The information in this profile may be out-of-date.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