Environmental Carcinogens

When individuals are exposed to compounds like infectious agents, environmental life style, occupation and diet, humans develop cancer. These compounds are classified as environmental carcinogens. A subset of human carcinogen is referred as environmental carcinogen. Such anticipated potential human carcinogens are metallic compounds, pesticides, dioxins, poly aromatic hydrocarbons, asbestos and erionite. Major contaminants spread via air, water, soil and in specific through food. It is difficult to understand the environmental carcinogens and carcinogenesis development. The parameters like duration, composition, dose and specificity of exposure to carcinogens are determined to study the carcinogenic effect.

Environmental Protection Agency has classified carcinogens based on epidemiologic study of humans, animals and other such mechanistic studies. Potentiality of environmental contaminants to cause cancer depends ultimately on the dose of exposure to carcinogens. Some contaminants accumulate as bioaccumulants in environmental conditions and tissues of human. It is characterized that some carcinogens has lipophilic properties and gets accumulated in tissues at smaller quantity. Single compound can never be counted to cause cancer. However interaction of every single compound with chemicals and complex mixtures result in development of cancer. This interaction may increase or decrease the interaction with complex mixture, thereby carcinogen come in contact with human populations.

Classification of environmental carcinogen

Environmental carcinogens are classified as following.

• Chemical agents
• Hormones
• Viruses
• Physical agents

Mechanism of action of environmental carcinogens

Cancer cascading steps are initiation, promotion and progression. Environmental carcinogens involvement can interrupt any stages of cell cycle either by repairing DNA, apoptosis, cell differentiation, growth of cells and such biological processes. Poly aromatic hydrocarbons are known to cause cancer. PHA forms covalent bond with DNA thereby it repairs the cell growth and repair. It may interact with epigenetic mechanism. There is no interaction with genome but with mitogenic expression of cells where the mechanism of cell growth is altered and thereby cell death occurs. Some genes like tumor suppressor genes and proto oncogenes are known to cause cancer. One such classified proto oncogene is ras and myc and tumor suppressor gene is p53. Mutation of genes may lead to cancer. Individuals with mutations develop cancer especially from cigarette smoking.

Anticipated environmental carcinogens list

• Asbestos
• Cigarette smoking
• Coke oven emissions
• Nickel compounds
• Aflatoxins
• Benzene
• Inorganic compounds
• Arsenic
• Solar radiations
• Wood dust
• Uranium
• Ionizing radiations
• Coal tar compounds
• X rays
• Ultra violet rays
• Vinyl chloride