At least two-thirds of cancer cases of are caused by environmental factors. Many of these cancers are linked to lifestyle factors that can be modified, such as cigarette smoking, excessive alcohol consumption, poor diet, physical inactivity, and being overweight or obese. For example, one-third of all the cancer deaths in this country could be prevented by eliminating the use of tobacco products. After tobacco, being overweight or obese appears the most important preventable cause of cancer.

In addition to lifestyle choices, precautions can be taken in the home and workplace to reduce exposure to other harmful substances.

Here are some rules you can follow to reduce your risk of developing cancer.

• Do not smoke cigarettes, pipes, or cigars. Do not chew tobacco or dip snuff. Avoid smoke-filled rooms. The use of tobacco products is linked to many cancers.
• Lose weight if you are overweight. Obesity is strongly linked to breast cancer in older women and cancers of the endometrium, kidney, colon, and esophagus.
• Exercise regularly, at least 30 minutes per day for most days of the week. Evidence strongly suggests that exercise by itself reduces the risk of colon and breast cancer. Among very active people, that risk is decreased the most.
• Avoid high-calorie, high-fat food. The chief causes of obesity are a lack of physical activity and eating too much high-calorie food.
• Avoid consuming large amounts of red and preserved meats, salt, and salt-preserved foods. These may increase the risk of colorectal and stomach cancers.
• Eat a daily diet that includes a variety of foods from plant sources, such as fresh fruits, vegetables, whole grains, and whole grain breads and cereals. Fruits and vegetables contain substances (e.g., antioxidants) that help defend against toxic agents and disease.
• Drink alcohol in moderation, if at all, especially if you smoke. (One or two alcoholic drinks a day is considered moderate.) Heavy drinking is linked to cancers of the mouth, throat, esophagus, voice box, liver, and breast.
• Avoid too much sunlight, particularly if you are fair skinned, by avoiding sun exposure at midday (10 a.m.–4 p.m., when sun exposure is strongest), wearing protective clothing, and using sunscreen. Many of the more than one million skin cancers diagnosed every year can be prevented by protection from the sun’s rays. Avoid tanning beds and other artificial sun or UV exposure.
• Avoid viral or bacterial infections:
  • Do not engage in unprotected or otherwise unsafe sexual intercourse that may result in HIV, HPV, hepatitis B, or hepatitis C infection.
  • Do not use recreational injection drugs, such as heroin or cocaine, which may result in HIV, hepatitis B, or hepatitis C infection.
  • Get vaccinated against hepatitis B infection, an easy and safe procedure if you are 18 years of age or younger. Also, get vaccinated if you are over 18 and at risk of infection. At-risk people include health care workers, IV drug users, and homosexual men. Currently, no vaccine is available for hepatitis C.

    For vaccination information, visit www.cdc.gov/vaccines/.)

  • Get vaccinated against genital human papillomavirus (HPV) that cause most cases of cervical cancer and genital warts.

    For vaccination information, visit
    www.cdc.gov/std/hpv/STDFact-HPV-vaccine-young-women.htm

  • Seek medical attention for chronic stomach problems—they might be caused by H. pylori infection, which can be treated.
• If you have HIV or hepatitis C infection, seek medical attention and adhere to recommended treatments. These infections increase your risk of developing certain cancers.
• Because repeated exposure to diagnostic X-rays could be harmful, talk to your doctor about the need for each X-ray and the use of shields to protect other parts of the body.
• Check your home for high levels of radon. Radon levels in a home can be greatly reduced by a professionally installed ventilation system in the basement.

  For more information, visit the Environmental Protection Agency Web site: www.epa.gov/radon/.)

• Avoid contact with pesticides. Exposure to pesticides comes largely through the skin. If contact occurs, wash up quickly.
• When working with solvents, make sure the room is well ventilated. If possible, work outside or open the windows.
• If you work in an environment with high exposures to fine particles, fibers, or dusts, wear the appropriate protective mask over your nose and mouth. Make sure it fits properly and does not obstruct your view.
• When handling chemicals in the home or workplace, use good work practices. Wear proper personal protective equipment, keep protective equipment well maintained, clean spills immediately, keep work surfaces as free of dust and chemicals as possible, and use wet cleaning methods to avoid generating dust.
• Be aware that certain occupations are known to be associated with high cancer risks. Some of these include painters, furniture makers, workers in the iron, steel, coal, and rubber industries, and workers involved in boot and shoe manufacture or repair.

  For more information, call the National Institute for Occupational Safety and Health toll-free number, 1-800-356-4674.) or visit
  ehp.niehs.nih.gov/roc/tenth/append/appa.pdf

• Inquire at your workplace about Material Safety Data Sheets (MSDSs). A MSDS is a document that manufacturers of chemical products are required to develop for any product that contains hazardous substances. The MSDS contains information on the toxicity of a substance, whether it is considered carcinogenic, the recommended exposure levels of the ingredients in the product, and appropriate precautions to take or appropriate recommended personal protective equipment to wear. Employers are required to make the MSDSs accessible to employees and to inform/train employees about the information.

  For information about possible workplace issues, call the toll-free number, 1-800-356-4674 or visit the National Institute for Occupational Safety and Health Web site at
  www.cdc.gov/niosh/topics/chemical-safety

• Make sure your employer has put in place appropriate engineering controls such as local exhaust ventilation.

Key Points

• Do not smoke cigarettes, pipes, or cigars. Do not chew tobacco or dip snuff. Avoid smoke-filled rooms.
• If you are overweight, lose weight.
• Exercise regularly, at least 30 minutes per day for most days of the week.
• Avoid high-calorie, high-fat food.
• Avoid consuming large amounts of red and preserved meats, salt, and salt-preserved foods.
• Eat a daily diet that includes a variety of foods from plant sources.
• Drink alcohol in moderation, if at all, especially if you smoke.
• Avoid too much sunlight, particularly if you are fair-skinned.
• Avoid viral or bacterial infections.
• If you have HIV or hepatitis C infection, seek medical attention and adhere to recommended treatments.
• Talk to your doctor about the need for each X-ray and the use of shields to protect other parts of the body.
• Check your home for high radon levels.
• Avoid contact with pesticides.
• When working with solvents, make sure the room is well ventilated.
• When you work in an environment with high exposures to fine particles, fibers, or dusts, wear the appropriate protective mask over your nose and mouth.