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Posttest Instructions

Posttest Questions

Choose the best answer.
  1. Which of the following statements concerning the development of cancer is INCORRECT?
    1. Cancer develops over many years and has many causes.
    2. Exposure to a wide variety of natural and manufactured substances in the environment accounts for at least two-thirds of all the cases of cancer in the United States.
    3. Cancer rates DO NOT change when groups of people move from one country to another.
    4. Different environmental exposures are linked to specific kinds of cancer.
  2. Which of the following statements concerning factors inside the body that make some people more likely to develop cancer than others is INCORRECT?
    1. Certain factors inside the body make some people more likely to develop cancer than others.
    2. One of the ways scientists know that genes play an important role in the development of cancer is from studying certain rare families where family members over several generations develop similar cancers.
    3. Gene alterations may also contribute to individual differences in susceptibility to environmental carcinogens.
    4. Exposure to cancer-causing substances ALONE determines who will get cancer.
  3. Which of the following statements concerning the interaction of environmental factors and genes in the development of cancer is INCORRECT?
    1. Mechanisms to repair damage to our genes and healthy lifestyle choices help to protect us from harmful exposures.
    2. The chance that a person will develop cancer in response to a particular environmental agent depends on length of exposure, alone.
    3. Because of the complex interplay of many factors, it is not possible to predict whether a specific environmental exposure will cause a particular person to develop cancer.
    4. Particular patterns of gene alterations and environmental exposures make people more susceptible or more resistant to cancer.
  4. Which of the following statements concerning the development of cancer is INCORRECT?
    1. When cancer develops, cells continue to divide even when new cells are not needed, and that growth or extra mass of cells called a tumor.
    2. It takes many years for the development of a tumor and even more years until detection of a tumor and its spread to other parts of the body.
    3. NOT MUCH EVIDENCE is available to suggest that permanent changes in our genes are responsible for tumor development.
    4. One explanation for the fact that cancer occurs more frequently in older people may be that, for a tumor to develop, a cell must acquire several gene alterations that accumulate as we age.
  5. Which of the following statements concerning the different types of tumors INCORRECT?
    1. Benign tumors are not cancerous.
    2. Benign tumors spread to other parts of the body.
    3. A malignant tumor can metastasize and spread to nearby parts of the body and eventually to sites far away from the original tumor.
    4. Most cancers are named for the organ or type of cell in which they begin to grow.
  6. Which of the following statements concerning different types of cancers is INCORRECT?
    1. Melanoma is a cancer of cells in the skin, eyes, and some other tissues, known as melanocytes.
    2. Leukemias are cancers of the blood cells.
    3. Lymphomas are cancers that develop in the lymphatic system.
    4. Carcinomas are cancers that develop in the connective tissue of certain organs, such as the lung, liver, skin, or breast.
  7. Which of the following statements concerning substances either known to cause cancer or suspected of causing cancer in humans is INCORRECT?
    1. Exposure to carcinogens in tobacco products accounts for about one-third of all cancer deaths in the United States each year.
    2. Several studies show that heavy consumption of red and preserved meats, salt-preserved foods, and salt probably increase the risk of colorectal and stomach cancers.
    3. Being overweight or obese appears to be one of the most important, modifiable causes of cancer, after tobacco.
    4. Heavy drinkers (more than two drinks/day) have a lesser risk of cancer, particularly among those who also smoke.
  8. Which of the following statements concerning substances that are either known to cause cancer or suspected of causing cancer in humans is INCORRECT?
    1. Of the nearly 900 active ingredients in registered pesticides in the United States, most have been found to be carcinogenic in animals, although not all have been tested.
    2. Some drugs used to treat cancer have been shown to increase the occurrence of second cancers.
    3. Several solvents used in paint thinners, paint and grease removers, and in the dry cleaning industry are known or suspected in animal studies of causing cancer.
    4. Infectious agents such as viruses and bacteria contribute to the development of several types of cancer.
  9. Which of the following statements concerning substances either known to cause cancer or suspected of causing cancer in humans is INCORRECT?
    1. Radiation from cosmic rays may account for a very small percentage (about 1 percent) of our total cancer risk.
    2. It is estimated that about 20,000 lung cancer deaths every year are caused by radon exposure in homes.
    3. People exposed to radioactive fallout in the form of Iodine-131 may have an increased risk of thyroid disease, including thyroid cancer.
    4. Most studies on the long-term effects of exposure to radiation (for example, X-Rays) used to diagnose or screen for cancers or other diseases have shown an elevated cancer risk.
  10. Which of the following statements concerning fibers, fine particles, and dust is INCORRECT?
    1. Asbestos fibers and all commercial forms of asbestos are human carcinogens.
    2. Asbestos exposures account for the largest percentage of occupational cancer, with the highest risks among workers who smoke.
    3. Increased rates of mesothelioma—a rare cancer of the lining of the lung and abdominal cavity—and cancer of the lung have been consistently observed in a variety of occupations involving asbestos exposure.
    4. Ceramic fibers are now used as insulation materials and are a replacement for asbestos. These fibers are not carcinogenic.
  11. Which of the following statements concerning dioxins is INCORRECT?
    1. Dioxins are chemical products synthesized for commercial purposes.
    2. Dioxins are widespread environmental contaminants.
    3. The general population is exposed to low levels of TCDD primarily from eating dairy products, fish, and meat, including poultry.
    4. Modifications of industrial processes such as bleaching and incineration have resulted in reduced dioxin emissions and have lowered dioxin levels in people.
  12. Which of the following statements concerning vinyl chloride is INCORRECT?
    1. Vinyl chloride, a colorless gas, is a human carcinogen associated with lung cancers and angiosarcomas (blood vessel tumors) of the liver and brain.
    2. The major source of releases of vinyl chloride into the environment is believed to be from the plastics industries.
    3. People living near a plastics plant are exposed to possible carcinogens by breathing contaminated air.
    4. The general population away from the plant also shows levels of exposure.
  13. Which of the following statements concerning the association of environmental factors and cancer is INCORRECT?
    1. At least two-thirds of the cases of cancer are caused by environmental factors.
    2. One-third of all the cancer deaths in this country could be prevented by eliminating the use of tobacco products.
    3. After tobacco, exposure in the home and workplace appears to be the most important preventable cause of cancer.
    4. Precautions can be taken in the home and workplace to reduce exposure to other harmful exposures.
  14. Which of the following statements concerning the association of environmental factors and cancer is INCORRECT?
    1. The use of tobacco products is linked to many cancers.
    2. Obesity is strongly linked to breast cancer in older women and cancers of the endometrium, kidney, colon, and esophagus.
    3. Inherited traits from parents are the chief causes of obesity.
    4. Large amounts of red and preserved meats, salt, and salt-preserved foods may increase the risk of colorectal and stomach cancers.
  15. Which of the following statements concerning reducing the risk of developing cancer associated with viral or bacterial infections is INCORRECT?
    1. HIV, HPV, hepatitis B, or hepatitis C viral infections increase the risk of developing certain cancers.
    2. The use of recreational injection drugs such as heroin or cocaine may result in HIV, hepatitis B, or hepatitis C infection.
    3. Unprotected or otherwise unsafe sexual intercourse may result in HIV, HPV, hepatitis B, or hepatitis C infection.
    4. Vaccines can prevent HIV, HPV, hepatitis B, or hepatitis C infections.
  16. Which of the following statements concerning detecting cancers at an early stage is INCORRECT?
    1. Men and women (as applicable) should get regular screening tests for breast, cervix, colon and rectum cancers.
    2. Changes in bowel or bladder habits, indigestion or difficulty swallowing and unexplained changes in weight are sure signs of cancer.
    3. You should tell your health care provider about the chemicals you use at work or at home.
    4. You should ask your health care provider if increased cancer risks are associated with your family’s or your personal medical history or medical drugs you are taking.
  17. Which of the following statements concerning detecting cancer at an early stage is INCORRECT?
    1. A mammogram is the best method of finding breast cancer before symptoms appear.
    2. The Pap test or Pap smear is the most successful tool to screen for cancer of the cervix.
    3. A fecal occult blood test, a sigmoidoscopy, or a colonoscopy are screening tests used to find colon and rectal cancer.
    4. With a fecal occult blood test, a sigmoidoscopy or a colonoscopy, abnormal tissue can be removed and examined under a microscope.
  18. Which of the following statements concerning challenges for scientists in identifying substances that cause cancer is INCORRECT?
    1. Americans commonly use more than 100,000 different chemicals.
    2. During the synthesis or combustion of other chemicals, cancer-causing substances are sometimes created.
    3. All cancer-causing substances are manufactured as opposed to natural.
    4. Every year, manufacturers introduce another 1,000 or so new chemicals.
  19. Which of the following statements concerning sources of evidence for identifying cancer-causing substances is INCORRECT?
    1. Evidence for identifying cancer-causing substances is derived IN PART from human studies.
    2. Evidence for identifying cancer-causing substances is derived IN PART from animal studies.
    3. Evidence for identifying cancer-causing substances is derived IN PART from laboratory experiments with human cells.
    4. Evidence for identifying cancer-causing substances is derived IN PART from theoretical chemical computational calculations.
  20. Which of the following statements concerning the role animal studies play in identifying causes of cancer in humans is INCORRECT?
    1. Nearly all of the approximately 200 agents known to cause cancer in humans have also been shown to cause cancer in rats or mice.
    2. We do not know how many of the several hundred other chemicals that cause cancer in animals are also human carcinogens.
    3. Public health officials do not have to heed the warnings provided by animal tests.
    4. Positive tests in animals are often used as a basis for reducing or eliminating human exposure to probable cancer-causing agents.
  21. Which of the following statements concerning dosage levels given to animals in testing possible cancer-causing substances is INCORRECT?
    1. Mice or rats are given dosages much higher than those to which humans normally would be exposed.
    2. Large numbers of people are exposed to low doses of chemicals, but the total effect may not be small at all.
    3. Using high dosages, any potential cancer-causing effects are more likely to be detected—even in small groups of rodents.
    4. We have greater assurance that the chemical will not cause cancer in people when LOW doses do not cause cancer in animals.
  22. Which of the following statements concerning use of human cells grown in the laboratory in testing for cancer is INCORRECT?
    1. Experiments with human cells grown in the laboratory are not useful when evaluating whether to perform studies in rats and mice.
    2. For epidemiologists, results from experiments with human cells grown in the laboratory provide clues regarding hypotheses to test in human population studies.
    3. Although in toxicology research experiments with human cells grown in the laboratory might reduce reliance on animal testing, rodent testing of potential carcinogens remains an important part of cancer prevention strategies.
    4. The combination of human studies, animal studies, and laboratory experiments provide scientists with the most complete understanding of the chemical risks of cancer.
  23. In deciding which substances should be selected for testing in animals or with human cells, scientists DO NOT use
    1. Chemicals that affect a large number of persons or chemicals for which exposure levels have been unusually high.
    2. Chemicals that in laboratory cells cause human DNA alterations.
    3. Reports that people exposed to a particular chemical in the workplace develop certain cancers at rates similar to the general population.
    4. Chemicals that concerned citizens groups first brought to the attention of public health officials.
  24. Which of the following factors ARE NOT TAKEN INTO CONSIDERATION by epidemiologists when beginning large population studies?
    1. Data from animal studies suggesting a cancer-exposure link.
    2. Cancer trends or rates that do not change over time or with location.
    3. Changes in cancer rates within a population after that population has migrated to new area.
    4. Pockets of cancers that cluster in a particular town or place or that are the subjects of unusual case reports.
  25. Public health agencies classify substances as known or suspected human carcinogens based on evidence of cancer from at least one type of exposure, EXCEPT FOR
    1. Either high short- or long-term workplace exposures.
    2. Continuous low-level exposure or occasional exposure to carcinogens in the environment.
    3. Continuous low-level exposure or occasional exposure to carcinogens in the workplace.
    4. Single, acute exposures following industrial accidents or similar incidents.
  26. Which of the following statements concerning acceptable risk levels by regulatory agencies is INCORRECT?
    1. Acceptable risks are generally LOWER for exposure in the workplace than for exposure in the general environment.
    2. Acceptable risks are generally HIGHER for exposure in the workplace than for exposure in the general environment.
    3. The range of the risk level considered acceptable by regulatory agencies for a linear dose response starts at one cancer in every million persons exposed.
    4. The risk level range considered acceptable by regulatory agencies for a linear dose response ends at one cancer in every 1,000 persons exposed.
  27. Which of the following statements concerning dose-response levels and risk of cancer is INCORRECT?
    1. In a linear dose response, the risk decreases as the exposure decreases—all the way to zero.
    2. In a linear dose response, a minuscule risk of cancer is predicted for any exposure, no matter how limited the exposure might be.
    3. In a threshold-dose response, a minuscule risk of cancer is predicted for any exposure, no matter how limited the exposure might be.
    4. A threshold dose response may include an exposure level below which an increase in risk is not detectable.
  28. Which of the following statements concerning the setting of acceptable exposure levels for environmental chemicals is INCORRECT?
    1. One of the first considerations by regulatory agencies is to determine whether a carcinogen exhibits linear or threshold-like dose-response behavior.
    2. Absent compelling evidence for a linear response, agencies assume that to protect public health, the dose response is threshold-like.
    3. Absent compelling evidence for a threshold-like mechanism, to protect the public health agencies assume that the dose response is linear.
    4. Absent compelling evidence to the contrary, agencies assume that any exposure—no matter how small—has some risk.
  29. Which of the following statements concerning threshold-like dose responses is INCORRECT?
    1. If carcinogens exhibit threshold-like dose responses, and if the cancer testing is done in rats and mice, scientists consider the possibility that people are EQUALLY AS SENSITIVE AS are rats or mice to a particular chemical’s cancer-causing effects.
    2. If carcinogens exhibit threshold-like dose responses, and if the cancer testing is done in rats and mice, scientists consider the possibility that people are MORE SENSITIVE THAN are rats or mice to a particular chemical’s cancer-causing effects.
    3. If carcinogens exhibit threshold-like dose responses, the potentially greater health effects on children of pesticide residues in food are taken into consideration when setting acceptable pesticide exposure levels.
    4. If carcinogens exhibit threshold-like dose responses, and if the cancer testing is done in rats and mice, acceptable levels of exposure are set as much as 1,000 times below the level that causes a substantial increase in cancer in rodents.
  30. Which of the following statements about risk versus benefit when regulating environmental chemical exposure is INCORRECT?
    1. Many substances that may cause cancer in people also have some benefits.
    2. Tamoxifen, effective in preventing the recurrence of breast cancer in many women, also increases the risk of uterine cancer, blood clots, and strokes.
    3. The serious risks associated with tamoxifen for women who have had breast cancer or for a relatively small number of women who are at high risk of developing breast cancer strongly outweigh the drug’s benefits.
    4. Tamoxifen benefits strongly outweigh its serious risks for women who have had breast cancer or for the relatively small number of women who are at high risk of developing breast cancer.
  31. Which of the following statements concerning interpreting incidence rates of cancer is INCORRECT?
    1. An increase in new cancer cases may result from exposure to a harmful substance in the environment.
    2. An increase in new cancer cases may reflect certain changes in clinical practice in hospitals or doctors' offices resulting in detection of more cases.
    3. A decrease in cancer incidence may be due to a decreased exposure to harmful substances.
    4. A decrease in cancer incidence may be due to late detection and nonremoval of precancerous growths.
  32. Which of the following statements concerning changing rates for specific cancers is INCORRECT?
    1. The incidence and mortality rates have been declining for testicular, childhood, cervical, stomach, throat and cancers, and cancers of the mouth (lip, tongue, gums).
    2. The incidence and mortality rates are not improving for breast, lung (in females), bladder, prostate, kidney, liver, esophagus, and brain, non-Hodgkin's lymphoma and melanomas of the skin.
    3. The larger percentage increase in lung cancer incidence for women compared with men reflects the fact that women smoke more than do men.
    4. Improvements in treatment are thought to account for the reduction in childhood cancer deaths, while increased screening (i.e., Pap smears) accounts for the decrease in cervical cancer rates.
  33. Which of the following statements concerning changing rates for specific cancers is INCORRECT?
    1. The incidence rates of liver, thyroid, and melanoma cancers had the greatest percentage decrease between the years 1992 and 2000.
    2. The death rates for liver cancer, lung cancer in women, and esophageal cancers showed the largest increase between the years 1992 and 2000.
    3. The yearly rate of new cancer cases increased between 1975 and 1992. Some evidence shows a decline after 1992 followed by stable rates since 1995.
    4. For cancer deaths, the rates increased steadily from 1975 to 1990, stabilized between 1990 and 1994, then declined from 1994 to 1998. Since 1998, the rates again stabilized.
Relevant Content To review content relevant to the posttest questions, see
Question Subsection(s) Section
1 Introduction and Environmental Factors What causes cancer?
2 Factors inside the Body What causes cancer?
3 Interaction of Environmental Factors and Genes What causes cancer?
4 Introduction The Nature of Cancer
5 Types of Tumors The Nature of Cancer
6 Types of Tumors The Nature of Cancer
7 Tobacco, Diet, Weight, Physical Inactivity and Alcoholic Drinks What substances in the environment are known to cause or are likely to cause cancer in humans? Where are they found?
8 Viruses and Bacteria’, Pesticides, Solvents, and Medical Drugs What substances in the environment are known to cause or are likely to cause cancer in humans? Where are they found?
9 Ionizing Radiation What substances in the environment are known to cause or are likely to cause cancer in humans? Where are they found?
10 Fibers, Fine Particles and Dust What substances in the environment are known to cause or are likely to cause cancer in humans? Where are they found?
11 Dioxins What substances in the environment are known to cause or are likely to cause cancer in humans? Where are they found?
12 Vinyl Chloride What substances in the environment are known to cause or are likely to cause cancer in humans? Where are they found?
13 Introduction What are some ways to reduce the risk of developing cancer?
14 Risk Reduction What are some ways to reduce the risk of developing cancer?
15 Risk Reduction What are some ways to reduce the risk of developing cancer?
16 Detecting Cancers at an Early Stage What are some ways to detect cancer at an early stage?
17 Detecting Cancers at an Early Stage What are some ways to detect cancer at an early stage?
18 Introduction How do scientists identify cancer-causing substances?
19 Introduction How do scientists identify cancer-causing substances?
20 How well do animal tests predict whether a substance can cause cancer in humans? How do scientists identify cancer-causing substances?
21 We often read about mice or rats being given dosages much higher than those to which humans normally would be exposed. Are high doses really used and, if so, why? How do scientists identify cancer-causing substances?
22 Experiments with Human Cells Grown in the Laboratory How do scientists identify cancer-causing substances?
23 Strategies for Testing in Animals or Human Laboratory Cells How do scientists decide which substances to test in animals, human laboratory cells, or human population studies?
24 Strategies for Carrying out Large Population Studies How do scientists decide which substances to test in animals, human laboratory cells, or human population studies?
25 Type of Exposure What factors do scientists consider in determining the risk associated with different cancer-causing substances?
26 Acceptable Risk Levels What factors do scientists consider in determining the risk associated with different cancer-causing substances?
27 Dose Response What factors do scientists consider in determining the risk associated with different cancer-causing substances?
28 Linear Dose Response How do public health officials set acceptable exposure levels for environmental chemicals?
29 Threshold-Like Dose Response How do public health officials set acceptable exposure levels for environmental chemicals?
30 Risks versus Benefits How do public health officials set acceptable exposure levels for environmental chemicals?
31 Introduction How have cancer trends changed over the past few years?
32 Changing Rates for Specific Cancers How have cancer trends changed over the past few years?
33 Introduction and Changing Rates for Specific Cancers How have cancer trends changed over the past few years?

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