RNA splicing, in molecular biology, is a form of RNA processing in which a newly made precursor messenger RNA transcript is transformed into a mature messenger RNA. Splicing occurs only in eukaryotic introns. During splicing, introns are removed and exons are joined together. For nuclear-encoded genes, splicing takes place within the nucleus either during or after transcription. For those eukaryotic genes that contain introns, splicing is required in order to create an mRNA molecule that can be translated into protein. For many eukaryotic introns, splicing is carried out in a series of reactions which are catalyzed by the spliceosome, a complex of small nuclear ribonucleo proteins. Self-splicing introns, or ribozymes capable of catalyzing their own excision from their parent RNA molecule exist. Several methods of RNA splicing occur in nature; the word intron is derived from the terms intragenic region, intracistron, that is, a segment of DNA, located between two exons of a gene. The term intron refers to both the DNA sequence within a gene and the corresponding sequence in the unprocessed RNA transcript.
As part of the RNA processing pathway, introns are removed by RNA splicing either shortly after or concurrent with transcription. Introns are found in the genes of many viruses, they can be located in a wide range of genes, including those that generate proteins, ribosomal RNA, transfer RNA. Within introns, a donor site, a branch site and an acceptor site are required for splicing; the splice donor site includes an invariant sequence GU at the 5' end of the intron, within a larger, less conserved region. The splice acceptor site at the 3' end of the intron terminates the intron with an invariant AG sequence. Upstream from the AG there is a region high in pyrimidines, or polypyrimidine tract. Further upstream from the polypyrimidine tract is the branchpoint, which includes an adenine nucleotide involved in lariat formation; the consensus sequence for an intron is: G-G--G-U-R-A-G-U... intron sequence... Y-U-R-A-C... Y-rich-N-C-A-G--G. However, it is noted that the specific sequence of intronic splicing elements and the number of nucleotides between the branchpoint and the nearest 3’ acceptor site affect splice site selection.
Point mutations in the underlying DNA or errors during transcription can activate a cryptic splice site in part of the transcript, not spliced. This results in a mature messenger RNA with a missing section of an exon. In this way, a point mutation, which might otherwise affect only a single amino acid, can manifest as a deletion or truncation in the final protein. Splicing is catalyzed by the spliceosome, a large RNA-protein complex composed of five small nuclear ribonucleoproteins. Assembly and activity of the spliceosome occurs during transcription of the pre-mRNA; the RNA components of snRNPs are involved in catalysis. Two types of spliceosomes have been identified; the major spliceosome splices introns containing GU at the 5' splice site and AG at the 3' splice site. It is composed of the U1, U2, U4, U5, U6 snRNPs and is active in the nucleus. In addition, a number of proteins including U2 small nuclear RNA auxiliary factor 1, U2AF2 and SF1 are required for the assembly of the spliceosome; the spliceosome forms different complexes during the splicing process:Complex E The U1 snRNP binds to the GU sequence at the 5' splice site of an intron.
The spliced RNA is released, the lariat is released and degraded, the snRNPs are recycled. This type of splicing is termed canonical splicing or termed the lariat pathway, which accounts for more than 99% of splicing. By contrast, when the intronic flanking sequences do not follow the GU-AG rule, noncanonical splicing is said to occur; the minor spliceosome is similar to the major spliceosome, but instead it splices out rare introns with different splice site sequences. While the minor and major spliceosomes contain the same U5 snRNP, the minor spliceosome has different but functionally analogous snRNPs for U1, U2, U4, U6, which are called U11, U12, U4atac, U6atac. Trans-splicing is a form of splicing that joins two exons that are not within the same RNA transcript. In most cases, splicing removes introns as single units from precursor mRNA transcripts. However, in some cases, especially
The melting point of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium; the melting point of a substance depends on pressure and is specified at a standard pressure such as 1 atmosphere or 100 kPa. When considered as the temperature of the reverse change from liquid to solid, it is referred to as the freezing point or crystallization point; because of the ability of some substances to supercool, the freezing point is not considered as a characteristic property of a substance. When the "characteristic freezing point" of a substance is determined, in fact the actual methodology is always "the principle of observing the disappearance rather than the formation of ice", that is, the melting point. For most substances and freezing points are equal. For example, the melting point and freezing point of mercury is 234.32 kelvins. However, certain substances possess differing solid-liquid transition temperatures.
For example, agar melts at 85 °C and solidifies from 31 °C. The melting point of ice at 1 atmosphere of pressure is close to 0 °C. In the presence of nucleating substances, the freezing point of water is not always the same as the melting point. In the absence of nucleators water can exist as a supercooled liquid down to −48.3 °C before freezing. The chemical element with the highest melting point is tungsten, at 3,414 °C; the often-cited carbon does not melt at ambient pressure but sublimes at about 3,726.85 °C. Tantalum hafnium carbide is a refractory compound with a high melting point of 4215 K. At the other end of the scale, helium does not freeze at all at normal pressure at temperatures arbitrarily close to absolute zero. Many laboratory techniques exist for the determination of melting points. A Kofler bench is a metal strip with a temperature gradient. Any substance can be placed on a section of the strip, revealing its thermal behaviour at the temperature at that point. Differential scanning calorimetry gives information on melting point together with its enthalpy of fusion.
A basic melting point apparatus for the analysis of crystalline solids consists of an oil bath with a transparent window and a simple magnifier. The several grains of a solid are placed in a thin glass tube and immersed in the oil bath; the oil bath is heated and with the aid of the magnifier melting of the individual crystals at a certain temperature can be observed. In large/small devices, the sample is placed in a heating block, optical detection is automated; the measurement can be made continuously with an operating process. For instance, oil refineries measure the freeze point of diesel fuel online, meaning that the sample is taken from the process and measured automatically; this allows for more frequent measurements as the sample does not have to be manually collected and taken to a remote laboratory. For refractory materials the high melting point may be determined by heating the material in a black body furnace and measuring the black-body temperature with an optical pyrometer. For the highest melting materials, this may require extrapolation by several hundred degrees.
The spectral radiance from an incandescent body is known to be a function of its temperature. An optical pyrometer matches the radiance of a body under study to the radiance of a source, calibrated as a function of temperature. In this way, the measurement of the absolute magnitude of the intensity of radiation is unnecessary. However, known temperatures must be used to determine the calibration of the pyrometer. For temperatures above the calibration range of the source, an extrapolation technique must be employed; this extrapolation is accomplished by using Planck's law of radiation. The constants in this equation are not known with sufficient accuracy, causing errors in the extrapolation to become larger at higher temperatures. However, standard techniques have been developed to perform this extrapolation. Consider the case of using gold as the source. In this technique, the current through the filament of the pyrometer is adjusted until the light intensity of the filament matches that of a black-body at the melting point of gold.
This establishes the primary calibration temperature and can be expressed in terms of current through the pyrometer lamp. With the same current setting, the pyrometer is sighted on another black-body at a higher temperature. An absorbing medium of known transmission is inserted between this black-body; the temperature of the black-body is adjusted until a match exists between its intensity and that of the pyrometer filament. The true higher temperature of the black-body is determined from Planck's Law; the absorbing medium is removed and the current through the filament is adjusted to match the filament intensity to that of the black-body. This establishes a second calibration point for the pyrometer; this step is repeated to carry the calibration to hi
Messenger RNA is a large family of RNA molecules that convey genetic information from DNA to the ribosome, where they specify the amino acid sequence of the protein products of gene expression. RNA polymerase transcribes primary transcript mRNA into processed, mature mRNA; this mature mRNA is translated into a polymer of amino acids: a protein, as summarized in the central dogma of molecular biology. As in DNA, mRNA genetic information is in the sequence of nucleotides, which are arranged into codons consisting of three base pairs each; each codon encodes for a specific amino acid, except the stop codons, which terminate protein synthesis. This process of translation of codons into amino acids requires two other types of RNA: Transfer RNA, that mediates recognition of the codon and provides the corresponding amino acid, ribosomal RNA, the central component of the ribosome's protein-manufacturing machinery; the existence of mRNA was first suggested by Jacques Monod and François Jacob, subsequently discovered by Jacob, Sydney Brenner and Matthew Meselson at the California Institute of Technology in 1961.
It should not be confused with mitochondrial DNA. The brief existence of an mRNA molecule begins with transcription, ends in degradation. During its life, an mRNA molecule may be processed and transported prior to translation. Eukaryotic mRNA molecules require extensive processing and transport, while prokaryotic mRNA molecules do not. A molecule of eukaryotic mRNA and the proteins surrounding it are together called a messenger RNP. Transcription is when RNA is made from DNA. During transcription, RNA polymerase makes a copy of a gene from the DNA to mRNA as needed; this process is similar in prokaryotes. One notable difference, however, is that eukaryotic RNA polymerase associates with mRNA-processing enzymes during transcription so that processing can proceed after the start of transcription; the short-lived, unprocessed or processed product is termed precursor mRNA, or pre-mRNA. Processing of mRNA differs among eukaryotes and archea. Non-eukaryotic mRNA is, in essence, mature upon transcription and requires no processing, except in rare cases.
Eukaryotic pre-mRNA, requires extensive processing. A 5' cap is a modified guanine nucleotide, added to the "front" or 5' end of a eukaryotic messenger RNA shortly after the start of transcription; the 5' cap consists of a terminal 7-methylguanosine residue, linked through a 5'-5'-triphosphate bond to the first transcribed nucleotide. Its presence is critical for recognition by the protection from RNases. Cap addition is coupled to transcription, occurs co-transcriptionally, such that each influences the other. Shortly after the start of transcription, the 5' end of the mRNA being synthesized is bound by a cap-synthesizing complex associated with RNA polymerase; this enzymatic complex catalyzes the chemical reactions. Synthesis proceeds as a multi-step biochemical reaction. In some instances, an mRNA will be edited, changing the nucleotide composition of that mRNA. An example in humans is the apolipoprotein B mRNA, edited in some tissues, but not others; the editing creates an early stop codon, upon translation, produces a shorter protein.
Polyadenylation is the covalent linkage of a polyadenylyl moiety to a messenger RNA molecule. In eukaryotic organisms most messenger RNA molecules are polyadenylated at the 3' end, but recent studies have shown that short stretches of uridine are common; the poly tail and the protein bound to it aid in protecting mRNA from degradation by exonucleases. Polyadenylation is important for transcription termination, export of the mRNA from the nucleus, translation. MRNA can be polyadenylated in prokaryotic organisms, where poly tails act to facilitate, rather than impede, exonucleolytic degradation. Polyadenylation occurs during and/or after transcription of DNA into RNA. After transcription has been terminated, the mRNA chain is cleaved through the action of an endonuclease complex associated with RNA polymerase. After the mRNA has been cleaved, around 250 adenosine residues are added to the free 3' end at the cleavage site; this reaction is catalyzed by polyadenylate polymerase. Just as in alternative splicing, there can be more than one polyadenylation variant of an mRNA.
Polyadenylation site mutations occur. The primary RNA transcript of a gene is cleaved at the poly-A addition site, 100–200 A's are added to the 3’ end of the RNA. If this site is altered, an abnormally long and unstable mRNA construct will be formed. Another difference between eukaryotes and prokaryotes is mRNA transport; because eukaryotic transcription and translation is compartmentally separated, eukaryotic mRNAs must be exported from the nucleus to the cytoplasm—a process that may be regulated by different signaling pathways. Mature mRNAs are recognized by their processed modifications and exported through the nuclear pore by binding to the cap-binding proteins CBP20 and CBP80, as well as the transcription/export complex. Multiple mRNA export pathways have been identified in eukaryotes. In spatially complex cells, some mRNAs are transported to particular subcellar destinations. In mature neurons, certain mRNA are transported from the soma to dendrites. One site of mRNA translation is at polyribosomes selectively localized beneath synapses.
The mRNA for Arc/Arg3.1 is induced by synaptic activity and localizes selectively near active synapses based on signals generated by NMDA receptor
Chloroform, or trichloromethane, is an organic compound with formula CHCl3. It is a colorless, sweet-smelling, dense liquid, produced on a large scale as a precursor to PTFE, it is a precursor to various refrigerants. It is one of a trihalomethane, it is a powerful anesthetic, euphoriant and sedative when inhaled or ingested. The molecule adopts a tetrahedral molecular geometry with C3v symmetry; the total global flux of chloroform through the environment is 660000 tonnes per year, about 90% of emissions are natural in origin. Many kinds of seaweed produce chloroform, fungi are believed to produce chloroform in soil. Abiotic process is believed to contribute to natural chloroform productions in soils although the mechanism is still unclear. Chloroform volatilizes from soil and surface water and undergoes degradation in air to produce phosgene, formyl chloride, carbon monoxide, carbon dioxide, hydrogen chloride, its half-life in air ranges from 55 to 620 days. Biodegradation in water and soil is slow.
Chloroform does not bioaccumulate in aquatic organisms. Chloroform was synthesized independently by several investigators circa 1831: Moldenhawer, a German pharmacist from Frankfurt an der Oder, appears to have produced chloroform in 1830 by mixing chlorinated lime with ethanol. Samuel Guthrie, an American physician from Sackets Harbor, New York appears to have produced chloroform in 1831 by reacting chlorinated lime with ethanol, as well as noting its anaesthetic properties. Justus von Liebig carried out the alkaline cleavage of chloral. Eugène Soubeiran obtained the compound by the action of chlorine bleach on both acetone. In 1834, French chemist Jean-Baptiste Dumas named it. In 1835, Dumas prepared the substance by the alkaline cleavage of trichloroacetic acid. Regnault prepared chloroform by chlorination of chloromethane. In 1842, Robert Mortimer Glover in London discovered the anaesthetic qualities of chloroform on laboratory animals. In 1847, Scottish obstetrician James Y. Simpson was the first to demonstrate the anaesthetic properties of chloroform on humans and helped to popularise the drug for use in medicine.
By the 1850s, chloroform was being produced on a commercial basis by using the Liebig procedure, which retained its importance until the 1960s. Today, chloroform — along with dichloromethane — is prepared and on a massive scale by the chlorination of methane and chloromethane. In industry, chloroform is produced by heating a mixture of chlorine and either chloromethane or methane. At 400–500 °C, a free radical halogenation occurs, converting these precursors to progressively more chlorinated compounds: CH4 + Cl2 → CH3Cl + HCl CH3Cl + Cl2 → CH2Cl2 + HCl CH2Cl2 + Cl2 → CHCl3 + HClChloroform undergoes further chlorination to yield carbon tetrachloride: CHCl3 + Cl2 → CCl4 + HClThe output of this process is a mixture of the four chloromethanes, which can be separated by distillation. Chloroform may be produced on a small scale via the haloform reaction between acetone and sodium hypochlorite: 3 NaClO + 2CO → CHCl3 + 2 NaOH + NaOCOCH3 Deuterated chloroform is an isotopologue of chloroform with a single deuterium atom.
CDCl3 is a common solvent used in NMR spectroscopy. Deuterochloroform is produced by the haloform reaction, the reaction of acetone with sodium hypochlorite or calcium hypochlorite; the haloform process is now obsolete for the production of ordinary chloroform. Deuterochloroform can be prepared by the reaction of sodium deuteroxide with chloral hydrate; the haloform reaction can occur inadvertently in domestic settings. Bleaching with hypochlorite generates halogenated compounds in side reactions. Sodium hypochlorite solution mixed with common household liquids such as acetone, methyl ethyl ketone, ethanol, or isopropyl alcohol can produce some chloroform, in addition to other compounds such as chloroacetone or dichloroacetone. In terms of scale, the most important reaction of chloroform is with hydrogen fluoride to give monochlorodifluoromethane, a precursor in the production of polytetrafluoroethylene: CHCl3 + 2 HF → CHClF2 + 2 HClThe reaction is conducted in the presence of a catalytic amount of mixed antimony halides.
Chlorodifluoromethane is converted into tetrafluoroethylene, the main precursor to Teflon. Before the Montreal Protocol, chlorodifluoromethane was a popular refrigerant; the hydrogen attached to carbon in chloroform participates in hydrogen bonding. Worldwide, chloroform is used in pesticide formulations, as a solvent for fats, rubber, waxes, gutta-percha, resins, as a cleansing agent, grain fumigant, in fire extinguishers, in the rubber industry. CDCl3 is a common solvent used in NMR spectroscopy; as a reagent, chloroform serves as a source of the dichlorocarbene CCl2 group. It reacts with aqueous sodium hydroxide in the presence of a phase transfer catalyst to produce dichlorocarbene, CCl2; this reagent effects ortho-formylation of activated aromatic rings such as phenols, producing aryl aldehydes in a reaction known as the Reimer–Tiemann reaction. Alternatively, the carbene can be trapped by an alkene to form a cyclopropane derivative. In the Kharasch addition, chloroform forms the CHCl2 free radical in addition to alkenes.
The anaesthetic qualities of chloroform were first described in 1842 in a thesis by Robert Mortimer Glover, which won t
Nucleic acids are the biopolymers, or small biomolecules, essential to all known forms of life. The term nucleic acid is the overall name for DNA and RNA, they are composed of nucleotides, which are the monomers made of three components: a 5-carbon sugar, a phosphate group and a nitrogenous base. If the sugar is a compound ribose, the polymer is RNA. Nucleic acids are the most important of all biomolecules, they are found in abundance in all living things, where they function to create and encode and store information in the nucleus of every living cell of every life-form organism on Earth. In turn, they function to transmit and express that information inside and outside the cell nucleus—to the interior operations of the cell and to the next generation of each living organism; the encoded information is contained and conveyed via the nucleic acid sequence, which provides the'ladder-step' ordering of nucleotides within the molecules of RNA and DNA. Strings of nucleotides are bonded to form helical backbones—typically, one for RNA, two for DNA—and assembled into chains of base-pairs selected from the five primary, or canonical, which are: adenine, guanine and uracil.
Using amino acids and the process known as protein synthesis, the specific sequencing in DNA of these nucleobase-pairs enables storing and transmitting coded instructions as genes. In RNA, base-pair sequencing provides for manufacturing new proteins that determine the frames and parts and most chemical processes of all life forms. Nuclein were discovered by Friedrich Miescher in 1869. In the early 1880s Albrecht Kossel further purifies the substance and discovers its acidic properties, he also identifies the nucleobases. In 1889 Richard Altmann creates the term nucleic acid In 1938 Astbury and Bell published the first X-ray diffraction pattern of DNA. In 1953 Watson and Crick determined the structure of DNA. Experimental studies of nucleic acids constitute a major part of modern biological and medical research, form a foundation for genome and forensic science, the biotechnology and pharmaceutical industries; the term nucleic acid is the overall name for DNA and RNA, members of a family of biopolymers, is synonymous with polynucleotide.
Nucleic acids were named for their initial discovery within the nucleus, for the presence of phosphate groups. Although first discovered within the nucleus of eukaryotic cells, nucleic acids are now known to be found in all life forms including within bacteria, mitochondria, chloroplasts and viroids.. All living cells contain both DNA and RNA, while viruses contain either DNA or RNA, but not both; the basic component of biological nucleic acids is the nucleotide, each of which contains a pentose sugar, a phosphate group, a nucleobase. Nucleic acids are generated within the laboratory, through the use of enzymes and by solid-phase chemical synthesis; the chemical methods enable the generation of altered nucleic acids that are not found in nature, for example peptide nucleic acids. Nucleic acids are very large molecules. Indeed, DNA molecules are the largest individual molecules known. Well-studied biological nucleic acid molecules range in size from 21 nucleotides to large chromosomes. In most cases occurring DNA molecules are double-stranded and RNA molecules are single-stranded.
There are numerous exceptions, however—some viruses have genomes made of double-stranded RNA and other viruses have single-stranded DNA genomes, and, in some circumstances, nucleic acid structures with three or four strands can form. Nucleic acids are linear polymers of nucleotides; each nucleotide consists of three components: a purine or pyrimidine nucleobase, a pentose sugar, a phosphate group. The substructure consisting of a nucleobase plus sugar is termed a nucleoside. Nucleic acid types differ in the structure of the sugar in their nucleotides–DNA contains 2'-deoxyribose while RNA contains ribose; the nucleobases found in the two nucleic acid types are different: adenine and guanine are found in both RNA and DNA, while thymine occurs in DNA and uracil occurs in RNA. The sugars and phosphates in nucleic acids are connected to each other in an alternating chain through phosphodiester linkages. In conventional nomenclature, the carbons to which the phosphate groups attach are the 3'-end and the 5'-end carbons of the sugar.
This gives nucleic acids directionality, the ends of nucleic acid molecules are referred to as 5'-end and 3'-end. The nucleobases are joined to the sugars via an N-glycosidic linkage involving a nucleobase ring nitrogen and the 1' carbon of the pentose sugar ring. Non-standard nucleosides are found in both RNA and DNA and arise from modification of the standard nucleosides within the DNA molecule or the primary RNA transcript. Transfer RNA molecules contain a large number of modified nucleosides. Double-stranded nucleic acids are made up of complementary sequences, in which extensive Watson-Crick base pairing results in a repeated and quite uniform double-helical three-dimensional structure. In contrast, single-stranded
Clover or trefoil are common names for plants of the genus Trifolium, consisting of about 300 species of flowering plants in the legume or pea family Fabaceae. The genus has a cosmopolitan distribution with highest diversity in the temperate Northern Hemisphere, but many species occur in South America and Africa, including at high altitudes on mountains in the tropics, they are small biennial, or short-lived perennial herbaceous plants. Clover can be evergreen; the leaves are trifoliate, cinquefoil, or septfoil), with stipules adnate to the leaf-stalk, heads or dense spikes of small red, white, or yellow flowers. Other related genera called clovers include Melilotus and Medicago. Several species of clover are extensively cultivated as fodder plants; the most cultivated clovers are white clover, Trifolium repens, red clover, Trifolium pratense. Clover, either sown alone or in mixture with ryegrass, has for a long time formed a staple crop for silaging, for several reasons: it grows shooting up again after repeated mowings.
In many areas on acidic soil, clover is short-lived because of a combination of insect pests and nutrient balance. When crop rotations are managed so that clover does not recur at intervals shorter than eight years, it grows with much of its pristine vigor. Clovers are most efficiently pollinated by bumblebees, which have declined as a result of agricultural intensification. Honeybees can pollinate clover, beekeepers are in heavy demand from farmers with clover pastures. Farmers reap the benefits of increased reseeding that occurs with increased bee activity, which means that future clover yields remain abundant. Beekeepers benefit from the clover bloom. Trifolium repens, white or Dutch clover, is a perennial abundant in good pastures; the flowers are pinkish, becoming brown and deflexed as the corolla fades. Trifolium hybridum, alsike or Swedish clover, is a perennial, introduced early in the 19th century and has now become naturalized in Britain; the flowers are white or rosy, resemble those of Trifolium repens.
Trifolium medium, meadow or zigzag clover, a perennial with straggling flexuous stems and rose-purple flowers, has potential for interbreeding with T. pratense to produce perennial crop plants. Other species are: hare's - foot trefoil. Shamrock, the traditional Irish symbol, which according to legend was coined by Saint Patrick for the Holy Trinity, is associated with clover, although alternatively sometimes with the various species within the genus Oxalis, which are trifoliate. Clovers have four leaflets, instead of the usual three; these four-leaf clovers, like other rarities, are considered lucky. Clovers can have five, six, or more leaflets, but these are rarer still; the record for most leaflets is 56, set on 10 May 2009. This beat the "21-leaf clover", a record set in June 2008 by the same discoverer, who had held the prior Guinness World Record of 18. A common idiom is "to be in clover", meaning to live a carefree life of ease, comfort, or prosperity; the cloverleaf interchange is named for the resemblance to the leaflets of a clover when viewed from the air.
The first extensive classification of Trifolium was done by Zohary and Heller in 1984. They divided the genus into eight sections: Lotoidea, Mistyllus, Chronosemium, Trifolium and Involucrarium, with Lotoidea placed most basally. Within this classification system, Trifolium repens falls within section Lotoidea, the largest and least heterogeneous section. Lotoidea contains species from America and Eurasia, considered a clade because of their inflorescence shape, floral structure, legume that protrudes from the calyx. However, these traits are not unique to the section, are shared with many other species in other sections. Zohary and Heller argued that the presence of these traits in other sections proved the basal position of Lotoidea, because they were ancestral. Aside from considering this section basal, they did no propose relationships between other sections. Since molecular data has both questioned and confirmed the proposed phylogeny from Zohary and Heller. A genus-wide molecular study has since proposed a new classification system, made up of two subgenera and Trifolium.
This recent reclassification further divides subgenus Trifolium into eight sections. The molecular data supports the monophyletic nature of three sections proposed by Zohary and Heller, but not of Lotoidea. Other molecular studies, although smaller, support the need to reorganize Lotoidea; the genus Trifolium has 245 recognized
European Chemicals Agency
The European Chemicals Agency is an agency of the European Union which manages the technical and administrative aspects of the implementation of the European Union regulation called Registration, Evaluation and Restriction of Chemicals. ECHA is the driving force among regulatory authorities in implementing the EU's chemicals legislation. ECHA helps companies to comply with the legislation, advances the safe use of chemicals, provides information on chemicals and addresses chemicals of concern, it is located in Finland. The agency headed by Executive Director Bjorn Hansen, started working on 1 June 2007; the REACH Regulation requires companies to provide information on the hazards and safe use of chemical substances that they manufacture or import. Companies register this information with ECHA and it is freely available on their website. So far, thousands of the most hazardous and the most used substances have been registered; the information is technical but gives detail on the impact of each chemical on people and the environment.
This gives European consumers the right to ask retailers whether the goods they buy contain dangerous substances. The Classification and Packaging Regulation introduces a globally harmonised system for classifying and labelling chemicals into the EU; this worldwide system makes it easier for workers and consumers to know the effects of chemicals and how to use products safely because the labels on products are now the same throughout the world. Companies need to notify ECHA of the labelling of their chemicals. So far, ECHA has received over 5 million notifications for more than 100 000 substances; the information is available on their website. Consumers can check chemicals in the products. Biocidal products include, for example, insect disinfectants used in hospitals; the Biocidal Products Regulation ensures that there is enough information about these products so that consumers can use them safely. ECHA is responsible for implementing the regulation; the law on Prior Informed Consent sets guidelines for the import of hazardous chemicals.
Through this mechanism, countries due to receive hazardous chemicals are informed in advance and have the possibility of rejecting their import. Substances that may have serious effects on human health and the environment are identified as Substances of Very High Concern 1; these are substances which cause cancer, mutation or are toxic to reproduction as well as substances which persist in the body or the environment and do not break down. Other substances considered. Companies manufacturing or importing articles containing these substances in a concentration above 0,1% weight of the article, have legal obligations, they are required to inform users about the presence of the substance and therefore how to use it safely. Consumers have the right to ask the retailer whether these substances are present in the products they buy. Once a substance has been identified in the EU as being of high concern, it will be added to a list; this list is available on ECHA's website and shows consumers and industry which chemicals are identified as SVHCs.
Substances placed on the Candidate List can move to another list. This means that, after a given date, companies will not be allowed to place the substance on the market or to use it, unless they have been given prior authorisation to do so by ECHA. One of the main aims of this listing process is to phase out SVHCs where possible. In its 2018 substance evaluation progress report, ECHA said chemical companies failed to provide “important safety information” in nearly three quarters of cases checked that year. "The numbers show a similar picture to previous years" the report said. The agency noted that member states need to develop risk management measures to control unsafe commercial use of chemicals in 71% of the substances checked. Executive Director Bjorn Hansen called non-compliance with REACH a "worry". Industry group CEFIC acknowledged the problem; the European Environmental Bureau called for faster enforcement to minimise chemical exposure. European Chemicals Bureau Official website