acetylcholinesterase is an enzyme present in nerve tissue, muscles and red blood cells that catalyzes the hydrolysis of acetylcholine (a neurotransmitter)to choline and acetic acid, allowing neural transmission across synapses to occur.
The inhibition of acethylcholinesterase by an acetylcholinesterase inhibitor substance results in an increase in the level and life-time of acethylcholin in the neuromuscular junction resulting in prolonged muscle contraction.
The compound or group of compounds of acetylcholinesterase inhibitor (e.g., organophosphorus compounds) block the action of the enzyme acetylcholinesterase.
In luck of cholinestherase the repeated and unchecked firing of electrical signals can cause uncontrolled, rapid twitching of some muscles, paralyzed breathing, convulsions, and in extreme cases, death. Workers, farmers, gardeners using this kind of pesticides should use protective wear and tools not to be in contacts with the pesticide through skin or eye or swallowing.
Based on this activity acetylcholinesterase inhibitors are used as pesticides. Any pesticide that can bind, or inhibit, cholinesterase, making it unable to breakdown acetylcholine, is called a "cholinesterase inhibitor," or "anticholinesterase agent." The two main classes of cholinesterase inhibiting pesticides are the organophosphates (OPs) and the carbamates (CMs). Some newer chemicals, such as the chlorinated derivatives of nicotine can also affect the cholinesterase enzyme.
Organophosphate insecticides include some of the most toxic pesticides. They can enter the human body through skin absorption, inhalation and ingestion. They can affect cholinesterase activity in both red blood cells and in blood plasma, and can act directly, or in combination with other enzymes, on cholinesterase in the body. The following list includes some of the most commonly used OPs:
- acephate (Orthene)
- azinphos-methyl (Guthion)
- carbofuran (Furadan, F formulation)
- carbophenothion (Trithion)
- chlorfenvinphos (Birlane)
- chlorpyrifos (Dursban, Lorsban)
- coumaphos (Co-Ral)
- crotoxyphos (Ciodrin, Ciovap)
- crufomate (Ruelene)
- demeton (Systox)
- diazinon (Spectracide)
- dichlorvos (DDVP, Vapona)
- dicrotophos (Bidrin)
- dimethoate (Cygon, De-Fend)
- dioxathion (Delnav)
- disulfoton (Di-Syston)
- ethoprop (Mocap)
- fenamiphos (Nemacur)
- fenitrothion (Sumithion)fensulfothion (Dasanit)
- fenthion (Baytex, Tiguvon)
- fonofos (Dyfonate)
- isofenfos (Oftanol, Amaze)
- malathion (Cythion)
- methamidophos (Monitor)
- methidathion (Supracide)
- methyl parathio
- mevinphos (Phosdrin)
- naled (Dibrom)
- oxydemeton-methyl(Meta systox-R)
- parathion (Niran, Phoskil)
- phorate (Thimet)
- phosalone (Zolonc)
- phosmet (Irnidan, Prolate)
- phosphamidon (Dimecron)
- temephos (Abate)
- terbufos (Counter)
- tetrachlorvinphos (Rabon, Ravap)
- trichlorfon (Dylox, Neguvon)
Carbamates, like organophosphates, vary widely in toxicity and work by inhibiting plasma cholinesterase. Some examples of carbamates are listed below:
- aldicarb (Temik)
- bendiocarb (Ficam)
- carbaryl (Sevin)
- formetanate (Carzol)
- methiocarb (Mesurol)
- methomyl (Lannate, Nudrin)
- oxamyl (Vydate)
- pinmicarb (Pirimor)
- propoxur (Baygon)
adopted in 1989 and entered into force on 5 May 1992. The Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and their Disposal aims to minimise the generation of hazardous wastes and control their movement.
separate liquid phase of a non-water-soluble organic contaminant in surface and subsurface waters, sediments and soils.
International Uniform Chemical Information Database, an IT tool of REACH and ECHA.
a knowledge base is a special kind of database for knowledge management, providing the means for the computerized collection, organization, and retrieval of knowledge. Also a collection of data representing related experiences, their results are related to their problems and solutions.
multi-phase extraction uses a vacuum system to remove various combinations of contaminated groundwater, separate-phase petroleum product, and vapors from the subsurface. The system lowers the water table around the well, exposing more of the formation. Contaminants in the newly exposed vadose zone are then accessible to vapor extraction. Once above ground, the extracted vapors or liquid-phase organics and ground water are separated and treated.
Source: US-EPA, Clu-In:http://www.clu-in.org/techfocus/default.focus/sec/Multi-Phase_Extraction/cat/Overview/
disease or disability resulting from conditions of employment, usually from long exposure to a noxious substance or from continuous repetition of certain acts.
A disease or an ailment caused due to excessive exposure of noxious fumes or substances in a working environment that are injurious to health. It includes asthma, poisoning due to use of pesticides, black lung disease among miners, lung cancer due to use of asbestos and other respiratory problems. Any employee who gets affected by disease or a disability under such condition is liable to receive compensation under the laws of workmen's compensation or any other related provision.
PCR is a method for amplifying a DNA base sequence using a heat-stable polymerase and two 20-base primers, one complementary to the (+) strand at one end of the sequence to be amplified and one complementary to the (-) strand at the other end. Because the newly synthesized DNA strands can subsequently serve as additional templates for the same primer sequences, successive rounds of primer annealing, strand elongation, and dissociation produce rapid and highly specific amplification of the desired sequence. PCR also can be used to detect the existence of the defined sequence in a DNA sample.
Under Directive 67/548/EEC these are standard phrases indicating the special risks arising from the dangers involved in using the substance or preparation. For example "Danger of very serious irreversible effects", "Limited evidence of a carcinogenic effect". When the current provisions are repealed and GHS enters into force, the R-phrases will be replaced by "hazard statements". (Source: REACH Glossary)
The concrete risk-phrases are enlisted in the entry of verbal characterisation of risk of chemicals
for the in situ or ex situ remediation of hydrocarbons, pesticides, chlorinated substances contaminated soils the altering oxic-anoxic or aerobic-anaerobic treatment is an efficient bioremediation alternative. The steps of the technology application are:
1. Addition of organic soil amendment, zero valent iron, and water to produce anoxic conditions.
2. Periodic tilling of the soil to promote oxic conditions.
3. Repetition of the anoxic-oxic cycle until the desired cleanup goals are achieved.
The addition of DARAMEND® organic amendment, zero valent iron, and water stimulates the biological depletion of oxygen, generating strong reducing anoxic conditions within the soil matrix. The diffusion of replacement oxygen into the soil matrix is prevented by near saturation of the soil pores with water. The depletion of oxygen creates a low redox potential, which promotes dechlorination of organochlorine compounds. A cover may be used to control the moisture content, increase the temperature of the soil matrix and eliminate runon/run off.
The soil matrix consisting of contaminated soil and the amendments is left undisturbed for the duration of the anoxic phase of treatment cycle typically 1-2 weeks. In the oxic phase of each cycle, periodic tilling of the soil increases diffusion of oxygen to microsites and distribution of irrigation water in the soil. The dechlorination products formed during the anoxic degradation process are subsequently removed trough aerobic oxic biodegradation processes, initiated by the passive air drying and tilling of the soil to promote aerobic conditions.
environmental risk assessment provides an objective, technical evaluation of the likelihood of unacceptable impacts to human health and the environment. The purpose is to assess the need for protective measures, since a specific risk assessment is a precondition for any such protective measures. (Source: EUGRIS)
standard phrases relating to the safe use of dangerous chemical substance. For example "Keep container tightly closed" or "avoid contact with skin" or "do not empty into drains". When the current provisions are repealed and GHS enters into force, the S-phrases will be replaced by "precautionary statements". (Source: REACH Glossary).
The S-phrases are enlisted under the entry of "safety advice for the use of dangerous substances".
soil bioremediation based on aerobic oxidation means that the soil remediation is based on aerobic biodegradation. The microbiological biodegradation occurs in this case on a high redoxpotential of +0,8-+0,6 Volt. The degrading microorganisms utilise the pollutant as enbergy sources. The source of oxigen is the atmospheric air, soil air, or dissolved oxigen in soil moisture or ground water. If the oxigen-concentration is low, the technologist can increase it by aeration of the soil or the groundwater as well as by adding peroxide substances or other oxigene release compounds ORC to serve as oxigene source for the activation of the aerobic soil microbes.
soil remediation based on aerobic biodegradation is an oxidative process catalysed by microbes. Microbes, mainly bacteria utilise the contaminant as substrate for producing energy. Aerobic bacteria use athmospheric oxigen for the oxidation of the polluting organic compounds and produce inorganic products, such as CO2, NO3 and H2O. This process is also called mineralisation.
When athmospheric oxigen is limited, the biodegradation is catalysed by facultative anaerobic microbes, which use NO3 for their alternative respiration. In this case the oxidation/mineralisation products from the substrate the contaminant are alcohols or aldehydes.
anaerobic biodegradation of soil contaminants is based on the aternative respiration of soil microorganisms, using oxigen from NO32-, SO42-or CO2, as hydrogen-acceptor instead of atmospheric oxigen. Paralel to the oxidation of the contaminant energy source in this case, nitrate, sulfate and carbonate are reduced into N2 via nitrite NO2−, nitric oxide NO, nitrous oxide N2O, H2S and CH4 respectively.
There are some metals which can also be reduced and function as electronacceptor, such as ferric ion Fe3+reduction to Fe2+ or Fe0, manganic ion Mn4+ reduction to Mn2+, selenate SeO42- reduction to selenite: SeO32- and Se0, arsenate AsO43- reduction to arsenite: AsO33- or uranyl ion UO22+ reduction to uranium dioxide UO2 for the electron transport chain.
The anaerobic biodegradation of xenobiotics needs a microorganism- and metabolism-specific redoxpotential. The soil remedial biotechnology is responsible for ensuring the proper redoxpotential in the soil to control the process and run biodegradation on the optimum.
To control the redoxpotential the technologist should ensure sufficient quantity of nitrate, sulfate or any other electronacceptors in the soil.
a chromatographic technique used to prepare samples for subsequent analysis, an effective method to concentrate or isolate the non-volatile analytes. It is a kind of column chromatography. The extract is eluted through the column (cartridge) containing the preconditioned sorbent by applying vacuum. The substance of interest is retained on the column and all the interfering components are eluted or the interfering components are retained and the substance of interest is eluted. This sample preparation technique is suitable for any compounds. The low solvent need, no need of concentration by evaporation and in this way avoiding the concentration of the polluting components, cheap sorbents, saving time, no emulsion formation, enhanced selectivity and potential for automatization are the advantages of SPE over the traditional liquid/liquid extraction (LLE).
in chromatography, the porous solid or liquid phase through which an introduced sample passes. The different affinities the stationary phase has for a sample allow the components in the sample to be separated or resolved.