computer series, 148 JAMES P. BIRK

Arizona State University Tempe, AZ 85287

Bits and Pieces, 49 Guidelmes for Authors ufBtla ondPteces appeared in July I98R

the number oFHils and Piecrs rnnnuscripts 1s expected to decrease in the future--see the duly 1988 and March 1989 ~~sue;i.

Bits and Pieces authors who describe programs will make avail- able listings andlor machine-readable versions of their programs. Please read each description carefully t o determine compatibility with your awn computing environment before requesting materi- als fmm any of the authors. Some programs described in this arit- cle and marked as such are available fmm Project SERAPHIM at $15 per disk ($20 foreign and Canada). Make checks payable to Project SERAPHIM. To order, or to bemme a member of SERA- PHIM Clearinghouse and receive a Catalog ($20 per year), write to: John W. Moore, Director, Project SERAPHIM, Department of Chemistry, University of Wisconsin-Madison, 1101 University Av- enue, Madison, WI 53706.

Teaching Risk Assessment in Undergraduate Chemistry Using BCTC

Daniel Y. Pharr Virginia Military Institute Lexington,VA 24450

The role of scientist in our society has changed from one who offers solutions based on verifiable experimental fads to one who must help make policy decisions based on sci- entific data that is often incomplete and ambiguous. Risk assessment and management places new demands on sci- entists who are more comfortable with laboratory results and a Deer review system. Risk manaeement decisions - must confront environmental, economic, political, and so- cial trade-offs in order to make the best decision in the eves of the public. In order to illustrate better these dynamics, a role-playing scenario of an environmental problem from a computer program is used to maximize student involve- ment in general chemistry.

The history of risk analysis has been traced back to an- cient Babvlon. but it was the svstematic use of statistics and the i k r a n c e companies bf the 19th century, with their professional actuaries, that supplied a large enough data base for quantitative riskassessment ( I ) . Today, how- ever, the public perception of risk is not based on tables of mortality or a statistical probability of illness; rather it is based on a fear of the unknown. a lack of oersonal control. risk to future generations, uncertain benefits, and per: sonal expectations of a no-risk environment (13).

In fact when scientists are required to make judgments based on incomplete information they are predisposed to many of the same prejudices as those of lay people (2). If people exhibit strong prior opinions, then continued dis- agreement does not disappear even in the presence of new evidence, because these initial views color the way that subsequent information is construed (2).

An lllustrat~on of such presuppositions is demonstrated as the students act out a role-playing debate about a risk assessment situation. The students gain insight into their

294 Journal of Chemical Education

own wlnerability as they seek scientific objectivity to an ambiguous problem. To our students science appears to be an orderly progression of facts, but this occurs only after the theory has been verified. At the advancing edge of sci- ence. the debate can be chaotic and fiercelv controversial (4). 1t would be difficult to recapture the flu& of emotions, the chaneine ebb and flow of facts. and the intense media - - attention that came from the debate over ethylene dibro- mide, EDB, that occurred in 1983-1984 (6, 8). The EPA was being forced through public pressure to make a deci- sion on complex, poorly understood, and controversial is- sues using deficient data.

William D. Ruckelshaus, of the Environmental Protec- tion Agency, points out that risk assessment is used by gov- ernment agencies to deal with scientifically ambiguous sit- uations. "It is the attempt to quantify the degree of hazard that mieht result from human activities: for examule. the risk to &an health and the environment from iniustrial chemicals" (4). Risk management is the manner of action that will be taken by the government agencies to protect the public or the e&ron&ent based on the risk Hssess- ment. Under Ruckelshaus. risk communication became the major policy used today to resolve conflicts between those that make the decisions and citizens affected by those decisions (5-8). These decisions have permeated in- dustry and government, resulting in right&-know ordi- nances, consumer uroduct labeline, chemical hazard wam- ings through material safety data sheets and worker hazard communications (5).

Risk assessment in the classroom should have real stu- dent involvement, even passion to mimic the real life epi- sodes that have caused risk assessment to become the im- portant topic that it is. Although the debate over EDB may seem like recent history to us, our freshmen students were in third or fourth made 10 years ago. Controversies of the past that are now~esolved&eld little impact on students in contrast to c m n t controversies. To be the most effec- tive, the subject matter must be current. To maintain this type of current controversy the computer program BCTC by David M. Whisnant (9) available through Project Sera- phim has been used in a unique manner. -

In that BCTC comuuter simulation the students are suo- posed to be members of an impartial task force sent to in- vestigate a contamination problem downstream from a plant. The contaminant is BCTC an abbreviation for a fic- titious chemical. BCTC might be carcinogenic, but as the data is gathered one realizes that the evidence is ambigu- ous. The main menu of the program allows the student to look up information in the library, ask advice of a task force member who acts as a guide, conduct an economic analysis for the cost feasibility of pollution control devices, sample the river water in several locations. then use these sam- ples in the laboratory for further a&lytical testing, and do animal experiments to determine the toxicity of BCTC.

The computer program offers the starting material and a data base for the paper and subsequent debate.

In addition to thekormation sipplied by the computer oroeram. our students are eiven a brief introduction to risk A - . - assessment, risk management, and an explanation of the term LDs0 . To generate controversy and debate about the BCTC problem the students are assigned specific roles. Each student assumes a specific role and writes a five-oaee . - paper. The role-playing continues, more effectively as the students present their papers in an oral presentation that usually results in lively debates.

The instructions for the paper given to each student state:

There mav be a ~mblem in a small town in South Carolina. You willgain informarion from a task force that hns bwnenllrd in to help study this potential prohlem and perform a risk ar- sessment evaluatxun uf the situation. Achernical called HCTC is involved

Several items should be included in all papers:

What is BCTC? Is BCTC a health hazard? Is BCTC in the environment? Will BCTC effect the health of the people in the city below the plant? What effect does it have on animals or humans? What will it cast to dean it up and operate the plant?

Although you are being assigned only one role, you cannot totally ignore the other factors. The following is the list of char- acters available: reoorters from liberal and conservative and domestic and foreign newspapem and Loeal and national tele- vision; scientists including a physician, veterinarian, chemist, and environmentalist; businessmen from the company includ- ing the plant's vice president, economic advisor, and public in- formation officer; political leaders all of whom are up for reelection including the mayor, the mayor's economic advisor, a member of the county industrial development board, the dis- trict coneressman. a local lawver runnine aeainat the con- .. ., gressman, and clttrens lnrludlnfi a farmer who llvea downstream from the plant, a downtown busmessman, a mcm- ber of Greenpeace, and the head of the lural unwn

In writing the report, most of the students fall into their assigned roles with ease. The most descriptive writing comes from the students given the role of television re- porter. For example: "As our boat moves slowly up the river we see a group of unsuspecting Boy Scouts playing in the river downstream from the deadly plant. Will this be the last summer the camp will be open? This is I.D. Rather reporting for 50 Minutes from trouble-ridden South Caro- lina" (10). Once the students have written their papers and read them during the followine laboratorv period. it is - - " A

amazing how they keep their preconceived ideas even aRer the ~rofessor has exolained that the results of the com- puter program are meant to be ambiguous.

This exercise has been effective in teaching students how scientists research. collect. and analvze data.The student' 'papers emphasize their inkrpretatiGe skills and points to- ward their strengths and weaknesses in their risk assess- ment, which is the main objective of the exercise. The oral resenta at ions allow all the different views to be presented. Pinally, the instructor must pull i t all together and put the exercise in its proper perspective by giving a summary to the students of what risk assessment and risk manage- ment are. along with a brief lecture in the importance of s c i e n t i f i c ' o b j e ~ ~ t ~ and ethics. Employing such teaching methods in the classroom not only makes chemistry tangi- ble, but also it gives the students a more comprehensive learning experience bv brin!zing together interdisciplinary

A Potential Energy Surface Experiment for the Undergraduate Computational Chemistry

D. C. Buss and K. R. ~ountain' hortheast miss our^ State Ln vers ry Klrksv le. M~sso~r 63501

Recently several authors have noted the desirability of placing computational chemistry in the undergraduate curriculum (11. 12). At NMSU we have two vears ofexoe- rience in teaching computational chemis&y in our i d - vanced Organic Chemistry course. The course is well re- ceived by students, as shown by student questionnaires, and produces a deep understanding and appreciation of theoretical material presented in previous courses. Con- crete experiments using the computer as an instrument are embhasized, usingmodern modelling methods. One important concept that students fmd hard to masp when presented in theabstract is the notionofa potential-energy surface (PESI. Two-dimensional representations, such as reaction energy profiles, are more easily grasped, but have limited usefulness when it is necessary actually to deal with n three-dimensiunal tor hieher) relationshio. Such re- . - . lationships oRen are encountered when calculating transi- tion states with MO oackaees. -

A computerized animation of a three-dimensional PES has been reoorted (1.71. but it is soecificallv related onlv to simple chekical reactions. The present ekperiment $vex experience in m a ~ ~ i n g a PES and uses a research (discov-

&. - ery) mode.

Local minima, saddle points, and hill tops often are use- ful, because they allow students exposureto them in some concrete way. This paper describes such an exercise. Stu- dents const&ct t h e - ~ ~ s for rotations around the 1 ,2 and 2 ,3 bonds of 2-hydroxy methyl acetoacetate, 1.

2-hydmxy methylacetoacetate

The computer used was either a 286 PC clone or a Zenith 386 (16 mHz). The software was PCMODEL 4.0 (Serena Software, Box 3076, Bloomington, IN 47402-3076) and SURFER (Golden Software, 809 14th Street, P.O. Box 281, Golden, CO 80402-0281). PCMODEL uses a variant of the molecular mechanics orneram bv Allineer (MM2-87) with the extension of gene;al k r m fiild (MM% for groups not included in the MM2 force field. The ability to compute conformational energies is greater than that of MM2-87 due to these eeneralized oarameters. The pro- gram uses standard grld search methods to minimize a classical mechanics e n e m function consisting of a sum of terms for each mode of freedom for a given molecule (14, 15). Surfer allows input in a spreadsheet format. The input from this project was put into SURFER as a set of three- column vectors summarized in the table.

The orocess of obtainine the PES beeins bv minimizing n-hexke in the all trans-conformatior;, usiGg the DRAG and MINIM routines of PCMODEL 4.0. Redacine the ao- - pmpriate ki atums with 0 atums, double bonded to the C , and the 62 C atom to get the ester linkage gives the hegin-

- - - studies. 'Author to whom correspondence should be addressed.

Volume 70 Number 4 Aprii 1993 295