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| Parathion | |
|---|---|
| General | |
| Systematic name | O,O-Diethyl-O-4-nitro | -phenylthiophosphate
| Other names | E605 |
| Molecular formula | C10H14NO5PS |
| SMILES | C(C)OP(OCC)(=S)Oc1 | (ccc(*(*)=O)cc1)
| Molar mass | 291,3 g/mol |
| Appearance | White crystals (pure form) |
| CAS number | 56-38-2 |
| Properties | |
| Density as the solid | 1,3 g/cm3 |
| Solubility in water | and organic solvents24mg/l in water, high solubility | in xylene or n-butanole
| Melting point | 6 C |
| Hazards | |
| MSDS | * |
| OSHA Exposure Limits | PEL 0.1 mg/m3 |
| Flash point | 120 °C |
| R Statements | , , , |
| S Statements | , , , , |
| RTECS number | ? |
| Supplementary data page | |
| Structure and properties | n, εr, etc. |
| Thermodynamic data | Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Related compounds | |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Chemical infobox | |
Properties and uses
Parathion, or diethyl parathion, is a very potent insecticide and acaricide. In its purest form, it consists of white crystals; however more commonly distributed forms take the form of a brown liquid which smells of rotting eggs or garlic. The insecticide is more or less stable, though it darkens when exposed to sunlight. It is generally applied by spraying, and often used on cotton, rice and fruit trees. Usual concentrations of the ready-to-use solutions are 0.05 to 0.1%. The chemical is banned for use on many food crops. As per 2005 at least 18 countries (e.g. many EU countries, Switzerland, Peru, Chile) have already forbidden its use in general due to its high toxicity (LD50 in men 5 to 10mg/kg) and pollutant properties. Additionally, Parathion is an experimental mutagen, teratogen, and carcinogen. It is very harmful to bees, fish, birds, and other forms of wildlife. Parathion can be replaced by many safer and less toxic alternatives (less toxic organophosphates, carbamates, or synthetic pyrethroids).
History
Parathion was developed by the German trust IG Farben in the 1940's. Dr. Gerhard Schrader was the inventor. After the war the Western allies seized the according patent and Parathion was thereafter marketed worldwide by different companies and under different brandnames. The most common German brandname was E605 (banned in Germany after 2002); this was not an E number (not a food additive). "E" stands for Entwicklungsnummer (German for "development number"), not for "European".
Toxicity in humans
Parathion is a cholinesterase inhibitor. It generally disrupts neural function by inhibiting the essential enzyme acetylcholinesterase. It is absorbed via skin, mucous membranes, and orally. Absorbed Parathion is rapidly metabolized to Paraoxon in which the sulfur atom is replaced by oxygen. Paraoxon exposure can result in headaches, convulsions, poor vision, vomiting, abdominal pain, severe diarrhea, unconsciousness, tremor, dyspnea and finally lung-edema as well as respiratory arrest. Symptoms of poisoning are known to last for extended periods of time, sometimes months. The most common and very specific antidote is atropine in doses of up to 100mg daily. Because Atropine may also be toxic, it is now recommended to use small doses which are frequently repeated. If human poisoning is detected early and the treatment is prompt (antidote and artificial respiration), fatalities are infrequent. Insufficient respiration may lead to cerebral hypoxia and permanent brain damage. Additionally, peripheral neuropathy including paralysis is noticed as late sequelae after recovery from acute intoxication. Parathion has been extensively used for committing suicide and deliberately killing other persons. For the latter reason most formulations contain a blue dye providing warning.
Protection against poisoning
To assure human protection the end user must wear protective gloves, clean protective clothing, and a respirator of the organic-vapour type when handling this material. He/she should bathe immediately after work. Industrial safety during the production process requires special ventilation and continuous measurement of air contamination in order not to exceed PEL levels as well as keeping personal hygiene. Frequent determination of workers' serum acetylcholinesterase activity is also helpful in regards of occupational safety, because the action of Parathion is cumulative.
Proposals to ban
According to the NGO PAN (International Pesticide Network) Parathion is the most dangerous pesticide used. PAN lists Parathion also as 'bad actor chemical'. In the US alone more than 650 agricultural workers have been poisoned since 1966, of which 100 died. In underdeveloped countries many more people have suffered fatal and nonfatal intoxications. The WHO, PAN and numerous environmental organisations propose a general and global ban.
"Parathion"