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EXTOXNET primary files maintained and archived at Oregon State
Revised June 1996
Trade and Other Names:
Trade names include Farmaneb, Manesan, Manex, Manzate, Nereb, and
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.
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
- 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 .
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 . Goiter
(increased thyroid weight) and reduced growth rate were
seen in rats fed daily doses of 62.5 mg/kg/day after 97
days . 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 . Rats that
received 1500 mg/kg/day for 10 days showed weight loss,
weakness of the hind legs, and increased mortality .
- 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 . 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 . In mice, the lowest single oral
toxic dose administered during gestation which caused
toxicity to the fetus was 1420 mg/kg . 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 . 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 . From these data and
information about other EBDCs, it is likely that maneb
will not be teratogenic in humans under normal
- Mutagenic effects: Several tests have
shown that maneb is not mutagenic .
- Carcinogenic effects: In one study,
maneb did not display significant carcinogenicity in
laboratory tests with experimental animals . 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 . 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 . A study in mice showed that
elimination was mainly through the feces. The metabolites
of maneb include ethylene diamine,
ethylene(bis)thiurammonosulfide, and ethylenethiourea
. 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 .
- 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 .
- 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 . The reported 48-hour LC50
is 1.9 mg/L in rainbow trout, and 1.8 mg/L in carp .
The 72-hour LC50 is more than 40 mg/L in crayfish, and
the 48-hour LC50 is 40 mg/L in tadpoles .
- Effects on other organisms:
Maneb-treated crop foliage may be toxic to livestock
. The fungicide is not thought to be toxic to bees
- Breakdown in soil and groundwater: Maneb
is similar in its environmental fate to mancozeb .
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
. Since it is strongly bound by most soils and is not
highly soluble in water , 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 . In one
study, residues of maneb did not leach below the top 5
inches of soil .
- Breakdown in water: Maneb degraded
completely within 1 hour under anaerobic aquatic
- 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.
- Appearance: Maneb is a yellow powder
with a faint odor . It is a polymer of
ethylene(bis)dithiocarbamate units linked with manganese.
- Chemical Name: manganese
ethylenebis(dithiocarbamate) (polymeric) 
- CAS Number: 12427-38-2
- Molecular Weight: 265.29
- Water Solubility: 6 mg/L (estimated) 
- Solubility in Other Solvents:
Practically insoluble in common inorganic solvents 
- Melting Point: Decomposes before melting
@ approximately 192 C 
- Vapor Pressure: Negligible @ 20 C 
- Partition Coefficient: Not Available
- Adsorption Coefficient: <2000(estimate)
- ADI: 0.03 mg/kg/day 
- MCL: Not Available
- RfD: 0.05 mg/kg/day 
- PEL: Not Available
- HA: Not Available
- TLV: Not Available
ELF Atochem North America, Inc.
2000 Market Street
Philadelphia, PA 19103-3222
- Phone: 215-419-7219
- Emergency: 800-523-0900
References for the information in this PIP can be found in
Reference List Number 4
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