MULTIPLE CHOICE

1. Regulatory toxicology aims at guarding the public from dangerous chemical exposures, and depends primarily on which form of study:

• a. observational human studies.
• b. controlled laboratory animal studies. - pg. 12-7
• c. controlled human studies.
• d. environmental studies.

2. Risk from a public health perspective, is best described as the following:

• a. undesirable endpoint is reached.
• b. a possibility of a bad outcome.
• c. likelihood of an unwanted outcome combined with uncertainty of when it will occur. - pg. 12-5
• d. a bad outcome is assured and its mechanism is well understood.

3. Which of the following statements is true regarding Risk Analysis:

• a. it is a field of study that has been around for the last century.
• b. it was developed by the pharmaceutical companies in response to concerns over new medications.
• c. it is a relatively new field of study, spurred by new technologically-based risks. - pg. 12-5
• d. it was largely a private sector venture.

4. Which of the following are tools used in risk analysis?

• a. toxicology
• b. epidemiology
• c. clinical trials
• d. all of the above. - pg. 12-6

5. Which of the following are common endpoints:

• a. death
• b. No Observable Effect Level
• c. No Observable Adverse Effect Level
• d. Lowest Observable Adverse Effect Level
• e. All of the above. - pg. 12-7

6. The LD50 is best described as which of the following:

• a. the dose at which 50% of all test animals die - pg. 12-8
• b. the dose at which 50% of the animals demonstrate a response to the chemical
• c. the dose at which all of the test animals die
• d. the dose at which at least one of the test animals dies

7.. The effective dose is best described as which of the following:

• a. the dose at which 50% of all test animals die
• b. the dose at which some of the animals demonstrate a response to the chemical
• c. the dose at which all of the animals demonstrate a response to the chemical
• d. the dose at which 50% of all test animals demonstrate a response to the chemical - pg. 12-8

8. Extrapolation is best described as which of the following:

• a. using known information to reach a conclusion.
• b. using known information to infer something about the unknown. - pg. 12-9
• c. using speculative information to infer something about the known.
• d. a "best guess" approach.

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TRUE AND FALSE 

1. Environmental risk is a well-understood entity.

T ______ F ______ False: pg. 12-4

2. Cross-sectional studies look at the exposure and disease at the same time.

T ______ F ______ True: pg.12-11

3. Bias is a problem primarily of Clinical Trials.

T ______ F ______ False: pg.page 12-11

4. Subchronic studies are shorter than Acute studies.

T ______ F ______ False: pg.12-9

5. The lethal dose refers to the dose at which 50% of test animals die.

T ______ F ______ True: pg.12-8

6. The Maximum Tolerated Dose (MTD) is the level of chemical exposure where 10% of the animals die.

T ______ F ______ False: pg.12-8

7. Case Control Studies start with the exposure and follow for the disease.

T ______ F ______ False: pg.12-11

8. Case Control Studies are good for rare diseases.

T ______ F ______ True: pg.12-11

9. Clinical Trials look at dose-response in animals.

T ______ F ______ False: pg.12-11

10.Dose refers to the amount of a substance in the environment.

T ______ F ______ False: pg.12-13

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ESSAY QUESTIONS

1. Describe the four steps involved in the process of Risk Analysis.

The four steps used in risk analysis include: hazard identification, dose response evaluation, exposure assessment and risk characterization. The initial step is hazard identification, which identifies the chemical that present a risk to human health. This is a qualitative step, which involves a thorough evaluation of current scientific evidence, including animal studies, human studies, epidemiological studies and cellular studies. If a chemical is identified as a potential hazard to human health, the process continues.

The second step of risk analysis, is the dose-response evaluation, which is a quantitative step. This step measures the magnitude of the response at different doses. If available, human studies showing the potency of the agent, or its ability to produce negative health effects in humans, is also assessed.

The next step, is the exposure assessment. this step seeks to estimate people's level of exposure. Exposure refers to the amount of a substance in the environment, and such an estimation includes the length of exposure, duration of exposure and route of exposure, among other considerations. The difference between the actual dose, or level of a substance taken in, and the amount of the substance measured (exposure) is included in this assessment. This assessment must also quantify various properties of a substance-e.g. volatility, as well as the group exposed and whether the exposure is continuous, intermittent, short term, long term or chronic.

The final step is risk characterization. This step uses all of the previously gathered information through the first three steps, and creates a picture of risk that describes its likelihood, severity and consequences. This characterization includes an estimate of the negative effects-e.g. deaths or cancer cases per 100,000 people. The final step also takes into account any limitations and or uncertainties that were involved in creating the estimate. (Answer : pgs. 12-12 to 12-15)

2. Discuss the limitations inherent in risk analysis.

Limitations to this process include uncertainty of effect, variability of exposure, and the possibility of multiple exposures, among others. Often, too little is known about a substance to provide any real assurance. Despite laboratory testing and careful risk analysis, uncertainty will remain. Interpersonal variability may also strongly affect a specific individual's risks, as a general overview may not identify people who may be more sensitive to exposures than others, and thus may have a higher "safe" dose. Multiple-exposures are difficult to study, although they certainly exist in the real world. In addition, any additive effects are ignored, which may heighten the risk and which are sure to occur outside of the laboratory. However, despite its limitations, risk analysis is still an important tool to explore and understand risks in the modern world. (Answer: pgs. 12-15 to 12-16)