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The information in this profile may be out-of-date.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

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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

Chloramben

Trade and Other Names: The trade names and synonyms for chloramben are Ambiben, Amiben, Amiben DS, Chlorambene, Ornamental Weeder, and Vegiben.

Regulatory Status: Chloramben is classified as a General Use Pesticide (GUP) by the U.S. Environmental Protection Agency. A toxicity class IV pesticide, chloramben is practically nontoxic. Chloramben products bear the Signal Word CAUTION. It is no longer produced or sold in the U.S.

Chemical Class: benzoic acid compound

Introduction: Chloramben is a selective, preemergence benzoic acid herbicide that is primarily soil-applied to control annual grass and broadleaved weed seedlings. It is mostly used for soybeans, but it is also used for dry beans, peanuts, sunflowers, peppers, cotton, sweet potatoes, squash, hardwood trees, shrubs, and some conifers. Chloramben inhibits seedling root development and causes plants to bend and die as they emerge from the soil.

Formulation: Not Available

Toxicological Effects:

• Acute toxicity: The oral LD50 for chloramben in rats is 3500 mg/kg [5,7] and in mice is 3725 mg/kg. Chloramben irritates the throat, lungs, skin, and the eyes. However, chloramben is not known to move through the skin. On rats, a low dose skin application caused mild irritation that subsided within 24 hours [7]. The dermal LD50 for rabbits is 3136 mg/kg [6,7]; and for albino rats, it is greater than 3160 mg/kg. This indicates that chloramben has about the same toxicity when applied to the skin as when ingested. The major health concern for humans is dermatitis resulting from skin exposure to chloramben.
• Chronic toxicity: In long-term tests on rats, mice, and dogs, no chloramben-related effects on body weight, body function, and organs were observed, even at very high concentrations [7,10].
• Reproductive effects: No effects on fertility, survival of the fetus, or on nursing ability were found in a long-term study of rats fed large daily doses of chloramben [9]. These data suggest that chloramben does not cause reproductive toxicity.
• Teratogenic effects: When pregnant rabbits were given high doses of chloramben during the sensitive period of gestation, no developmental defects were seen in the fetuses. Pregnant rats fed lower doses of chloramben during the sensitive period of gestation were not affected, but fetal deaths increased and fetal skeletal development was not complete. At even lower doses, no increase in fetal deaths was seen, but the bones were not fully developed. No changes were seen at the lowest doses [9]. This evidence indicates that chloramben is unlikely to cause teratogenic effects at expected exposure levels.
• Mutagenic effects: Most bacterial and mammalian cell assays of chloramben indicate that it is not toxic to genetic material. However, mutagenicity was seen in one test using Chinese hamster ovary cells [9]. These data suggest chloramben shows slight or no mutagenic potential.
• Carcinogenic effects: Rats given high daily doses of chloramben for 80 weeks did not show carcinogenicity. But mice given similar doses (up to 300 mg/kg) each day for 80 weeks developed cancerous tumors [7]. Thus, the carcinogenic status of chloramben is not clear.
• Organ toxicity: Long-term animal studies did not show evidence of chronic injury to the organs examined.

• Fate in humans and animals: Several animal studies have shown that once ingested, chloramben is rapidly excreted in the urine and feces, with no residues found in tissues. Very small amounts of chloramben fed daily to lactating cows left the body via urine (88%) and the feces (5%) within 4 days. No residues were found in the milk [7]. Similarly, dogs fed very small amounts showed rapid chloramben excretion, with no residues found in the tissues [7]. Chloramben is quickly absorbed from the gastrointestinal tract of female rats. About 97% of an oral dose is absorbed and then excreted through the urine and expired air. In rats fed a single dose, 70% of that recovered 24 hours later from the urine was the original compound. Only 0.6% of the dose remained in the body after 3 to 4 days [9].

Ecological Effects:

• Effects on birds: The LC50 of chloramben is 4640 mg/l in mallard ducks, indicating that the compound is practically nontoxic to this species [6].
• Effects on aquatic organisms: Chloramben is not toxic to fish [5].
• Effects on other organisms: Chloramben is not toxic to bees [6,7].

Environmental Fate:

• Breakdown in soil and groundwater: Chloramben is active in the soil. It is moderately persistent. The wetter the soil, the greater the toxicity of this compound to target plants. Rainfall or irrigation within 10 to 14 days of application is needed for chloramben to be effective against weeds. In a soil solution, chloramben formulations readily break down into forms which are quite mobile in the soil [34]. Thus, much of it is lost from the soil due to leaching, although some loss is due to breakdown by soil microorganisms. Leaching is greatest in sandy soil [5]. As the organic matter content of the soil increases, binding of chloramben also increases, and leaching decreases. Like most preemergence herbicides, the activity is nearly the same on muck soils as on mineral soils. In general, chloramben activity lasts for about 6 to 8 weeks in soil [6,21]. The compound does not evaporate appreciably. Of 188 groundwater samples tested, chloramben was found in only one, at a concentration of 0.0017 mg/L [9].
• Breakdown in water: Chloramben readily degrades in water exposed to sunlight [9].
• Breakdown in vegetation: Chloramben reacts with plant constituents to form a stable and nontoxic product in both susceptible and tolerant plants. The ease of formation of this metabolite seems to be the reason the herbicide is not totally degraded within the plant [5]. When soil-applied, plant roots are the primary site of absorption and chloramben action. Roots of resistant species, like soybeans, can absorb large amounts of the compound, but translocate very little of it to the above-ground portions of the plant. In contrast, the susceptible barley plant translocates a significant amount into its leaves, and thus dies [5].

Physical Properties:

• Appearance: Chloramben is a colorless and odorless crystalline solid [6].
• Chemical Name: 3-amino-2,5-dichlorobenzoic acid [6]
• CAS Number: 133-90-4
• Molecular Weight: 206.03
• Water Solubility: 700 mg/L @ 25 C [6]
• Solubility in Other Solvents: alcohol v.s.; ether s.; acetone v.s.; ethanol v.s. [6]
• Melting Point: 200-201 C [6]
• Vapor Pressure: 930 mPa @ 100 C [6]
• Partition Coefficient: Not Available
• Adsorption Coefficient: 15 (estimated) (salts at pH < 5) [21]

Exposure Guidelines:

• ADI: Not Available
• MCL: Not Available
• RfD: 0.015 mg/kg/day [31]
• PEL: Not Available
• HA: 0.1 mg/L (lifetime) [9]
• TLV: Not Available

Basic Manufacturer:

Chloramben is no longer produced or sold in the U. S.

Not Available

• Phone: Not Available
• Emergency: Not Available
  

References:

References for the information in this PIP can be found in Reference List Number 7

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.