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

Molinate

Trade and Other Names: Trade names include Hydram, Molinate, Ordram, and Yalan.

Regulatory Status: Molinate is a slightly to moderately toxic compound in EPA toxicity class III, and is a registered as a General Use Pesticide (GUP). Products containing molinate must bear the Signal Word WARNING or CAUTION.

Chemical Class: thiocarbamate

Introduction: Molinate is a selective thiocarbamate herbicide used to control broad-leaved and grassy plants in rice and other crops. Molinate is available in granular and emulsifiable liquid formulations.

Formulation: Molinate is available in granular and emulsifiable liquid formulations.

Toxicological Effects:

• Acute toxicity: Molinate is moderately toxic by ingestion with reported oral LD50 values of 369 to 720 mg/kg in rats, and 530 to 795 mg/kg in mice. Dermal LD50 values are 4000 to 4800 mg/kg in rats [3,7]. It is mildly irritating to rabbit skin and moderately irritating to rabbit eyes, and is not a skin sensitizer [7]. The 4-hour inhalation LC50 of 1.36 mg/L indicates moderate toxicity by this route as well [4]. Some formulations show a lower degree of acute toxicity [6,7]. Symptoms of exposure to molinate include nausea, diarrhea, abdominal pain, fever, weakness, and conjunctivitis [7,13].
• Chronic toxicity: The only reported human exposure to molinate resulting in adverse health effects comes from a report of well contamination in Japan. After field application of approximately 60 kg active ingredient to a 2-hectare rice paddy, several people noticed an odor emitted from a nearby well, and fell ill as a result of repeated consumption of water from that well [6]. Their symptoms, which were apparently quite rapid in onset, included abdominal and gastrointestinal disorders, fever, weakness, and conjuntivitis [6]. These symptoms disappeared following the use of an alternative water source, and there were no reports of long-term complications or lingering effects due to this exposure [6]. The concentration of the well water sampled 15 days following the first reported symptoms was 6 ug/L; it is not known what the initial concentration was [6].
• Reproductive effects: Administration of molinate to young male rats at a dose of 3.6 mg/kg/day for 2 months caused changes in spermatozoa but did not decrease sperm fertility [6]. When these rats were mated to normal females, many of the embryos were resorbed and postnatal mortality was increased [6]. It is unlikely that such effects will occur in humans at expected exposure levels.
• Teratogenic effects: Reports on the teratogenicity of molinate are conflicting, with one suggestion that it is teratogenic [35] and another that it is not [7]. Thus, its teratogenicity is unknown.
• Mutagenic effects: No data were located regarding the potential mutagenic effects of molinate although it has been reported to be nongenotoxic [4,7].
• Carcinogenic effects: In a 2-year assay in rats, no carcinogenic activity was reported at doses up to 2 mg/kg/day [6].
• Organ toxicity: The primary target organ affected by molinate is the thyroid.

• Fate in humans and animals: Molinate is only fairly well absorbed through oral, dermal, and inhalation exposure [4]. It is metabolized in the rat liver, and rapid excretion occurs primarily through the urine (88% of the applied dose) with a small amount lost in the feces (11% of the applied dose). Excretion by rats was practically complete within 48 hours [6].

Ecological Effects:

• Effects on birds: Molinate appears to be practically nontoxic to birds. The reported 5-day dietary LC50 in Japanese quail is greater than 5000 ppm, and that in mallards is greater than 13,000 ppm [4,13].
• Effects on aquatic organisms: The reported toxicity to fish varies greatly, from slightly to highly toxic. One source reports the 96-hour LC50 values at 0.21 mg/L in rainbow trout and 0.32 mg/L in bluegill sunfish [16], while another reports tham as 1.3 and 29 mg/L, respectively [3]. A 96-hour LC50 value of 30 mg/L in goldfish has also been reported [4]. Fish kills of carp due to molinate were observed in Japan. The pesticide caused an anemia-like condition in these fish [4]. Reported 96-hour LC50 values in aquatic invertebrates such as Daphnia and stoneflies are about 0.3 to 0.6 mg/L, indicating that molinate is highly toxic to these invertebrates [4,16].
• Effects on other organisms: No data are currently available.

Environmental Fate:

• Breakdown in soil and groundwater: Molinate is of low persistence in the soil environment, with a field half-life of 5 to 21 days [20]. It is poorly bound to soils, soluble in water, and thus may be mobile [20] and present a risk to groundwater contamination. Soil microorganisms are responsible for most molinate breakdown [4]. Molinate may rapidly volatilize if not plowed into the soil, and may undergo breakdown by sunlight [4].
• Breakdown in water: Molinate may be degraded by hydrolysis (reaction with water).
• Breakdown in vegetation: Molinate is rapidly taken up by plant roots and transported to the leaves. In the leaves, molinate inhibits leaf growth and development. It is rapidly metabolized to carbon dioxide and other naturally occurring plant products such as amino acids and organic acids in nonsusceptable plants.

Physical Properties:

• Appearance: Molinate is a noncorrosive, clear liquid with an aromatic or spicy odor [3].
• Chemical Name: S-ethyl hexhydro-1 H-azepine-1-carbothiate [3]
• CAS Number: 2212-67-1
• Molecular Weight: 187.30
• Water Solubility: 880 mg/L [3]
• Solubility in Other Solvents: v.s. in acetone, xylene, ethanol, kerosene, and 4-methylpentan-2-one [3]
• Melting Point: Not Available
• Vapor Pressure: 746 mPa @ 25 C [3]
• Partition Coefficient: 2.8808 [3]
• Adsorption Coefficient: 190 [20]

Exposure Guidelines:

• ADI: Not Available
• MCL: Not Available
• RfD: 0.002 mg/kg/day [27]
• PEL: Not Available
• HA: Not Available
• TLV: Not Available

Basic Manufacturer:

Zeneca Ag Products
1800 Concord Pike
Wilmington, DE 19897

• Phone: 800-759-4500
• Emergency: 800-759-2500
  

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.