Identification of Ergonomic-Related Hazards in an Industrial Sample Using the National Occupational Exposure Survey. U.S. Department of Labor, USA

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1 INTERNATINAL JURNAL F UPATINAL SAFETY AND ERGNMIS 1998, VL. 4, N. 3, Identifiatin f Ergnmi-Related Hazards in an Industrial Sample Using the Natinal upatinal Expsure Survey Rbert J. Biersner U.S. Department f Labr, USA Franis J. Winn, Jr. East arlina University, USA The Natinal upatinal Expsure Survey (NES) was used t determine prbabilities fr 4 ptential physial-agent and 1 ptential ergnmi-related expsure hazards amng a representative sample f U.S. industries. Ptential physial-agent hazard expsures, prinipally whle-bdy and segmental vibratin, were highest amng railrad and heavy nstrutin industries. Several nstrutin industries had high prbabilities f ptential ergnmi-related expsure hazards, espeially t the bak and upper extremities. Establishments with 1 t 249 emplyees had the highest prbability f ptential expsures t the 2 types f hazards. Measures f safety and health limate did nt differ nsistently between high-hazard and lw-hazard establishments. The apprah taken in this paper may be used t help identify highrisk industries, evaluate interventins, and develp inspetin strategies. expsures hazard analysis upatinal hazard survey safety and health limate vibratin This artile represents the views, pinins, and interpretatin f the authrs nly; n supprt r endrsement by any gvernment department r ageny is intended r shuld be inferred. This artile is a mpilatin and revisin f tw papers presented by the authrs at the 1th Annual Internatinal Industrial Ergnmis and Safety nferene held in Seattle, W A, June 13-16, F.J. Winn als has appintments with the Medial llege f Gergia (USA), the Nrth arlina Agrmediine Institute (USA), and the Duke University Shl f Nursing (USA). rrespndene and requests fr reprints shuld be sent t Franis J. Winn, Jr., Department f Physiian Assistant Studies, Shl f Allied Health Sienes, East arlina University, Greenville, N , USA. winnf@mail.eu.edu >.

2 3 R.J. BIERSNER AND F.J. WINN 1. INTRDUTIN Prir t the Natinal upatinal Expsure Survey (NES), a systemati attempt t determine the prevalene f expsure t ergnmi-related expsure hazards amng a general and representative sample f U.S. industries had nt been nduted. Typially, ergnmi surveys have emphasized end-stage effets (e.g., arpal tunnel syndrme, bak pain), and have used these effets data t determine prevalene rates fr entire ppulatins r fr speifi upatinal grups (e.g., designated by jb tasks perfrmed r jb titles). The assumptin underlying these studies is that these effets are prprtinal t the number f ergnmi expsure hazards present in the wrkplae. Fr example, in a study in whih the Natinal Health Interview Survey was administered t a sample f adult respndents emplyed fr any perid during the mst reent 12 mnths, the prevalene f self-reprted bak pain and hand dismfrt was fund t vary substantially amng different upatinal grups (Behrens, Seligman, amern, Mathias, & Fine, 1994). Whereas epidemilgial studies f end-stage ergnmi effets are a neessary mpnent f a prgram designed t prevent ergnmi injuries, suh a prgram wuld be inmplete absent f ergnmi expsure hazards arss industrial setrs. Reently, the Amerian Natinal Standards Institute and the upatinal Safety and Health Administratin develped prpsed ergnmi safety and health prgrams (Bureau f Natinal Affairs, 1994); these prgrams are based n using bth effets data and surveys f ergnmi expsure hazards t redue ergnmi injuries. Additinally, data regarding the prevalene f ergnmi expsure hazards arss industrial setrs wuld be useful in determining the enmi nsequenes f implementing preventin prgrams. The Natinal Institute fr upatinal Safety and Health (NISH) develped the NES t llet data in a systemati fashin arss a wide spetrum f U.S. industries n expsures t ptential wrkplae hazards, inluding ergnmi and physial-agent hazards. (Whereas the NES als lleted bilgial- and hemial-agent expsure data, this artile will desribe nly the ptential expsures t ergnmi and physial-agent hazards.)

3 2.1. Sample Seletin EXPSURE PRBABILITIES T ERGNMI HAZARDS METHD The sample f industries t be surveyed was nfigured using a mplex sampling strategy (Sieber, 199). The sample nsisted f 45 U.S. industries identified using tw-digit, Standard Industrial lassifiatin (SI) ategries defined by the ffie f Management and Budget (ffie f Management and Budget, 1972). These SIs were lassified under the fllwing nine Majr Industrial Grups (MIGs), with the tw-digit SI identifiers within eah MIG prvided in parentheses: Agriultural Servies (7); il and Gas Extratin (13); nstrutin (15 17); Manufaturing (2-39); Transprtatin (4-49); Whlesale/Retail Trade (5-59); Servies (7-79); Health Servies (8); and Museums and Btanial and Zlgial Gardens (84). (The MIGs fr Agriulture Servies, Health Servies, and Museums and Btanial and Zlgial Gardens eah nsist f a single tw-digit SI.) The sample did nt inlude agriultural prdutin, mining (exept fr il and gas extratin), railrad transprtatin, private husehlds, finanial institutins, and gvernment (i.e., lal, state, and federal) failities. T limit sampling sts, nly establishments within eah SI that emplyed mre than seven wrkers were identified fr the sampling pl. T prevent large establishments (i.e., with 2,5 r mre emplyees) frm being under-represented in determining expsure hazards, these establishments were divided int a separate sampling pl frm establishments with fewer emplyees. These latter establishments (i.e., with fewer than 2,5 emplyees) were dispersed amng 64 primary sampling units (PSUs). PSUs were designed gegraphially by unties, with a few PSUs eah being mpsed f a single unty, and the remainder nsisting f multiple, ntiguus unties. The 64 PSUs were then mpiled int 98 strata f nearly equal size that were hmgenus in terms f several variables, inluding gegraphy (i.e., based n ensus regins), number f emplyees, nentratin f establishments f interest t the survey, and the prprtin f wrkers likely t be expsed t health hazards. Using these hmgeneity riteria, 26 f the resulting strata nsisted f a single PSU eah (i.e., eah f these PSUs met the hmgeneity riteria); these strata were referred t as selfrepresenting (SR) strata. The ther 72 strata were eah mpsed f multiple PSUs (i.e., lusters f PSUs frm the remaining 578 PSUs were mbined t frm 72 strata that met the hmgeneity riteria); these strata were named the nn-self-representing (NSR) strata.

4 32 R.J. BIERSNER AND F.J. WINN Seletin f establishments fr inlusin in the sample differed depending n whether the establishments were t be hsen frm the sampling pl f large establishments r frm SR r NSR strata. Fr the large-establishment sampling pl, seletin was pseudrandm in that these establishments were hsen by wrk fre size and SI ategry t nfrm with knwn wrk fre size and SI distributins amng large Amerian industries. Seletin f large establishments was amplished withut regard t PSUs. Seletin f establishments frm the SR strata was als nduted in a systemati fashin, with seletin f establishments being made frm eah f the 26 strata (with eah stratum nsisting f a single PSU) n the basis f predetermined wrk fre size and SI ategry distributins. The large number f PSUs in the NSR strata required that these strata first be delimited by randmly seleting a single PSU t represent eah f the 72 NSR strata. Establishments were then hsen frm eah f these 72 delimited strata in the same systemati fashin used fr seleting establishments frm the SR strata. This press resulted in identifiatin f 7,392 establishments fr pssible inlusin in the final sample. Telephne interviews were nduted with ffiers frm the establishments t verify that the establishments were still in business and nduting peratins within the spe f the designated SI, had eight r mre emplyees, and wuld partiipate in the survey. These interviews redued the final sample t 4,54 establishments. f this ttal, 125 establishments refused t partiipate in the survey, 111 substitutes were fund fr these refusals, making the final sample size f 4,49 establishments. The final set f establishments hsen fr this survey were representative f the universe f establishments within the varius SIs in terms f size, number f emplyees, and gegraphial latin. The mdel develped fr the NES allwed eah ptentially expsed wrker t be representative f a larger grup f wrkers within that SI. A detailed disussin f the mdel, inluding the develpment f the weights t extraplate ptential expsures frm individuals bserved in the survey t the universe f wrkers within the SIs, an be had in Sieber (199) Survey ntent Tables 1 and 2 list and prvide peratinal definitins fr the 1 ergnmi and fur physial-agent expsure hazards used in the present

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7 EXPSURE PRBABILITIES T ERGNMI HAZARDS 35 analysis. Whereas NISH subjet matter experts nminated 11 ptential ergnmi expsure hazards fr the survey, expsure prbabilities fr light glare are nt inluded in this analysis beause n expsures were rerded fr this ptential hazard by the surveyrs. In additin, a ttal f eight ptential physial agent expsure hazards were nminated by NISH subjet matter experts fr the survey, but expsure prbabilities are presented fr nly fur f these ptential physial agent expsure hazards beause previus researh has demnstrated that these fur ptential expsure hazards augment the effets f ergnmi expsure hazards. This researh has fund that expsure t ld temperatures and vibratin interat with several ergnmi expsure hazards t enhane the prevalene f ergnmi disrders amng a variety f wrkers mpared t referene wrkers nt expsed t these hazards (Hagberg, Mrgenstern, & Kelsh, 1992). athde ray expsures have been assiated with data entry and wrd pressing peratins, and these peratins have been shwn t result in high levels f ergnmi disrders (Hales et al., 1994) Seletin and Training f the Surveyrs Thirty-tw surveyrs were reruited by NISH t administer the NES. The surveyrs had t pssess undergraduate llege degrees in industrial hygiene, upatinal health, r the bilgial sienes. A minimum f 15 quarter-redit hurs f llege hemistry r equivalent urses were als required. Turnver amng the surveyrs was abut 2%. Replaements were hired fr thse surveyrs wh left the prgram. After hiring, teams nsisting f three t 1 surveyrs were frmed with eah team led by an experiened industrial hygienist. n asin, surveyrs wrked alne. In sum, an average f 15 surveyrs per mnth partiipated in the NES during the survey perid. During this perid, eah surveyr administered an average f 9.85 surveys per mnth. Whereas the team struture f the survey prgram enhaned the auray and unifrmity f the data lletin press, extensive training was neessary t ensure the auray f the survey data and t prvide quality ntrl. T amplish this training bjetive, eah new surveyr was prvided with nine weeks f training by subjet matter experts. The majr training setins nsisted f industrial hygiene; industrial presses and regnitin f ptential bilgial, physial, hemial, and ergnmi hazards; interviewing and data-ending predures and field

8 36 R.J. BIERSNER AND F.J. WINN training. Field training, whih lasted abut 3 days, was nduted fr eah individual surveyr by industrial hygienists, an NES surveyr, and team leaders familiar with NES predures. Field training was initiated with pratie exerises, fllwed by field exerises in whih the nvie surveyr ampanied an experiened surveyr n sheduled surveys that varied, and inreased, in mplexity. The nvie surveyr was assisted by an experiened surveyr as needed and the survey results were reviewed and disussed by the team leader. A mplete desriptin f surveyr qualifiatins, reruitment, seletin, and training is available (Seta, Sundin, & Pedersen, 1988) Survey Administratin A surveyr initiated the survey by nduting a management interview that invlved lleting data n majr ativities (inluding years invlved in these ativities), prduts made and servies perfrmed, unin histry, shift wrk shedules, health and safety praties and resures available, health and safety inspetin histry and the nsequenes f these inspetins, rates f absenteeism and turnver, and SHA s 2 lg entries (i.e., illness and injury rerds). The wrk site sampling predure nsisted f a surveyr diretly dumenting the previusly-desribed ptential ergnmi and physialagent expsure hazards while walking thrugh the entire establishment. Every peratinal task was bserved at least ne by the surveyr, wh asked jb inumbents abut jb perfrmane, ttal wrkers invlved in the task, envirnmental nditins, and pressing demands (inluding task duratins). Als rerded were the latin f the task within the establishment, upatinal speialty f the jb inumbent, and the type f peratins perfrmed. Nte that ptential ergnmi expsure hazards were nt determined diretly, but were estimated frm the number f wrkers perfrming jb tasks that were likely t expse them t these hazards. As disrders resulting frm these jb tasks were nt dumented diretly, the authrs have hsen t use the term ptential in desribing the expsure hazards. Detailed guidelines prvided t the surveyrs as t what nstituted ptential expsure, the numbers f wrkers t be rerded as subjet t the expsure at the partiular wrkstatin mnitred, examples f the frms used fr rerding the expsures, and ther pertinent infrmatin an be fund in Seta, Sundin, and Pedersen (1988, pp ).

9 EXPSURE PRBABILITIES T ERGNMI HAZARDS 37 Briefly, fr the ptential ergnmi expsure hazards, the surveyr assessed extremes f fre, repetitin, and pstural angle by bserving several wrk yles and using the definitins prvided earlier in this artile. Additinally, assessment was based n signs f pain and sreness (e.g., wining, grans), interviewing the jb inumbents regarding the effrt invlved in the task and nting symptms f ergnmi illness (e.g., numbness, tingling). The task had t be perfrmed by the jb inumbent at least 3 min per day t be rerded. Despite this extensive training, infrmatin prvided by a NISH supervisr invlved in managing the NES prgram indiates that at least ne f the surveyrs failed t rerd any expsures t ptential ergnmi and physial-agent hazards althugh repeatedly asked t d s. This bservatin indiates that the expsure prbabilities disussed later are likely t be nservative General Findings 3. RESULTS The surveyrs dumented ver 5, ergnmi and physial-agent expsure hazards amng the 4,49 establishments surveyed. These establishments, lated in 4 states and the Distrit f lumbia in the USA, nsisted f 523 different industries emplying abut 1.8 millin wrkers in 41 upatinal grups. Arding t Pedersen and Sieber (1988), apprximately 65.5% f the emplyees surveyed were males. A higher perentage f male wrkers (74.2%) was fund in small establishments (i.e., emplying between 8 and 99 wrkers) than in medium-sized establishments emplying between 1 and 499 wrkers (63.9% male), r large establishments emplying mre than 5 wrkers (59.2% male). verall, 48.2% f the wrkers were in establishments that had unin representatin. Unins were fund in mre than 5% f the medium-sized and larger establishments, but in abut 25% f the small establishments. Abut 73% f the emplyees were in nn-administrative jbs, ranging frm a high f 75.8% in medium-sized establishments t a lw f 7.5% in large establishments. Small establishments had 73.3% f the wrk fre in nn-administrative jbs.

10 38 R.J. BIERSNER AND F.J. WINN 3.2. Expsure Prbabilities Arss SIs A deisin rule was adpted t assure the reliability f estimated expsure prbabilities. This deisin rule required that an SI, t be inluded in this analysis, had t have at least fur ptential ergnmi and physial-agent hazards t whih emplyees in that SI were expsed and that at least 1% f the emplyees in that SI had t be expsed t eah f these ptential hazards. Eighteen SIs failed t meet this deisin rule. These SIs were Agriultural Servies; rude Petrleum and Natural Gas; Natural Gas Liquids; il and Gas Field Servies; Printing and Publishing; hemials and Allied Prduts; Petrleum and al Prduts; Primary Metal Industries; Transprtatin Equipment; Instruments and Related Prduts; ther Manufaturing Industries; Water Transprtatin; mmuniatin; Eletri, Gas, and Sanitary Servies; Business Servies; Repair Servies; Health Servies; Museums; Btanial and Zlgial Gardens. Fr the 27 remaining SIs meeting the deisin rule, the fllwing estimates were derived frm the survey data: ttal number f wrkers emplyed, ttal number f expsures t eah hazard, and prbabilities f expsure t eah expsure hazard. Expsure prbabilities were btained by dividing the estimated ttal number f expsures fr eah ptential expsure hazard by the estimated ttal number f emplyees in the SI. Tables 3 and 4 list, fr these 27 SIs, the expsure prbabilities and the estimated number f wrkers expsed fr eah f the 1 ptential ergnmi hazards. The estimated ttal number f emplyees (expsed and nn-expsed) fr eah SI is listed in the far right lumn f Table 4. (Nte that these ttal numbers pertain, as well, t the data fr ptential physial-agent hazards.) The sample had, verall, lw and infrequent expsure prbabilities fr the fur ptential physial-agent hazards. The fllwing SIs (amng the 27 SIs meeting the deisin rule) had ptential physial-agent expsure hazards (with estimated expsure prbabilities and estimated number f wrkers expsed prvided, respetively, in parentheses; see Table 2 fr the abbreviatins fr eah ptential physial-agent expsure hazard): General Building ntrating (SV, 13/119634); Heavy nstrutin ntrating (W-BV, 24/143149; SV, 14/83925); Speial Trade ntrating (SV, 11/17633); Fd and Kindred Prduts (DT, 1/15823); Railrad Transprtatin (W-BV, 31/774); Lal and Suburban Passenger Transprtatin (W-BV, 19/37933); Truking and Warehusing (W-BV,

11 e III TABLE 3. Expsure Prbability fr Ptential Ergnmi Hazards fr Tw-Digit Standard Industrial lassifiatins sa. 5 I X h- 2 i- L Q. a. T3 "D 55 ) rt -4- S I I w T D. rt 1 Q " s *!- rt rt ^ rt (D X - T E L T3! 2 rt D T 3 Ql a- 1 z: I ) Q_ 13 L U t n " rt is S 'S P P. L = x! E - rt a) ;? X» I. L U 2 U T 3 rt T D ~ rt rt a a) rt a. E a. d -J 13 r t «^.Q a. n rt d Q_ rt rt ) rt (rj v-' rt a 5 rt ^ a T3» 3 w _ ID rt D r a 5 5 ^ >, " n - _ * rt D rt > w /D m x S.2 t t S- n rt rtk h w 'rt "rt 1S s - "5 B t t. ra _ a. h= m a> t ' : - x:. ~ S rt.g. l E = S Q = 3 r t ^ rt W 2 rt 2. ~ rt _ rt _ j; 5. -g H 3 ) LL LU E - I L H I - ^ ^ Q_ rt rt ; 'u rt Z rt. " > rt a) /3 rt E J 1 rt S. See Table 1 fr the abbreviatins fr eah ptential ergnmi hazard. Q) 1

12 TABLE 4. Estimated Number f Wrkers Expsed t Ptential Ergnmi Hazards at the Time the Survey Was nduted (by Tw Digit Standard Industrial lassifiatins) 5 LU Q - 2 a. a. 15 u w U) w a k. a 13 J2 55 ^r L \J M M N -a- 'T l N M L L L T - r - m d ^ t L h - L L r- t ^ L M L ^ L M I - L T - h - -i- d r - - ^ r L J ^ I D M N M I N ' T I ^ M T - l f i ^ t D D N ' f 'VT D D i N I N D M T T ^ N M L L N ' t ^ i n D l T - ^ t- M M r - M N D ' f r r- \J 1-1 M M 1 1 L (M r- M M L M L 'S "3- L S- T- L h- M M M T i I D D ^ M L - ^ L D t- N t- M L D M f f l L r - ^ t X J N ^ M N N N N M I t I ( D D N t- M t i- M i t- t- M D M ^ t- L ^ D D D N L ^ t- ^ M D D L M L m d l t ^ M T - T T M T L L M '*3- 'tf- L f^- ^r Lfi L tj- Is- m L L L L L s ^r M r- h~ L L M M M T T- i D M I D N t- L M N N i- L t- N D L L ^ D t- D t- D D M ^ D D D N I N D ^ D ^ M L M D r - ^ r - N M - N M M *- t- M M L h- M M i- t r N- i M h L N 1- r- N r- M M N M L i- L M N- h- 't Is- M ^r ':3- n =3 B T3 a =J a 2 «D ) S _d "5 i «r T3 u- -jz 1 _ 1? X ' X) n~ " >- al I L JK a D L h=.2 j ^ ^ ^ - D «I ~ ^ ^ js -3 a5 g 3 SB 1 k_ >, D I " -n d _ -Q D I I - TD E " "2 S il =3 m ^ r- ^ r- "S J ^ 3 V - 2 " T3 LU >- x.2.2 ^ H LLI i ir _ T3 J9. 2 _ ^ ai d L. S -Q a. E JZi aj JZ d" _ r n r ^ ^ 1 - ~ Q- m E.Q Q. - =S => =3 _ _Q ±= _..2 E 13 I I LL L _l 2 l l lu a: i b_ L M g r U) a).2 "D 3 ) E 2 LL IB z s E- 5 TD U a) ~~ Ntes. * See Table 1 fr the abbreviatins fr eah ptential ergnmi hazard.

13 EXPSURE PRBABILITIES T ERGNMI HAZARDS /9553); Transprtatin by Air (W-BY, 1/4438; SV, 1/46242); Whlesale Trade, Nndurable Gds (RT, 14/28766); and Aut Repair, Servies, and Garages (SY, 1/4785). These data shw that emplyees in these SIs have the highest prbability f expsure t whle-bdy vibratin, fllwed by segmental vibratin; expsure t depressed temperatures and athde ray tubes are negligible amng these SIs. As demnstrated by Hagberg et al. (1992), emplyees with high prbabilities f expsure t the ptential hazards f whle-bdy vibratin and segmental vibratin are at enhaned risk fr ergnmi-related disrders. The results shw that seven SIs eah had fur hazards (ergnmi and physial-agent hazards mbined) fr whih at least 1% f the wrk fre was ptentially expsed, whereas nine SIs eah had five ptential expsure hazards. Fur SIs had seven ptential expsure hazards apiee. These latter SIs were Speial Trade ntrating; Fd and Kindred Prduts; Textile Mill Prduts; and Transprtatin Servies. The seven SIs with six hazards were: General Building ntrating; Heavy nstrutin ntrating; Paper and Allied Prduts; Railrad Transprtatin; Lal and Suburban Passenger Transprtatin; Persnal Servie, and Aut Repair, Servies and Garages. Amng the nine MIGs, the highest average expsure t ptential ergnmi-related hazards was fund fr the nstrutin MIG. The SIs in the nstrutin MIG are General Building ntrating; Heavy nstrutin ntrating and Speial Trade ntrating. Fr this MIG, the fur ptential ergnmi-related hazards with the highest prbability f expsure were lifting pstures, arm-transprt mvements, shuldertransprt mvements, and hand-wrist manipulatins. Expsure prbabilities fr these ptential ergnmi-related hazards ranged frm 18 t 26% fr emplyees in this MIG. These results are nsistent with earlier researh (Hlmstrm, 1992) demnstrating a high level f ergnmirelated disrders, invlving bth stati- and dynami-pstural stresses amng emplyees in the nstrutin trades. The high prbability f ergnmi-related expsures fr these emplyees indiates that this grup shuld reeive speial attentin fr interventin prgrams that emphasize preventin f ergnmi-related disrders Expsure Prbabilities by Establishment Size A mmn assumptin regarding small establishments is that mre emplyees in these establishments are expsed t wrkplae hazards than

14 312 R.J. BIERSNER AND F.J. WINN in large establishments. nsequently, small establishments shuld have higher upatinally-related injury and illness rates than larger establishments. The ratinale fr this assumptin is that small establishments, mpared t large establishments, have prly-rganized emplyees (i.e., unin representatives are nt available t interede n emplyees behalf t rret health and safety prblems) and annt affrd adequate safety and health prgrams. Prir analysis f upatinally-related injury and illness reprting data, hwever, fund that small establishments (5 emplyees) have signifiantly lwer injury and illness rates than establishments emplying between 1 and 499 wrkers (leinik, Gluk, & Guire, 1995). These researhers, hwever, attribute the lwer rates fr small establishments t underreprting f illnesses and injuries. T determine the ptential hazard-expsure rates (and, by inferene, the likely injury and illness rates) fr establishments differing in the number f wrkers emplyed, the establishments in the NES sample were divided int 1 ategries based n size. These 1 size ategries, and the number f establishments in eah ategry (in parentheses), were 8-19 emplyees (1,19), 2^49 emplyees (914), 5-99 emplyees (675), emplyees (838), emplyees (512), emplyees (344), emplyees (18), emplyees (94), and 5 r mre emplyees (97). The prprtin f ttal ptential expsures t the mbined ergnmi and physial-agent hazards was then alulated fr eah size ategry; every SI was inluded in this analysis, regardless f the expsure prbabilities t the ptential hazards. These results indiate that smaller establishments have a lwer prprtin f ptential expsures t ergnmi and physial-agent hazards than larger establishments. Rather than finding a deline in ptential expsure hazards frm the smallest t the largest establishments, bimdal r skewed distributins were btained instead. This analysis shwed that establishments with the largest number f ptential hazard expsures emplyed between 1 and 249 wrkers. Twelve f the ergnmi and physial-agent hazards urred mst ften in establishments f this size. These findings nt nly repliate the results fr upatinally-related injuries btained by leinik et al. (1995), but indiate that the lwer rates f upatinal injuries experiened amng small establishments mpared t larger establishments may result, at least t a substantial degree, frm lwer hazard expsure, and nt just t under-reprting as leinik and lleagues had surmised (1995).

15 EXPSURE PRBABILITIES T ERGNMI HAZARDS Safety and Health harateristis f High- and Lvv-Hazard SIs Based n the data frm Table 3, the MIG fr Whlesale/Retail Trade, whih had the lwest average perentage f emplyees expsed t ptential ergnmi and physial-agent expsure hazards mbined, was mpared t the MIG fr nstrutin, whih had the highest average perentage f emplyees expsed t these hazards, n 12 variables (r harateristis) indiative f the safety and health (S&H) limate within the establishments that nstituted these MIGs. (Admittedly, average perentage f emplyee expsures assumes that expsure t eah ptential hazard is nt independent, whih is unlikely t be the ase. In the absene f any methd fr determining interatins amng the ptential hazards frm the NES data available t the authrs, this metri is suffiient t btain a rugh estimate f the extreme MIGs fr this purpse.) The Whlesale/Retail M IG is referred t as the lwhazard r LH grup, whereas the nstrutin MIG is labeled as the high-hazard r HH grup. Data fr the 12 S&H limate harateristis were btained frm the management interview prtin f the NES (Pedersen & Sieber, 1988), and are expressed as the perentage f establishments within eah grup having a speifi S&H limate harateristi. The S&H limate harateristis and the perentage f establishments having eah f these harateristis fr the LH and HH grups are listed here: 1. Santining unin representatin: 13.5% fr the LH grup and 43.9% fr the HH grup. 2. Prviding health units with designated staff in harge: 1.2% fr the LH grup and.9% fr the HH grup. 3. Prviding health are at an ff-site latin: 41.7% fr the LH grup and 36.% fr the HH grup. 4. Administering pre-plaement and pre-hiring medial examinatins: 27.3% fr the LH grup and 7.2% fr the HH grup. 5. Requiring an exit-medial examinatin:.5% fr the LH grup and.% fr the HH grup. 6. Emplying upatinal health and safety persnnel: 1.7% fr the LH grup and 3.5% fr the HH grup. 7. Mnitring fr ptential physial-agent hazards: 2.% fr the LH grup and 1.3% fr the HH grup. 8. nduting peridi safety inspetins: 49.4% fr the LH grup and 49.3% fr the HH grup.

16 314 R.J. BIERSNER AND F.J. WINN 9. Establishing a regularly-sheduled, safety training prgram: 18.8% fr the LH grup and 21.% fr the HH grup. 1. Regularly assessing emplyee knwledge f safety rules: 23.6% fr the LH grup and 31.4% fr the HH grup. 11. Taking rretive measures fr the safety rule vilatins: 69.8% fr the LH grup and 79.9% fr the HH grup. 12. Maintaining summaries f upatinal injury and illness frm (SHA 2 frm): 36.1% fr the LH grup and 46.9% fr the HH grup. These mparisns shw that, verall, the nly systemati differene between the LH and HH grups regarding these S&H limate harateristis is that establishments in the LH grup appear t plae mre emphasis n health-related ativities than establishments in the HH grup. Even the differenes fr these health-related ativities are nt striking. Additinally, the disparity in health-related ativities between the tw grups des nt appear t be suffiiently large t aunt fr the differenes in ptential hazard expsure dumented fr these tw grups by this analysis. Fr the remaining mparisns, the tw grups are either similar r the HH grup had muh higher perentages fr the S&H limate harateristis than the LH grup. The largest differene in favr f the HH grup was fund fr unin representatin. The higher perentage f establishments santining unin representatin in the HH grup mpared t the LH grup merely nfirms the high degree f labr rganizatins fund amng the nstrutin trades. The nlusin t be drawn frm these mparisns is that the differene between the tw grups in ptential hazard expsure is, in large part, attributable t the disparate wrk tasks perfrmed by the tw grups, with nly a small prtin f this differene being related t the S&H limate harateristis f the establishments in whih these tasks are perfrmed. 4. DISUSSIN These results shw a high degree f variability amng the NES industrial sample in the prbability f expsure t ptential ergnmirelated hazards. verall, emplyees had lwer, and less frequent, expsures t ptential physial-agent hazards than t ptential ergnmi hazards. The ptential physial-agent hazards with the highest expsure prbabilities were whle-bdy vibratin and segmental vibratin, indiating that emplyees wh are expsed t these ptential hazards, in mbinatin with ergnmi hazards, are at enhaned risk fr ergnmi-

17 EXPSURE PRBABILITIES T ERGNMI HAZARDS 315 related disrders. The grup having the highest expsure prbabilities t these ptential hazards nsisted f emplyees in the nstrutin trades. This finding repliates earlier researh demnstrating a high prevalene f ergnmi-related hazards amng nstrutin wrkers (Hlmstrm, 1992). Als nsistent with this earlier researh, these hazards appear t invlve high stati and dynami lads n the bak and upper extremities. Althugh ptential physial-agent hazards did nt appear t be invlved in the expsure prbabilities fr this grup, ld temperatures during winter nstrutin and segmental vibratin assiated with use f pwered hand tls shuld nt be ignred. These results indiate that the nstrutin industry shuld be nsidered fr interventin prgrams emphasizing preventin f ergnmi-related disrders. Smaller establishments, mpared t larger, were fund t have a lwer prprtin f ptential expsures t ergnmi-related hazards. The highest expsures t these hazards were fund amng medium-sized establishment having between 1 and 249 emplyees. These mparisns indiate that the mparatively lw rates f upatinal injuries fund amng small establishments (leinik et al., 1995) may, t a signifiant degree, be related t redued levels f hazard expsures fr small establishments. A mparisn f harateristis indiative f the safety and health limate amng establishments in MIGs with high and lw expsure prbabilities t ptential ergnmi-related hazards fund few differenes between these tw grups. Lw-hazard establishments appeared t engage in mre health-related ativities than high-hazard establishments, but the differenes in these ativities were insuffiient t aunt fr the variatin in ptential hazard-expsure prbabilities between the tw grups. These data indiate that the differene in ptential ergnmirelated expsures between lw- and high-hazard establishments is likely t relate, in large part, t the disparate wrk tasks perfrmed by the emplyees in these tw grups. Whereas the NES was administered t a representative sample f selet industries, these results must be interpreted with autin beause f the fllwing: lak f health and safety expertise (espeially ergnmi) amng the surveyrs, whih may have resulted in under-estimates f hazard expsure and unreliability in the data lletin press; bslesene f the data resulting frm the redesign f jbs and enhaned awareness f ergnmi hazards that urred amng Amerian industries after the survey was mpleted; absene f data indiating that the NES results

18 316 R.J. BIERSNER AND F.J. WINN are valid (e.g., by mparing these results t prevalene rates fr ergnmi injuries arss industrial ategries); and lak f any statistial analysis f the data that wuld identify imprtant interatins amng the independent and dependent variables. Future researh, hwever, uld use these expsure-prbability data, in njuntin with ergnmi injury data, t identify the riskiest industries fr ergnmi interventins, as well as evaluating the effetiveness f these interventins. Disparities between hazard-expsure and ergnmi-injury data als uld identify industries that are under-reprting ergnmi injuries, thereby aiding in the develpment f effetive strategies fr health and safety inspetins. Finally, future attempts at determining ptential expsure prbabilities t ergnmi hazards may use these findings as the yardstik with whih t measure imprvements in the wrk envirnment. REFERENES Behrens, V., Seligman, P., amern, L., Mathias,.G., & Fine, L. (1994). The prevalene f bak pain, hand dismfrt, and dermatitis in the U.S. wrking ppulatin. Amerian Jurnal f Publi Health, 84, Bureau f Natinal Affairs. (1994). Members f panel drafting ANSI standard say SHA rule shuld nt deter vluntary effrt. upatinal Safety and Health Reprter, 24, 86. Hagberg, M., Mrgenstern, H., & Kelsh, M. (1992). Impat f upatins and jb tasks n the prevalene f arpal tunnel syndrme. Sandinavian Jurnal f Wrk, Envirnment and Health, 18, Hales, T.R., Sauter, S.L., Petersn, M.R., Fine, L., Putz-Andersn, V., Shleifer, L.R., hs, T.T., & Bernard, B.P. (1994). Musulskeletal disrders amng visual display terminal users in a telemmuniatins mpany. Ergnmis, 37, Hlmstrm, E. (1992). Musulskeletal disrders in nstrutin wrkers related t physial, psyhlgial and individual fatrs. Lund, Sweden: Lund University. ffie f Management and Budget. (1972). Standard industrial lassifiatin manual (U.S. GP # ). W ashingtn, D: U.S. Gvernment Printing ffie. leinik, A., Gluk, J.V., & Guire, K.E. (1995). Establishment size and risk f upatinal injury. Amerian Jurnal f Industrial Mediine, 28, Pedersen, D.H., & Sieber, W.K. (1988). Natinal upatinal Expsure Survey. Vlume III: Analysis f management interview respnses. (DHHS [NISH] Publiatin N ). W ashingtn, D: U.S. Gvernment Printing ffie. Seta, J.A., Sundin, D.S., & Pedersen, D.H. (1988). Natinal upatinal Expsure Survey. Vlume I: Survey manual. (DHHS [NISH] Publiatin N ). W ashingtn, D: U.S. Gvernment Printing ffie. Sieber, W.K., Jr. (199). Natinal upatinal Expsure Survey. Vlume II: Sampling methdlgy. (DH H S [NISH] Publiatin N ). Washingtn, D: U.S. Gvernment Printing ffie.