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Leptophos. Maria Yukiko Komiyama Christopher Louis P. Orquiza III-BSCT Chemical and Molecular Toxicology. Leptophos. C 13 H 10 BrCl 5 O 2 PS O - (4-bromo-2,5-dichlorophenyl) O -methyl phenylphosphonothioate Organophosphate Compound. Leptophos.
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Leptophos Maria Yukiko Komiyama Christopher Louis P. Orquiza III-BSCT Chemical and Molecular Toxicology
Leptophos • C13H10BrCl5O2PS • O-(4-bromo-2,5-dichlorophenyl) O-methyl phenylphosphonothioate • Organophosphate Compound
Leptophos • Stable white, crystalline solid at room temperature • a.k.aPhosvel, Abar and Vcs506 • Used as pesticide and fungicide for rice, cotton, fruit and vegetables • First discovered to be toxic in 1974 when more than 1000 water buffaloes died after exposure to leptophos in Egypt • Discontinued for use by the year 1975
Toxicity • Moderately toxic with LD50 values in excess of 50 mg/kg and less than 500 mg/kg. • Stable to photodegradation under atmospheric conditions • Stable in acidic medium but hydrolyzes at strong basic conditions • Efficiently absorbed by inhalation, ingestion, and skin penetration
Mode of Action • Inhibits acetylcholinerase (AChE) through phosphorylation of the esteraticsite. • Causes increase in levels of acetylcholine (ACh)
Mode of Action High AChconcentrations in: • Smooth muscles and gland cells: muscle contraction and secretion, respectively. • Skeletal muscle junctions: excitatory (cause muscle twitching), but may also weaken or paralyze the cell
High AChconcentrations in: • Central Nervous System: sensory and behavioral disturbances, incoordination, depressed motor function, and respiratory depression
Signs and Symptoms • Inhalation results in the fastest appearance of toxic symptoms. • Tightness of chest and wheezing • Increased in bronchial secretion, salivation, sweating, gastrointestinal tone • Peristalsis with consequent development of nausea, vomiting, abdominal cramps, diarrhea & bradycardia
Signs and Symptoms • Easy fatigue and mild weakness • Involuntary twitching and muscular weakness that may affect respiratory muscles causing dyspnea and cyanosis • Cause of death is asphyxia
Treatment • Airway protection • Atropine Sulfate (antagonist for excess acetylcholine) • Skin and Gastrointestinal Decontanimation • Monitoring of pulmonary and cardiac status
References • http://toxipedia.org/display/toxipedia/Leptophos • http://nepis.epa.gov/Exe/ZyNET.exe/20013S5N.txt?ZyActionD=ZyDocument&Client=EPA&Index=1976%20Thru%201980&Docs=&Query=&Time=&EndTime=&SearchMethod=1&TocRestrict=n&Toc=&TocEntry=&QField=&QFieldYear=&QFieldMonth=&QFieldDay=&UseQField=&IntQFieldOp=0&ExtQFieldOp=0&XmlQuery=&File=D%3A%5CZYFILES%5CINDEX%20DATA%5C76THRU80%5CTXT%5C00000009%5C20013S5N.txt&User=ANONYMOUS&Password=anonymous&SortMethod=h%7C-&MaximumDocuments=1&FuzzyDegree=0&ImageQuality=r75g8/r75g8/x150y150g16/i425&Display=p%7Cf&DefSeekPage=x&SearchBack=ZyActionL&Back=ZyActionS&BackDesc=Results%20page&MaximumPages=3&ZyEntry=1 • http://www.inchem.org/documents/jmpr/jmpmono/v075pr25.htm
References • Katzung, Pharmacology Ebook