E X T O X N E T
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
Publication Date: 9/93
TRADE OR OTHER NAMES
Some trade names include Molinate, Hydram, Ordram and Yalan.
Molinate is a registered as a general use pesticide by the EPA. Products
containing molinate must bear the signal word "Warning" or "Caution" (4).
Molinate is a selective herbicide which belongs to the thiocarbamate
chemical class. It is used to control weeds in rice paddies (1, 4, 6, 8). It
is toxic to germinating broad-leafed and grassy weeds. Molinate is available
in granular and emulsifiable liquid formulations (4).
Molinate is moderately toxic by ingestion and slightly toxic by dermal
absorption . It may cause skin irritation or sensitization (9, 10). Symptoms
of exposure to molinate include nausea, diarrhea, abdominal pain, fever,
weakness and conjunctivitis (3, 9).
Molinate is volatile and may be irritating when inhaled (11). Inhalation
exposure to large amounts of thiocarbamates may cause itching, scratchy
throat, sneezing and coughing (9). In male rats, the lowest dosage that will
produce a toxic effect when inhaled (TDlo) is 0.6 to 0.64 mg/m3 over 6 hours
of exposure (NIOSH RTECS Online File # 85/8406).
The amount of a chemical that is lethal to one-half (50%) of experimental
animals fed the material is referred to as its acute oral lethal dose fifty,
or LD50. The oral LD50 for molinate is 369-955 mg/kg in rats, and 530 mg/kg
in mice (3, 9). For granular formulations (10G) the oral LD50 in rats is
greater than 5,000 mg/kg (4). The dermal LD50 for the rabbit is 3536 to
greater than 10,000 mg/kg (3, 4). The inhalation LCLO for molinate in both
rats and cats is 200 mg/m3 (9). An LCLO is the lowest dose to produce deaths
in test animals.
Prolonged or repeated exposure to molinate may cause symptoms similar to
the pesticide's acute effects. Chronic dermal exposure may cause
sensitization dermatitis or conjunctivitis.
Administration of molinate to young male rats at a rate of 3.2 mg/kg/ day
for 2 months caused changes in spermatozoa but did not decrease sperm
fertility. When these rats were mated to normal females, many of the embryos
were resorbed and postnatal mortality was increased (3).
Molinate is suspected of being a human teratogen (10).
No information found.
No information found.
Molinate causes conjunctivitis (swelling of the tender inner layer of the
eyelid) (10). Chronic exposure of test animals inhibited thyroid functions
and decreased energy metabolism (9).
Fate in Humans and Animals
Molinate is only fairly well absorbed through oral, dermal and inhalation
exposure. It is metabolized in the liver. No accumulation occurs. Excretion
is primarily through the urine with a small amount lost in the feces.
Excretion of radio-labeled molinate by rats was 95-96% complete in 48 hours.
Approximately 88% of the eliminated molinate was in the urine and 11% in the
feces. Less than 1% was expired to the air (3).
Harmful Effects on Birds
Molinate appears to be fairly low in toxicity to birds such as mallards.
Harmful Effects on Fish
The toxicity of molinate varies in fish. The lethal concentration fifty,
or LC50, is that concentration of a chemical in air or water that kills half
of the experimental animals exposed to it for a set time period. The 96-hour
LC50 is 1.3 mg/l for rainbow trout and 30 mg/l for goldfish (4, 8). Cold
water fish species seem to be more susceptible to molinate poisoning than
others (Spence. Guide to Chem. in Crop Protection 1982). In some species,
like carp, molinate produces anemia.
Effects on Other Animals (Nontarget species)
The symptoms of poisoning in wildlife species are similar to those in
humans, and may include excessive salivation and tearing of the eyes,
difficulty walking, weakness, tremors, and labored breathing (Rumack.
Breakdown of Chemical in Soil and Water
Because molinate is highly soluble in water and because it has a soil
half-life of moderate duration (12 days), it is expected to have a large
potential to contaminate groundwater. Molinate binds strongly to soil
Soil microorganisms are responsible for most of the breakdown of
molinate. It is relatively stable to breakdown by hydrolysis (3). When
applied at recommended rates, it does not persist in soil. Molinate has a
soil half-life of 3 weeks (4, 8).
Molinate rapidly volatilizes if the soil is wet. To prevent loss of the
herbicide to evaporation, molinate should be plowed into the soil. Molinate
may be broken down by sunlight once in the air (J. Environ. Sci. Health B. 15
Breakdown of Chemical in Water
Some hydrolysis occurs in the breakdown of molinate (8).
Breakdown of Chemical in Vegetation
Molinate is rapidly taken up by plant roots and transported to the
leaves. In the leaves, molinate inhibits leaf growth and development (2, 8).
It is rapidly metabolized in non-susceptible plants. Resistant plants produce
carbon dioxide and other naturally occurring plant products such as amino
acids, organic acids, etc. (7).
PHYSICAL PROPERTIES AND GUIDELINES
Molinate is a non-corrosive, clear liquid with an aromatic or spicey odor
(3, 9). It is stable under normal temperatures and pressures, but thermal
decomposition may release toxic oxides of nitrogen and sulfur (9).
Like the organophosphates and other carbamates, molinate has several
important drug interactions. Poisoning victims should not be given any of the
following drugs: morphine, aminophylline or theophylline, major tranquilizers
(phenothiazines) or reserpine, high ceiling diuretics like furosemide (lasix)
or ethacrynic acid (12).
Occupational Exposure Limits:
No occupational exposure limits have been established for molinate by
OSHA, ACGIH or NIOSH (9).
|CAS #: ||2212-67-1
|Solubility in Water: ||800 mg/L at 21 degrees C (3, 5) or 0.088% (9).
|Solubility in other solvents: ||Molinate is soluble in acetone, benzene, 2-propanol, methanol, xylene, ethanol, kerosene, and 4-methylpentan-2-one (9).
|Boiling point: ||202 degrees C at 10 mm Hg (3, 5).
|Flash point: ||139 degrees C (2).
|Specific gravity: ||1.0626-1.0669 at 20 degrees/20 degrees C (4)
|Vapor pressure: ||0.0056 mm Hg at 25 degrees C (3, 13).
|Density: ||1.5156 at 30 degrees C (Spencer. guide to chem. in crop protection. 1982).
|Koc: ||50 g/ml (7).
Zeneca Ag Products
Wilmington, DE 19897
Review by Basic Manufacturer:
Comments solicited: November, 1992
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Meister Publishing Co.
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Hayes, W.J. and E.R. Laws (ed.). 1990. Handbook of Pesticide
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