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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.

Sodium chlorate

Publication Date: 9/95


The active ingredient sodium chlorate is found in a variety of commercial herbicides. Some trade names for products containing sodium chlorate include Atlacide, Defol, De-Fol-Ate, Drop-Leaf, Fall, Harvest-Aid, Kusatol, Leafex, and Tumbleaf. The compound may be used in combination with other herbicides such as atrazine, 2,4-D, bromacil, diuron, and sodium metaborate (1, 2, 3, 4).


Sodium chlorate is not a restricted use pesticide. Check with specific state restrictions which may apply. Products containing the active ingredient sodium chlorate must bear the Signal Word "Warning" on their label (4).


Sodium chlorate is a non-selective herbicide. It is considered phytotoxic to all green plant parts. It can also kill through root absorption. Sodium chlorate may be used to control morningglory, Canada thistle, johnsongrass and St. Johnswort (3, 5). The herbicide is mainly used on non-crop land for spot treatment and for total vegetation control on roadsides, fenceways, ditches, etc. Sodium chlorate is also used as a defoliant and desiccant for cotton, safflower, corn, flax, peppers, soybeans, grain sorghum, southern peas, dry beans, rice and sunflowers (1, 5). If used in combination with atrazine, it increases the persistance of the effect. If used in combination with 2,4-D, it improves performance of the material. Sodium chlorate has a soil-sterilant effect. Mixing with other herbicides in aqueous solution is possible to some extent, so long as they are not susceptible to oxidation (1)

Sodium chlorate comes in dust, spray and granule formulations. There is a risk of fire and explosion in dry mixtures with other substances, especially organic materials, i.e. other herbicides, sulphur, powdered metals, strong acids, etc. (1). Marketed formulations contain a fire depressant (2).



The acute oral LD50 for sodium chlorate in rats ranged between 1,200- 7,000 mg/kg (1, 2, 3, 4, 6). The compound was a mild skin irritant in rabbits (6). The dermal LD50 was 500 mg/kg over 24 hours (4, 6, 7). The oral LD50 was 7,200 mg/kg for rabbits (6). The acute toxicity values for mice were 8,350 mg/kg for the oral toxicity and 596 mg/kg for the intraperitoneal LD50 (6). Another study found sodium chlorate to have an oral LDlo of 700 mg/kg for dogs; and an oral LDlo of 1350 mg/kg for cats (6).

A single dose of 5-10 g/person of sodium chlorate can prove to be fatal in adults, as can a single dose of 2 g/child in small children. Another source reported that a dose of 15 to 30 g/person may be fatal to humans (5). Irritation of the skin, eyes, and mucous membranes has been noted (1, 2, 3). Symptoms of oral ingestion of sodium chlorate include abdominal pain, nausea, vomiting, diarrhea, pallor, blueness, shortness of breath, unconsciousness and collapse (3, 6).


Chronic exposure may render lack of appetite and weight loss, as well as all those symptoms listed under acute exposure to sodium chlorate. A prolonged chronic exposure to inhalation of sodium chlorate may cause mucous membrane irritation (6).

Reproductive Effects

No information was available.

Teratogenic Effects

No information was available.

Mutagenic Effects

No information was available.

Carcinogenic Effects

No carcinogenic effects were noted for sodium chlorate (6).

Organ Toxicity

Sodium chlorate may affect blood cells and damage kidneys. Acute exposure to the compound may damage the liver. The kidney tubules may be severely damaged without producing detectable methemoglobinemia. Repeated ingestion of small doses may cause anorexia and weight loss (6).

Fate in Humans and Animals

No information was found.


Effects on Birds

The long-term toxicity of sodium chlorate to birds resulted in reduced egg production and fertility (8).

Effects on Aquatic Organisms

Sodium chlorate is considered non-toxic to fish. The possible 48-hour LC50 for various species of fish was 10,000 mg/l (1).

Effects on Other Animals (Nontarget species)

Sodium chlorate is considered non-toxic to bees (1). Toxicity to animals may occur if they feed on freshly treated areas. This chemical has a salty taste and salt-hungry animals may eat enough to become poisoned (5).


Breakdown of Chemical in Soil and Groundwater

The duration of residual activity for sodium chlorate in soil was 3-4 months after using 1,000 liters of a 1% solution/ha (1). Sodium chlorate may persist in soil for 6 months to 5 years, depending on rate applied, soil type, fertility, organic matter, moisture, and weather conditions. Toxicity in soil is decreased considerably by a high nitrate content, alkaline conditions, and high soil temperatures. Decomposition of the compound occurs more readily in moist soils above 70 degrees F (5).

Breakdown of Chemical in Surface Water

No information was available.

Breakdown of Chemical in Vegetation

Plants absorb sodium chlorate through both roots and leaves. The herbicide is carried downward through the xylem since it kills the phloem tissue. It also increases the rate of respiration, decreasing catalase activity, and depleting the plant's food reserves. Chlorate-injured plants are more susceptible to frost. Sodium chlorate is 30-50 times more toxic to plants than sodium chloride (table salt) (5).


Physical Properties:

CAS No.: 7775-09-9 (1)
Chemical name: Sodium chlorate
Chemical Class/Use: Non-selective contact herbicide; defoliant, dessiccant, harvest aid (4)
Specific gravity: 2.490 at 15 degrees C (3)
Solubility in water: In water at 0 degrees C, 79 g/100 ml; at 100 degrees C, 230 g/100 ml (1, 2, 3)
Solubility in other solvents: In 90% alcohol, 1.6 g/100 g (1); soluble in ethanol and glycerol (2)
Melting point: 248 degrees C (1, 2, 3); 478-502 degrees F (6)
Decomposition temperature: 300 degrees C (1)
Vapor pressure: Zero (1)


Drexel Chemical Co.
2487 Pennsylvania St.
Memphis, TN 38109
Fax: 901-774-4666
Telephone: 901-774-4370

Review by Basic Manufacturer:

Comments solicited: October, 1994
Comments received: December, 1994

Wilbur-Ellis Co.
320 California Street
San Francisco, CA 94104
Fax: 415-772-4011
Telephone: 415-772-4000
Emergency: 209-226-1934

Review by Basic Manufacturer:

Comments solicited: October, 1994
Comments received:


  1. The Agrochemicals Handbook. 1983. The Royal Society of Chemistry, The University, Nottingham, England.
  2. Worthing, C. R. (ed.). 1983. The Pesticide Manual: A World Compendium. Seventh edition. Published by The British Crop Protection Council.
  3. Herbicide Handbook of the Weed Science Society of America. 1989. Sixth edition. Champaign, IL.
  4. Farm Chemicals Handbook. 1994. Meister Publishing Co. Willoughby, OH.
  5. Thomson, W. T. 1992. Agricultural Chemicals. Book II: Herbicides. Thomson Publications, Fresno, CA.
  6. OHS Database. 1993. Occupational Health Services, Inc. 1993 (August) MSDS for Sodium chlorate. OHS Inc., Secaucus, NJ.
  7. U.S. Environmental Protection Agency. 1986. Office of Pesticides. TOX Oneliners -- Sodium chlorate. May, 1986.
  8. Briggs, S. A. 1992. Basic Guide to Pesticides: Their Characteristics and Hazards. Hemisphere Publishing Corp., Washington, Philadelphia, London.