Wednesday, October 7, 2009

chemical carcinogens-8thunit-cellbiology-btechbiotechnology

A carcinogen is a substance that is capable of causing cancer in humans or animals. If a substance is known to promote or aggravate cancer, but not necessarily cause cancer, it may also be called a carcinogencarcinogencarcinogen. Though there are many things that are believed to cause cancer, a substance is only considered carcinogenic if there is significant evidence of its carcinogenicity.
Hundreds of chemicals are capable of inducing cancer in humans or animals after prolonged or excessive exposure. There are many well-known examples of chemicals that can cause cancer in humans. The fumes of the metals cadmium, nickel, and chromium are known to cause lung cancer. Vinyl chloride causes liver sarcomas. Exposure to arsenic increases the risk of skin and lung cancer. Leukemia can result from chemically induced changes in bone marrow from exposure to benzene and cyclophosphamide, among other toxicants. Other chemicals, including benzo[a]pyrene and ethylene dibromide, are considered by authoritative scientific organizations to be probably carcinogenic in humans because they are potent carcinogens in animals. Chemically-induced cancer generally develops many years after exposure to a toxic agent. A latency period of as much as thirty years has been observed between exposure to asbestos, for example, and incidence of lung cancer.

different types of chemical carcinogens involve:
aromatic hydrocarbons, aromatic amines, nitroseamines, alkylating agents, mustard gas,
effects of chemical carcinogens:
mutation and chromosal aberrations which finally edas to unregulated proliferation of cells thus leads to cancer
cytochromep-450: they usually detoxify the action of these toxins whicha re usually deactivated during cancer thus allows carcinogens to effect the dna expression which leads to cancer
other chemical carcinogens include:
benzopyrene from coaltar aswell as tobacco
carcinogens are usually called as tumour initiators if the body is continuously exposed to any of the carcinogen then they act as tumour promoters

phorbolesters like 2 naphthyl amine asbestos causes lung cancer
aflotoxin b1 from fungus contaminated acts as carcinogens and causes colon cancer.
thus carcinogens play a vital role in causing cancers

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