safety tips edited by

TIM CHAMPION Johnson C. Smith University

Charlotte, NC 28216

Teaching Safety Between Theory and Empiricism

Beno Zaidman Casali Institute of Applied chemist^. School of A ~ ~ l i e d Science and Technology, The Hebrew university of Jerusalem, 91904 Jerusalem, Israel

The practice of introducinglaboratory safety as a topic in the curriculum of the science faculties is actually wide- spread in manv universities. At the Hebrew Universitv of Jerusalem, co&ses on this topic are offered to gradiate students working toward the MSc degree in chemistni and applied chemis&y, and to the undergraduate (BSC~ stu- dents of the Life Sciences Institute and of the Faculty of Agriculture. The introduction of the safety courses in the universities has been initiated by the University's Safety Committee and their professional level is supervised by the teaching committees of each Institute. Between 30& 350 students are enrolled yearly to those one-semester hour, required courses in which they earn one credit point.

Integrating Safety into the Curriculum After a period of more than five years of teaching chemi-

cal safety to graduate students of chemistry, it appears to me that some conclusions, perhaps of some general inter- est, can be reached. It is already evident that the one-hour semester time (about 15 clock hours) allocated to a labora- tow safetv course in our universitv. which is common to a nukber of universities (1,2), is ins&cient in order to offer an acceptable coverage of all the potential sources of haz- ards inan academicresearch labbratory and of the ways for eliminating or reducing their negative effects on the laboratory population and on the environment. The obser- vation is not made with the intention of arguing for a more generous time allocation for the topic of safety. Facing the already crowded curriculum of the science faculties such a pretention will be at least naive and possibly not really jus- tified when compared with other pressing topics that need to be developed. The chronic lack of time with which the teacher is faced has been brought up here, because it amulifies the difficdtv of teachine safetv in the universitv. - he real dilemma, in our opinion, is the ;ay of partitioniig teaching time between the theoretical explanation of the source and nature of safety hazards and the presentation of practical measures and tools for dealing with them.

1s it preferable to confer to the student a basic under- standing of the principles of toxicology (like difficulties of extrapolating dose-effect results from high dose to low dose areas) or to present to him efficient wavs of proteetine the " &

respiratory system (like means for choosing and mainiain- ing respiratory masks and filters)? Is it preferable to re- view the thermodynamics of the decomposition of chemi- cals or to present the way of using and building portable shields in the chemistry laboratory?

The ideal answer. we all know. would be to urovide the students with both aspects of thelaboratory s$ety, but be- cause of the scarcity of allocated time, this is not possible.

1016 Journal of Chemical Education

A choice between the two approaches must be made, or more plausibly, a right mixture between them must be built. Thus, the debate begins here.

Practical versus Theoretical Approach The supporters of the practical approach will claim, cor-

rectly, that the ultimate target of teaching a course in lab- oratory safety is to confer to the participants ways of act- ing, that will permit them to fulfill their duties without damage to them, to others, or to the environment. For this aim, the learning of precise rules of conduct and of ways of using specific tools or methods is the important thing. The "how"is more significant than the "why". As for the general explanation of the phenomena connected with the safety hemrds, we iirr driling with a srientilically educated pop- ulation which, i l ' i t feels so, is able to obtaln elsewhere, the information needed for understandine the nature of safetv - hazards.

The defendants of the second approerh, emphasis on the- orcticill aspects, (including myself emphasize the fact that the course on laboratorysafety is the frst-and for most students the last-occasion to receive an ordered and for- mal education on safetv to assist them in their future um- fessional lives. As suc6, this course must convey the dasic knowledge and approaches that will permit them to ana- lyze each future research situation from the safety point of view. As for emphasizing only practical rules of safe behav- ior and specific safety devices to be used in the laboratory, we cannot anticipate all possible situations thev mav face " " in the future. A&ientistmust, in each case, exercise his basic understanding of the safetv aspects of the research activity, in order tolidentify specific hazards and to figure out the specific solutions. He will be further assisted in cre- ating safe conditions of work for himself and for his team by the safety organization of the institution, the local and national authorities, and by safety consultants and repre- sentatives of commercial companies of safety devices. If we teach the student to be safety conscious, the administra- tion, the regulations, and the free market will make the rest. As for assuring safe conditions for students in the uni- versity laboratories, the practical training must be done directly by instructors in the general laboratories and by staff members in the research laboratories.

This way of teaching safety in universities-emphasis on the theoretical aspect has, in my opinion, a supplemen- tarv advantaee. If we want to have the attention of science stu"dents on safety aspects of their research work and to exercise an impact that lasts after the final examination of the safety course, we must show them clearly that safety hazards are undesirable but unavoidable facets of the sci-

General aspects of laboratory safety

nammabllity Chemicd reactivity hazards

Safeiy aspects In laboratory planning

Resuming wxerclse

'Safety m cnemistry course' - strLctJre an0 t me sched~le. 'NLrnber of class ho~rs Dedicated lo tne toptc.

entific phenomena that they are studying, and that the search for neutralizing or limiting those hazards is an in- divisible part of their scientific work. This aspect is espe- cially relevant when we are dealing with students working toward an advanced demee. In mv ex~erience. thev have some tendency to disregard any materih taught that is not directly connected with scientific activity.

Organization of the Course I have blended for the safety course a mixture of theory

and empiricism, biased toward the theoretical aspects of safety

The course entitled "Safety in Chemistry" is a required course for students studying for their second degree in chemistry and applied chemistry. Between 40-50 students participate each year. The course mainly deals with safety hazards connected with the work with chemicals, toxicity, flammability, chemical explosions and ways of preventing them. Other possible sources of hazards in a laboratory mechanical, electrical, radiation, etc. not treated. A gen- eral presentation of the course structure and time sched- ule is presented in the figure.

In the frst lesson, general notions connected to safety are presented. Emphasis is placed on the concepts of dan- ger and risk (voluntary and involuntary, social and individ- ual, levels of acceptance) and on legal aspects (responsibil- ity, legislation, and liabilities).

The chapter that deals with the toxicity of chemicals com~rises basic notions of toxicitv (twe of toxic resDonse and kxposure, dose-response relaGo&;effective and iethal doses or concentrations) and ways of their translation into safety standards (like threshold limits for long-term, low- dose exposure). Ways of monitoring the level of toxic sub- stances (environmental and biological) also are treated to- gether with some technical means of protection from toxic &bstances.

The third Dart of the course deals with the safetv haz- ards related 'to thermochemical processes. Basic notions of thermodynamics such as energies of activation and reac-

tion, heat of formation and decomposition are reviewed and utilized in order to characterize reaction and chemical omducts with a h i ~ h thermochemical ex~losion ~oteutial. ~ e t h o d s for quan;itative experimental ihecks i f this po- tential ras the Dilferential Thermal Analvsis method, also are discussed. Ways of controlling heat emission and evac- uation in exothermic reactions are ~resented. In the fu- ture, we hope to he able to omer to the students the possi- bihv of using the ASTM comDuter Dromam CHETAH 0). . -

~iammablematerials and hazards connected with their utilization are dealt with in a section of the course. Fire is presented as an oxidation process between an oxygen ac- ceptor in the gaseous ~ h a s e and air in the Dreseuce of a source of activation eiergy. Notions like flash point, and limits of inflammability are presented and their connec- tion with the physical properties of the chemicals is ex- plained. The phenomena of deflagration and detonation are presented as special cases of f r e in which the stoichio- metric mixture of flammable vapors of gases with air in are involved. Apresentation of ways and devices for fire extinc- tion is made, together with an explanation of their techni- . - cal basis.

These three parts constitute the bulk of the teaching pro- gram and are followed by two sessions dealing with:

environmental impact of chemistry laboratories, and safety aspects of laboratory planning.

The environmental impact of the laboratories is dis- cussed with emphasis on solid and liquid waste disposal. The principles and some specific methods for in-house neu- tralization of laboratory-generated hazardous waste are presented.

The chapter dealing with the laboratory planning treats topics like methods of ventilation (general, local, hood con- struction, and use), fire regulations related to chemical laboratory buildings, safety equipment and systems, and some rules for locating research operations in consider- ation of their specific safety hazards.

The last lesson of the course is dedicated to an applica- tion of the safety principles studied to the planning of a specific chemical laboratory task. The students will repeat this type of exercise in the frame of their final work.

Textbook

Due to the variety of topics treated in the course, no sin- gle textbook was found to be adeauate. and each tooic is iiasedon different literature sour& ~ e t a i l s are in Table 1. Overhead trans~arencies are used widelv in the course, and copies of most of them are distribute2 to the students, allowing them to focus on the topic instead of copying what they see on the screen. This partially substi- tutes for the lack of a manual.

An extensive bibliography list is distributed to the stu- dents with the aim of helping them to identify, in their fu- ture professional activities, reliable sourees of information in the field of safety. This list also contains information about computerized data bases specializing in safety and toxicology data.

.

Table 1. Safety in Chemistry

Topic Literature Source

General aspects of safety (67, Ch. 1.3,4,7

Flammability hazards (7), Ch. 2.3,7, (4). Ch. C Chemical reactivity hazards (8, Ch. 4.5,16,17, (3) Ch. C. 8

Chemical waste disposal (3, Ch. 1-6, (4 Ch. E

Plannina safe laboratories (41. Ch. F. H. 8

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Table 2. "Safety in the Chemical Laboratory"

1. Indicate the right answer to the following questions:

1 .I The preferred location of a chemical laboratory hood is:

a. near the door, in a possible air path.

b. near the door, out of a possible air path.

C. far from the door, in a possible air path.

d. far from the door, out of a possible air path.

1.2 The fire resistance of a separation wall is expressed in:

a. thickness of the wall.

b. nature of materials.

c. finishing and coating.

d. length of time.

1.3 The need for electrical equipment of the explosion-proof type is determined by:

a. nature of chemicals used.

b. risk of a work failure.

c. the two previous factors together.

d. number of people working in the laboratory.

2. The purification of chloroform by distillation is performed in a laboratory that has an internal volume of 50 cubic meters. It is estimated that a quantity of 25 g of chloroform vapors can be released each hour in the laboratory. What is the minimum number of air changes to be assured by the general ventilation system of the laboratory in order to maintain a concentration of chloroform in the air smaller than the (TLV-TWA) of the chloroform?

Assigned Work At the end of each division of the course. the students are

required to complete a homework paper. ~ i v e such papers are olanned aRer each of the followina chaoters: toxicitv of - . chemicals, thermochemical processes, flammable ma&- als, environmental impact, and laboratory planning. The grades achieved will be part of the grade of the final course. Every homework paper is composed of two to three questions to which the student must choose the right an- swer and a quantitative problem. An example of a home- work paper related to labratory planning is presented in Table 2.

Final Paper The final work, done by the students, is the elaboration

of a safety plan for performing a chemical synthesis in the

Each student receives a procedure of a n organic synthe- sis and will be asked to write out a detailed safetv olan

" A

treating the following topics:

Presentation of safety information on the materials con- nected with their specific reaction (as readants, solvents, catalvsts. intermediates. seeandam oroducts). This informa- . . - . twn 1s to relate ur areas like tomcnlog); flammah!lir): semi- t i v q to heal and mechanical shwk and .iu on. Analysis of thermochrmiral aspccta rclarcd to rhc synthesis to be performed (exathermidty~ energV of activation) ~efmition of the safety hazards connected to various stages of their specific synthesis procedure (reaction, separation, purification, and drying). Setting the physical conditions needed for safely performing the assigned synthesis as: type of laboratory (fire resistance, ventilation); fixed safety equipment (hoods, local ventila- tion); mobile safety equipment (fire extinction, gas masks, and filter). Establishing work procedures for routine operations and possible emergency situations.

Table 3. "Safety in Chemical Laboratory" Course Topics for Final Paper

Substance Source' Substance Source'

Allyl cyanide (?I), 46 Ethyl cyanoacetate (!I), 254

2-Hydroxymercury Ethyl cyanohydrin (II), 256

3-nitroknzoic acid (If), 56 RHexyl alcohol (IT), 306 (anh) Azobenzene (13, 103 Hydrazine sulfate (II), 309

Benzensulfonyl (11),84 Methylene bromide (11),357 chloride

1,2,~Benzotuazole (14, 106 Nicotinic acid (If) , 385

Benzoyl cyanide (14.112 p Nitrobenzoic (If), 392 acid

Benzyl cyanide (I!), 107 p Nlrobenzoyl (If), 394 chloride

6-Brom-2-naphtol (14, 132 p Nnrobenzoyl (If), 396 cyanide

2-Bromc-3-nitrobenz (11),125 mNitrophenol (II), 404 acid

p-Bromophenol (If), 128 3-Nitrophthalic (If), 408 acid

3-Bromopyridine (14, 136 Nitrostyrene (II), 413

a-Bromotoluene (11),135 Nitrotoluene (IT), 415

a-Chloroknzoyl (l4,I 55 Perbenzoic acid (!I), 431 chloride

c- (14,185 Phenyl acetic acid (II), 436 Chlorobmmobenzene

oGhioromercuri phen. (11),161 c-Sulfobenzoic (11),495 anhydride

mchloronitro benzene (11),162 Thiophenol (II), 504

pCresol (11).175 Trimethylene (I!), 536 cyanide

Diallylcyanamide (If), 203

9,l& (11),207 2.4,6- (11),543 Dibromoanthracene Trinitmbenzoic acid

3.5-Dinitroanisole (II), 219

Diphenyl mercury (11). 228

Planning of monitoring of toxic substances (environmental and biological). Proposals for improving, from the safety point of view, the assigned work procedure.

The topics of assigned homework are synthesis of vari- ous chemical entities as they appear in "Organic Synthe- sis". A list of subjects proposed to the students and their bibliographic source appear in Table 3. The possibility of choosing, as subject for the final work, the synthesis of an organic molecule in which they are particularly interested, is also offered to the students.

The majority of students present their final work on a high level, devoting to this task a greater effort than usu- ally invested in a one-point credit course.

Assessment of the Course The response of the students to the course has been pos-

itive. The fact is inferred from discussions and reactions of individuals, especially from the level of the final papers. Some of the students wntact the teacher after the wurse consulting him on specific safety aspects of their research work.

1018 Journal of Chemical Education

No data have been collected to prove statistically a posi- tive connection between the safety course and the level of safety in the laboratories of the university, but we are con- vinced that these teaching activities succeed in giving the students the right approach to the safety aspects of their laboratory work and tools for coping with them. Our five years of experience indicate that the greater emphasis on general theoretical aspects of laboratory safety contrib- uted to improve students' attitudes relative to the course and, therefore, increased its efficiency.

Literature Cited 1. L o w , G. G. In Safely in the Chemical Laboratory. Renfcew. Malmm, M. Ed.; J.

Chem. Edue.: Easton, PA, 1981, Vol.4, pp. 11&118.

4. Nat. Rea. Council,Prudent PmcticeaforHondlingHolordol~pChemicols in Lobom- larks: Nat. Academy Press: Washington. DC. 1981.

5. Net. Re*. council, Rudrnf Prucfkes for Disp0s.i of Charnicak fmm Lobomtoria% Nat. Academy P-8: Washingon, DC, 1983.

6. G"ffths, R. F., Ed. Dealing with Rid; J. Wiky & Sans: New York, 1982. 7. Bodurths, F T. Industrial E ~ p l o s i i i Pnuenilon ond P m t t t i i i ; MMGGGG-Hill: New

10. Kirk & Othmer. Eneyelop& of Chamicol Dchnology, 3rd ed., W k y & Sms: New ""~k lqsl . .. . . , . . . ..

11. Gilman, H., Ed. Orgonic Synfhehehehe, Coll. Vol. I: J. Wiley & Sona: New York, 1941. 12. Haming, E. C., Ed.; O~gonic S~mfhe~es, Coll. Vol. 111; J. Wiley & Sons: NewYork,

1955.

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