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Edited by N O R M A N V. STEERE, 140 Melbourne Ave., S.E. Minneclpolis, Minn. 5541.4
XCXII. Identifying Multiple Causes of Laboratory Accidents and lniuries-Part 1 Norman V. Steere. CSP. Safetv Consultant, 140 Melbourne Ave. S.E., Minneapolis, Minn. 55414 The basic premise of this article is that there is a lack of comprehensive data on causation of laboratory accidents and injuries, and that more sophisticated accident and injury investigation is needed to provide a basis for laboratory safety standards, training, and cost-effective control efforts. Even though the fundamental principle of all laboratory activity is systematic ohservation, laboratory accidents and injuries are seldom observed or investigated systematically. Before we consider improved systems and models for studying laboratory accidents and injuries, we need to examine both the deficiencies of most commonly-used accident recording methods and the main reasons why information is Lacking on mast types of accidents and injuries.
REASONS FOR LACK O F INFORMATION ABOUT ACCIDENTS A N D INJURIES One reason why accidents and accidental injuries are not well studied is the common belief that accidents are inevitable, unpredictable, uncontrollable, unpreventable. Commenting on this fatalism in "Accident Research," Haddon, Suchman and Klein observe that "People who protect themselves against disease by inoculation and the observance of appropriate nutritional and personal habits nevertheless tend to look upon aecidents either as a punishment for misdeeds or as unwamanted blows delivered by a capricious fate." ( I ) Planek comments that " . . . for centuries accidents were seen as chance events or tricks of fate. Therefore the search for cause was unnecessary. Today accidents are viewed as outcomes of a series of interacting factors, consequently the study of accident phenomena consists first of detailing the accident sequence in terms of the victim,* his behavior, the environment, and the hardware. Such detailing must be reliable, valid and comprehensive." (2) The basic premise for rational efforts toward safety is that accidents and injuries are caused and can be prevented. Unintentional injuries are caused by acci'"Person" would seem more appropriate.
dents, and a workable operational definition of an accident has been proposed by Lucille Huher "An accident is the unplanned, occasional, hut forseeable consequence of one or more unsafe acts in combination with hazardous circumstances." (3) This definition implies the concept that accidents can not be attributed solely to "human factors" or to "mechanical factors," hut that a chain or sequence of circumstances and events is necessary before most accidents can occur. Recognition of this concept of multiple factor causation is important to avoiding investigations that are no more than a simplistic search to decide upon "the cause." As Clark says "There are a great many contributing factars, not one cause affecting the outcome of any human event. I consider i t more important to see whether or not we can reduce the injuries by understanding the many contributing factors than ta seek the 'one cause'." (4) The concept of multiple causation is also important for recognizing the choices available for preventive measures and the desirability of selecting the accident or injury prevention measures that will be mast effective for the lowest cost. Huber emphasizes selecting the prevention measures that "will in the long run be most effective with the least sustained effort and the least chance of failure or breakdown." (3) A second major reason why laboratory accidents and injuries are not adequately studied or recorded is the wish to avoid being blamed. Many accidents and injuries are concealed and not reported hecause, as Clark has observed (4), most of us when we are hurt or have an accident blame ourselves. Whether or not people blame themselves for accidents and accidental injuries, the events are often concealed because no one wants to he blamed. Instructors, teaching assistants, and supervisors may be reluctant to investigate accidents and minor injuries because af their apprehension of being blamed. Emplayers may have various reasons for not wanting to encourage the reporting of accidents and injuries. If employees are not required and encouraged to report injuries or illnesses that mav be attributable to their .iobs.. thev . may not blame the employer for their disability. Employers benefit from lower costs
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of Workmen's Compensation insurance if their employees accept occupationally-related injuries and ill~essesas their fault and an expected part of life, and pay their own medical costs and charge their days of disability to vacation allowances. Emplayers certainly want to avoid heing blamed (and charged) for injuries and illnesses that are not work-related. Some employers have been able to avoid being blamed far unsafe working conditions, in a general way, by enhancing their image and.safety record through artificially reducing their disabling injury frequency rate. More accurately, if two employers with an identical number of employees and with identical work injury experience were using the USA Standard Method of Recording and Measuring Work Injury Experience, USAS Z16. 1-1967,the employer with a number of vacancies in regularly established jobs is much more likely to have a lower disabling injury frequency rate. This "artificial" reduction is due to the peeularities of USAS Z16. 1-1967, which defines Day of Disability as "any day on which a n employee is unable, because of injury, ta perform effectively throughout a full shift, the essential functions of a regularly established job which is open t o and available to him." Regularly Established Job is defined as "One which has not been established especially to accommodate an injured employee, either for therapeutic reasons or to avoid counting the case as a temporary total disability." Since USAS Z16. 1-1967 specifies that the day of injury and the day of return to full employment shall not be counted as days of disability, if a work-injured employee can he gotten hack to work on some regularly established job on the day after the day of injury, there has been NO disabling injury, even if the person is in a cast. An employer with a range of unfilled regularly-established jobs is much more likely to be able to maintain a favorably low rate of disabling injuries, as long as fatalities and amputations and similar permanently-disabling injuries do not occur. (In the U S A . the Occupational Safety and Health Administration is using similar definitions for calculating Lost Workdays, hut has added a requirement that all employers governed by OSHA identify significant injuries not causing lost workdays. Specifically, OSHA requires the reporting of all cases of occupational injuries or illness which resulted in: Transfer to another job or termination of employment, or Medical treatment, other than first aid, or Diagnosis of occupational illness, or Loss of consciousness, or Restriction of work or motion. It may be possible with (Continued onpageA224)
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this additional information to develop a more equitable measure of work-related disabilities, for comparisons between similar and different types of employment, and within a single company.)
LIMITATIONS OF MANY ACCIDENT REPORTING SYSTEMS As indicated earlier, a major deficiency in any accident or injury reporting system is the emphasis on a single cause alone, or on a single type of cause, such as mechanical factors. Another deficiency is presented by a system which though detailed is so narrow that the best analyses obtainable provide v r v lmle useful cnusnlivedata. The Iq69 ednion of the ".Xcrldenr Prevenrmn h l u n m l for Industrial Opernliona" (5) provides detailed information on the use of the ASA Standard Method of Recording Basic Facts Relating to Nature and Occurrence of Work Injuries, ASA 216.2. The information also illustrates some of the limitations of the Standard Method. Some excerpts follow. Referring to the Standard, the "Accident Prevention Manual" explains "the purpose of the Standard is to identify certain key facts about each injury and the accident that produced it and to record those facts in a form which will permit summarization t o show general patterns of injury and accident occurrence in as great analytical detail as possible. These pat-
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terns are intended to serve as guides t o the areas, conditions, and circumstances to which accident prevention efforts mast profitably may be directed." The "Accident Prevention Manual" explains that for a complete recording of an injury case, "one item for each key fact should be selected from the injury report." The definitions of "key facts" are given as: "1. Nature of injury-the type of physical injury incurred. 2. Part of body-the part of the injured person's body directly affected by the injury. 3. Source of injury-the object, substance, exposure or bodily motion which directly produced or inflicted the injury. 4. Accident type-the event which directly resulted in the injury. 5. Hazardous condition-the physical condition or circumstance which permitted or occasioned the occurrence of the accident type. 6. Agency of aecident-the object, substance, or part of the premises in which the hazardous condition existed. 7. Agency of aecident part-the specific part of the agency of accident that was hazardous. 8. Unsafe act-the violation of a eammonly accepted safe procedure which directly permitted or occasioned the occurrence of the accident event." The "Manual" also adds "Contributory factors should he indicated." The "Accident Prevention Manual" provides detail on the bases on which identification of Key Facts should be made.
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'hree excerpts are illustrative: "Source of Injury. Sometimes an injury results from forcible contacts with two or more obj8tts; occurring either simultaneously or in rapid sequence, and it is impossible t o determine which object directly produced the injury. In such cases, the source of injury should be determined as follows. When the choice is hetween a moving object and a stationary object, the moving object should be selected. When the choice is between two moving objects or between two stationary objects, the one contacted last should be selected. For example, if a person fell from an elevation, struck one or more objects in the course of the fall and finally struck the floor, the floor should be named as the source of injury."
"Hazardous Condition. Generally . . . the hazardous condition selected will determine the agency of accident to be named. Since the hazardous condition classification represents the physical or environmental causes of accidents, tabulations of the data in this category properly may be labeled 'accident causes'." "UnsafeAct. The unsafe personal action which directly caused or permitted the occurrence of the accident event should be designated. The selected unsafe act may be something a person did which he should not have done, something he should have done differently, or his failure to do something which he should have done. The person who committed
the unsafe act may or may not have been the person who was injured. The person who acted unsafely may have done so deliberately, or he may not have known that he was acting unsafely. Since the unsafe act classification represents the personal causes af accidents, tabulations of data in ths this category properly may he labeled 'accident caus. .. es'." Some of the Unsafe Act Listings include the following: "Operating without authority Failure to warn or secure. Making safety devices inoperatwe Using defective equipment, materials, tools or vehicles Taking a n unsafe position Distracting, teasing Using equipment, twls, materials or vehicles unsafely Failure to use ~ e r s o n a protective l equipment Unsafe loading, placing and mixing Unsafe lifting and carrying (including insecure grip) Adjusting, clearing jams, cleaning machinery in motion P w r housekeeping" All of the Contributing Factors listed in the checklist in the "Accident Prevention Manual" are as follows: "Disregard of instructions Lack of knowledge or skill Failure to report to medical department Bodily defects Act of other than injured Others-" (Contrast this with the listings t o be shown later in this article for Basic Causes.)
Commenting on same of the accident data that has been developed, possibly including some based an use of the Standard Method just described briefly, one recent source has this to say "Many reports of accident statistics are available, however, they are generally of inadequate depth t o identify accident causative factors or aid in setting research priorities." The same source also states "Present 'causes' listed in most forms really only describe last action. Accidents usually result because af a series of factors rather than a single one." (6) Referring to the systems for reporting accidental injury data obtained by the National Health Survey and the National Safety Council, Marland states that "As valuable as this information has heen, however, it is not detailed enough to serve as a n adequate base for the development of major programs to correct the situation and to prevent injuries. The nature of descriptive data is such that, with adequate analysis and experimental design, careful investigations can be instituted, hut precise information on specific causative factors is lacking." (7) The American Society of Safety Engineers submitted a statement t o Congress on the Occupational Safety and Health Act of 1970 which in part commented on the new recordkeeping system for occupational injuries and illnesses: "This system still does not, nor can it, produce the required meaningful information on causes of accidents. Substantive eausative information will he of immeasurable value in providing guidance to OSHA and NIOSH to achieve the intent of the Act." (8)
Literature Cited (1) Haddon, William, Jr., Suchman, Edward A., and Klein, David, "Accident Research-Methods and Approaches," Harper &Raw, New York, 1964. Planek, Thomas W., J. School Health, 38 (6). 365 (1968). Huber, Lucile A,, in "Eighth National Conference on Campus SafetyMonograph No. 12," National Safety Council, Chicago, 1961. Clark, Carl C., ASSE J., 18 (2). 28 (1973). (5) McElroy, Frank E., Editor, "Accident Prevention Manual for Industrial Operations,'' tithed., National Safety Council, Chicago, 1969, p. 270. (6) "The Present Status and Requirements for Occupational Safety Research," National Institute For Occupational Safety and Health, PHS, HSMHA, U S . Department of Health, Eduestion and Welfare, Rockville, Md.. 1972. (7) Marland, Richard E., Safety Research.. l(3I. . .. 100 (19691. (8) American Society df safety Engineers, ASSEJ., 17 (9), 10 (1972).
(To be continued next month.)
TENTATIVE STANDARD PROPOSED FOR LABORATORY FIRE PROTECTION A praposed "Tentative Standard an Fire Protection for Laboratories Using Chemicals" will he presented for adoption a t the May 1973 Annual Meeting of the National Fire Protection Association (NFPA). When adopted the Tentative Standard will be available for comment and criticism, with the goal of having a n official concensus standard adopted in 1974 or 1975. Official NFPA Standards are adopted as regulations by many States, and many NFPA Standards are part of the regulations adopted under the 1970 Occupational Safety and Health Act (OSHA). A preliminary outline of the proposed tentative standard and a list of committee members preparing the standard appeared in the Journal of Chemical Education in May, 1970, in a brief report by committee chairman R. H. Scott entitled "Progress on a Standard for Fire Protection of Lahoratories". The 59-page proposed tentative standard for laboratoriesusing chemicals prescribes operating and construction requirements for fire prevention and control in both existing and new laboratories. The standard is designed to prevent personnel injury from toxic, corrosive, or otherwise hazardous chemicals by exposures which may result from fire or explosion. The proposed "Tentative Standard on Fire Protection for Laboratories Using Chemicals" has been published for review in the "1973 NFPA Technical Committee (Continued onpogeA226)
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Reports" which may be purchased from the National Fire Protection Association, 60 Batterymarch St., Baston, Mass. 02110, for about $7.50. These Reports also include the text of five other newly-proposed Tentative Standards, eight Tentative Standards being propwed far official adoption, and revisions proposed to 79 existing NFPA Standards. Many fire departments, insurance compnnlec, mstnutimi, and industrial firms are memhers of the NFPA and mny ha\,e a ruov of the "19":, NFPA Technical Com. m%ee Reports". NFPA membership is onen t o anv interested nerson or institution for $30.00, which includes a Fire Jourml subscription not otherwise available.
Meeting Notice The Southern Area Research and Development Safety Symposium will be held Mey 7 and 8, 1973 a t the University of Tennessee Space Institute a t Tullahoma, Tenn. The Symposium will be sponsored by the Research and Development Section of the National Safety Council, Union Carbide Nuclear Division, and the University of Tennessee Space Institute. Far further information, contact Harry Hoy a t Oak Ridge National Laboratory, Oak Ridge, Tenn. (615)483-8611, ext. 35234.
started the stirrer, the contents of the flask " b u m p e d and spewed out. The same kind of boiling over can occur (1) when adding a finely divided material (e.g., charcoal, filter aid) to a liquid near its boiling point and (2) when restarting a vacuum distillation after interruption and without removing the source of heat. Preventive Measures: (1) In all the eases described above, the liquid should be cooled well below its hailing point. (2) It is also goad practice to shield experimental equipment because the unexpected often happens in laboratory work. (Report 150) Reprinted with permission from Research and Development Section Safety Newsletter Jan. 1973 published by the National Safety Council.
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ELECTRICAL SHOCK FROM ULTRASONIC CLEANER
WORKSHOP ON LABORATORY SAFETY STANDARDS A Workshop on Laboratory Safety Standards will be held June 13-15, 1973, in Minneapolis by N. V. Steere & Associates. First in a series being planned, this workshop will discuss effective ways of meeting standards on eye protection, fire safety, and accident prevention in the laboratory. Further information may be obtained by writing to N. V. Steere, 140 Melbourne Ave. SE, Minneapolis, Minn. 55414.
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MAGNETIC STIRRING AND BUMPING A chemist was sprayed on the face and body with a hot solution of a polymer in formic acid, which erupted from a flask in which it was being heated under reflux. The magnetic stirrer in the flask had hung up. When the chemist noticed this and re-
A Seattle laboratory recently had an accident in which a worker received a severe electrical shock from a Sonagen Ultrasonic cleaner, Model LG-40, manufactured by Branson Lnstrument Ine., Stamford, Connecticut. The shock occurred while attempting to connect the six-prong transducer plug into its socket a t the bottom af the bath well. The generator switch and heater switch was in the "off" position at the time.
Investieation of the accident showed that " even though the generator switch is in the
"off" position, the transducer connector socket is hot. Additionally, even though the six-prong connector is made t o he engaged only one way, enough contact can he made to produce a severe shock if the plug is engaged backward. Although the instruction manual does have a warning against reversing this transducer plug, the best safety measure would he to make sure the instrument is not plugged into the line power when changing water. In order to eliminate the hazard of any further electrical shocks from this instmment while connected to line power, i t was decided to modify the wiring system so that the generator switch would also control power to the transducer connector. (Report 157) Reprinted with permissian from Research and Devela~ment Section Safetv Newsletter Jan. i973 published by t h e ~ a t i o n a l Safety Council.
2. Purge with argon gas for several hours until system reaches room temperature. 3. Open furnace and remove plated ohject. On this particular day the following sequence took place: 1. The hydrogen was not secured. 2. The assembly was purged with argon gas for approximately 30 minutes. 3. Air was then admitted as a coolant t o Saee argon gas. The result was: 1. AN EXPLOSION-Cause: hydrogen + air + hat component. The argon purge was ineffective, because hydrogen gas was still flowing through the system. 2. A LOST TIME INJURY-from multiple lacerations to the face, arms, and ear of one of the experimenters. A Wise Owl Award for saving eyesight through the wearing of safety eyeglasses. Cause: Shattered quartz viewing window from the chamber. The lessons are: 1. Overfamiliarity can cause problems. Chances of this occurring can be reduced by usine a checklist far re~etitiveseauential
HYDROGEN FURNACE EXPLOSION Two employees performed a chemical vapor deposition experiment in a hydrogen atmosphere furnace as had been done many times. Normally the shutdown phase consisted of the following sequence of operations: 1. Secure all hydrogen gas tosystem.
viewing part is necessary and it is the weakest link, then protect people if it should shatter. (Report 143) Reprinted with permission from Research and Development Section Safety Newsletter Jan. 1973 ~ublishedbv the National Safety Council.
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