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in 1996. EXTOXNET no longer updates this information, but it may be useful
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E X T O X N E T
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University of Idaho, and the University of California at Davis
and the Institute for Environmental Toxicology, Michigan State
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USDA/Extension Service/National Agricultural Pesticide Impact
EXTOXNET primary files maintained and archived at Oregon State
Revised June 1996
Trade and Other Names:
Trade or other names for metiram include arbatene, NIA 9102,
Polyram, Polyram-Combi, and Zinc metiram.
Metiram is a practically nontoxic compound in EPA toxicity class
IV. Labels for products containing it must bear the Signal Word
CAUTION. It is a General Use Pesticide (GUP).
Metiram may be used to prevent crop damage in the field, during
storage, or transport. Metiram is effective against a broad
spectrum of fungi and is used to protect fruits, vegetables,
field crops, and ornamentals from foliar diseases and damping
- Acute toxicity: Metiram is practically
nontoxic when ingested, with reported oral LD50 values of
greater than 6180 mg/kg to greater than 10,000 mg/kg in
rats, greater than 5400 mg/kg in mice, and 2400 to 4800
mg/kg in guinea pigs [1,4]. The dermal LD50 is greater
than 2000 mg/kg in rats, indicating slight toxicity .
It is reported to be a mild skin and eye irritant .
Via the inhalation route, it is slightly toxic with a
reported 4-hour inhalation LC50 of greater than 5.7 mg/L
. Metiram is a cholinesterase inhibitor. Early
symptoms of cholinesterase inhibition are blurred vision,
fatigue, headache, vertigo, nausea, pupil contraction,
abdominal cramps, and diarrhea. Severe inhibition of
cholinesterase may cause excessive sweating, tearing,
slowed heartbeat, giddiness, slurred speech, confusion,
excessive fluid in the lungs, convulsions, and coma.
- Chronic toxicity: When rats were fed
metiram at dietary doses of 50 mg/kg/day 5 days a week
for 2 weeks, no symptoms of illness were produced.
Adverse effects did occur at 500 mg/kg/day . No
ill-effect was observed in dogs that received 45 mg/kg
daily of the fungicide for 90 days, or 7.5 mg/kg daily
for almost 2 years . When metiram was fed to rats at
dietary doses of 0.25, 1, 4, or 16 mg/kg/day, the only
effect observed was muscle atrophy in rats receiving 16
mg/kg/day . The major toxicological concern in
situations of chronic exposure to metiram, however, is
ethylenethiourea (ETU), a contaminant and a breakdown
product of metiram that has been shown to cause birth
defects and cancer in experimental animals.
- Reproductive effects: Pregnant rats fed
80 and 160 mg/kg/day exhibited reduced rates of body
weight gain. Litter size was reduced for rats fed 0.25, 2
or 16 mg/kg/day metiram. Rats receiving the 16 mg/kg/day
dose also exhibited decreases in parental body weight and
in food consumption . The evidence suggests that
reproductive effects are unlikely in humans under normal
- Teratogenic effects: No teratogenic
effects were found in female rats fed 40, 80 and 160
mg/kg/day of metiram [1,11].
- Mutagenic effects: The majority of
mutagenicity studies on metiram have been negative. Out
of six tests performed, only one highly sensitive test
indicated that metiram may be mutagenic [10,11]. These
data indicate that metiram is either nonmutagenic or
- Carcinogenic effects: All of the EBDC
pesticides can be degraded or metabolized into
ethylenethiourea (ETU), which has been shown to produce
cancer in mice and rats . However, other EBDCs do not
appear to be carcinogenic. There were no data available
regarding the carcinogenic properties of metiram itself.
- Organ toxicity: No data were available
regarding the target organs of metiram. It is likely that
its target organs will be similar to those affected by
closely related compounds such as maneb and mancozeb.
Those compounds exert their principal effects on the
- Fate in humans and animals: Metiram is
not well absorbed through the skin; less than 1% of a 240
mg/kg dose, applied topically, was absorbed through the
skin of rats after 8 hours . Metabolic fate studies
in rats indicate that ingested metiram is readily
absorbed by the body and eliminated through the urine and
feces. Residues remaining in the body were highest in the
kidneys, thyroid, and gastrointestinal tract and were
higher in females than in males . In mammalian
tissues the ethylene(bis)dithiocarbamates break down into
- Effects on birds: Metiram is slightly
toxic to birds, with 5- to 8-day LC50 values in both
mallard ducks and bobwhite quail of greater than 3712 ppm
- Effects on aquatic organisms: Metiram is
slightly to moderately toxic to fish; reported 96-hour
LC50 values are 85 mg/L in carp and 1.1 mg/L in rainbow
trout [1,11]. The 48-hour LC50 for metiram in harlequin
fish is 17 mg/L [1,11].
- Effects on other organisms: Metiram is
practically nontoxic to bees; the reported oral LD50 is
greater than 40 ug per bee, and the contact LD50 is
reported to be greater than 16 ug per bee .
- Breakdown in soil and groundwater:
Metiram is probably similar in its environmental fate to
closely related compounds such as maneb and mancozeb.
They are of low persistence and are strongly bound to
most soils . This property, and their low water
solubilities, indicate that they probably do not pose a
significant risk to groundwater. They are unstable in the
presence of atmospheric moisture and oxygen and are
rapidly degraded in biological systems to ETU and other
metabolites . These products are of moderate
persistence and more mobile, and therefore may pose a
slight risk to groundwater. ETU, the primary metabolite
of metiram in water, has been detected (at 0.016 mg/L) in
only 1 out of 1295 drinking water wells tested .
- Breakdown in water: Breakdown of metiram
to ETU is very rapid, mainly by hydrolysis, and to a
lesser degree by photodegradation .
- Breakdown in vegetation: Metiram is not
taken up by plants to a significant degree .
- Appearance: Metiram is a yellow powder
at room temperature .
- Chemical Name: zinc ammoniate
- CAS Number: 9006-42-2
- Molecular Weight: 1088.70
- Water Solubility: <1 mg/L 
- Solubility in Other Solvents:
practically insoluble in most organic solvents 
- Melting Point: Decomposes at 140 C 
- Vapor Pressure: 0.01 mPa @ 20 C 
- Partition Coefficient: 0.3010 
- Adsorption Coefficient: 500,000
- ADI: 0.03 
- MCL: Not AVailable
- RfD: Not Available
- PEL: Not Available
- HA: Not Available
- TLV: Not Available
Agricultural Products Group
P.O. Box 13528
Research Triangle Park, NC 27709-3528
- Phone: 800-669-2273
- Emergency: 800-832-4357
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