|
|Section2= |Section3= }} 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.〔(EPA: Federal Register: Benomyl; Cancellation Order )〕〔(DuPont Withdraws Benlate from Market PANNA 7may01 )〕 However, as DuPont's patents expired long ago and in some countries benomyl's registration has not been revoked, other manufacturers still produce it. ==Toxicity== Benomyl is of such a low toxicity to mammals, it has been impossible to administer doses large enough to establish an . 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. In 1993, the Observer, a UK national newspaper, published a series of articles alleging a possible link between exposure of pregnant mothers to benomyl and their children being born without eyes (anophthalmia) or with related syndromes, including reduced eyes and blindness, due to severe damage of the optic stem. The newspaper cited a number of suspected clusters in the UK that may have corresponded to areas of benomyl use. Studies have shown eye defects can occur at relatively high doses. A test in which rats were dosed orally demonstrated evidence of microphthalmia at dose levels of 62.5 mg/kg and above. In regards to occupational exposures to benomyl, the Occupational Safety and Health Administration has set a permissible exposure limit of 15 mg/m3 for total exposure over an eight-hour time-weighted average, and 5 mg/m3 for respiratory exposures. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「benomyl」の詳細全文を読む スポンサード リンク
|