Benomyl (also marketed as Benlate) is a

fungicide Fungicides are biocidal chemical compounds or biological organisms used to kill parasitic fungi or their spores. A fungistatic inhibits their growth. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality, ...

introduced in 1968 by

DuPont DuPont de Nemours, Inc., commonly shortened to DuPont, is an American multinational chemical company first formed in 1802 by French-American chemist and industrialist Éleuthère Irénée du Pont de Nemours. The company played a major role in ...

. It is a systemic

benzimidazole Benzimidazole is a heterocyclic aromatic organic compound. This bicyclic compound may be viewed as fused rings of the aromatic compounds benzene and imidazole. It is a colorless solid. Preparation Benzimidazole is produced by condensation of o ...

fungicide that is selectively

toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...

to microorganisms and

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

s, especially

earthworm An earthworm is a terrestrial invertebrate that belongs to the phylum Annelida. They exhibit a tube-within-a-tube body plan; they are externally segmented with corresponding internal segmentation; and they usually have setae on all segments. Th ...

s, but nontoxic toward mammals. Due to the prevalence of resistance of parasitic fungi to benomyl, it and similar pesticides are of diminished effectiveness. Nonetheless it is widely used.

Toxicity

Benomyl is of low toxicity to mammals. It has an arbitrary LD₅₀ of "greater than 10,000 mg/kg/day for rats". Skin

irritation Irritation, in biology and physiology, is a state of inflammation or painful reaction to allergy or cell-lining damage. A stimulus or agent which induces the state of irritation is an irritant. Irritants are typically thought of as chemical age ...

may occur through industrial exposure, and

florists Floristry is the production, commerce, and trade in flowers. It encompasses flower care and handling, floral design and arrangement, merchandising, production, display and flower delivery. Wholesale florists sell bulk flowers and related sup ...

, 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 Liver function tests (LFTs or LFs), also referred to as a hepatic panel, are groups of blood tests that provide information about the state of a patient's liver. These tests include prothrombin time (PT/INR), activated partial thromboplastin tim ...

at the highest dose (150 mg/kg). With longer exposure, more severe liver damage occurred, including

cirrhosis Cirrhosis, also known as liver cirrhosis or hepatic cirrhosis, and end-stage liver disease, is the impaired liver function caused by the formation of scar tissue known as fibrosis due to damage caused by liver disease. Damage causes tissue repai ...

. The

US Environmental Protection Agency The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it be ...

classified benomyl as a possible

carcinogen A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive subs ...

. 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 regards to occupational exposures to benomyl, the

Occupational Safety and Health Administration The Occupational Safety and Health Administration'' (OSHA ) is a large regulatory agency of the United States Department of Labor that originally had federal visitorial powers to inspect and examine workplaces. Congress established the agenc ...

has set a

permissible exposure limit The permissible exposure limit (PEL or OSHA PEL) is a legal limit in the United States for exposure of an employee to a chemical substance or physical agent such as high level noise. Permissible exposure limits are established by the Occupational ...

of 15 mg/m³ for total exposure over an eight-hour time-weighted average, and 5 mg/m³ for respiratory exposures.

Birth defects

In 1996, a

Miami Miami ( ), officially the City of Miami, known as "the 305", "The Magic City", and "Gateway to the Americas", is a East Coast of the United States, coastal metropolis and the County seat, county seat of Miami-Dade County, Florida, Miami-Dade C ...

jury awarded US$4 million to a child whose mother was exposed in pregnancy to Benlate. The child was born without eyes (anophthalmia). The mother had been exposed to an unusually high dose of Benlate through her exposure from a near by farm, during pregnancy. An important issue in the case was the timing and magnitude of exposure. In October 2008, DuPont paid confidential settlements to two

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

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 Christchurch ( ; mi, Ōtautahi) is the largest city in the South Island of New Zealand and the seat of the Canterbury Region. Christchurch lies on the South Island's east coast, just north of Banks Peninsula on Pegasus Bay. The Avon River / ...

parks worker before his birth.

Environmental effects

Benomyl binds strongly to

soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ...

and does not dissolve in water to any great extent. It has a

half-life Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable ato ...

turf Sod, also known as turf, is the upper layer of soil with the grass growing on it that is often harvested into rolls. In Australian and British English, sod is more commonly known as ''turf'', and the word "sod" is limited mainly to agricult ...

of three to six months, and in bare soil, a half-life of six months to one year. In 1991, DuPont issued a recall of its Benlate 50DF formula due to suspected contamination with the herbicide

atrazine Atrazine is a chlorinated herbicide of the triazine class. It is used to prevent pre-emergence broadleaf weeds in crops such as maize (corn), soybean and sugarcane and on turf, such as golf courses and residential lawns. Atrazine's primary manu ...

. In the wake of the recall, many US growers blamed Benlate 50DF for destroying millions of dollars' worth of crops. Growers filed over 1,900 damage claims against DuPont, mostly involving ornamental crops in Florida. Subsequent testing by DuPont determined the recalled product was not contaminated with atrazine. The reason for the alleged crop damage is unclear. The

Florida Department of Agriculture and Consumer Services The Florida Department of Agriculture and Consumer Services (FDACS) is an executive department of the government of Florida. The Commissioner of Agriculture (directly elected by voters statewide for a four-year term, and a member of the Florid ...

suggested Benlate was contaminated with dibutylurea and

sulfonylurea Sulfonylureas (UK: sulphonylurea) are a class of organic compounds used in medicine and agriculture, for example as antidiabetic drugs widely used in the management of diabetes mellitus type 2. They act by increasing insulin release from the bet ...

herbicides. After several years of legal argument, DuPont paid out about US$750 million in damages and out-of-court settlements. By 1993, a coalition of farm worker and environmental groups came together to form "Benlate Victims Against DuPont", a group which called for a nationwide boycott of DuPont products. After carrying out tests, DuPont denied Benlate was contaminated with dibutylurea and sulfonylureas and stopped compensation pay-outs. In 1995, a Florida judge rejected a complaint from the Florida Department of Agriculture that had alleged such a link.

Cellular biology

Benomyl is used in molecular biology to study the cell cycle in yeast; in fact, the name of the protein class "Bub" (Bub1, etc.) comes from their mutant in which budding was uninhibited by benomyl. Benomyl acts by depolymerizing microtubules. Benomyl is also useful in the laboratory because it is selectively toxic to most members of the

Ascomycota Ascomycota is a phylum of the kingdom Fungi that, together with the Basidiomycota, forms the subkingdom Dikarya. Its members are commonly known as the sac fungi or ascomycetes. It is the largest phylum of Fungi, with over 64,000 species. The def ...

, whereas members of the

Basidiomycota Basidiomycota () is one of two large divisions that, together with the Ascomycota, constitute the subkingdom Dikarya (often referred to as the "higher fungi") within the kingdom Fungi. Members are known as basidiomycetes. More specifically, Basi ...

are largely resistant.

References

External links