Surya K. De - Fundamentals of Cancer Detection, Treatment, and Prevention

Tobacco smoke from cigarettes, however, is a much more significant source of exposure to acrylamide than food.

In studies using rodent models, acrylamide exposure was linked to an increased risk of developing several types of cancer [107–117]. According to the National Toxicology Program's Report on Carcinogens, acrylamide is likely carcinogenic based on its effect in laboratory animals given drinking water contaminated with this compound. More studies, however, need to be done to find out the levels and length of exposure required to affect humans.

Certain occupations involve more employee contact with cancer‐causing substances. Some workers are exposed daily. A few occupations at higher risk include aluminum workers, painters, tar pavers (who are exposed to carcinogenic benzene), rubber and plastic manufacturers, hairdressers, and manicurists in nail salons.

A carcinogen is any substance that promotes carcinogenesis, the formation of cancer. An English physician John Hill first observed in 1761 that certain chemical exposures have been linked to the development of cancer [118]. He noted that the snuff users developed nasal cancer more frequently than the general population. Over 100 000 chemicals are used, and about 1000 new chemicals are listed each year, but not all chemicals are carcinogens. These chemicals are found in everyday items, including as foods, personal products, packaging, prescription drugs, and household and lawn care products [119–122]. While some chemicals may be harmful, not all contact with chemicals is dangerous to your health. Examples of known human carcinogens are asbestos, arsenic, benzene, beryllium, cadmium, nickel, vinyl halides, and others. Examples of possible human carcinogens are chloroform, DDT, polycyclic aromatic hydrocarbons, aromatic amines, azo dyes, nitrosamines and nitrosamides, hydrazo and azoxy compounds, carbamates, halogenated compounds, natural products, and others. DNA bases such as purine and pyrimidine are nucleophiles and react with any electrophiles resulting in DNA damage. Some reactive chemicals such as alkylating agents (alkyl halides), aldehydes, and others directly make a covalent bond with nucleophilic sites in the purine and pyrimidine rings of nucleic acids. Some chemicals react with DNA after being metabolized by the liver cytochrome P450 enzymes. For example, some alkenes and polycyclic aromatic hydrocarbons are metabolized by human liver enzymes to produce an electrophilic epoxide. DNA attacks the epoxide and is bound permanently to it and damages normal cells.

An estimation of some factors contributing to cancer development and their relative significance is shown in ( Figure 2.19).

The following are the current American Cancer Society guidelines for early detection of cancer in most men and women:

Figure 2.19 Factors contributing to cancer development and their relative significance.

a)Women at the time of menopause should consider testing for endometrial cancer. Any unexpected vaginal bleeding or spotting should be reported to a physician immediately.

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