]
• Solubility in Other Solvents: v.s. in alcohol, ethanol, and heptane; s. in spray oil and in most organic solvents and oils [1]
• Melting Point: 32-42 C [1]
• Vapor Pressure: 6.7 mPa @ 25 C [53]
• Partition Coefficient: Not Available
• Adsorption Coefficient: 30 (estimated) [53]

Exposure Guidelines:

• ADI: Not Available
• MCL: Not Available
• RfD: 0.001 mg/kg/day [13]
• PEL: Not Available
• HA: Not Available
• TLV: Not Available

Basic Manufacturer:

DowElanco
9330 Zionsville Road
Indianapolis, IN 46268-1054

• Phone: 317-337-7344
• Emergency: 800-258-3033
  

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.