Name:________________________

ENVM 647

Mid-term Exam

Take a stab at answering every question. If you leave a blank, I can’t give you any credit at all. If you post some kind of an answer I may be able to give you a few points.  For questions involving calculations, please show your work.  You might even find that you know more than you think you do. Post any general questions or comments you have about the exam to the Conference.   Any personal issues should be addressed via messaging.

Please post your completed exams to your assignment folders by 11:59 PM (Eastern time) March 22nd.  Please label your exam and any attachments with your last name first (e.g., jones-midterm.doc)

In completing this exam, you may refer to books, course materials or other appropriate resources.  Individual work is expected and required. Please provide detailed answers, and references where appropriate.  Superficial answers earn only “superficial credit.”

Good Luck!

1.      (20 points) What are the advantages and disadvantages of animal studies and epidemiological studies for establishing dose-response relationships? 

I had thought this question was sufficiently clear.  But in reaction to some of the answers submitted to past exams, please break your answer into the following parts:

a)                  Advantages of animal studies

b)                  Disadvantages of animal studies

c)                  Advantages of epidemiological studies

d)                 Disadvantages of epidemiological studies.

1.      (20 points) Underline or highlight in color the correct answer to each of the following:

A.    The 95% confidence interval is:

(a)    Larger than the 99% confidence interval

(b)   Smaller than the 99% confidence interval

(c)    The same as the 99% confidence interval

B.  The dose for an incremental lifetime cancer risk of 10^-6

(a)    Increases as the estimated cancer slope factor increases

(b)   Decreases as the estimated cancer slope factor increases

(c)    Is independent of the value of the cancer slope factor

        C.  For two normal distributions with the same mean, but different standard deviations, the 95% confidence interval will be:

            (a) The same for both distributions

             (b) Larger for the distribution with the smaller standard deviation

(c) Smaller for the distribution with the smaller standard deviation

D.  Equal concentrations of heptachlor, a known human carcinogen, are found at two different sites.

(a)    The incremental risk is the same at the two sites

(b)   The incremental risk is different at the two sites

(c)    The incremental risk at the two sites might be the same or it might be different.

3.      (20 points)  Go to the EPA IRIS data base at http://www.epa.gov/iris  .  Right under the Integrated Risk Information System banner (or on the right, depending on which browser you are using), there is a search IRIS by keyword option.  Please enter Bromomethane.   You may also go to http://cfpub.epa.gov/ncea/iris/index.cfm?fuseaction=iris.showSubstanceList&list_type=alpha&view=B    and look for the name of the substance.   Open the summary, NOT the QuickView.  After reading the information on Bromomethane.  Answer fully the following questions in your own words:

a.       What is meant by inhalation reference concentration?

b.      What types of studies did the EPA use to estimate the inhalation reference concentration?  (human, animal, or both?)

c.       What was the adverse effect upon which the Agency based its estimate?

d.      What are the major uncertainties in the estimate?

e.       What additional studies would be needed to determine whether bromomethane should be classified as a carcinogen?

For definitions of terms you do not understand, click on IRIS Glossary on the front page.

4.  (20 points) Bromomethane (Methyl bromide) has been banned internationally as a soil fumigant because of its adverse effects on the ozone layer and its contribution to global warming. Methyl iodide has been proposed as a substitute. Go to http://epa.gov/ttn/atw/hlthef/hapindex.html  .  Look at the fact sheets for methyl bromide and methyl iodide. Based on the fact sheets and other information you find on the Web, do you favor the use of methyl iodide as a replacement of methyl bromide?   Explain your answer.  Please provide citations to your answers, as appropriate.

5.  (20 points)  David Hassenzahl discusses the relative risks of eating peanut butter contaminated with aflatoxin and apple juice contaminated with UDMH, a degradation product of Alar, in the Power Point presentation in a conference in one of our earlier weeks. The following Table shows his input data.   Some of the data in this table are different than those in the PowerPoint presentation.  The table below contains the correct information.

a.       Calculate the daily cancer risk for a child who weighs 20 kg and who eats an average amount of peanut butter.  Please use the average values for the required parameters.

b.      Do the same for a 20 kg child who drinks an average amount of apple juice.

NOTE: Daily cancer risk = Intake x Concentration x Potency / Body Weight

c.       Calculate the maximum daily cancer risks for peanut butter and apple juice based on the 95^th percentiles.

d.      Discuss your results briefly.

Note that question 5, and the entire exam, do not require the use of Crystal Ball. Your calculations may be performed using an Excel spreadsheet, or otherwise.  Please submit your spreadsheet, if any, and any other calculations as part of your midterm exam.