The information in this profile may be out-of-date.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.
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E X T O X N E T
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
EXTOXNET primary files maintained and archived at Oregon State
Revised June 1996
Trade and Other Names:
Trade names for products containing glyphosate include Gallup,
Landmaster, Pondmaster, Ranger, Roundup, Rodeo, and Touchdown. It
may be used in formulations with other herbicides.
Glyphosate acid and its salts are moderately toxic compounds in
EPA toxicity class II. Labels for products containing these
compounds must bear the Signal Word WARNING. Glyphosate is a
General Use Pesticide (GUP).
Chemical Class: Not
Glyphosate is a broad-spectrum, nonselective systemic herbicide
used for control of annual and perennial plants including
grasses, sedges, broad-leaved weeds, and woody plants. It can be
used on non-cropland as well as on a great variety of crops.
Glyphosate itself is an acid, but it is commonly used in salt
form, most commonly the isopropylamine salt. It may also be
available in acidic or trimethylsulfonium salt forms. It is
generally distributed as water-soluble concentrates and powders.
The information presented here refers to the technical grade of
the acid form of glyphosate, unless otherwise noted.
itself is an acid, but it is commonly used in salt form, most
commonly the isopropylamine salt. It may also be available in
acidic or trimethylsulfonium salt forms. It is generally
distributed as water-soluble concentrates and powders.
- Acute toxicity: Glyphosate is
practically nontoxic by ingestion, with a reported acute
oral LD50 of 5600 mg/kg in the rat. The toxicities of the
technical acid (glyphosate) and the formulated product
(Roundup) are nearly the same [58,96]. The oral LD50 for
the trimethylsulfonium salt is reported to be
approximately 750 mg/kg in rats, which indicates moderate
toxicity . Formulations may show moderate toxicity as
well (LD50 values between 1000 mg/kg and 5000 mg/kg)
. Oral LD50 values for glyphosate are greater than
10,000 mg/kg in mice, rabbits, and goats [8,96]. It is
practically nontoxic by skin exposure, with reported
dermal LD50 values of greater than 5000 mg/kg for the
acid and isopropylamine salt. The trimethylsulfonium salt
has a reported dermal LD50 of greater than 2000 mg/kg. It
is reportedly not irritating to the skin of rabbits, and
does not induce skin sensitization in guinea pigs .
It does cause eye irritation in rabbits . Some
formulations may cause much more extreme irritation of
the skin or eyes . In a number of human volunteers,
patch tests produced no visible skin changes or
sensitization . The reported 4-hour rat inhalation
LC50 values for the technical acid and salts were 5 to 12
mg/L , indicating moderate toxicity via this route.
Some formulations may show high acute inhalation toxicity
. While it does contain a phosphatyl functional
group, it is not structually similar to organophosphate
pesticides which contain organophosphate esters, and it
does not significantly inhibit cholinesterase activity
- Chronic toxicity: Studies of glyphosate
lasting up to 2 years, have been conducted with rats,
dogs, mice, and rabbits, and with few exceptions no
effects were observed . For example, in a chronic
feeding study with rats, no toxic effects were observed
in rats given doses as high as 400 mg/kg/day . Also,
no toxic effects were observed in a chronic feeding study
with dogs fed up to 500 mg/kg/day, the highest dose
- Reproductive effects: Laboratory studies
show that glyphosate produces reproductive changes in
test animals very rarely and then only at very high doses
(over 150 mg/kg/day) [58,96]. It is unlikely that the
compound would produce reproductive effects in humans.
- Teratogenic effects: In a teratology
study with rabbits, no developmental toxicity was
observed in the fetuses at the highest dose tested (350
mg/kg/day) . Rats given doses up to 175 mg/kg/day on
days 6 to 19 of pregnancy had offspring with no
teratogenic effects, but other toxic effects were
observed in both the mothers and the fetuses. No toxic
effects to the fetuses occurred at 50 mg/kg/day .
Glyphosate does not appear to be teratogenic.
- Mutagenic effects: Glyphosate
mutagenicity and genotoxicity assays have been negative
. These included the Ames test, other bacterial
assays, and the Chinese Hamster Ovary (CHO) cell culture,
rat bone marrow cell culture, and mouse dominant lethal
assays . It appears that glyphosate is not mutagenic.
- Carcinogenic effects: Rats given oral
doses of up to 400 mg/kg/day did not show any signs of
cancer, nor did dogs given oral doses of up to 500
mg/kg/day or mice fed glyphosate at doses of up to 4500
mg/kg/day . It appears that glyphosate is not
- Organ toxicity: Some microscopic liver
and kidney changes, but no observable differences in
function or toxic effects, have been seen after lifetime
administration of glyphosate to test animals .
- Fate in humans and animals: Glyphosate
is poorly absorbed from the digestive tract and is
largely excreted unchanged by mammals. At 10 days after
treatment, there were only minute amounts in the tissues
of rats fed glyphosate for 3 weeks . Cows, chickens,
and pigs fed small amounts of glyphosate had undetectable
levels (less than 0.05 ppm) in muscle tissue and fat.
Levels in milk and eggs were also undetectable (less than
0.025 ppm). Glyphosate has no significant potential to
accumulate in animal tissue .
- Effects on birds: Glyphosate is slightly
toxic to wild birds. The dietary LC50 in both mallards
and bobwhite quail is greater than 4500 ppm .
- Effects on aquatic organisms: Technical
glyphosate acid is practically nontoxic to fish and may
be slightly toxic to aquatic invertebrates. The 96-hour
LC50 is 120 mg/L in bluegill sunfish, 168 mg/L in
harlequin, and 86 mg/L in rainbow trout . The
reported 96-hour LC50 values for other aquatic species
include greater than 10 mg/L in Atlantic oysters, 934
mg/L in fiddler crab, and 281 mg/L in shrimp . The
48-hour LC50 for glyphosate in Daphnia (water flea), an
important food source for freshwater fish, is 780 mg/L
. Some formulations may be more toxic to fish and
aquatic species due to differences in toxicity between
the salts and the parent acid or to surfactants used in
the formulation [58,96]. There is a very low potential
for the compound to build up in the tissues of aquatic
invertebrates or other aquatic organisms .
- Effects on other organisms: Glyphosate
is nontoxic to honeybees [1,58]. Its oral and dermal LD50
is greater than 0.1 mg/ bee . The reported contact
LC50 values for earthworms in soil are greater than 5000
ppm for both the glyphosate trimethylsulfonium salt and
- Breakdown in soil and groundwater:
Glyphosate is moderately persistent in soil, with an
estimated average half-life of 47 days [58,11]. Reported
field half-lives range from 1 to 174 days . It is
strongly adsorbed to most soils, even those with lower
organic and clay content [11,58]. Thus, even though it is
highly soluble in water, field and laboratory studies
show it does not leach appreciably, and has low potential
for runoff (except as adsorbed to colloidal matter)
[3,11]. One estimate indicated that less than 2% of the
applied chemical is lost to runoff . Microbes are
primarily responsible for the breakdown of the product,
and volatilization or photodegradation losses will be
- Breakdown in water: In water, glyphosate
is strongly adsorbed to suspended organic and mineral
matter and is broken down primarily by microorganisms
. Its half-life in pond water ranges from 12 days to
10 weeks .
- Breakdown in vegetation: Glyphosate may
be translocated throughout the plant, including to the
roots. It is extensively metabolized by some plants,
while remaining intact in others .
- Appearance: Glyphosate is a colorless
crystal at room temperature .
- Chemical Name: N-(phosphonomethyl)
- CAS Number: 1071-83-6
- Molecular Weight: 169.08
- Water Solubility: 12,000 mg/L @ 25 C 
- Solubility in Other Solvents: i.s. in
common organics (e.g., acetone, ethanol, and xylene) 
- Melting Point: 200 C 
- Vapor Pressure: negligible 
- Partition Coefficient: -3.2218 - -2.7696
- Adsorption Coefficient: 24,000
- ADI: 0.3 mg/kg/day 
- MCL: Not Available
- RfD: 0.1 mg/kg/day 
- PEL: Not Available
- HA: 0.7 mg/L (lifetime) 
- TLV: Not Available
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- Emergency: 314-694-4000
References for the information in this PIP can be found in
Reference List Number 10
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