prepared for

Summer Institute

July 23-26, 2001

Johns Hopkins Medical School Campus

by

Arthur Renkwitz

Douglas Becker

I. Cancer is a disorder that involves the transformation of normal benign body cells into malignant rapidly dividing cells. Our Cancer Quest into the possible carcinogenic effects of various chemicals on normal cells begins with an examination of cells. First, let's define;

1. In the text box below briefly summarize what is cancer? Click on the text box to activate it. Type in your answer. Click off the box to deactivate it.

2. List three characteristics that would label cell growth as cancerous. Click on the text box to activate it. Type in your answer. Click off the box to deactivate it.

II. How Cancer Grows extends the What is Cancer? section and will explain some of the molecular biology of the disease. It is a bit more technical, but necessary if you are to affectively grasp the implications of this unfolding Cancer Quest.

When you've finished the presentation, answer the following two questions . Click on the box next to the correct answers and place an X in them.

1. The first genetic mutation in the early stages of carcinoma (epithelial cancer) formation can take different forms such as: (3 answers)

2. For a cell to become cancerous it generally requires a series of more than two mutations to occur.

III. What are the risk factors associated with cancer? Read Possible Causes and Prevention of Cancer . Focus your attention on the Chemicals and Other Substances section of the reading.

1. List five possible causes of cancer in the box below. Click in the box to activate it.

The reading explains that there are many causes of cancer, but this Quest will focus its attention on the possibility that agricultural chemicals could be carcinogenic (cancer causing) agents. Your goal in this Cancer Quest investigation will be to answer the following question:

To investigate this question, a fairly common and universally used agricultural herbicide named atrazine will be examined because of its well documented chemical properties and their possible carcinogenic effects. Let us begin this Quest by introducing you to atrazine through the manufacturer's Web site. When you arrive at the site Introducing atrazine  read the introduction, visit each of the links and then respond to the following questions.

1. Was there any data in the atrazine brochure that indicated any negative affects from the use of the herbicide?

2. Read all of the information on atrazine under the heading ATRAZINE SAFETY and then briefly summarize the data starting with Drinking Water Safety , True Extent of Atrazine Detections in Drinking Water , and Water Quality Stewardship in the scroll box provided below.

3. Should all numerical data and the details of the research procedures used to determine the absence of carcinogenic properties of atrazine be made available to the public in support of the statements made about testing results? Please, comment on this question in the text box below.

Information used to solve problems can come in many forms from anecdotal to experimental. There can be a vast difference in the validity of the conclusions drawn about specific problems based on the nature of the evidence used. If a scientific answer to the proposed carcinogenic problem is to be realized, then certain standards must be established and met for any valid conclusions to be drawn. 

1. Any numerical test data that is presented should have the details of procedures used to arrive at that data. Missing those procedures, there should be a secondary reference to experimental procedures, or protocols, used to arrive at any similar data.

2. If experimental procedures are available, they should be sufficiently detailed to allow for a peer review, or minimized for the reader to comprehend how the numbers were determined. In other words, should you leave with any unanswered questions about the data after reading the report, then the report is incomplete.

3. There should be other references to previously done investigations that contain documented protocols and results, if they are available. You may find that the paper you are reading contains the only information that exists on the chemical substance being studied and that all of the previous reports have drawn from this one.

4. Scientific data associated with the carcinogenic affects of a specific chemical substance should contain the following components:

a. Animals used in test (type, age, sex)

b. Dosage levels and mode of administration of chemical substance 

c. Length of time of exposure

d. Types of cancer, if any

These criteria are stringent and when applied must be done with a degree of judgement on your part. It is improbable that any data can be 100% conclusive about the affect of a chemical substance on tissue given all the variables that can occur in natural settings. However, if experiments are reasonably done and their data reasonably applied by the practitioner, then a probable conclusion based on valid assumptions can be reached and decisions made about future use of said chemical. Keep all of these criteria in mind as you examine the information on your Cancer Quest. Make the data live up to your expectations and don't settle for hype in place of facts 

  So far our Cancer Quest has gotten us background information on cancer and charged us with the responsibility of recognizing when, and if, data is scientific as opposed to anecdotal or overstated. It's time now that we begin the task of interpreting and organizing reports on atrazine.

  Let's be perfectly clear here concerning what this Cancer Quest is about. You and your partner are going to see a large amount of information concerning the herbicide atrazine. You are to consider the following question: 

Now that you know what the question is, let's discuss how we are going to answer the question, if the question can be answered.

   All good science begins with a question and then is usually followed by some sort of tentative answer. However if you have no prior knowledge about atrazine, then any attempt to answer the question would be a mere guess. We need some information before we can venture any hypothetical answer to the question, so let's get some basic knowledge first and then we'll discuss hypotheses later.

   When information is as plentiful on a subject as it is on atrazine, then there is a need to be selective concerning which particular paper is completely read or which site should be examined in detail.  To hasten this first tutorial Cancer Quest, a large number of sources have been reviewed and a group of sites culled out for your perusal. You will be given specific directions at each location, but you can certainly investigate other aspects of these sites if you wish. First, move through the links in order and follow the directions at each site. Your task is to judge the quality of the information and assess its validity as you attempt to answer the question: 

   The question is to be answered in the form of an essay. The essay should be a minimum of 500 words written or typed. This should be a persuasive argument, therefore upon stating your position you should cite evidence from the resources provided in this Cancer Quest. The quality of the essay will be judged using the Maryland State Department of Education's Rubric designed for Extended Response Questions. A copy of the rubric can be found at this location. Essay Rubric Take advantage of the cooperative nature of this activity by discussing the readings with your partner as to the scientific veracity of each site using the list presented earlier under the heading of Evaluative Criteria for the Determining Scientific Validity of Data.

Here are the physical properties of the molecule atrazine along with its structural formula. This data will be fundamental to your understanding of other information that you will be examining.

So, now we come to the moment of truth. You have have evaluated the data from several different sources and perspectives.It is time for you and your partner to consider what you have seen and discuss it in light of the original question. Is the herbicide atrazine a chemical carcinogen in the environment? Remember that the question is to be answered in the form of an essay. The essay should be a minimum of 500 words written or typed. This should be a persuasive argument, therefore upon stating your position you should cite evidence from the resources provided in this Cancer Quest. The quality of the essay will be judged using the Maryland State Department of Education's Rubric designed for Extended Response Questions. A copy of the rubric can be found at this location. Essay Rubric Take advantage of the cooperative nature of this activity by discussing the readings with your partner as to the scientific veracity of the information at each site using the list presented earlier under the heading of Evaluative Criteria for Determining the Scientific Validity of Data.