United States
Environmental Protection
Agency
Office of Water
4601
EPA811-F-95-003q-T
October 1995
National Primary Drinking
Water Regulations
Glyphosate
CHEMICAL/ PHYSICAL PROPERTIES
CAS NUMBER: 1071-83-6
COLOR/ FORM/ODOR:
Odorless white crystals
M.P.:230°C B.P.: N/A
VAPOR PRESSURE: Negligible
OCTANOL/WATER PARTITION (Kow): N/A
DENSITY/SPEC. GRAV.: 0.5g/ml at 15° C
SOLUBILITY: 12 g/L of water at 25° C;
Soluble in water
SOIL SORPTION COEFFICIENT:
Strong, reversible adsorption
ODOR/TASTE THRESHOLDS: N/A
HENRY'S LAW COEFFICIENT: N/A
BlOCONCENTRATION FACTOR:
BCF <1 in fish; not expected to biocon-
centrate in aquatic organisms.
TRADE NAMES/SYNONYMS:
N-(phosphonomethyl) glycine; Glialka;
Roundup; Sting; Rodeo; Spasor;
Muster; Tumbleweed; Sonic; Glifonox;
Glycel; Rondo
DRINKING WATER STANDARDS
MCLG: 0.7 mg/L
MCL: 0.7 mg/L
HAt(child): 1- to 10- day: 20 mg/L
Longer-term: 1 mg/L
HEALTH EFFECTS SUMMARY
Acute: EPA has found glyphosate to potentially cause
the following health effects from acute exposures at
levels above the MCL: congestion of the lungs; increased
breathing rate.
Drinking water levels which are considered "safe" for
short-term exposures: For a 10-kg (22 Ib.) child consum-
ing 1 liter of water per day, upto a ten-day exposure to 20
mg/L or up to a 7-year exposure to 1 mg/L.
Chronic: Glyphosate has the potential to cause the
following health effects from long-term exposures at
levels above the MCL: kidney damage, reproductive
effects.
Cancer: There is inadequate evidence to state whether
'or not glyphosate has the potential to cause cancer from
a lifetime exposure in drinking water.
USAGE PATTERNS
beans, field-corn; ornamentals, lawns, turf, forest plant-
ings, greenhouses, rights-of-way.
Glyphosate is among the most widely used pesticides
by volume. In 1986, an estimated 6,308,000 pounds of
glyphosate was used in the United Sates. Usage in 1990
was estimated to be 11,595,000 pounds. It ranked elev-
enth among conventional pesticides in the US during
1990-91. In recent years, 13 to 20 million acres were
treated with 18.7 million Ibs. annually. Glyphosate is
generally sold as the isopropylamine salt and applied as
a liquid foliar spray.
RELEASE PATTERNS
Glyphosate is released to the environment in its use as
a herbicide for controlling woody and herbaceous weeds
on forestry, right-of-way, cropped and non-cropped sites.
These sites may be around water and in wetlands.
It may also be released to the environment during its
manufacture, formulation, transport, storage, disposal
and cleanup, and from spills. Since glyphosate is not a
listed chemical in the Toxics Release Inventory, data on
releases during its manufacture and handling are not
available.
ENVIRONMENTAL FATE
Glyphosate is a non-selective herbicide registered for Glyphosate is most often applied as a spray of the
•se on many food and non-food crops as well as non- isopropylamine salt and is removed from the atmosphere
crop areas where total vegetation control is desired. bV gravitational settling. After glyphosate is applied to
When applied at lower rates, it serves as a plant growth forests- fields' and other land bv spraying, it is strongly
regulator. The most common uses include control of adsorbed to soil, remains in the upper soil layers, and has
broadleaf weeds and grasses in : hay/pasture, soy- a Iow Propensity for leaching. Iron and aluminum clays
and organic matter adsorbed more glyphosate than
October 1995
Technical Version
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sodium and calcium clays and was readily bound to
kaolinite, illite, bentonite, charcoal and muck but not to
ethyl cellulose.
Glyphosate readily and completely biodegrades in soil
even under low temperature conditions. Its average half-
life in soil is about 60 days. Biodegradation in foliage and
litter is somewhat faster. In field studies, residues are
often found the following year.
Glyphosate may enter aquatic systems through acci-
dental spraying, spray drift, or surface runoff. It dissipates
rapidly from the water column as a result of adsorption
and possibly biodegradation. The half-life in water is a
few days. Sediment is the primary sink for glyphosate.
After spraying, glyphosate levels in sediment rise and
then decline to low levels in a few months. Due to its ionic
state in water, glyphosate would not be expected to
volatilize from water or soil.
Based on its water solubility, glyphosate is not ex-
pected to bioconcentrate in aquatic organisms. It is
minimally retained and rapidly eliminated in fish, birds,
and mammals. The BCF of glyphosate in fish following a
10-14 day exposure period was 0.2 to 0.3.
Occupational workers and home gardeners may be
exposed to glyphosate by inhalation and dermal contact
during spraying, mixing, and cleanup. They may also be
exposed by touching soil and plants to which glyphosate
was applied. Occupational exposure may also occur
during glyphosate's manufacture, transport storage, and
disposal.
OTHER REGULATORY INFORMATION
MONITORING:
FOR GROUND/SURFACE WATER SOURCES:
INITIAL FREQUENCY- 4 quarterly samples every 3 years
REPEAT FREQUENCY- If no detections during initial round:
2 quarterly per year if serving >3300 persons;
1 sample per 3 years for smaller systems
TRIGGERS - Return to Initial Freq. if detect at > 0.006 mg/L
ANALYSIS:
REFERENCE SOURCE METHOD NUMBERS
EPA 600/4-88-039 547
Standard Methods 6651
TREATMENT:
BEST AVAILABLE TECHNOLOGIES
Granular Activated Charcoal
FOR ADDITIONAL INFORMATION:
* EPA can provide further regulatory and other general information:
• EPA Safe Drinking Water Hotline - 800/426-4791
* Other sources of lexicological and environmental fate data include:
• Toxic Substance Control Act Information Line - 202/554-1404
• Toxics Release Inventory, National Library of Medicine - 301/496-6531
• Agency for Toxic Substances and Disease Registry - 404/639-6000
• ???National Pesticide Hotline - 800/858-7378
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