Benomyl
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IUPAC names
Methyl [1-[(butylamino)carbonyl]-1H-benzimidazol-2-yl]carbamate
Methyl 1-(butylcarbamoyl)-2-benzimidazolecarbamate |
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| Other names
Benomyl
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| Identifiers | |
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3D model (Jmol)
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| ChEBI | |
| ChemSpider | |
| ECHA InfoCard | 100.037.962 |
| KEGG | |
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PubChem CID
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| UNII | |
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| Properties | |
| C14H18N4O3 | |
| Molar mass | 290.32 g·mol−1 |
| Appearance | white crystalline solid |
| Odor | acrid |
| Melting point | 290 °C (554 °F; 563 K) decomposes |
| 0.0004% (20°C) | |
| Hazards | |
| Flash point | noncombustible |
| US health exposure limits (NIOSH): | |
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PEL (Permissible)
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TWA 15 mg/m3 (total) TWA 5 mg/m3 (resp) |
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REL (Recommended)
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none |
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IDLH (Immediate danger)
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N.D. |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 (what is   ?) |
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| Infobox references | |
Benomyl (also marketed as Benlate) is a fungicide introduced in 1968 by DuPont. It is a systemic benzimidazole fungicide that is selectively toxic to microorganisms and invertebrates, especially earthworms. Benomyl binds to microtubules, interfering with cell functions, such as meiosis and intracellular transportation. The selective toxicity of benomyl as a fungicide is possibly due to its heightened effect on fungal rather than mammalian microtubules.
Due to the development and worldwide prevalence of resistance of parasitic fungi to benomyl, it and similar pesticide compounds became largely ineffective. High legal costs associated with it caused DuPont to cease its production in 2001 after 33 years on the market, and voluntarily requested cancellation for its registration. However, as DuPont's patents expired long ago and in some countries benomyl's registration has not been revoked, other manufacturers still produce it.
Benomyl is of such a low toxicity to mammals, it has been impossible to administer doses large enough to establish an LD50. It has an arbitrary LD50 of "greater than 10,000 mg/kg/day for rats". Skin irritation may occur through industrial exposure, and florists, mushroom pickers and floriculturists have reported allergic reactions to benomyl.
In a laboratory study, dogs fed benomyl in their diets for three months developed no major toxic effects, but did show evidence of altered liver function at the highest dose (150 mg/kg). With longer exposure, more severe liver damage occurred, including cirrhosis.
The US Environmental Protection Agency classified benomyl as a possible carcinogen. Carcinogenic studies have produced conflicting results. A two-year experimental study on mice has shown it "probably" causes an increase in liver tumours. The British Ministry of Agriculture Fisheries and Food took the view this was brought about by the hepatotoxic effect of benomyl.
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