Mutagen - Wikipedia
Mutagen: In genetics, a mutagen is a physical or chemical agent that changes the genetic material, What is the difference between carcinogen and oncogene?. What are carcinogens and mutagens? subir human studies that establish a causal relationship between human exposure to a substance and the development. Relationship between Mutagenesis and Carcinogenesis and on the frequency of neoplastic transformations, which are not readily explained by a mutational.
Tumors were described more than 2, years before the discovery of chromosomes and DNA ; in B. Robson found that mustard gas can cause mutations in fruit flies. Sodium azide for example may be mutagenic and highly toxicbut it has not been shown to be carcinogenic. Mutagenesis Mutagens can cause changes to the DNA and are therefore genotoxic.
They can affect the transcription and replication of the DNA, which in severe cases can lead to cell death. The mutagen produces mutations in the DNA, and deleterious mutation can result in aberrant, impaired or loss of function for a particular gene, and accumulation of mutations may lead to cancer. Mutagens may therefore be also carcinogens. However, some mutagens exert their mutagenic effect through their metabolites, and therefore whether such mutagens actually become carcinogenic may be dependent on the metabolic processes of an organism, and a compound shown to be mutagenic in one organism may not necessarily be carcinogenic in another.
Powerful mutagens may result in chromosomal instability,  causing chromosomal breakages and rearrangement of the chromosomes such as translocationdeletionand inversion.
Such mutagens are called clastogens. Mutagens may also modify the DNA sequence; the changes in nucleic acid sequences by mutations include substitution of nucleotide base-pairs and insertions and deletions of one or more nucleotides in DNA sequences.
Although some of these mutations are lethal or cause serious disease, many have minor effects as they do not result in residue changes that have significant effect on the structure and function of the proteins.
Many mutations are silent mutationscausing no visible effects at all, either because they occur in non-coding or non-functional sequences, or they do not change the amino-acid sequence due to the redundancy of codons. Some mutagens can cause aneuploidy and change the number of chromosomes in the cell.
They are known as aneuploidogens.
ISTAS: Carcinogens and mutagens
Similar results are also obtained in studies with radiations, indicating that there may be no safe threshold for mutagens. However, the no-threshold model is disputed with some arguing for a dose rate dependent threshold for mutagenesis. More recent approaches with sensitive analytical methods have shown that there may be non-linear or bilinear dose-responses for genotoxic effects, and that the activation of DNA repair pathways can prevent the occurrence of mutation arising from a low dose of mutagen.
Some however may act on the replication mechanism and chromosomal partition. Transfer the affected workers to a workstation compatible with her condition whenever the adaptation of working conditions is not possible. Subsidised job suspension due to risks during pregnancy or breast feeding when changes of the workplace are not technically feasible.
Classification Many national authorities, international agencies and even professional associations have developed lists of carcinogens according to their own classification criteria, which often do not coincide.
It defines as a carcinogen: Substances which have induced benign and malignant tumours in well performed experimental studies on animals are also considered to be presumed or suspected human carcinogens unless there is strong evidence that the mechanism of tumour formation is not relevant for humans. Carcinogenic substances are classified in three categories according to the following criteria see Annex I, point 3.
A substance may also be included in category 1A if it is known that it is a human carcinogen, based on the existence of human testing, or category 1B if it is supposed to be a human carcinogen, based on the existence of animal testing. The classification in Category 1A and 1B is based on the strength of evidence and others. This evidence may come from: In addition, on a case-by-case basis, scientific judgment may warrant a decision of presumed human carcinogenicity derived from studies showing limited evidence of carcinogenicity in humans together with limited evidence of carcinogenicity in experimental animals.
Danger H May cause cancer indicate exposure route if it is conclusively proven that the danger is not caused by any other route Category 2 Suspected human carcinogens. Such evidence may be derived either from limited evidence of carcinogenicity in human studies or from limited evidence of carcinogenicity in animal studies.Mutagens and carcinogens - Biomolecules - MCAT - Khan Academy
For the purpose of classification for germ cell mutagenicity, substances are allocated to one of two categories: Category 1A and Category 1B Substances known to induce heritable mutations or to be regarded as if they induce heritable mutations in the germ cells of humans. Substances known to induce heritable mutations in the germ cells of humans. The classification in Category 1A is based on positive evidence from human epidemiological studies. Substances to be regarded as if they induce heritable mutations in the germ cells of humans.
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The classification in Category 1B is based on: Positive result s from in vivo heritable germ cell mutagenicity tests in mammals; or Positive result s from in vivo somatic cell mutagenicity tests in mammals, in combination with some evidence that the substance has potential to cause mutations to germ cells.
Danger H May cause genetic defects state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard Category 2 Substances which cause concern for humans owing to the possibility that they may induce heritable mutations in the germ cells of humans The classification in Category 2 is based on: Somatic cell mutagenicity tests in vivo, in mammals; or Other in vivo somatic cell genotoxicity tests which are supported by positive results from in vitro mutagenicity assays.
Substances which are positive in invitro mammalian mutagenicity assays, and which also show chemical structure activity relationship to known germ cell mutagens, shall be considered for classification as Category 2 mutagens.
DSD defines as carcinogenic substances and mixtures: