Этион: свойства, применение и метаболизм

Chembox
| Watchedfields = changed
| verifiedrevid = 455008977
| ImageFile=Ethion ACS. svg
| ImageSize=220px
| ImageAlt = Skeletal formula of ethion
| ImageFile1 = Ethion 3D ball. png
| ImageSize1=240px
| ImageAlt1 = Ball and stick model of the ethion molecule
| IUPACName=O,O,, Tetraethyl S, methylene bis(phosphorodithioate)
| OtherNames=Diethion;[(Dethoxyphosphinothioylthio)methylthio] diethoxy thioxophosphorane
|Section1=
|Section2=Chembox Properties
| Formula=C9H22O4P2S4
| MolarMass=384.48 g/mol
| Appearance=Colorless to amber colored, odorless liquid
| Density=1.22 g/cm3
| MeltingPtC= 12.2
| BoilingPtC=150
| BoilingPt notes = (decomposes)
| Solubility=0.0001% (20 °C)
| FlashPtC = 176.1
| AutoignitionPtC =
| PEL = none
| IDLH = N. D.

In the 1950s, Ethion was first registered in the US as an insecticide. However, the usage of ethion has varied during the years due to overall crop values and weather conditions. For example, 1999 was a very dry year; the drought reduced yields, and the usage of ethion became less economically advantageous. Since 1998, serious studies for the risk assessment of ethion have been conducted by (among others) the EPA (United States Environmental Protection Agency). The risk assessments for ethion were presented at a July 14, 1999 briefing with stakeholders in Florida, which was followed by an opportunity for public comment on risk management for this pesticide.

Ethion is produced under controlled pH conditions, by reacting dibromomethane with Diethyl dithiophosphoric acid in ethanol. Other methods of manufacturing are the reaction of methylene bromide and sodium diethyl phosphorodithioate, and the reaction of diethyl dithiophosphoric acid and formaldehyde.

Goats exposed to ethion showed clear distinctions in excretion, absorption half life and bioavailabilities. These differences depend on the method of administration. Intravenous injection resulted in a half life time of 2 hours, while oral administration resulted in a half life time of 10 hours. Dermal administration lead to a half life time of even 85 hours. These differences in half life times can be completed with a difference in bioavailability. The bio availability of ethion in oral administration was less than 5%, whereas the bio availability of dermal administration of ethion was 20%. In a study conducted among rats, after oral administration it was found that ethion is quite readily metabolized. The metabolization products in found in urine are four to six polar water soluble products. A study among chickens reveals more about the ethion distribution in the body. After 10 days of ethion exposure liver, muscle, and fat tissues were examined. In all three cases ethion or ethion derivatives were present, indicating that it is widely spread in the body. Also chicken eggs were investigated. It was found that the egg white reaches a steady ethion derivative concentration after four days while the concentration in yolk was still rising after ten days. Also in the investigated chicken about six polar water soluble metabolites were found. LD50 values for pure ethion in rats of 208 mg/kg, and for technical ethion of 21 to 191 mg/kg. Other reported oral LD50 values are 40 mg/kg in mice and guinea pigs. Furthermore, inhalation of ethion is very toxic. During one study which was looking at technical grade ethion, an LC50 of 2.31 mg/m^3 was found in male rats and of 0.45 mg/m^3 in female rats. Other data reported a 4 hour LC50 in rats of 0.864 mg/L.

Ethion will result in toxic effects by absorption via the skin, ingestion and via inhalation. When the skin is exposed it may cause burns. Hypothermia, AC heart blocks and arrhythmias are also found to be possible consequences of ethion poisoning. Testing on rats with 10 mg/kg/day and 2 mg/kg/day showed no histopathological effect on the respiratory tract, neither did 13 week testing on dogs (8.25 mg/kg/day). values for pure ethion in rats of 208 mg/kg, and for technical grade ethion of 21 to 191 mg/kg,. Other reported oral LD50 values (for the technical product) are 40 mg/kg in mice and guinea pigs. In a group of six male volunteers no differences in blood pressure or pulse rate were noted, neither in mice or dogs. Diarrhea did occur in mice orally exposed to ethion, severe signs of neurotoxicity were also present. The effects were consistent with cholinergic overstimulation of the gastrointestinal tract.

There are no indications that ethion is carcinogenic in rats and mice. Studies has been conducted in which rats and mice were fed ethion for two years. However, these animals didn't develop cancer any faster than animals that weren't given ethion. Ethion has not been classified for carcinogenicity by the United States Department of Health and Human Services (DHHS), the International Agency for Research on Cancer (IARC) or the EPA. In a chronic toxicity study, rats were fed 0, 0.1, 0.2 or 2 mg/kg/day ethion for 18 months. However, no severe toxic effects were observed. The only significant change was a decrease of cholinesterase levels in the group with the highest dose. Therefore, the NOEL of this study was 0.2 mg/kg. The oral LD50 for pure ethion in rats is 208 mg/kg. The dermal LD50 in rats is 62 mg/kg, 890 mg/kg in rabbits, and 915 mg/kg in guinea pigs. For rats, the 4 hour LD50 is 0.864 mg/L ethion.

Ethion remains a major contaminant of the environment in among others Australia because of (former) usage in agriculture. However, there are some microbes that can convert ethion. The Pseudomonas and Azospirillum species were able to digest ethion when cultivated in minimal salts medium. A significant decrease of the Ethion concentration was observed. On top of that, ethion was the only available source of carbon. After analysis of the compounds present in the media after digestion of ethion through bacteria, it turned out that no abiotic hydrolytic degradation products of Ethion (like ethion dioxon and ethion monoxon) were present. The biodigestion of ethion is probably used to support rapid growth.