Technical Factsheet on: GLYPHOSATE
List of Contaminants
As part of the Drinking Water and Health pages, this fact sheet is part of a larger publication:
National Primary Drinking Water Regulations
Drinking Water Standards
MCLG: 0.7 mg/L
MCL: 0.7 mg/L
HAL(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 lb.) child consuming 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
Glyphosate is a non-selective herbicide registered for use on
many food and non-food crops as well as non-crop areas where
total vegetation control is desired. When applied at lower rates,
it serves as a plant growth regulator. The most common uses
include control of broadleaf weeds and grasses in : hay/pasture,
soybeans, field corn; ornamentals, lawns, turf, forest plantings,
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 eleventh among conventional pesticides in the
US during 1990-91. In recent years, 13 to 20 million acres were
treated with 18.7 million lbs. 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 most often applied as a spray of the isopropylamine
salt and is removed from the atmosphere by gravitational
settling. After glyphosate is applied to forests, fields, and
other land by spraying, it is strongly adsorbed to soil, remains
in the upper soil layers, and has a low propensity for leaching.
Iron and aluminum clays and organic matter adsorbed more
glyphosate than 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 accidental 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 expected 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.
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
Bioconcentration Factor: BCF <1 in fish; not expected to
bioconcentrate in aquatic organisms.
Trade Names/Synonyms: N-(phosphonomethyl) glycine; Glialka;
Roundup; Sting; Rodeo; Spasor; Muster; Tumbleweed; Sonic;
Glifonox; Glycel; Rondo
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 toxicological 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
List of Contaminants
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