Benzene has been shown to cause cancer in both sexes of multiple species of laboratory animals exposed via various routes. It is sometimes abbreviated PhH. In 2006, a computer investigation by Environmental Working Group (EWG) uncovered results from a Food and Drug Administration (FDA) testing program that contradicted safety assurances about benzene contamination in soft drinks made by a top agency official on March 21, 2006. CYP2E1 is involved at multiple steps: converting benzene to oxepin (benzene oxide), phenol to hydroquinone, and hydroquinone to both benzenetriol and catechol. As a gasoline (petrol) additive, benzene increases the octane rating and reduces knocking. Toluene disproportionation (TDP) is the conversion of toluene to benzene and xylene. Benzene is hepatically metabolized and excreted in the urine. A quarter teaspoon of benzene will make an average sized swimming pool exceed the EPA benzene limit. The current ACGIH biological exposure limits for occupational exposure are 500 μg/g creatinine for muconic acid and 25 μg/g creatinine for phenylmercapturic acid in an end-of-shift urine specimen.[85][86][87][88]. Benzene and cyclohexane have a similar structure, only the ring (of delocalized electrons) inside Benzene distinguishes it from cyclohexane. [66][67][68] The specific hematologic malignancies that benzene is associated with include: acute myeloid leukemia (AML), aplastic anemia, myelodysplastic syndrome (MDS), acute lymphoblastic leukemia (ALL), and chronic myeloid leukemia (CML).[69]. This reaction is practiced on a large scale industrially. [32][33] Kekulé used evidence that had accumulated in the intervening years—namely, that there always appeared to be only one isomer of any monoderivative of benzene, and that there always appeared to be exactly three isomers of every disubstituted derivative—now understood to correspond to the ortho, meta, and para patterns of arene substitution—to argue in support of his proposed structure. […] benzene poisoning a toxic condition caused by ingestion of benzene, inhalation of benzene fumes, or exposure to benzene-related products such as toluene or xylene, characterized by blurred vision, nausea, headache, dizziness, and incoordination. The initial symptoms in benzene poisoning are slight and easily overlooked. [35] This vision, he said, came to him after years of studying the nature of carbon-carbon bonds. The extraction step of aromatics from the reformate is designed to produce aromatics with lowest non-aromatic components. Benzene. Claus, Adolph K.L. The antiseptic properties of phenol were used by Sir Joseph Lister (1827–1912) in his pioneering technique of antiseptic surgery. This page was last edited on 25 December 2019, at 18:50. [52] The molecular orbital description involves the formation of three delocalized π orbitals spanning all six carbon atoms, while the valence bond description involves a superposition of resonance structures. Sulfonation of benzene involves the use of oleum, a mixture of sulfuric acid with sulfur trioxide. The controversial process has fuelled protests from landholders in Australia and the United States, where government tests have detected harmful levels of hydrocarbons, including BTEX, in drinking water wells in areas where fracking is used. Via hydrogenation, benzene and its derivatives convert to cyclohexane and derivatives. Benzene poisoning may result in a headache and unexplained drowsiness. For example, mutations in CYP2E1 increase activity and result in increased generation of toxic metabolites. Curiously, a similar, humorous depiction of benzene had appeared in 1886 in a pamphlet entitled Berichte der Durstigen Chemischen Gesellschaft (Journal of the Thirsty Chemical Society), a parody of the Berichte der Deutschen Chemischen Gesellschaft, only the parody had monkeys seizing each other in a circle, rather than snakes as in Kekulé's anecdote. Exposure to long term low levels of benzene in the work environment or acute short term exposure can lead to a number of health problems ranging from nausea, insomnia, headache and dizziness to convulsions, coma, cancer, chromosomal aberrations, anemia and even death. Benzene causes acute myeloid leukaemia (acute non-lymphocytic leukaemia), and there is limited evidence that benzene may also cause acute and chronic lymphocytic leukaemia, non-Hodgkin's lymphoma and multiple myeloma. CBP could give the appearance of different types of disorders such as leukopenia, agranulocytosis, anemia, pancytopenia, aplastic anemia (AA), myelodysplastic syndrome (MDS), and leukemia. Benzene is a natural constituent of crude oil, and may be synthesized from other compounds present in petroleum. These aberrations can be monitored using fluorescent in situ hybridization (FISH) with DNA probes to assess the effects of benzene along with the hematological tests as markers of hematotoxicity. [100][101], This article is about the chemical compound. [80] These legal limits were based on studies demonstrating compelling evidence of health risk to workers exposed to benzene. [99] Benzene leaked into the Songhua River, which supplies drinking water to the city, after an explosion at a China National Petroleum Corporation (CNPC) factory in the city of Jilin on 13 November 2005. [62] European petrol specifications now contain the same 1% limit on benzene content. Hydrogenation cannot be stopped to give cyclohexene or cyclohexadienes as these are superior substrates. It has a sweet odor and is highly flammable. biphenyl (aka diphenyl) at higher temperature: If the raw material stream contains much non-aromatic components (paraffins or naphthenes), those are likely decomposed to lower hydrocarbons such as methane, which increases the consumption of hydrogen. Non-cancer effects of over-exposure to benzene include effects on the respiratory system, the nervous system, the cardiovascular system, the gastrointestinal system, and the kidney. Although of no commercial significance, many other routes to benzene exist. The affected batches were removed from sale. benzene poisoning are characterized by anaemia, leucopenia, and thrombocytopenia, either alone or incombination. Hydroquinone, benzenetriol and catechol are converted to polyphenols. Symptoms are often described as "flu-like" and commonly include headache, dizziness, weakness, vomiting, chest pain, and confusion.Large exposures can result in loss of consciousness, arrhythmias, seizures, or death. Even if it is not a common substrate for metabolism, benzene can be oxidized by both bacteria and eukaryotes. Linking benzene rings gives biphenyl, C6H5–C6H5. Centric affinities (i.e., bonds) acted within a designated cycle of carbon atoms. A small-area case-crossover study", "Advances in understanding benzene health effects and susceptibility", American Petroleum Institute, API Toxicological Review, Benzene, September 1948, "Advances in Understanding Benzene Health Effects and Susceptibility", International Agency for Research on Cancer, IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Overall Evaluations of Carcinogenicity: An Updating of IARC Monographs, "Benzene-induced cancers: abridged history and occupational health impact", "The toxicity of benzene and its metabolism and molecular pathology in human risk assessment", Occupational Safety and Health Standards, Toxic and Hazardous Substances, 1910.1028, Public Health Statement for Benzene, Agency for Toxic Substances and Disease Registry. With the global phaseout of leaded gasoline, benzene has made a comeback as a gasoline additive in some nations. Symptoms may progress from lightheadedness, headache, and euphoria, to respiratory depression, apnea (cessation of breathing), coma, and death. Jump to navigation Jump to search. The following features of chronic benzene poisoning should be borne in mind during the examination of exposed workers :- 1. [51] The C–C bond lengths are greater than a double bond (135 pm) but shorter than a single bond (147 pm). In the bone marrow, MPO converts these polyphenols to benzoquinones. (August 2007). [70] There is no safe exposure level; even tiny amounts can cause harm. You may redistribute it, verbatim or modified, providing that you comply with the terms of the CC-BY-SA. [91] Benzene causes chromosomal aberrations in the peripheral blood leukocytes and bone marrow explaining the higher incidence of leukemia and multiple myeloma caused by chronic exposure. [59], Four chemical processes contribute to industrial benzene production: catalytic reforming, toluene hydrodealkylation, toluene disproportionation, and steam cracking. Benzene also is found in products such as glue, furniture wax, paint and detergent. In 2013, the biggest consumer country of benzene was China, followed by the USA. As benzene is ubiquitous in gasoline and hydrocarbon fuels that are in use everywhere, human exposure to benzene is a global health problem. From: Public Health England Published: 1 July 2014 Benzene has 6 hydrogen atoms, fewer than the corresponding parent alkane, hexane, which has 14. These intermediates and metabolites induce genotoxicity by multiple mechanisms including inhibition of topoisomerase II (which maintains chromosome structure), disruption of microtubules (which maintains cellular structure and organization), generation of oxygen free radicals (unstable species) that may lead to point mutations, increasing oxidative stress, inducing DNA strand breaks, and altering DNA methylation (which can affect gene expression). Examples of simple benzene derivatives are phenol, toluene, and aniline, abbreviated PhOH, PhMe, and PhNH2, respectively. ([6]-annulene), a cyclic hydrocarbon with a continuous pi bond. [92] Benzene metabolism involves enzymes coded for by polymorphic genes. Benzene concentrations of about … NQ01 mutations result in loss of function and may result in decreased detoxification. The next year he published a much longer paper in German on the same subject. [76], OSHA regulates levels of benzene in the workplace. [6] Short-term exposure to high levels of benzene can cause drowsiness, dizziness, unconsciousness, and death. See, The word "benzoin" is derived from the Arabic expression ", Laurent, Auguste (1836) "Sur la chlorophénise et les acides chlorophénisique et chlorophénèsique,". Origin refused to disclose the mixture of chemicals used in the fracking fluid that it was using on the site. What is Benzene Poisoning? Benzene is an organic chemical compound with the molecular formula C 6 H 6.The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Dubbed the new “Gulf War” syndrome, deep oil well Horizon is vomiting out thousands of barrels of crude oil daily into the Gulf of Mexico, and with it an ever-growing list of health risks including benzene poisoning from the high levels of Benzene and Corexit being used as … In 2005, the water supply to the city of Harbin in China with a population of almost nine million people, was cut off because of a major benzene exposure. Archibald Scott Couper in 1858 and Johann Josef Loschmidt in 1861[31] suggested possible structures that contained multiple double bonds or multiple rings, but too little evidence was then available to help chemists decide on any particular structure. Benzene is a clear, liquid, petroleum-based chemical that has a sweet smell. [46], Trace amounts of benzene are found in petroleum and coal. It is a byproduct of the incomplete combustion of many materials. Benzene poisoning Definition Benzene is a clear, liquid, petroleum-based chemical that has a sweet smell. This article is for information only. "Cost Benefit Analysis: Replacing Ontario's Coal-Fired Electricity Generation" by DSS Management Consultants Inc. and RWDI Air Inc., for the Ontario Ministry of Energy, April, 2005, 93 pages. Prior to the 1920s, benzene was frequently used as an industrial solvent, especially for degreasing metal. To accurately reflect the nature of the bonding, benzene is often depicted with a circle inside a hexagonal arrangement of carbon atoms. This amount is about 10 times the average daily intake of benzene by nonsmokers. Derivatives of benzene occur sufficiently often as a component of organic molecules that the Unicode Consortium has allocated a symbol in the Miscellaneous Technical block with the code U+232C (⌬) to represent it with three double bonds,[57] and U+23E3 (⏣) for a delocalized version.[58]. A typical reaction yield exceeds 95%. This was 7 years after he had solved the problem of how carbon atoms could bond to up to four other atoms at the same time. CDC: COVID-19 vaccines cause mostly mild side effects. Replacing one CH with N gives the compound pyridine, C5H5N. For other uses, see, Except where otherwise noted, data are given for materials in their, Biological oxidation and carcinogenic activity, Critics pointed out a problem with Kekulé's original (1865) structure for benzene: Whenever benzene underwent substitution at the ortho position, two distinguishable isomers should have resulted, depending on whether a double bond or a single bond existed between the carbon atoms to which the substituents were attached; however, no such isomers were observed. [42][43] It was the German chemist Karl Gräbe who, in 1869, first used the prefixes ortho-, meta-, para- to denote specific relative locations of the substituents on a di-substituted aromatic ring (viz, naphthalene). Chlorination is achieved with chlorine to give chlorobenzene in the presence of a Lewis acid catalyst such as aluminium tri-chloride. Employers are required to monitor benzene in coal mining and other industries when levels reach 0.5 parts per million. [90], The paradigm of toxicological assessment of benzene is shifting towards the domain of molecular toxicology as it allows understanding of fundamental biological mechanisms in a better way. Sometimes, xylenes and heavier aromatics are used in place of toluene, with similar efficiency. [12], Benzene is a natural constituent of crude oil and is one of the elementary petrochemicals. Winslow's new plea deal: 14 years in prison. [63] In many European languages, the word for petroleum or gasoline is an exact cognate of "benzene". Under these conditions, aliphatic hydrocarbons form rings and lose hydrogen to become aromatic hydrocarbons. Depending on the feedstock used to produce the olefins, steam cracking can produce a benzene-rich liquid by-product called pyrolysis gasoline. Human exposure to hydrocarbons is a common problem. NQ01 metabolizes benzoquinone toward polyphenols (counteracting the effect of MPO). Benzene targets the liver, kidney, lung, heart and brain and can cause DNA strand breaks, chromosomal damage, etc. [2], The standards set by the Occupational Safety and Health Administration (OSHA) require that levels of benzene in coal mining and other workplace environments cannot exceed one part per million for an eight hour day and five parts per million in a fifteen minute period. After exposure to 63 to 405 mg/m3 of benzene for 1 to 5 hours, 51 to 87% was excreted in the urine as phenol over a period of 23 to 50 hours. Benzene: Patient information sheet, Drinking Water Contaminants|Organic Chemicals|Benzene, Benzene Toxicity: Standards and Regulations|ATSDR – Environmental Medicine & Environmental Health Education – CSEM, Documentation for Immediately Dangerous to Life or Health Concentrations (IDLH): Introduction, "Blood concentrations of volatile organic compounds in a nonoccupationally exposed US population and in groups with suspected exposure", "100 tonnes of pollutants spilled into Chinese river", "A Former Nazi Labor Camp in Austria, Now Billed as a Tourist Site", Dept. [34] Kekulé's symmetrical ring could explain these curious facts, as well as benzene's 1:1 carbon-hydrogen ratio. Thus, a double bond would exist with one neighbor during the first interval and with the other neighbor during the next interval. - Samsung and Apple factories in China Benzene and its effects where benzene is found The seriousness of poisoning caused by benzene depends on the amount, route, and length of time of exposure, as well as the age and preexisting medical condition of the exposed person. This process was later discontinued. [95] After smoking 32 cigarettes per day, the smoker would take in about 1.8 milligrams (mg) of benzene. Agency for Toxic Substances and Disease Registry. In the body, benzene is enzymatically converted to a series of oxidation products including muconic acid, phenylmercapturic acid, phenol, catechol, hydroquinone and 1,2,4-trihydroxybenzene. It is also a carcinogenic emission produced in the coking process of coal mining. [65] Highly instructive but of far less industrial significance is the Friedel-Crafts alkylation of benzene (and many other aromatic rings) using an alkyl halide in the presence of a strong Lewis acid catalyst. Similar problems were reported by the FDA in the United States.[98]. Smaller amounts of benzene are used to make some types of rubbers, lubricants, dyes, detergents, drugs, explosives, and pesticides. [97], Under specific conditions and in the presence of other chemicals benzoic acid (a preservative) and ascorbic acid (Vitamin C) may interact to produce benzene. In the United States, concern over its negative health effects and the possibility of benzene's entering the groundwater have led to stringent regulation of gasoline's benzene content, with limits typically around 1%. Several tests can determine exposure to benzene. He said that he had discovered the ring shape of the benzene molecule after having a reverie or day-dream of a snake seizing its own tail (this is a common symbol in many ancient cultures known as the Ouroboros or Endless knot). Although a major industrial chemical, benzene finds limited use in consumer items because of its toxicity.[13]. The short term exposure limit for airborne benzene is 5 ppm for 15 minutes. -Benzene In particular, acute myeloid leukemia or acute nonlymphocytic leukemia (AML & ANLL) is not disputed to be caused by benzene. Benzene poisoning can be lethal because it causes the cells in the body to work incorrectly. Toluene hydrodealkylation converts toluene to benzene. NQ01 and GSH shift metabolism away from toxicity. Benzene is sufficiently nucleophilic that it undergoes substitution by acylium ions and alkyl carbocations to give substituted derivatives. Long-term exposure to excessive levels of benzene in the air causes leukemia, a potentially fatal cancer of the blood-forming organs. 11,960) for the fractional distillation of coal tar. The recent decree which requires medical examinations before hiring workers, medical visits every two months supplemented by haematological examinations (red cells, haemoglobin, white cells, leukocyte formula), the posting of the dangers, of benzene poisoning and the precautions which should be taken to … Even if most patients probably recover, provided Some 20% of the benzene production is used to manufacture cumene, which is needed to produce phenol and acetone for resins and adhesives. Toluene is also processed into benzene.[61]. Chronic poisoning may occur in employees of gasoline filling stations and bulk gasoline loading facilities because of the high concentration of benzene in gasoline. The catechol is then metabolized to acetyl CoA and succinyl CoA, used by organisms mainly in the Citric Acid Cycle for energy production. People can contact one of the following: Glutathione seems to play an important role by protecting against benzene-induced DNA breaks and it is being identified as a new biomarker for exposure and effect. [79] This regulation is based on preventing benzene leukemogenesis. The risk from exposure to 1 ppm for a working lifetime has been estimated as 5 excess leukemia deaths per 1,000 employees exposed. [44] In 1870, the German chemist Viktor Meyer first applied Gräbe's nomenclature to benzene.[45]. In another human study, 30% of absorbed dermally applied benzene, which is primarily metabolized in the liver, was excreted as phenol in the urine. Das Benzol." [47] Benzene molecules have been detected on Mars.[48][49][50]. Benzene is used in the manufacture of plastics, detergents, pesticides, and other chemicals. [5], Research has shown benzene to be a carcinogen (cancer-causing). [71] The US Department of Health and Human Services (DHHS) classifies benzene as a human carcinogen. One way of understanding the carcinogenic effects of benzene is by examining the products of biological oxidation. In similar fashion to this catalytic reforming, UOP and BP commercialized a method from LPG (mainly propane and butane) to aromatics. In 1865, the German chemist Friedrich August Kekulé published a paper in French (for he was then teaching in Francophone Belgium) suggesting that the structure contained a ring of six carbon atoms with alternating single and double bonds. [39], The cyclic nature of benzene was finally confirmed by the crystallographer Kathleen Lonsdale in 1929. [14] An acidic material was derived from benzoin by sublimation, and named "flowers of benzoin", or benzoic acid. [69][89], Genetic polymorphisms in these enzymes may induce loss of function or gain of function. Birch reduction, a non catalytic process, however selectively hydrogenates benzene to the diene. Acute benzene toxicity is characterized by central nervous system depression. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. [15] Michael Faraday first isolated and identified benzene in 1825 from the oily residue derived from the production of illuminating gas, giving it the name bicarburet of hydrogen. The EPA has also set the level of benzene permissible in outdoor air levels at five parts per billion. GSH is involved with the formation of phenylmercapturic acid. The hydrocarbon derived from benzoic acid thus acquired the name benzin, benzol, or benzene. There are several types of leukemia that have been linked to benzene exposure, which hinders or disables an individual's bone marrow from properly producing red blood cells, white blood cells and/or platelet cells in the blood. Benzene is a component of products derived from coal and petroleum and is found in gasoline and other fuels. [20] Four years later, Mansfield began the first industrial-scale production of benzene, based on the coal-tar method. Benzene is an organic chemical compound with the molecular formula C6H6. The most important variations contain nitrogen. The purpose of establishing an IDLH value is (1) to ensure that the worker can escape from a given contaminated environment in the event of failure of the respiratory protection equipment and (2) is considered a maximum level above which only a highly reliable breathing apparatus providing maximum worker protection is permitted [NIOSH 2004[82]]. The pathway for the metabolism of benzene is complex and begins in the liver. In 1903, Ludwig Roselius popularized the use of benzene to decaffeinate coffee. Long-term exposure may affect bone marrow and blood production, lung cancer and anemia. The reaction involves the acylation of benzene (or many other aromatic rings) with an acyl chloride using a strong Lewis acid catalyst such as aluminium chloride or Iron(III) chloride. The incidence of benzene poisoning has increased, owing-chiefly to war industries. In some systems, even the benzene-to-xylenes ratio is modified to favor xylenes. ), pp. We report a case of fatal acute intoxication which occurred aboard a chemical cargo ship. Here Kekulé spoke of the creation of the theory. Similarly, the Friedel-Crafts acylation is a related example of electrophilic aromatic substitution. To provide a mechanism for the conversion process, Kekulé proposed that the valency of an atom is determined by the frequency with which it collided with its neighbors in a molecule. [21][22] Gradually, the sense developed among chemists that a number of substances were chemically related to benzene, comprising a diverse chemical family. Chronic effects following repeated exposure to low doses of benzene have been well assessed, whereas few data are available about acute exposure to benzene. Cookie-policy; To contact us: mail to admin@qwerty.wiki [73][74], According to the Agency for Toxic Substances and Disease Registry (ATSDR) (2007), benzene is both a man-made and naturally occurring chemical from processes that include: volcanic eruptions, wild fires, synthesis of chemicals such as phenol, production of synthetic fibers, and fabrication of rubbers, lubricants, pesticides, medications, and dyes. Manufacture of some of these benzene-containing formulations ceased in about 1950, although Liquid Wrench continued to contain significant amounts of benzene until the late 1970s. This discovery led to the production of Sanka. It is an aromatic compound, meaning the ring has alternating double bonds.. Benzene is carcinogenic, which means it can cause cancer. The current NIOSH definition for an IDLH condition, as given in the NIOSH Respirator Selection Logic, is one that poses a threat of exposure to airborne contaminants when that exposure is likely to cause death or immediate or delayed permanent adverse health effects or prevent escape from such an environment [NIOSH 2004]. Chronic benzene poisoning (CBP) can be found among workers with excessive benzene exposure. 125–129. Using electrophilic aromatic substitution, many functional groups are introduced onto the benzene framework. Abstract. The most common reactions of benzene involve substitution of a proton by other groups. [1], In drinking water, the Environmental Protection Agency (EPA) has set the maximum contamination level at five parts per billion. In March 2006, the official Food Standards Agency in Britain conducted a survey of 150 brands of soft drinks. The American Petroleum Institute (API) stated in 1948 that "it is generally considered that the only absolutely safe concentration for benzene is zero". Benzene causes cancer in animals including humans. In 1836, Auguste Laurent coined the name "phène" for benzene; this is the root of the word "phenol" and "phenyl". Benzene is a colorless petroleum-based chemical that is used to manufacture industrial dyes, explosives, synthetic rubber, detergents, plastics and pesticides. Origin's manager of oil and gas operations, Paul Zealand, said BTEX was not being used as a fracking fluid, and that the contamination may have come from diesel fuel or lubricants used on machinery at the gas drilling sites. Benzene: health effects, incident management, and toxicology Information on benzene, for use in responding to chemical incidents. The major sources of benzene exposure are tobacco smoke, automobile service stations, exhaust from motor vehicles, and industrial emissions; however, ingestion and dermal absorption of benzene can also occur through contact with contaminated water. Benzene. [23] In 1997, benzene was detected in deep space.[24].
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