Benomyl

Benomyl and the other benzimidazole fungicides are toxic to earthworms (Stringer and Wright, 1973) and may seriously disturb the earthworm population, for instance, in orchards, so that the leaf litter is not removed. Some benzimidazole fungicides (thiabendazole and mebendazole) may be used as anthelmintica. 

Benomyl metabolizes to carbendazim (MBC) and 5-HBC. Animal stndies indicated that benomyl and its metabolites rapidly eliminated out within 24 honrs of exposnre. They do not accumnlate in tissnes over longterm exposure. 

In one case report of a 70-year-old worker exclusively exposed to the dust of raw bauxite, deposits of bauxite were found in the lungs in areas of mild pulmonary fibrosis. There were no clinical symptoms, and it is not clear whether the fibrosis was a response to the bauxite or whether the bauxite accumulated in preexisting fibrotic areas. 

No serious adverse effects on respiratory health as determined by self-reported symptoms and spirometry were found in current employees at three bauxite mines in Australia.  

The nuisance dust aspect of bauxite is in sharp contrast to the limited industrial situation where lung injury was reported in Canadian workers, who in the 1940s engaged in the manufacture of alumina abrasives in the virtual absence of fume control. Fusing of bauxite at 2000°C gave rise to a fume composed of freshly formed particles of amorphous silica and aluminum oxide. Despite the poor choice of the term—bauxite fume pneumoconiosis—sometimes used to describe the disease, scientific opinion favors the silica component as the probable toxic agent. It should be emphasized that bauxite from some sources may contain small amounts of silica. 

The 2003 ACGIH threshold limit value-time-weighted average (TLV-TWA) for bauxite is lOmg/mh 

ACGIH Nuisance particulates. Documentation of TLVs and BEL, 6th ed, pp 1166-1167. Cincinnati, OH, American Conference of Government Industrial Hygienists (AGGIH), 1991 

IUPAC name Methyl-1-[(butyl) carbamoyl]-H-benzimidazol-2-ylcarbamate) Molecular formula C14H18N4O3 Toxicity class USEPA IV WHO III 

Uses Benomyl is a crystalline solid compound. It has little or no odor, and the USEPA has grouped it under GUP. Benomyl is a systemic benzimidazole fungicide that is selectively toxic to microorganisms and invertebrates, especially 

IUPAC name Tetrachloroisophthalonitrile Molecular formula C8Cl4N2 Toxicity class USEPA II WHO III 

000 mg/kg in mice. The acute dermal LD50 in both albino rabbits and albino rats is 10,000 mg/kg. In albino rabbits, 3 mg of chlorothalonil applied to the eyes caused mild irritation that subsided within 7 days of exposure. 

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Microtubulin Polymerization Inhibitors. The ben2imida2oles were first reported to have systemic fungicidal activity in 1964 (29). Prominent examples include thiabendazole [148-79-8] (42) fuberida2ole [3878-19-1] (43) carbendazim [10605-21-7] (44) benomyl [17804-35-2] (45) and thiophanate methyl [23564-05-8] (46). Benomyl (45), the most widely used member of this group is almost certainly inactive as a fungicide until it is converted in plants and soil to carbendazim (44). Likewise, thiophanate and thiophanate methyl (46) are nonfungitoxic until converted to carbendazin (44). 

Carbamate hydrolysis is frequendy observed as the initial reaction for pesticides having carbamate bonds, such as aldicarb, carbofuran, carbaryl, and benomyl (eq. 12) (19). Numerous genera of carbamate-hydroly2ing bacteria have been identified, including Pseudomonas, Jhihrobacter, Bacillus, Nocardia, Achromobacter, Flavobacterium, Streptomyces, Alcaligenes, A spirillum, Micrococcus, and Bhodococcus. 

These drugs are closely related to fungicides such as benomyl [17804-35-2J (13),... 

Phenylurea herbicides (urons). Dinocap, Dinoseb, Benomyl, Carbendazim and Metamitron in Waters [e.g. determination of phenylurea herbicides by reverse phase HPLC, phenylurea herbicides by dichloromethane extraction, determination by GC/NPD, phenylurea herbicides by thermospray LC-MS, Dinocap by HPLC, Dinoseb water by HPLC, Carbendazim and Benomyl (as Carbendazim) by HPLC], 1994... 

No APCI or ESI data had been previously reported for two of the five pesticides which were to be determined, i.e. imazalil and benomyl, and therefore although some information was available from the literature it was not possible to make a totally informed decision on the best methodology to employ. 

APCI and ESI spectra were obtained by using a range of cone-voltages, with the major ions observed being detailed in Table 5.12. With the exception of benomyl, under APCI conditions all compounds produced abundant molecular... 

The method was then applied to extracts of orange peel but neither benomyl or thiophanate methyl were recovered as the parent compounds due to their well-known conversion to carbendazim during the extraction process - this is an effect that is not encountered when analysing standards. 

Several extraction techniques have also been described that use enzymatic or chemical reactions to improve extraction efficiency. A technique that has been used to increase the overall recovery of the marker residue is enzymatic hydrolysis to convert specific phase II metabolites (glucuronides or sulfates) back into the parent residue. Cooper etal used a glucuronidase to increase 10-fold the concentration of chloramphenicol residues in incurred tissue. As an example of a chemical reaction, Moghaddam et al. used Raney nickel to reduce thioether bonds between benomyl and polar cellular components, and as a result achieved a substantially improved recovery over conventional solvent extraction. In choosing to use either of these approaches, thorough characterization of the metabolism in the tissue sample must be available. 

Marvin, C. H., Brindle, I. D., Singh, R. P., Hall, C. D., and Chiba, M., Simultaneous determination of trace concentrations of benomyl, carbendazim (MBC) and nine other pesticides in water using an automated on-line pre-concentration high-performance liquid chromatographic method, /. Chromatogr., 518, 242, 1990. 

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