Ira Janowitz

Ergonomics in Agriculture: Workplace Priority Setting in the Nursery Industry

Although agriculture is generally recognized as the nations most hazardous industry and displays high rates of musculoskeletal disorders with evidence to suggest that ergonomic risk factors are involved, there is very little history of application of ergonomic approaches in agricultural workplaces. A three-year National Institute for Occupational Safety and Health-supported study has been initiated in California nurseries to describe and design engineering interventions for priority musculoskeletal disorders. In this article are reported the results of the projects initial workplace job task screening for ergonomic risk factors and associated musculoskeletal disorder reports to define landmark ergonomic risk factors for the nursery industry and select priority job tasks for intervention.

Priority risk factors for back injury in agricultural field work: vineyard ergonomics

ABSTRACT With support of a NIOSH Community Partners grant, the authors reviewed data from three cooperating vineyard companies in Napa and Sonoma Counties, finding both high rates of evidence of musculoskeletal disorders (MSDs) and identifying priority MSD hazards for intervention. Data from OSHA 200 injury report logs identified 29 reported MSDs and 435 lost workdays in a working population of 194 in a 30-month period. The majority of these (20) involved backstrain. High risk job tasks were identified, including: employer-identified tasks, analysis of injury reports, and ergonomics risk factor checklist survey of task work. Triangulating across these three data groups resulted in identification of high priority tasks, including: hand harvest work, hand pruning, and weeding using shovels. Priority risk factors for back injury in these jobs were: repetitive lifting of heavy loads, repetitive exertion of force by the trunk and upper extremities, and repetitive or sustained awkward postures of the trunk (including full stoop and twisting with loads).

A randomized controlled trial evaluating the effects of new task chairs on shoulder and neck pain among sewing machine operators: the Los Angeles garment study.

Study Design. This is a 4-month randomized controlled trial to evaluate the effect of chair design on neck/shoulder pain among sewing machine operators. Objective. Determine whether a chair with a curved seat pan leads to improved changes in monthly neck/shoulder pain scores compared with a control intervention. Summary of Background Data. Sewing machine operators experience a high prevalence and severity of neck and shoulder pain in comparison to other working populations probably due to the sustained shoulder abduction and neck and upper back flexion required of the task. An adjustable height task chair that supports a forward sitting posture may reduce these posture-related risk factors and reduce neck/shoulder pain. Materials and Methods. A total of 277 sewing machine operators with neck/shoulder pain were assigned to receive 1) miscellaneous items (control group), 2) a chair with a flat seat pan plus miscellaneous items, or 3) a chair with a curved seat pan plus miscellaneous items. Participants completed a monthly questionnaire assessing neck/shoulder pain severity. Results. Based on estimates of pain score changes from a repeat-measures linear regression, participants who received the flat seat chair experienced a decline in pain of 0.14 (95% confidence interval, 0.07–0.22) points per month compared with those in the control group, while those who received the curved seat experienced a decline of 0.34 (95% confidence interval, 0.28–0.41) points per month compared with those in the control group. These estimates did not change after adjustment for potential covariates. Conclusions. These findings demonstrate that an adjustable height task chair with a curved seat pan can reduce neck and shoulder pain severity among sewing machine operators.

High Risk Tasks for Musculoskeletal Disorders in Agricultural Field Work

Agricultural work involves heavy physical exertion and is characterized by evidence of high rates of musculoskeletal disorders. Currently ergonomics is a low priority for injury and illness prevention in agriculture. However, based on costs and incidence rates ergonomics risk factors should rank among the highest farm safety priorities. Analysis of field work jobs by the University of California with support from NIOSH yield an industry generalizable set of high risk tasks which should have high intervention priority. These are: repetitive and awkward forward flexion, repetitive lifting and carrying heavy loads, and highly repetitive hand work.

Field Evaluation of a Modified Intervention for Overhead Drilling

Drilling holes into concrete or metal ceilings is one of the most physically demanding tasks performed in construction. The work is done overhead with rotary impact hammer drills that weigh up to 40 N. The task is associated with pain and musculoskeletal disorders at the wrist, forearm, shoulder, and back. The mechanism of injury is thought to be the high forces and non-neutral shoulder and wrist postures applied during drilling. Previously, we described a field study of a foot lever and inverted drill press intervention devices that received poor usability ratings compared with the usual method for overhead drilling based on problems with mobility and productivity. Using a participatory intervention model, feedback from construction workers (N = 13) was used to develop a new intervention design that incorporated a wheeled tripod base and a unique method of aligning the drilling column to vertical. A different group of construction workers (N = 23) evaluated usability and fatigue of the new device during their regular overhead drilling in comparison with the usual method. Four of 12 usability ratings were significantly better with the intervention device compared with the usual method. Subjective shoulder fatigue was less with the new intervention (1.1 vs. 3.3; scale 0 to 5; p < 0.001). This difference was supported by objective outcome measures; the mean hand forces during drilling were 26 N with the intervention compared with 245 N with the usual method. The percentage of time with the shoulder flexed or abducted to more than 60 degrees was less with the intervention compared with the usual method (21 vs. 40%; p = 0.007). There was significantly less head extension with the intervention compared with the usual method. There were no significant differences in overall productivity between the two methods. This study demonstrates that a new intervention device for overhead drilling has improved usability and subjective fatigue ratings compared with the usual method. These improvements are most likely due to the reduced hand forces, reduced shoulder abduction and flexion, and reduced drilling time.

Ergonomics Interventions in the Manual Harvest of Wine Grapes

Winegrape operations, especially at harvest, produce a high incidence of work-related musculoskeletal disorders, predominantly involving back injury. The Agricultural Ergonomics Research Center of the University of California initiated a study of vineyard operations and recruited four cooperating growers representing 191 permanent workers. The goal was to develop, field-test, and evaluate interventions to reduce ergonomics risk factors for WRMSDs during winegrape harvest. We assessed pre- and post-intervention injury records and other indicators of musculoskeletal symptoms to monitor the impact of interventions on involved workers, and used biomechanical, metabolic, and postural analyses to evaluate the effectiveness of various approaches for handling cut grapes during vineyard harvest. We introduced a smaller, lighter tote bin with improved handles, reducing the average full bin load from 25.5 kg to 20.9 kg. The proportion of workers reporting pain lasting more than a week dropped from 61% to 26%. Biomechanical and metabolic assessments indicated reduced risk for WRMSDs. We are currently field-testing a conveyor system to reduce the height at which the bins are dumped.

A new method for overhead drilling.

In the construction sector, overhead drilling into concrete or metal ceilings is a strenuous task associated with shoulder, neck and back musculoskeletal disorders due to the large applied forces and awkward arm postures. Two intervention devices, an inverted drill press and a foot lever design, were developed then compared to the usual method by construction workers performing their normal overhead drilling activities (n = 14). While the intervention devices were rated as less fatiguing than the usual method, their ratings on usability measures were worse than the usual method. The study demonstrates that the intervention devices can reduce fatigue; however, additional modifications are necessary in order to improve usability and productivity. Devices designed to improve workplace safety may need to undergo several rounds of field testing and modification prior to implementation.

A randomized controlled trial of chair interventions on back and hip pain among sewing machine operators: the los angeles garment study.

Objective: Determine whether an adjustable chair with a curved or a flat seat pan improved monthly back and hip pain scores in sewing machine operators. Methods: This 4-month intervention study randomized 293 sewing machine operators with back and hip pain. The participants in the control group received a placebo intervention, and participants in the intervention groups received the placebo intervention and one of the two intervention chairs. Results: Compared with the control group, mean pain improvement for the flat chair intervention was 0.43 points (95% CI = 0.34, 0.51) per month, and mean pain improvement for the curved chair intervention was 0.25 points (95% CI = 0.16, 0.34) per month. Conclusions: A height-adjustable task chair with a swivel function can reduce back and hip pain in sewing machine operators. The findings may be relevant to workers who perform visual- and hand-intensive manufacturing jobs.

The effect of two alternative arm supports on shoulder and upper back muscle loading during pipetting.

OBJECTIVE Pipetting involves static upper arm positions with the pipette held away from the body for sustained periods of time, putting increased musculoskeletal load on the shoulder and upper back. This study explores the effect of using two alternative arm supports while pipetting on muscle loading in the shoulder/neck region. PARTICIPANTS 15 experienced pipette users participated in this study. METHODS In a repeated-measures design, participants performed simulated pipetting in a laboratory setting under three arm support conditions: (1) a gel pad on the work surface, (2) a freely-moving counter-balanced forearm support, and (3) no support (control). Surface electromyography (EMG) of the anterior deltoid and upper trapezius muscles were recorded, as well as productivity and subjective usability. RESULTS Both arm support conditions resulted in significantly lower mean muscle activity of the anterior deltoid and upper trapezius muscles (p<0.001) and significantly higher subjective comfort ratings (p<0.001) compared to the control condition. The freely moving forearm support resulted in significantly lower peak muscle activity in the anterior deltoid compared to the control condition (p<0.001). Productivity was not affected by the arm supports. These findings suggest that arm support may be beneficial in reducing muscle loading and improving comfort in the shoulder and upper back during pipetting. Future studies are needed to measure the impact of these arm supports in the workplace.

Ergonomic evaluation of ten single-channel pipettes.

UNLABELLED Repetitive pipetting is a task that is associated with work-related musculoskeletal disorders of the hand and arm. OBJECTIVE The purpose of this study was to evaluate the usability and ergonomic performance of commercially available pipettes as determined by user ratings and objective measurements. PARTICIPANTS Participants were laboratory technicians and scientists at the Lawrence Berkeley National Laboratory with experience performing pipetting tasks. METHODS Twenty-one experienced pipette users completed a standardized pipetting task with 5 manual and 5 electronic pipettes. After using each pipette, the user rated it for attributes of comfort and usability. RESULTS Although no single pipette was rated significantly better than all of the others for every attribute tested, some significant differences were found between pipettes. The Rainin Pipet-Lite received the highest overall quality score among manual pipettes, while the Thermo Scientific Finnpipette Novus was the top-ranked electronic pipette. Features correlated with greater hand and arm comfort were lower tip ejection force, lower blowout force, and pipette balance in the hand. CONCLUSIONS The findings, when considered with participant comments, provide insights into desirable pipette features and emphasize the value of user testing and the importance of the interactions between task, workplace layout, and pipette design.