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The information in this profile may be out-of-date.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

Maneb

Trade and Other Names: Trade names include Farmaneb, Manesan, Manex, Manzate, Nereb, and Newspor.

Regulatory Status: Maneb is a practically nontoxic ethylene(bis)dithiocarbamate in EPA toxicity class IV. It is registered as a General Use Pesticide (GUP). Labels for products containing mancozeb must bear the Signal Word CAUTION.

Chemical Class: ethylene(bis)dithicarbamate

Introduction: Maneb is an ethylene(bis)dithiocarbamate fungicide used in the control of early and late blights on potatoes and tomatoes and many other diseases of fruits, vegetables, field crops, and ornamentals. Maneb controls a wider range of diseases than other fungicides. It is available as granular, wettable powder, flowable concentrate, and ready-to-use formulations.

Formulation: It is available as granular, wettable powder, flowable concentrate, and ready-to-use formulations.

Toxicological Effects:

• Acute toxicity: Maneb is practically nontoxic by ingestion, with oral LD50 values of greater than 5000 mg/kg to 8000 in rats, and 8000 mg/kg in mice [1,3]. Via the dermal route, it is slightly toxic, with a dermal LD50 in rats of greater than 5000 mg/kg [3]. Inflammation or irritation of the skin, eyes, and respiratory tract have resulted from contact with maneb [1,8]. The 4-hour inhalation LC50 is greater than 3.8 mg/L, indicating slight toxicity. Acute exposure to maneb may result in effects such as hyperactivity and incoordination, loss of muscular tone, nausea, vomiting, diarrhea, loss of appetite, weight loss, headache, confusion, drowsiness, coma, slowed reflexes, respiratory paralysis, and death [1,8].
• Chronic toxicity: Rat feeding trials over 2 years showed no evidence of adverse health effects at dietary doses of about 12.5 mg/kg/day [1]. Goiter (increased thyroid weight) and reduced growth rate were seen in rats fed daily doses of 62.5 mg/kg/day after 97 days [10]. Dogs that received maneb orally at doses of 200 mg/kg/day for 3 or more months developed tremors, lack of energy, gastrointestinal disturbances, and incoordination. In addition, they experienced damage to the spinal cord but not the thyroid gland [1]. Rats that received 1500 mg/kg/day for 10 days showed weight loss, weakness of the hind legs, and increased mortality [1].
• Reproductive effects: Female rats that were given 50 mg/kg/day on every other day during gestation showed increased rates of embryo death and stillbirth, and decreased newborn survival [4]. In rats given a single dose of 770 mg/kg of maneb, the lowest dose tested, on the 11th day of gestation, early fetal deaths occurred [4]. In mice, the lowest single oral toxic dose administered during gestation which caused toxicity to the fetus was 1420 mg/kg [4]. It appears that a very high level of exposure is necessary to cause reproductive effects in humans, and this level of exposure is not likely under normal circumstances.
• Teratogenic effects: Fetal abnormalities of the eye, ear, body wall, central nervous system, and musculoskeletal system were seen in rats given single doses of 770 mg/kg [4]. Maneb is metabolized to ethylenethiourea (ETU), a compound which has been shown to cause birth defects in laboratory animals such as rats, mice, and hamsters [12]. From these data and information about other EBDCs, it is likely that maneb will not be teratogenic in humans under normal circumstances.
• Mutagenic effects: Several tests have shown that maneb is not mutagenic [10].
• Carcinogenic effects: In one study, maneb did not display significant carcinogenicity in laboratory tests with experimental animals [8]. In another study, malignant tumors were observed in rats which were given scrotal injections of 12.5 mg/kg body weight of 82.6% pure maneb [4]. Based on these data and evidence from other EBDCs, maneb is unlikely to cause cancer in humans [1,10].
• Organ toxicity: Target organs affected by maneb include the thyroid, kidneys, and heart.

• Fate in humans and animals: Animal studies show that maneb is readily absorbed through the gastrointestinal tract, and is rapidly eliminated. In rats, 55% of an administered dose of over 300 mg/kg was eliminated within 5 days [1]. A study in mice showed that elimination was mainly through the feces. The metabolites of maneb include ethylene diamine, ethylene(bis)thiurammonosulfide, and ethylenethiourea [1]. Maneb was not found to accumulate in the tissues of rats given 125 mg/kg/day over 2 years, nor in dogs given 75 mg/kg/day for 1 year [1].

Ecological Effects:

• Effects on birds: Maneb is practically nontoxic to birds; the 5-day dietary LC50 for maneb in bobwhite quail and mallard ducklings is greater than 10,000 ppm [34].

• Effects on aquatic organisms: Maneb is highly toxic to fish and aquatic species. The 96-hour LC50 for maneb is 1 mg/L in bluegill sunfish [34]. The reported 48-hour LC50 is 1.9 mg/L in rainbow trout, and 1.8 mg/L in carp [34]. The 72-hour LC50 is more than 40 mg/L in crayfish, and the 48-hour LC50 is 40 mg/L in tadpoles [34].
• Effects on other organisms: Maneb-treated crop foliage may be toxic to livestock [26]. The fungicide is not thought to be toxic to bees [3].

Environmental Fate:

• Breakdown in soil and groundwater: Maneb is similar in its environmental fate to mancozeb [20]. Like mancozeb, maneb is of low persistence (with a reported field half-life of 12 to 36 days) but it is readily transformed into ETU, which is more persistent [20]. Since it is strongly bound by most soils and is not highly soluble in water [20], it should not be very mobile. It therefore does not represent a significant threat to groundwater. Its breakdown product, ETU, may however be more highly mobile. Maneb breaks down under both aerobic and anaerobic soil conditions [4]. In one study, residues of maneb did not leach below the top 5 inches of soil [4].
• Breakdown in water: Maneb degraded completely within 1 hour under anaerobic aquatic conditions.
• Breakdown in vegetation: The main metabolite of maneb in plants is ethylenethiourea (ETU); this is then rapidly metabolized further. Significant amounts of ETU were formed in cooking vegetables that had been experimentally treated with maneb.

Physical Properties:

• Appearance: Maneb is a yellow powder with a faint odor [3]. It is a polymer of ethylene(bis)dithiocarbamate units linked with manganese.
• Chemical Name: manganese ethylenebis(dithiocarbamate) (polymeric) [3]
• CAS Number: 12427-38-2
• Molecular Weight: 265.29
• Water Solubility: 6 mg/L (estimated) [3]
• Solubility in Other Solvents: Practically insoluble in common inorganic solvents [3]
• Melting Point: Decomposes before melting @ approximately 192 C [3]
• Vapor Pressure: Negligible @ 20 C [3]
• Partition Coefficient: Not Available
• Adsorption Coefficient: <2000(estimate)

Exposure Guidelines:

• ADI: 0.03 mg/kg/day [33]
• MCL: Not Available
• RfD: 0.05 mg/kg/day [27]
• PEL: Not Available
• HA: Not Available
• TLV: Not Available

Basic Manufacturer:

ELF Atochem North America, Inc.
2000 Market Street
Philadelphia, PA 19103-3222

• Phone: 215-419-7219
• Emergency: 800-523-0900
  

References:

References for the information in this PIP can be found in Reference List Number 4

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.