mfety in the chemkol loboratory
edited by MALCOLM M. RENFREW University 01 Idaho MOSCOW, Idaho 83843
Risk Assessment and Hazard Elimination for Undergraduate Laboratory Experiments Jay A. Young Chemical Consultant, 12916 Allerton Lane, Silver Spring, MD 20904
W r h perhapsafeu~rxeeptlons,allrhemlcah have prupenwr that ran make the uqe of there chrm~calshuarduus. For almost all uf these, however, it is possible to take precautions in their use so as to prevent any hazardous properties from causing harm. Examples of precautionary actions easily come to mind. For examole. no knowledeeable chemist would eve; add conrcntra;ed perchloric acid to sugar errept in wry small amounts under conditions that would divert the certain explosive forces in a direction away from persons and property. ~~
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The precautions to he taken in the use of chemicals with hazardous properties are typically delineated on the labels of containers of such chemicals. The principles governing the preparation of precautionary labels are found in "ANSI 2129.1-1976" (1). According to ANSI 2129.1-1976, alabel is prepared by first identifying the hazardous properties of the chemical to belabeled, and then deducing all reasonably forseeable ways in which, unless prevented, such properties would cause harm to persons or property. Most recently (1977-80)Dr. Yo~ngwas the Manager of Tschn cai Publlcat ons far
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Jay A. Vovng a chemical urnsultant soecializina in the safe manufacture. use. pecaulonary faceling, Moper hand1 ng. and apprapr ate d sposar of chemicals ~ s e din mdustry, the hoLseholo, and me laoaatay. He writes articles and bwks, and organizes and participates as a contributor to conferences, seminars. and symposia in these areas. He deDOSeS and/or testifies as an exoert witness lfar or defense1 in . ~laintifl . lot gat ons mrolv ng cnem cals or chemical reactions an0 product haot ry. rle s Ed,ror of the lntemational Journal of Chemical Health and Safety. F~
the Chemical Manufacturers Association. Dr. Young taught for many years ag King's College in Pennsylvania and was a Visiting Professor at Carleton University in Dtfawa. He tauaht for seven vears in Sotaheastern Jnwd States and war assoclald wlth the lSlS protect at F orm State Unlvers ty 0 V o q lo the a h of several art.cles on the teaching of chemistry, most ofthem published in Uw JOCRNAL OF CHEMICAL ED UCATION. These and other publications, including more than a dozen books, have sbesed IBbO(atmas a meansot insbuction and the mponance 01 amtegoes des gned toenhance ind vtom student contacts worn their professor in b& large and small class environments. Recently or currently ha was or is involved with nationally based groups. He sewed for many years as Secretary of the ACS Division of Chemical Education and memoel 01 the Boam ol Publlcat on of tne Jomal of Chem ca Eo~catlon,and a so IS or has been a member of various ACS Council comminees, chairman of various committees and subcomminees, or a member of such, in the ACS Divisions of Chemical Health and Safetv and of Educat m of NSTA, and other organ zations. IclJdmg tne Nat#onalAov saw Co~ncdon CO ege Chemtslry He is a fe low of the AAAS and a founding (charter)member of me American Conferenceon Chemical Labeling.
Volume 59
From this assembled information the label is prepared, according to the following outline: 1) State the name of the chemical or if a mixture, the names of the potentially hazardous components. 2) State one of three degrees of potential hazard, using one of three "signal" words, Danger, Warning, or Caution (in order from most to least hazardous-by definition). 3) Describe the potential hazards in short statements. such as "Harmful if swallowed." "Flnmmnhle." "Cause; revere burns." etc., ordering these wirh the most likely ur most adverse cffwrs first tu the least likely or lea91 adverse last. 4) Describe the steps to be taken hy the user in order to avoid the hazards that miaht hrief hut nmplrte rtatemmlu,such as"Wa*h thoroughly afwr handling," Keep away inm heat, sparks and flame," "Wear protective clothing including face and eye protection and gloves," etc., again ordering these as above. 5 ) Statements oertainine to first aid treatmmt, spill clmn-up, fire fi~hting, storage, err., fbllow, along uith any aprcinl ~ n structions that may pertain to the rhrmicsl because of its unique but not well-known properties. As an example of the latter, labels for cyanides would describe the use of amyl nitrite, a unique antidote for cyanide poisonine. iic,te particulnrly that the preceding five steps oulltrze the procedure for the prrpnmt i m of labels. The nhwe d r s ~ r i p t i wis~hy no means a complm dwuwVm uf the prurrd~ue hy which asatisfnctory lnlwl is prepared. With . o r r h a.~ s ofrrr e x r r v t i u n s , a l l e x ~ ~ ~ r i ~ ments performed by ~"dergraduates in chemistry laboratories have features that can make the performance of these experiments hazardous. For almost all of these, however, it is possible to take precautions in their execution so as to prevent such features from causing harm. If it is impossible to take the appropriate precautions, the experiment should not be ~erfarmed.In this paper I (Continuedonpage A266) Number 9
September 1982
A265
propose a procedure which if followed identifies an experiment as unreasonably hazardous or indicates the precautions t o he taken that render the experiment acceptable for assignment to undergraduate students. This procedure follows in parallel form the procedure used to prepare labels, as will be seen.
Procedure for Evaluating Experiments Of all the experiments common to undergraduate laboratory instruction, one stands out as distinctly hazardous (fatalities have resulted from its execution by students). A detailed evaluation of this eiperiment will illustrate the proposed procedure:
Stating the Experiment The experiment (if indeed it is a true experiment) is the generation of oxygen by heating a mixture of potassium chlorate and manganese dioxide, with potassium chloride as the major solid residual product.
Choosing Degree of Hazard Following our parallel with labelling we next choose the "signal" word, for which I propose a "degree of hazard" statement instead.
Very High Degree of Hnrard-if i t is forseeable that a careless student fumbling
A266
Journal of Chemical Education
the directions could cause a loss of life or serious permanent injury. High Degree of Hozard-if i t is forseeable that a careless student fumbling the directions could cause permanent but not serious injury. Moderate Degree of Hozord-if it is forseeable that a careless student fumbling the directions could cause serious but reversible injury. Low Degree of Harard-if it forseeable that a careless student fumbling the directions could only cause a minor and reversible injury. If more than one degree of hazard applies, the most serious degree is selected for the degree of hazard statement. Any experiment classified as Very High or High Degree of Hazard should not be assigned to students. As performed in the past, the thermal decomposition of KC1O8 has resulted in fatalities. Therefore, Very High Degree of Hazard applies. Unless the forseeable risk can be reduced, this experiment should not he performed by students. The next steps in the proposed evaluation procedure will show, for this or any other experiment, either how the risks can he reduced or that they cannot he.
~escribin Potential ~ Hazards Tocutninue the parallel uith lahrling, the reasonably fc,meeal>lrtmmrds are li>ted,di. vided into these categories: Those due toApparatus Separate chemicals Experimental procedure Inadvertent chemical spills Routine clean-up and disposal of residues
Environmental effects Violation of Occupational Safety and Health Administration Reeulations Taking r h r v in order, thr Appnratu cntrgury indudes cuttiuy n lenyth o t ' , h i tubing, firr-polishing the rndi.nnd hending it in the center to approximately SO9; inserting this tuhe into the hole in a stopper; and using a test tuhe that is not thoroughly cleaned af all combustible residue or which mav contain. say, a hit of fiber from a test tube brush. The potassium ehlorate may he partially decomposed, in the reagent bottle, into a variety unstahle compound* rontnining chhrine in unf2rniliar oxidationstatrs,surh as -5 2.3 C.rrc.'l'hat is,chlor~rcssuhirctrd to varvi'ne in storaee are dtered . ..&eratures . in U I I U S U ~ I way* and brrome urwtahlr to further heating, sharp impart, fri rtlon ' etc. Porsible use of a black pmvdered i u t ~ m n c e other than manganese dioxide is a wellknown student error, with dramatic consequences if the mistaken black powder is powdered charcoal, for example. The toxicity of the separate chemicals should he evaluated. See "RTECS" (2);it is probably the most readily available and complete toxicity reference, even if it is not alwaya as reliable as one would wish. According t o this referenceand using the criteria for "Toxic" and "Highly Toxic" from reference (11. . . . ootassium ehlorate is neither h~ghlytoxic nor tux^ nnd manganew d k d e may, at molt, perhaps he imic ,the r i t d data cnnn8,r be directl) applied to the criteria given in reference (I)). T o evaluate carcinogenicity, use (3) and ( 4 ) , or equivalent. Neither of the chemicals are Listed in references (3) . . and (41: . . . bv " definition therefore, they are not carcinogenic, nor suspected of being carcinogenic. ~
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Questions relat~dto teratogenirity, po. tenrial genetrr damage, emhry
