HHE Report No. HETA-2003-0146-2976, Genesis Steel Services .
This Health Hazard Evaluation (HHE) report and any recommendations made herein are for the specific facility evaluated and may not beuniversally applicable. Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individualinvolved. Additional HHE reports are available at http://www.cdc.gov/niosh/hhe/reportsNIOSH HEALTH HAZARD EVALUATION REPORTHETA #2003-0146-2976Genesis Steel Services, Inc.Baltimore, MarylandJuly 2005DEPARTMENT OF HEALTH AND HUMAN SERVICESCenters for Disease Control and PreventionNational Institute for Occupational Safety and Health
PREFACEThe Hazard Evaluation and Technical Assistance Branch (HETAB) of the National Institute forOccupational Safety and Health (NIOSH) conducts field investigations of possible health hazards in theworkplace. These investigations are conducted under the authority of Section 20(a)(6) of the OccupationalSafety and Health (OSHA) Act of 1970, 29 U.S.C. 669(a)(6) which authorizes the Secretary of Health andHuman Services, following a written request from any employers or authorized representative ofemployees, to determine whether any substance normally found in the place of employment haspotentially toxic effects in such concentrations as used or found.HETAB also provides, upon request, technical and consultative assistance to federal, state, and localagencies; labor; industry; and other groups or individuals to control occupational health hazards and toprevent related trauma and disease. Mention of company names or products does not constituteendorsement by NIOSH.ACKNOWLEDGMENTS AND AVAILABILITY OF REPORTThis report was prepared by Jim Albers, Steve Hudock and Yong-Ku Kong, OSHFB, Division of Appliedresearch and Technology (DART). Field assistance was provided by Dwight Werren (OSHFB).Analytical support was provided by Brian Lowe (OSHFB/DART), Sunil Sudhakaran (OSHFB/DART),and Ed Krieg (CST/DART). Desktop publishing was performed by Juanita Nelson. Review andpreparation for printing was provided by Rick Hartle and Ellen Galloway.Copies of this report have been sent to employee and management representatives at Genesis SteelServices, Inc. and the OSHA Regional Office. This report is not copyrighted and may be freelyreproduced. The report may be viewed and printed from the following internet address:http://www.cdc.gov/niosh/hhe. Single copies of this report will be available for a period of three yearsfrom the date of this report. To expedite your request, include a self-addressed mailing label along withyour written request to:NIOSH Publications Office4676 Columbia ParkwayCincinnati, Ohio 45226800-356-4674or visit the NIOSH web site at:http://www.cdc.gov/niosh/hheAfter this time, copies may be purchased from the National Technical Information Service (NTIS) at 5825Port Royal Road, Springfield, Virginia 22161. Information regarding the NTIS stock number may beobtained from the NIOSH Publications Office at the Cincinnati address.For the purpose of informing affected employees, copies of this reportshall be posted by the employer in a prominent place accessible to theemployees for a period of 30 calendar days.ii
Highlights of the Health Hazard EvaluationHighlights of the NIOSH Health Hazard EvaluationEvaluation of NIOSH Health Hazard EvaluationNIOSH Investigator evaluated workers’ risk of developing back and wrist disorders associated with tyingrebar and the possible benefits of using a battery powered tier (BPT) as a substitute for manual tying toprevent upper extremity and low back musculoskeletal disorders.What NIOSH Did What Managers Can Do Measured the posture of the dominant wristand the low back when workers tied rebarwith wire using one of three techniques: 1) apliers, 2) a battery powered tier (BPT), and3) the battery powered tier with an extensionhandle (BPT E).Made measurements of workers tying rebaron a freeway bridge deck.Videotaped workers tying rebar andevaluated the videotape later for trunkposture.Talked to reinforcing iron workers to seehow they liked the BPT and BPT E. What the Employees Can Do What NIOSH Found Minimize the frequency and time employeesmanually tie rebar using the pliers.Provide BPTs to employees when they tierebar more than 1 hour per day.Provide an extension handle for the BPTsfor ground level tying.Provide employees information describingthe signs and symptoms of low back andhand, wrist and elbow disorders. Manually tying rebar with a pliers involvesrapid and repetitive hand and forearmmovements associated with increased risk ofdeveloping a hand, wrist, or elbow disorder.Using the extension handle with the BPTrequires the least deep forward bending.The risk for developing a hand and wristmusculoskeletal disorder was reduced whenthe BPT or BPT E are used.Workers supported their upper body weightwith their free arm when tying at groundlevel using the BPT.Minimize the time spent in deep forwardbending when tying rebar using the pliers.Use the BPT and the extension handle whenthey are available.Report to management any low back orupper limb aches, stiffness, or pain that maybe due to work.What To Do For More Information:We encourage you to read the full report. If youwould like a copy, either ask your health andsafety representative to make you a copy or call1-513-841-4252 and ask forHETA Report 2003-0146-2976#iii
Health Hazard Evaluation Report 2003-0146-2976Genesis Steel Services, Inc.Baltimore, MarylandJune 2005Jim Albers, MPH, CIHSteve Hudock, PHD, CSPYong-Ku Kong, PHDSUMMARYDuring February 2003, the National Institute for Occupational Safety and Health (NIOSH) received amanagement request for a Health Hazard Evaluation (HHE) from the Genesis Steel Services, Inc. (GSSI).GSSI requested that NIOSH: Evaluate the risk that reinforcing ironworkers have for developing back and hand disorders as a resultof hand-tying reinforcement steel on concrete bridge decks and other large concrete slab jobs; andInvestigate whether the use of reinforcing steel battery powered tying tools can be an effectiveintervention for the prevention of work-related musculoskeletal disorders (WMSDs) of the upperlimbs and back.In response to the request, NIOSH investigators evaluated GSSI employees’ biomechanical loadingduring rebar tying on a freeway-bridge construction site.NIOSH investigators measured employees’ wrist and forearm movement with goniometers while crewmembers tied reinforcing steel using three different tying methods. The employees were videotaped andthe tape was analyzed to record trunk postures. NIOSH investigators analyzed the data collected andcompared the results with criteria used to describe and contrast the levels of hand-wrist and low-backbiomechanical loading for GSSI employees for each rebar tying technique used.Manually tying rebar at ground level using a pliers and wire involved sustained deeptrunk bending and rapid, repetitive, and forceful hand-wrist and forearm movements thatwould require limits on the amount of time workers can safely do the work. Using abattery powered rebar tying tool significantly reduced the use of rapid and repetitivehand-wrist and forearm movements and freed one hand to support the trunk during tying.Adding an extension handle to the battery powered rebar tying tool allowed workers to tierebar standing erectKeywords: NAICS 23412 (SIC 1622), ergonomics, reinforcement steel, bridge deck construction, workrelated musculoskeletal disorders, low back, hand-wristiv
Table of ContentsPreface.iiAcknowledgments and Availability of Report.iiHighlights of the Health Hazard Evaluation .iiiSummary.ivIntroduction. 1Background . 1Springfield Interchange Freeway Bridge. 1Installing and Fastening Rebar for the Bridge. 1Methods. 2Data collection . 2Data Analyses . 3Goniometric data . 3Positional data . 3Evaluation Criteria . 3Results . 5Discussion . 6Conclusions. 8Recommendations . 8References. 9
INTRODUCTIONIn February 2003, the National Institute forOccupational Safety and Health (NIOSH)received a request for a Health HazardEvaluation (HHE) from the vice-president of theGenesis Steel Service, Inc (GSSI). GSSI, aconstruction reinforcing and structural steelcontractor in Baltimore, MD, GSSI askedNIOSH to do the following: Evaluate the risk that GSSI reinforcingironworkers have for developing back andhand musculoskeletal disorders as a result ofhand-tying reinforcement steel on concretebridge decks, andInvestigate whether the use of a batterypowered tier (BPT) for rebar tying can be aneffective intervention for the prevention ofwork-related musculoskeletal disorders(WMSDs) of the upper extremities andback.In response to the request, NIOSH investigatorsconducted a field investigation of GSSIemployees’ exposures to biomechanical loadingwhen tying rebar for the concrete deck of anelevated freeway bridge in Springfield, VA. Theinvestigation was conducted on October 27-30,2003.BACKGROUNDGenesis Steel Service, Inc. is a minority ownedconstruction specialty subcontractor providingstructural and reinforcing steel services for newconstruction projects in the greater BaltimoreDistrict of Columbia metropolitan area. Thedistribution of GSSI’s work is approximately60% concrete reinforcement, 25% structural(bridge and buildings 4 stories), and 15%miscellaneous metals, including ornamental.GSSI does not operate a fabrication shop andreinforcing steel used on projects ispredominantly pre-cut and pre-formed.Health Hazard Evaluation Report No. 2003-0146-2976At the time of the HHE request, GSSI employed100 ironworkers (IWs). Around 40% of the IWsemployed by GSSI were minority workers - 20%African-American and 20% Hispanic. GSSIestimated that for 2/3 of the Hispanic workersEnglish is their second language. The IWs aremembers of the International Association ofBridge, Ornamental, and Reinforcing IronWorkers. GSSI estimated that 25-30% of theIWs employed at the time of the study had beenemployed by the contractor since 1988. Genesis’IWs tend to specialize in structural orreinforcing work, and most reinforcingironworkers (RIW), also known as ‘rodmen’,work exclusively on concrete reinforcing jobs.Springfield InterchangeFreeway BridgeAs a subcontractor on the SpringfieldInterchange Improvement Project, GSSIinstalled reinforcing steel bars for the concretedeck of the bridge connecting westbound I-495traffic to the southbound I-95 interstate highway.The bridge is approximately one mile long by60 feet wide. GSSI employees were responsiblefor placing and tying the steel bars used toreinforce the concrete deck and walls of thebridge. An estimated 2.2 million wire ties weremade on the bridge to secure the rebar at a rateof 7 wire ties per square foot (ft2) for the bridge.For most of the project, weather permitting,GSSI IWs worked a 5 day and 40 hour workweek. The amount of rebar placed and tied on agiven day depended on several factors, includingthe number of workers on the job, theenvironmental conditions, and the pace of thework preceding rebar installation.Installing and Fastening Rebarfor the BridgeBefore pouring the concrete deck that will be thesurface of the bridge, steel reinforcing bars (akarebar) must be placed inside the concrete forms.The rebar is used to reinforce and increase thetensile strength (i.e., bending and stretching) ofthe concrete in the deck and sidewalls. Tworebar ‘mats’ were placed one above the otherinside the concrete form over the full length ofPage 1
the bridge. Each mat consisted of a series of barsplaced perpendicular to each other and spacedabout seven (7) inches on-center. The bottommat was kept above the metal decking usingwire supports (aka chairs). Chairs were used toseparate the top mat from the bottom mat. Therebar are tied together to prevent the bars fromshifting when the concrete mixture is pouredinto the form, although the ties do not addstrength to the bridge.The specifications for the job, common forfreeway bridge decks in the Unites States,required tying 50% of the intersecting rebar onthe bottom mat and 100% of the intersections onthe top mat. GSSI employees used twotechniques to tie the intersecting rebar together,including: 1) pliers and spool of wire and 2) thebattery operated RB392 rebar tier (MAX USACorp., Garden City, New York) (Figure 1). TheBPT tier was used most frequently to make the‘snap’ or simple ties used to keep the rebar fromshifting. Pliers were used when more secure ties(i.e., ‘saddle’ or ‘figure 8’) were necessary toframe the sidewalls of the bridge deck or makethe first ties for each mat (Figure 2).Traditional tying (Figure 3) required the use oftwo hands – one to use the pliers to pull, wrap,twist, and cut the wire and the other to pull andpush the wire. Only one hand was necessary tooperate the BPT (Figure 4). Both techniquesrequired frequent and sustained deep trunkbending (aka stooping) ( 90º trunk inclination)to tie the rebar.NIOSH introduced a commercially availableextension handle developed for use with theBPT (Figure 5 and 6). This was the third rebartying technique used during the investigation.METHODSGSSI employees were directed to tie the rebarplaced for the bottom mat using three differenttying techniques: 1) pliers; 2) the RB392 BPTand 3) the BPT with an extension handle(BPT E). All employees were familiar with thefirst two techniques and used each on the site.NIOSH brought the extension handle to the siteand none of the employees had previously usedPage 2the device. Participants were encouraged, butnot required, to use the extension beforemeasurements were made.GSSI had purchased the BPTs approximately 2years prior to the study in part to reduceemployees’ exposures to biomechanical loadingrelated to tying using pliers. The power tier stillrequired deep forward bending when tying atdeck level, but workers now used one hand tohold the tier and the other to support their upperbody while tying.The investigation was conducted to answer thefollowing questions:1. How does the use of a battery powered rebartier (MAX USA RB392) affect thebiomechanical loading of the hand-wristand/or of the low back?2. How does the use of an adjustable extensionhandle with the battery powered rebar tier(MAXUSARB392)affectthebiomechanical loading of the hand-wristand/or low back?3. How does the use of the battery poweredrebar tier (MAX USA RB392) with andwithout the adjustable handle affect theproductivity of rebar tying?Data collectionEach worker tied rebar for about 30 minutesusing the: 1) pliers; 2) BPT; and 3) BPT E. Atwin-axis goniometer (Biometrics SG Series)and torsiometer (Biometrics Q110) were used tomeasure the dominant wrist motion and position(aka posture) in the flexion/extension,ulnar/radial, and pronation/supination planes(Figure 7) during tying.1Observational methods were used to record theposition of the trunk during tying and thenumber of ties each worker made. This consistedof videotaping each worker from three differentangles so that the trunk could be later viewedfrom both the side and front.Each worker was asked to describe the physicaleffort they used with their hand-wrist and lowback on a scale from 0 (‘nothing at all’) to 10Health Hazard Evaluation Report No. 2003-0146-2976
(‘extremely strong’) when using the three tyingmethods.2 Prior to conducting the study, the 10point scale was translated into Spanish by aNIOSH contractor.Personal information and work history wasobtained using self administered questionnairesavailable in English and Spanish.Data AnalysesGoniometric dataThe goniometric data were converted to readablefiles using proprietary Biometrics Ltd.management and analysis software. Statisticalanalysis, including summary and inferentialstatistics, was conducted using SAS Institutesoftware.Positional dataVideo tape was analyzed using the MultimediaVideo Task Analysis (MVTATM) softwareprogram, which allowed the analyst to run videotape through the computer.3 The analystrecorded the frequency and duration of the trunkposture angles and the time required to tie rebarfor each of the three tying techniques.Analysts used the computer-based 3-D StaticStrength Prediction ProgramTM to estimate thepressure (compressive forces) on the spinal discbetween the fifth lumbar vertebrae and the firstsacral vertebrae (aka L5/S1 spinal disc) duringrebar tying in stooped postures.4 Disc pressure isknown to vary depending on the amount andtype (e.g., forward, sideward, twisting) ofbending.EVALUATION CRITERIAOverexertion injuries and musculoskeletaldisorders, such as low back pain, tendinitis, andcarpal tunnel syndrome, are often associatedwith job tasks that include:1. Repetitive, stereotyped movement about thejoints;2. Forceful manual exertions;3. Lifting, pushing, and pulling;Health Hazard Evaluation Report No. 2003-0146-29764.5.6.7.Awkward and/or static body positions;Direct pressure on nerves and soft tissues;Work in cold environments;Exposure to whole-body or segmentalvibration; or8. Work-related psychosocial factors, such ashigh job demand, low decision latitude, andmonotonous activity, etc.The risk of injury appears to increase as theintensity and duration of exposures to the riskfactors increases and the recovery time (i.e., resttime) decreases. Individual characteristics (e.g.,age, gender, weight, fitness) are seen as“contributing and modifying influences in thedevelopment of pain and disability and in thetransition from acute to chronic pain.”5The preferred method for preventing andcontrollingwork-relatedmusculoskeletaldisorders (WMSDs) is to reduce or elim
NIOSH HEALTH HAZARD EVALUATION REPORT HETA #2003-0146-2976 Genesis Steel Services, Inc. Baltimore, Maryland July 2005 DEPARTMENT OF HEALTH AND HUMAN SERVICES Centers for Disease Control and Prevention National Institute for Occupational Safety and Health
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