Lexikon

a collective term for chlorinated derivatives of benzene, toluene, phenol, naphthalene and bi-phenyl and other compounds containing at least one benzene ring. Chlorinated aromatics are widely used as intermediates in the manufacture of medicines, agricultural chemicals and paints.

chlorinated paraffins are chemicals manufactured by chlorination of liquid n-paraffin or paraffin wax. The largest application for chlorinated paraffins is as a plasticiser and flame retardant in flexible PVC. They are also used as plasticisers in paint, sealants and adhesives. Higher chlorine content grades are used as flame retardants in a wide range of rubbers and polymer systems. Another major outlet for chlorinated paraffins is in the formulation of metalworking lubricants where they have long been recognised as one of the most effective additives for lubricants used in a wide range of machining and engineering operations. Finally, they are used in leather formulations.

chlorinated solvents are chloride containing organic liquids which have the power to dissolve organic substances and materials.Trichloroethylene, tetrachloroethylene (also known as perchloroethylene), and methylene chloride are the main solvents in this group. Due to their non-flammability, these compounds have been widely used for cleaning metals in the electronics industry and for dry cleaning of clothes. The use of 1,1,1-trichloroethane was phased out at the end of 1995 under the Montreal Protocol.

chlorine is a greenish yellow gas on normal temperature and pressure. At -34°C it turns to a liquid. It is the eleventh most common element in the earth's crust and is widespread in nature. Chlorine is a key building block of modern chemistry and used in three principal ways: direct use (e.g. to disinfect water); as a raw material for chlorine-containing products (e.g. plastics, pharmaceuticals, pesticides) and as an intermediate to manufacture non-chlorinated products.

chlorobenzenes are a group of cyclic aromatic compounds in which one or more hydrogen atoms of the benzene ring have been replaced by a chlorine atom. The generic molecular formula is C₆H_6–nCl_n, where n = 1–6. There are 12 different chlorinated benzenes: monochlorobenzene (MCB), dichlorobenzene (DCB) (three isomers), trichlorobenzene (TCB) (three isomers), tetrachlorobenzene (TeCB) (three isomers), pentachlorobenzene (PeCB), and hexachlorobenzene. MCB, 1,2-DCB, 1,3-DCB, and 1,2,4-TCB are colourless liquids, while all other congeners are white crystalline solids at room temperature. The solubility of chlorobenzenes in water is low (decreasing with increasing chlorination), flammability is low, the octanol/water partition coefficients are moderate to high (increasing with increasing chlorination), and vapour pressures are low to moderate (decreasing with increasing chlorination).
They are used mainly as intermediates in the synthesis of pesticides and other chemicals; 1,4-dichlorobenzene is used in space deodorants and as a moth repellent. The higher chlorinated benzenes have been used as components of dielectric fluids.
Clorobenzenes other than hexachlorobenzene have low or moderate toxicity to human, and the risk of chlorinated benzenes causing harm to aquatic and terrestrial organisms is considered to be low too.
Their physicochemical properties suggest that chlorobenzenes released to the environment are likely to be volatilized to the atmosphere. The Henry’s law constants measured for chlorobenzenes suggest that they are readily volatilized, especially from aquatic systems with long residence times, such as large lakes and oceans. However, chlorobenzenes released to water may also be adsorbed onto sediment, especially if it is rich in organic matter. Volatilization from soil is also likely, although, depending on the characteristics of the soil, there may also be sorption to soil. The most important factor affecting the behaviour and fate of chlorobenzenes in soil is sorption. adsorption–desorption processes in soil affect the rate of volatilization and leaching and the availability of chemicals to microbial and chemical degradation or uptake by plants or other organisms. The soil sorption coefficients for chlorobenzenes range from 466 to 58 700 and generally increase with increasing chlorination. sorption of chlorobenzenes to soil is affected by many parameters, and it increases with increasing organic matter content.
chlorobenzenes in soil, sediment, and sewage sludge can be degraded by microorganisms. The major mechanism of aerobic degradation is via oxidative dechlorination, usually initiated by dioxygenative hydroxylation, leading to the formation of hydroxylated aromatic compounds (mainly catechols), which undergo ring fission and subsequent mineralization to carbon dioxide and water. The less chlorinated benzenes are more readily degraded than the higher chlorinated ones. biodegradation under anerobic conditions has also been reported, although this occurs at a slower rate than aerobic biodegradation.
They are accumulated by water and terrestrial organisms, mainly in the fat tissue or in the liver of higher organisms.

chloroform is produced by the chlorination of methane (CHCl₃), and is used as an intermediate in the production of refrigerants, agrochemicals and fluoropolymers. It is no longer used as an anaesthetic.

chlorophenols are derivatives of phenols that contain one or morecovalenly bonded chlorine atoms. Most chlorophenols have a number of different isomer. Monochlorophenols have three isomers because there is only chlorine atom which can occupy one of three ring positions on the phenol molecule; dichlorophenols have 4, trichlorophenols: 6, tetrachlorophenols: 3, and pentachlorophenols only one.
In the past, it has been used as a herbicide, insecticide, fungicide, algaecide, disinfectant and as an ingredient in antifouling paint. Some applications were in agricultural seeds (for nonfood uses), leather, masonry, wood preservation, cooling tower water, rope and paper mill system.
Since the early 1980s, the purchase and use of PCP in the U.S has not been available to the general public. Nowadays most of the PCP is restricted to the treatment of utility poles and railroad ties.

structural chromosome damage expressed as breakage of single chromatids or breakage and reunion between chromatids.

the resultant electrical output of sample components passing through a detection system following chromatographic separation. A chromatogram may also be called a trace. The chromatogram gives qualitative and quantitative information on the sample.

representation of the composition of a substance from the characteristic distribution of constituents in an analytical chromatogram.

chromatography is a separation method based on the difference in interactions between the components of the sample dissolved in a fluid phase (gas or liquid) and the stationary phase. The driving force of the transport between the phases is the difference in chemical potential. The retention in the stationary phase (partition) depends on the interactions of the molecules, ions, atoms of the sample. As a consequence, their average velocity will be different, and they leave the stationary phase separated. The separated components are detected based on their physical or chemical properties. The stationary phase can be solid or liquid. The mobil phase can be gas, supercritical fluid or liquid. Depending on the mobil phase the chromatographic techniques are classified as gas chromatography, supercritical fluid chromatography and liquid chromatography. (Source: Balla J.: Analytical applications of gas chromatography. Budapest, 1987) All of these chromatographic techniques are widely used for characterization of various mixtures, e.g. environmental samples in site assessment, technology monitoring, etc.

structural chromosome damage expressed as breakage, or breakage and reunion, of both chromatids at an identical site.

Concise International Chemical Assessment Documents (CICAD). Concise documents that provide summaries of the relevant scientific information concerning the potential effects of chemical substances on human health and the environment; published by the IPCS (WHO International Programme on Chemical Safety).

circulating wells (CWs) provide a technique for subsurface remediation by creating a three-dimensional circulation pattern of the ground water. Ground Water is drawn into a well through one screened section and is pumped through the well to a second screened section where it is reintroduced to the aquifer. The flow direction through the well can be specified as either upward or downward to accommodate site-specific conditions. Because ground water is not pumped above ground, pumping costs and permitting issues are reduced and eliminated, respectively. Also, the problems associated with storage and discharge are removed. In addition to ground water treatment, CW systems can provide simultaneous vadose zone treatment in the form of bioventing or soil vapor extraction.

CW systems can provide treatment inside the well, in the aquifer, or a combination of both. For effective in-well treatment, the contaminants must be adequately soluble and mobile so they can be transported by the circulating ground water. Because CW systems provide a wide range of treatment options, they provide some degree of flexibility to a remediation effort.

Source: US-EPA, Clu-In: http://www.clu-in.org/techfocus/default.focus/sec/Ground-Water_Circulating_Wells/cat/Overview/

the cytoplasm is the part of a cell that is enclosed within the cell membrane. In eukaryotic cells, the contents of the cell nucleus are not part of the cytoplasm and are instead called the nucleoplasm. In eukaryotic cells, the cytoplasm contains organelles, such as mitochondria, Golgi, lysosomes and spherosomes. The cell organelles are filled with liquid that is kept separate from the rest of the cytoplasm by biological membranes. The cytoplasm is the site where most cellular activities occur, such as many metabolic pathways like glycolysis, and processes such as cell division. The inner, granular mass is called the endoplasm and the outer, clear and glassy layer is called the cell cortex or the ectoplasm.

The part of the cytoplasm that is not held within organelles is called the cytosol. The cytosol is a complex mixture of cytoskeleton filaments, dissolved molecules, and water that fills much of the volume of a cell. The cytosol is a gel, with a network of fibers dispersed through water. Due to this network of pores and high concentrations of dissolved macromolecules, such as proteins, an effect called macromolecular crowding occurs and the cytosol does not act as an ideal solution. This crowding effect alters how the components of the cytosol interact with each other.

(Crowding occurs since these high concentrations of macromolecules reduce the volume of solvent available for other molecules in the solution, which has the result of increasing their effective concentrations. This crowding effect can make molecules in cells behave in radically different ways than in test-tube assays. Consequently, measurements of the properties of enzymes or processes in metabolism that are made in the laboratory in dilute solutions may be different by many orders of magnitude from the true values seen in living cells. The study of biochemical processes under realistically crowded conditions is very important, since these conditions are a ubiquitous property of all cells and crowding may be essential for the efficient operation of metabolism.)

Source: Wikipedia

An Analysis of National and EU RTD Programmes related to Sustainable Land and Groundwater Management
Proceedings of the Conference on "Sustainable Management of Contaminated Land"
Variation in calculated human exposure. Comparison of calculations with seven European human exposure models
Special Edition on Land Contamination and Reclamation: The Sustainable Management and remediation of Contaminated Land

classification and labelling includes the evaluation of the hazard of a substance or preparation in accordance with Directive 67/548/EEC (substances) and 1999/45/EC (preparations) and a communication of that hazard via the label.
Classification is the process in which a given substance or preparation is assigned one of the 15 categories of danger depending on their intrinsic properties in accordance with the criteria for specified in directive 67/548/EEC. If the substance is not found to be dangerous, according to the said criteria, then it is not classified. Under GHS the substance or preparation will be assigned to hazard classes.
This evaluation must be made for any substance or preparation manufactured, imported or placed on the EU market for any tonnage level.
The classification of the substance and preparations as being dangerous is based on one or several endpoints concerning physical-chemical properties, health or environmental effects.

• explosive substances and preparations
• oxidising substances and preparations
• extremely flammable substances and preparations
• highly flammable substances and preparations
• flammable substances and preparations
• very toxic substances and preparations
• toxic substances and preparations
• harmful substances and preparations
• corrosive substances and preparations
• irritant substances and preparations
• sensitising substances and preparations
• carcinogenic substances and preparations
• mutagenic substances and preparations
• substances and preparations which are toxic for reproduction
• substances and preparations which are dangerous for the environment

Under REACH, any manufacturer or importer of a substance (regardless of quantity) will be required to submit all its classifications to the Agency, to be included in the classification and labelling Inventory. Classifications must be submitted by 1 December 2010 if the substance is put on the market and is either classified as dangerous (no tonnage threshold) or subject to registration.
The classification has to be included in all registration dossiers.
Classifications should also be communicated in the notifications which are required for substances for research and development (PPORD) and substances in articles.
The classification and labelling inventory is a database maintained by the European Chemical Agency (ECHA) containing the classification of all substances submitted either in registration dossiers or in notification of classification and labelling, including in PPORD notifications. Information from this inventory, which includes substance name and classification and labelling is made publicly available in accordance with the provisions of Article 119 of the REACH Regulation.

Source: REACH Glossary, http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:1999:200:0001:0068:EN:PDF

The CLP Regulation (Classification, Labelling and Packaging) ensures that the hazards presented by chemicals are clearly communicated to workers and consumers in the European Union through classification and labelling of chemicals.

Before placing chemicals on the market, the industry must establish the potential risks to human health and the environment of such substances and mixtures, classifying them in line with the identified hazards. The hazardous chemicals also have to be labelled according to a standardised system so that workers and consumers know about their effects before they handle them.

As a result of this process, the hazards of chemicals are communicated through standard statements and pictograms on labels and safety data sheets. For example, when a supplier identifies a substance as "acute toxicity category 1 (oral)", the labelling will include the hazard statement "fatal if swallowed", the word "Danger" and a pictogram with a skull and crossbones.

The CLP Regulation entered into force in January 2009, and the method of classifying and labelling chemicals it introduced is based on the United Nations' Globally Harmonised System (GHS).

The Regulation replaces over time two previous pieces of legislation, the Dangerous Substances Directive and the Dangerous Preparations Directive. There is a transition period until 2015.

Source: http://echa.europa.eu/web/guest/regulations/clp/understanding-clp

1999/45/EC directive on classification, packaging, labellingis the Directive of the European Parliament and of the Council of 31 May 1999, concerning the approximation of the laws, regulations and administrative provisions of the Member States relating to the classification, packaging and labelling of dangerous preparations.

classification is the process in which a given substance or preparation is assigned one of the 15 categories of danger depending on their intrinsic properties in accordance with the criteria for specified in directive 67/548/EEC. If the substance is not found to be dangerous, according to the said criteria, then it is not classified. Under GHS the substance or preparation will be assigned to hazard classes.

See also labelling of chemical substances and GHS.

(Source: REACH)

clay is a naturally occurring material composed primarily of fine-grained minerals, which show plasticity through a variable range of water content, and which can be hardened when dried and/or fired. Clay deposits are mostly composed of clay minerals phyllosilicate minerals, minerals which impart plasticity and harden when fired and/or dried, and variable amounts of water trapped in the mineral structure by polar attraction.

Clay minerals are typically formed over long periods of time by the gradual chemical weathering of silicate rocks.

Clays are distinguished from other fine-grained soils by their grain-size. The grain size of clay-minerals are close to the colloidal size-range. Geologists and soil scientists usually consider 2 µm and under, sedimentologists often use 4-5 μm and under, and colloid chemists use 1 μm border line. Geotechnical engineers measure the plasticity properties of the soil to indentify clay-content and its geotechnical consequences Atterberg limits. See also soil texture.

clay minerals are hydrous aluminium phyllosilicates, sometimes with variable amounts of iron, magnesium, alkali metals, alkaline earths and other cations. Clay minerals are common weathering products including weathering of feldspar and low temperature hydrothermal alteration products. Clay minerals are very common in fine grained sedimentary rocks such as shale, mudstone and siltstone and in fine grained metamorphic slate and phyllite.

Clays are ultra fine grained normally considered to be less than 2 micrometres in size on standard particle size classifications and so require special analytical techniques. Standards include x-ray diffraction, electron diffraction methods, various spectroscopic methods such as Mossbauer spectroscopy, infrared spectroscopy, and EDS or energy dispersive spectroscopy. These methods should always augment standard polarized light microscopy, a technique which is sometimes overlooked but often where fundamental occurrences or petrologic relationships are established.

Clays are fundamentally built of tetrahedral sheets and octahedral sheets. A 1:1 clay would consist of one tetrahedral sheet and one octahedral sheet, and examples would be kaolinite and serpentine. A 2:1 clay consists of an octahedral sheet sandwiched between two tetrahedral sheets, and examples are illite, smectite, attapulgite, and chlorite although chlorite has an external octahedral sheet often referred to as "brucite".

Clay minerals include the following groups:

• Kaolin group which includes the minerals kaolinite, dickite, halloysite and nacrite. Some sources include the serpentine group due to structural similarities Bailey 1980.
• Smectite group which includes dioctahedral smectites such as montmorillonite and nontronite and trioctahedral smectites for example saponite.
• Illite group which includes the clay-micas. Illite is the only common mineral.
• Chlorite group includes a wide variety of similar minerals with considerable chemical variation.
• Other 2:1 clay types exist such as sepiolite or attapulgite, clays with long water channels internal to their structure.

Mixed layer clay variations exist for most of the above groups. Clay minerals in soil have an important role in bonding both nutrients and pollutants.

Sorce: Wikipedia, http://en.wikipedia.org/wiki/Clay_minerals

clean matrix spike is a sample with no detectable analyte concentration to which an analyte spike has been added.

the term "climate change" is used to imply a significant change from one climatic condition to another. Sometimes, climate change is used synonymously with the term global warming; scientists however tend to use the term in the wider sense to also include natural changes in climate.

clinical toxicology is concerned with diseases and illnesses associated with short term or long term exposure to toxic chemicals. Forensic toxicology is based on the cause and effect relationships between exposure to a drug or chemical substance and the toxic or lethal effects that result in.

cloning is a in vitro DNA technology to produce multiple, exact copies of a single gene or other segment of DNA, even a whole genom to obtain enough material for further study or application.

The resulting cloned (copied) collections of DNA molecules are called clone libraries.

A second type of cloning exploits the natural process of cell division to make many copies of an entire cell, containing a gene or another segment of DNA or the whole genom.

The genetic makeup of these cloned cells, called a cell line, is identical to the original cell.

A third type of cloning produces complete, genetically identical organisms, microorganisms, plants or animals such as the famous Scottish sheep, Dolly.

Clostridium is a genus of Gram-positive bacteria, belonging to the Firmicutes. They are obligate anaerobes capable of producing endospores. Individual cells are rod-shaped.

There are four main species responsible for disease in humans:

C. botulinum, an organism producing a toxin in food/wound that causes botulism. Honey sometimes contains spores of Clostridium botulinum, which may cause infant botulism in humans one year old and younger. The bacteria produce botulinum toxin, which eventually paralyzes the infant's breathing muscles. Adults and older children can eat honey safely, because the clostridia do not compete well with the other rapidly growing bacteria present in the gastrointestinal tract.

C. difficile, can overgrow other bacteria in the gut during antibiotic therapy and cause pseudomembranous colitis.

C. perfringens, formerly called C. welchii, causes a wide range of symptoms, from food poisoning to gas gangrene. Also responsible for enterotoxemia (also known as "overeating disease" or "pulpy kidney disease") in sheep and goats. C. perfringens also takes the place of yeast in the making of salt rising bread.

C. tetani, the causative organism of tetanus.

C. sordellii has been linked to the deaths of more than a dozen women after childbirth.

Clostridium is sometimes found in raw swiftlet birds' nests, a Chinese delicacy. Nests are washed in a sulfite solution to kill the bacteria before being imported to the U.S.

Neurotoxin production is the unifying feature of the species C. botulinum.

As therapy, passive immunisation with human anti-tetanospasmin immunoglobulin or tetanus immunoglobulin is crucial. If specific anti-tetanospasmin immunoglobulin is not available, then normal human immunoglobulin may be given instead. All tetanus victims should be vaccinated against the disease or offered a booster shot.

Many clostridium stains are utilised by industry and commerce.

C. thermocellum can utilize lignocellulosic waste and generate ethanol, thus making it a possible candidate for use in ethanol production. It also has no oxygen requirement and is thermophilic, reducing cooling cost.

C. acetobutylicum, also known as the Weizmann organism, was first used by Chaim Weizmann to produce acetone and biobutanol from starch in 1916 for the production of gunpowder and TNT.

The anaerobic bacterium C. ljungdahlii, recently discovered in commercial chicken wastes, can produce ethanol from single-carbon sources including synthesis gas, a mixture of carbon monoxide and hydrogen that can be generated from the partial combustion of either fossil fuels or biomass. Use of these bacteria to produce ethanol from synthesis gas has progressed to the pilot plant stage at the BRI Energy facility in Fayetteville, Arkansas.

Fatty acids are converted by yeasts to long-chain dicarboxylic acids and then to 1,3-propanediol using Clostridium diolis.

Genes from C. thermocellum have been inserted into transgenic mice to allow the production of endoglucanase. The experiment was intended to learn more about how the digestive capacity of monogastric animals could be improved. Hall et al. published their findings in 1993.

Non-pathogenic strains of clostridia may help in the treatment of diseases such as cancer. Research shows that clostridia can selectively target cancer cells. Some strains can enter and replicate within solid tumours. Clostridia could, therefore, be used to deliver therapeutic proteins to tumours. This use of Clostridia has been demonstrated in a variety of preclinical models.

Source: Wikipedia

the CLP Regulation (for "Classification, Labelling and Packaging") is a European Union regulation which aligns the European Union system of classification, labelling and packaging chemical substances and mixtures to the Globally Harmonised System (GHS). It is expected to facilitate global trade and the harmonised communication of hazard information of chemicals and to promote regulatory efficiency. It complements the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) Regulation (EC No 1907/2006) and replaces the current system contained in the Dangerous Substances Directive (67/548/EEC)and the Dangerous Preparations Directive (1999/45/EC).

1272/2008 regulation of the European Parliament and of the Council of 16 December 2008 on classification, labelling and packaging of substances and mixtures, amending and repealing Directives 67/548/EEC and 1999/45/EC, and amending Regulation (EC) No 1907/2006.This Regulation says, that is should ensure a high level of protection of human health and the environment as well as the free movement of chemical substances, mixtures and certain specific articles, while enhancing competitiveness and innovation.

The regulation incorporates the classification criteria and labelling rules agreed at UN level, the so called Globally Harmonised System of Classification and Labelling of Chemicals (GHS). It introduces new classification criteria, hazard symbols (pictograms) and labelling phrases, while taking account of elements which are part of the current EU legislation.

The regulation requires companies to appropriately classify, label and package their substances and mixtures before placing them on the market. It aims to protect workers, consumers and the environment by means of labelling which reflects possible hazardous effects of a particular chemical. It also takes over provisions of the REACH Regulation regarding the notification of classifications, the establishment of a list of harmonised classifications and the creation of a classification and labelling inventory.

Harmonised classification (legal classification) results from the inclusion into the list of substances in Annex VI of the CLP Regulation (formerly Annex I Directive 67/548/EEC).

Full text of the regulation: http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2008:353:0001:1355:EN:PDF

it was founded in April 1968 and raised considerable public attention in 1972 with its report The Limits to Growth. The club states that its mission is "to act as a global catalyst for change through the identification and analysis of the crucial problems facing humanity and the communication of such problems to the most important public and private decision makers as well as to the general public." Since 1 July 2008, the organization has its headquarters in Winterthur, Switzerland.

See also: http://en.wikipedia.org/wiki/Club_of_Rome

chemical substances with carcinogenic, mutagenic or toxic effect to reproduction. The abbreviation of CMR is used for the characterisation of chemical substances with these properties. Consequences and obligations of being CMR are given by REACH.

Content Management System

see co-oxidation" target="_blank">co-metabolism, co-oxidation

a black or brownish black solid, combustible carbon-rich substance formed by the partial decomposition of vegetable matter without access to air. Coal is one of the most important of the primary fossil fuels. It constitutes humankind’s main source of energy.

coal tar and coal tar oil are principal liquid products resulting from the carbonisation of coal, what means the heating of coal in the absence of air at temperatures ranging from about 900º to 1,200ºC (1,650º to 2,200ºF). Many commercially important compounds are derived from coal tar, such as dyestuffs and pigments.