E X T O X N E T
Extension Toxicology Network
A Pesticide Information Project of Cooperative Extension Offices of
Cornell University, Michigan State University, Oregon State University, and
University of California at Davis. Major support and funding was provided
by the USDA/Extension Service/National Agricultural Pesticide Impact
Assessment Program.
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Pesticide
Information
Profile
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Dinoseb
Publication Date: 9/93
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TRADE OR OTHER NAMES
Product names for pesticides containing dinoseb included Basanite,
Caldon, Chemox, Chemsect DNBP, Dinitro, Dynamyte, Elgetol, Gebutox, Hel-
Fire, Kiloseb, Nitropone, Premerge, Sinox General, Subitex, and Vertac
Weed Killer. Approximately 180 different compounds contained some level
of dinoseb as an active ingredient before its cancellation by the EPA.
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 in corn. It is also used as an insecticide
in grapes; and as a seed crop drying agent.
In October 1986, the EPA issued an emergency suspension order which
immediately prohibited further sale, distribution, and use of pesticide
products containing dinoseb in the United States (2). This action was
based on the significant risk of birth defects and other adverse health
effects for applicators and other persons with substantial dinoseb
exposure (3). Since that time, the use of dinoseb has been cancelled in
the United States. The product is now not commercially available in the
U.S. (10).
TOXICOLOGICAL EFFECTS
ACUTE TOXICITY
Dinoseb is a highly to extremely toxic compound, and is labeled
with a DANGER signal word.
Exposure to dinoseb can occur by direct contact, ingestion, and
inhalation. Inhalation of dusts and sprays may be irritating to the
lungs and eyes, and may cause serious illness. Symptoms occurring in
humans include fatigue, thirst, sweating, insomnia, weight loss,
headache, flushing of the face, nausea, abdominal pain, and occasional
diarrhea.
Dinoseb is absorbed through animal and human skin, and direct skin
contact will cause irritation, yellow stains, burns, and dermatitis.
Spray operators have died upon dermal exposure to dinoseb. In one
fatality, a farm worker was using a backpack hand-held sprayer that
leaked dinoseb onto his body and penetrated his skin (11).
The oral LD50 of dinoseb for rats is 25-46 mg/kg, and dermal LD50
for rabbits is 75-80 mg/kg (8).
CHRONIC TOXICITY
At chronic and acute exposure levels, dinoseb interferes with a
cell's ability to convert food (such as glucose) into useable energy for
the body. More specifically, it disturbs the production of ATP, a
chemical in the cell that provides energy for all cellular activities
(9). This interference is the basis for most all toxic effects related
to the compound (9).
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 three weeks at low exposure levels (about 10
mg/kg/day) for 30 days (11, 12). 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 this pesticide (5).
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 (9).
Teratogenic Effects
Dinoseb is a potential teratogen (9). Low levels of dinoseb fed to
rats and rabbits caused birth defects in the fetuses of exposed females.
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) have shown maternal toxicity, decreased
fetal body weights and changes in fetal development (12). 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 the newborn rats (9).
It is primarily due to the risks of birth defects in humans that
this pesticide was banned for use in the United States by the EPA.
Mutagenic Effects
Dinoseb was not mutagenic in laboratory studies performed to date.
Carcinogenic Effects
Dinoseb is classified as a possible human carcinogen. While not
carcinogenic to male mice, it was found to be carcinogenic to female
mice. The compound caused liver cancer in the animals at moderate to
high doses (9).
Organ Toxicity
Dinoseb has the potential to damage human eyes; cataracts can
develop with exposure to low levels of the compound. It may also affect
the immune system, liver, kidneys, and spleen (5).
Fate in Humans and Animals
Dinoseb is absorbed through the skin. 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 (5). Dinoseb
can also pass through the placenta into the fetus of experimental
animals.
ECOLOGICAL EFFECTS
Dinoseb is highly toxic to fish (8). It is more toxic to fish in
acidic water than in neutral or alkaline water. The species that have
been tested include the cutthroat and lake trout, fathead minnow, and
catfish (1).
The compound is also very toxic to birds, mammals, and
invertebrates and may pose a threat to nontarget aquatic organisms
including endangered species (9). During normal (field) applications,
dinoseb could affect the survival of aquatic life if water from treated
irrigation ditches is released into a stream or river without sufficient
holding or detoxifying time. Dinoseb has caused fish-kills in small
Scottish streams when washed from fields by rain. It also has the
potential to cause field kills of pheasants and songbirds.
Dinoseb is rapidly taken up by fish. However, when the exposed fish
are placed in clean water, the chemical is rapidly eliminated. Thus,
the accumulation of the chemical in aquatic life is not a significant
environmental risk (1).
ENVIRONMENTAL FATE
Dinoseb affects plants by direct contact. No true translocation
occurs within the plant. Twenty-eight days after topical application of
dinoseb to apple fruits, about a third of the chemical remained.
Breakdown products were found in apple skin and flesh. Dinoseb residues
have not been detected in food samples. Dinoseb persists on treated
crop soils for 2-4 weeks, under average conditions of use.
Water soluble salts of dinoseb leach readily in soil. However, oil
soluble or water soluble formulations of true (non-salt) dinoseb leach
much less. There is some evidence that the herbicide binds to certain
organic and clay soils. Dinoseb does not accumulate in soil because of
microbial breakdown.
Over a ten year period, dinoseb was found to be one of three
particularly persistent contaminants in Ontario wells. 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 0.05-5,000 ppb in these wells, and removal of dinoseb proved
to be very difficult (4). Dinoseb is stable in surface water and has
been found in streams at about 5 ppb.
PHYSICAL PROPERTIES AND GUIDELINES
Dinoseb is a dark reddish-brown solid or dark orange viscous
liquid, depending on the temperature. It has a pungent odor. Dinoseb
is corrosive to mild steel in the presence of water.
Toxic fumes are emitted upon decomposition of dinoseb. The
chemical name for dinoseb is 2-(Sec-butyl)-4,6-dinitrophenol, and
synonyms include 2,4-dinitro-6-(1-methylpropyl)phenol and 2,4-dinitro-6-
sec-butylphenol.
The triethanolamine salt of dinoseb contains over 200 mg/kg N-
nitrosodie-thanolamine, a highly toxic contaminant.
Exposure Guidelines:
| NOEL: | 3 mg/kg/day (Dinitrophenol) |
| ADI: | 1.11 ug/kg (for females at least 13 years old) |
| Drinking water health advisory: | Drinking Water Equivalent Level (DWEL): 0.035 mg/L |
Physical Properties
| CAS #: | 88-85-7 |
| Solubility in water: | 0.0052 g/100 g (25 degrees C) |
| Solubility in solvents: | Soluble in alcohol, ethanol, heptane, spray oil, and most organic solvents and oils. |
| Melting point: | 32-42 degrees C |
| Vapor pressure: | 1 torr (151.1 degrees C), 760 torr (332 degrees C) |
| Log P: | 0.0 (151.1 degrees C) |
| Kow: | 2138(6) |
| Kd: | 2.4 x 10 to the minus 5 power |
| BCF: | 135.1(7) |
BASIC MANUFACTURER
DowElanco
P.O. Box 681428
Indianapolis, IN 46268-1189
Telephone: 317-871-8422
Review by Basic Manufacturer:
Comments solicited: December, 1992
Comments received:
REFERENCES
Call, D.J., et al. 1984. J. Environ. Qual. 13(3):493-498.
Federal Register, October 14, 1986. 51 FR 36634.
Federal Register, October 14, 1986. 51 FR 36650.
Frank, R., Sirons, G.J., and Ripley, B.D. 1979. Pesticides
Monitoring Journal 13(1):120-127.
Hall, L., et al. 1978. Toxicol. Appl. Pharm. 45(1):235-236.
Saarikoski, J., Lindstrom, R., Tyynela, M., and Viluksela, M. 1986.
Ecotoxicol. Environ. Safety 11:158-173.
Spacie, A. and Hamelink, J.L. 1982. Environ. Toxicol. Chem. 1:
309-320.
National Library of Medicine. 1992. Hazardous Substances Databank.
Dinoseb.
Walker, Mary M. and Lawrence H. Keith. 1991. EPA's Pesticide
Fact Sheet Database. Lewis Publishers. Chelsea, MI.
Farm Chemicals Handbook. 1992. Meister Publishing Company.
Willoughby, OH.
Gasiewicz, Thomas A. 1991. Nitro Compounds and Related Phenolic
Pesticides. in Handbook of Pesticide Toxicology, Volume 3, Classes of
Pesticides. Wayland J. Hayes and Edward R. Laws editors. Academic
Press, NY.
Health Advisories for 50 Pesticides. 1988. United States
Environmental Protection Agency.
Disclaimer: Please read
the pesticide label prior to use. The information contained at this web
site is not a substitute for a pesticide label. Trade names used herein
are for convenience only; no endorsement of products is intended, nor is
criticism of unnamed products implied. Most of this information is historical
in nature and may no longer be applicable.
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