According to effect According to nature Examples Mechanisms and effects 1. Carcinogens Mutagens that induce malignant transformation and development of cancer 2. Clastogens Mutagens that cause breakage of chromosomes 3. Teratogens Mutagens that cause congenital malformations in developing embryos 4. Non-specific mutagens Mutagens that cause non-specific mutagenic damage to the genetic material. 1. Physical mutagens 1.Particulate radiations: X- ray, alpha particles, neutrons, positrons, gamma rays, protons. 2. UV waves 3. Solar radiation & electromagnetic waves 4. Thermal exposure 5. Mechanical agitation 1. Breakage of nucleicacids 2. Chromosome breaks 3. Oxidation of deoxyribose 4. Formation of peroxides 5. Deamination of bases 6. Dehydroxylation of bases 7. Ionization and formation of ion tracks/ion clusters 8. Generation of freeradicals 9. Provocation of carcinogenesis 10. Formation of pyrimidine dimers 11. Denaturation of DNA 2. Chemical mutagens Organichydrocarbons, acridine derivatives, manganese, nitrous acid, hydroxylamine, base analogs, sulfonate compounds, insecticides, asbestos, herbicides, heavy metals. 1. Base transition 2. Base transversion 3. Deamination of bases 4. Generation of free radicals 5. Interruption of base Sequence by intercalation 6. Provocation of carcinogenesis 7. Cytopathic effects following mitDNA damage 8. Alkylation 9. Adduct formation 3. Biological mutagens 1. Viruses: rubella virus, cytomegalovirus, HIV and herpes virus. 2. Toxoplasma gondii. 1. Insertional mutagenesis 2. Provocation of carcinogenesis 4. Change of bases/energy States of bases of DNA Tautomerism, hydration of bases Base transition 5. Metabolic derangements 1. High acidity 2. Dehydration 3. Peroxidation Depurination of nucleic acids Provocation of aberrant DNA replication.

Table 2: Classification of mutagens.