Benomyl (also marketed as Benlate) is a fungicide which was introduced in 1968 by Du Pont. It is a systemic benzimidazole fungicide that is selectively toxic to micro-organisms and to 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 resistance of parasitic fungi to benomyl which had developed and is now prevalent worldwide benomyl and similar pesticide compounds became largely ineffective. Because of high legal costs associated with it in 2001 Du Pont ceased production of benomyl after 33 years on the market and voluntarily requested cancellation for its registration. However, as Du Pont's patents expired long ago and in some countries benomyl's registration has not been revoked, other manufacturers still produce it.
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 mouse study has shown it "probably" causes an increase in liver tumours. The British Ministry of Agriculture Fisheries and Food took the view that this was bought 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 that 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 1996 a Miami jury awarded US$4 million to a child whose mother was exposed in pregnancy to Benlate. The child was born without eyes. The mother had been exposed to an unusually high dose of Benlate through her occupation, during pregnancy. An important issue in the case was whether the timing of exposure - during the formation of the optic nerve in the foetus - was critical as well as the magnitude of exposure. A Benlate compensation case involving an English boy from Essex born without eyes is also due to be heard shortly in the US.
In October 2008, Du Pont paid confidential settlements to two New Zealand families whose children were born with either anophthalmia or other birth defects.. The mother of one of the children had been exposed to Benlate while working as a Christchurch parks worker before his birth.
The fate and efficacy of benomyl applied to field soils to suppress activity of arbuscular mycorrhizal fungi.(NOTE)(Report)
Jul 01, 2009; Soil fumigation or fungicides have often been used to suppress the activity of indigenous arbuscular mycorrhizal (AM) fungi. The...
USE OF ACEPHATE, BENOMYL AND ALGINATE ENCAPSULATION FOR ELIMINATING CULTURE MITES AND FUNGAL CONTAMINATION FROM IN VITRO CULTURES OF HARDY HIBISCUS (HIBISCUS MOSCHEUTOS L.)
May 01, 2006; SUMMARY Shoot cultures of three Hibiscus moscheutos (L.) cultivars were infested with micro-arthropods (mites). Nodal segments (1...