Skip to navigation

Skip to main content

Changing Face

contact us

NIOSH Case study #2: Wine Grape Vineyards -- John Miles

NIOSH Case study #2: Wine Grape Vineyards
Ergonomic Principles Applied to Reducing the Risk of Work-related
Musculoskeletal Disorders in a California Agricultural Setting

John Miles

Background of the Health Problem and Reason for the Study Nature of Health Problem

For many years agriculture has been regarded as one of the nation’s most hazardous industries. A review of the California’s agricultural work-connected injuries from 1981-1990 reveals that 40% of these injuries are sprains and strains; 43% of these injuries involve back strains or sprains. Back injuries are considered by employers--including agricultural employers--and workers’ compensation insurers to be among the most serious and most expensive of the current occupational health problems. The high percentage of work-related musculoskeletal disorders (or WRMDs) in agriculture, many of which represent chronic, recurring problems, has been increasing steadily during the last decade. In California, claims filed in the "cumulative injuries" category account for twice as many as are filed for any other specific injury category. This category of injury includes some of the most expensive injuries reported. A conservative estimate of the costs of the more than 3,000 back injuries reported each year in California agriculture, based on an analysis of more than 98,000 workers’ compensation claims from 45 states that includes California, would amount to over $22 million annually. When the high incidence--and expense--of musculoskeletal disorders are combined with an additional 25% of injuries attributed to overexertion, the need for immediate and practical workplace solutions becomes very clear.

In other industrial settings, a variety of approaches--ergonomic, administrative, and behavioral--have been tried to eliminate the sources of these costly and damaging occupational injuries. Behavioral approaches, typified by such activities as worker training aimed at promoting the use of proper body mechanics, have been favored over the years. But recently, ergonomically re-engineering work procedures to eliminate hazards has produced permanent and meaningful reductions in musculoskeletal symptoms and injuries. Combining ergonomic approaches with worker involvement, appropriate training, management commitment and timely administrative controls, can significant reduce injuries and increase employer savings.

Agricultural work clearly contains the traditional risk factors for serious, chronic WRMDs. Further, the occupational injury data support the need for innovative approaches to a growing personnel and economic problem. Conditions in agriculture are similar to those in work settings that have already successfully applied ergonomic principles to hazard reduction.

Despite all of these factors, and the ongoing changes in the scale of farming operations and the types of machinery in use, very little has changed about the way work is performed by most agricultural workers or in tasks--harvesting, weeding, irrigating, etc.--that can generate back injuries and/or musculoskeletal disorders. These tasks are still common in all agricultural fieldwork. Agricultural field work continues to be demanding, to be performed in stooped postures, to require lifting, carrying and handling of significant weights in awkward positions, and often to involve repetitive, damaging hand work. This work summarizes the kinds of risk factors consistently linked to musculoskeletal disorders. Further, these demands have been documented to have the highest priority for redress in California’s agricultural industry and research has shown that agricultural risk factors of this kind can be successfully addressed through ergonomic interventions.

The potential success of ergonomic interventions in agricultural work has received very little study to date. However, with California’s recent passage of the nation’s first occupational safety and health regulation targeting ergonomic risk factors and repetitive motion injuries, the state’s agricultural employers now have new legal pressure to apply ergonomic standards to work done at their various sites. This new regulation requires all California’s agricultural employers--with 10 or more employees and two, or more, repetitive motion injuries in the past 12 months--to implement a 3-step ergonomic program that includes worksite evaluation, taking direct steps to control damaging work exposures, and the implementation of a training program that explains the nature of these damaging work injuries and the steps the employer is taking to control them.

Need for Study and Need within Specific Settings

The impetus to study and redress the risk factors contributing to the WRMDs in agriculture is being fueled, then, by two forces: the practical need to reduce the occupational hazards in an admittedly dangerous industry; and a new occupational safety regulation that includes agricultural settings for the first time. Wine grape vineyards were chosen for study of the feasibility of ergonomic applications because the state’s vineyards represent a significant crop, employ agricultural workers who are typical of California’s field workers--a portion of whom are stable enough to participate in long-term research--and the sites are accessible to the University of California, Davis research team.

California’s wine grape crop is the fastest growing of the state’s agricultural commodities and a high value crop. Wine grapes account for over 400,000 planted acres. The state is home to over half of the wineries in the nation, and grapes rank second in the state’s cash crops, with a 1994 total value of over $2.3 billion. The California vineyard industry employs more than 31,000 workers per year, the majority of whom are Hispanic. In this industry, women are primarily employed inside the wineries; since the study looked exclusively at field work, most of the study participants were men. Like the nursery industry, these settings employ a percentage of workers who return each season: this stable group of employees are not migrant workers, and regard their California communities as their permanent homes, making fewer trips to Mexico They are older and more mature than those workers who work only during harvest with a primary view of returning to live in Mexico. Since the study requires an ability to look at cumulative data, it was imperative that this kind of older, more stable group of workers be available. This group of workers provided consistent sources of data, serving as their own control group for their pre- and post-intervention injury and symptom reports and study data.

California’s vineyards provide many of the challenges found in all agricultural work settings as well as some solutions to barriers to successful research. The occupational health data for vineyards are similar in terms of risk factors and types of injuries to agriculture as a whole: 42% of all reported non-fatal disabling injuries are sprains and strains; of these reported injuries, 41% were injuries to the back, with overexertion cited as the cause of injury in over 30% of all reported injuries. Clearly, these statistics suggest vineyards have a critical need for immediate attention and intervention.

Research Organization

The research team studying the application of ergonomic principles to California’s wine grape vineyards was organized under the University of California Agricultural Ergonomics Research Center (AERC) and included John Miles, Ph.D., Biological and Agricultural Engineering Department, UC Davis; Julia Faucett, RN, Ph.D., Occupational Health Nursing, UC San Francisco; Jim Meyers, Ed.D., School of Public Health, UC Berkeley; Ira Janowitz, R.P.T., CPE, Ergonomics Program, UC San Francisco. This interdisciplinary group had worked together previously, refining agricultural ergonomic issues as well as designing and implementing a similar study at southern California nursery worksites.

Local professionals rounded out the interdisciplinary team: Viticulture Farm Advisor Rhonda Smith, UCCE, Sonoma County; Viticulture Farm Advisor Ed Weber, UCCE, Napa County; and Advisor Linda Garcia, UCCE, Sonoma County. Their knowledge of the local industry made it possible to find vineyard owners willing to cooperate with the researchers and provide study sites.

The study took place in northern California with cooperating wine grape vineyard operations in Napa and Sonoma Counties. While the wine grape industry is expanding rapidly along the central coast and in the San Joaquin Valley, the northern California area remains the state’s premier wine production center. This area also contains the state’s and the world’s largest and best known wine producers--accounting for almost half of all wine grape acreage in the state.

Study Protocols

The overall goal of the study was to assess the efficacy of developing and initiating engineering interventions capable of significantly reducing target ergonomic risk factors and, consequently, work-related musculoskeletal disorders (WRMDs). A three-part procedure was used to identify ergonomic risk factors and any evidence of WRMDs:

1) all jobs in the vineyards were defined, described, and then screened for ergonomic risk factors;
2) the OSHA 200 logs and first aid records of cooperating vineyards were reviewed;

3) workers and supervisors were asked to identify job tasks that they consider especially difficult or hazardous.

The first portion of this multi-method evaluation, the ergonomic analysis, was accomplished through the use of a worksite screening checklist. Three trained ergonomic evaluators used the checklist to assess identified job tasks at each of the cooperating vineyards. Evaluators practiced with the checklists using videotapes of agricultural jobs to insure higher inter-rater reliability. The tasks given the highest scores from the first checklist survey received closer examination using a more detailed checklist.
The second assessment method involved a review of worksite records:
the OSHA 200 logs and "first aid" reports for each of the three cooperating
vineyards, covering both time lost injuries and more minor work-connected injuries not requiring time lost from work.

The third method involved both workers and field supervisors in a interview process designed to identify the specific tasks as particularly hazardous and with potential for injury (see discussion section for further discussion of the involvement process).

When the three separate data sets had been collected, individual results were compared to identify those job tasks consistently considered at highest risk for generating work-related musculoskeletal disorders.

After this triangulation process had identified problem tasks, videotape was used to develop more details about the highest risk jobs. This use of videotape allowed the engineers on the research team to closely examine all essential tasks and brainstorm alternative, easier ways in which the work could be performed.


Using the triangulation process, the team members, in collaboration with management staff and workers, identified pruning and harvesting as having highest priority for intervention planning. In addition, a Spanish language questionnaire, developed by Julia Faucett, Ph.D., was used to collect pain symptom data on these high risk tasks.

These general work categories were selected for attention because of their risk factors--harvesting because of the tasks involving lifting / carrying loads and repetitive cutting; pruning, because of its repetitive cutting hand work.

In trying to find solutions to the ergonomic risks identified in harvesting work, the engineering group has investigated alternative methods for moving harvested grapes down rows to bins and has reduced the size of the picking bins. They are presently investigating the possibility of using a standing frame into which the picking bin would fit, allowing harvested grapes to be deposited in the basket but keeping them from falling all the way to the ground. Using this system would mean that the worker would retrieve full picking bins from knee-level rather than from the ground. Although the engineers are still working on reducing the weight of the frames while retaining their stability, this system is another good example of the ways in which video tape has been used to diagnose problems and develop possible solutions.

A principle risk factor in pruning is the repetitive gripping of shears that can damage the hand. To reduce the risk of repetitive motion injuries, a number of currently marketed cutting devices have been considered. At this point, the researchers are planning to compare the present pruning device with two off-the shelf methods--electric cutters and air powered cutters. Both of these methods present their own hazards--air powered cutters, which use compressed air to reduce the stress and energy demands of repetitive grips, present problems with increased vibration; the electric cutters create problems with their added weight.

In addition, two transport systems have been tested. The first system is in almost daily use: it uses a trailers pulled behind a tractor; the trailer allows harvesting workers to dump their bins at waist level onto conveyor belts, eliminating the need for over-the-head lifts. This operation also includes a sorting belt, eliminating the need to do this work at a separate site as a separate step. The second system involves a "gullwing" device: the system operates by placing two "wings" over the top of the picking rows; each of the "wings" contain buckets into which the workers deposit their grapes as they pick them, eliminating both the need for over the head lifts and the need to climb through the vineyard trellises.


Combining direct observation, discussion with workers and managers, and record review has provided a means of strengthening each of these single approaches to identifying risk factors for WRMDs in agricultural fieldwork. The fact that the three different methods were shared without discussing the results, and that they yielded such similar outcomes, increased the confidence that the highest risk jobs and tasks were identified with this combination of approaches.

Videotape was a frequently used, highly effective diagnostic and creative tool. Initially, a lot of the taping was done to help the workers become comfortable with being filmed. With time, the film that was taken captured natural actions and accurately portrayed the way the work was actually being performed. Occasionally, specific tasks were simulated in the field in order to re-create the work-connected hazards. More often, the tape was integral to studying the job to fully understand the health hazards, to develop a clear statement of the problems involved, and to create alternative means of doing the same job.

In general, the approach to problem solving in this setting involved observing the work as performed, interviewing workers about the various demands, and video taping the work to allow for closer examination. The cooperating owners were involved in problem-solving; the innovations created included their ideas. This kind of collaboration not only increased the likelihood that management and workers would try the innovations presented to them but it also provided the means for giving the engineers feedback that further improved the innovations.

The process of involving the vineyard’s workers in these ergonomic changes deserves further discussion. Although this process was informal (i.e most of the worker input and feedback was collected through conversations rather than any formally organized worker groups) the principles were applied consistently throughout the research: there was to be respect for the workers’ knowledge of the job, as well as demonstrated understanding of the workers’ job demands; staff would show their respect for the workers’ culture and conversations were to be held in their first language; and long-term relationships would be established prior to seeking worker feedback.

But the key to the whole process can be summarized by explaining the ways long-term relationships were established. It was critical that the workers felt the researchers really understood their concerns and the work they performed--before any change in the job could be introduced. To help build these relationships, the project coordinators began working at the study sites before the actual intervention aspect of the study was instituted. The coordinators worked closely with the laborers--often along side them, doing exactly what the laborers did--and talked with workers in Spanish. The researchers intentionally introduced designs that were only partially complete to encourage workers to help in the development of the designs. In the context of these informal interactions, ideas could be discussed and modified, as necessary. Anytime workers were asked to try out a new work technique or tool project staff worked along with the laborers to guarantee that the workers would not lose any of their income by trying the innovation or by cooperating with some aspect of the study. In an industry that bases pay on production and speed such sensitivity is critical; knowledge of this kind cannot be underrated. And these working relationships proved critical. Because the relationships were carefully cultivated, the workers’ natural reticence and shyness was overcome and real participation could be secured.

The vineyard owners who cooperated in this study have been very open to the changes and innovations presented by the research team. Because of the level of profits in this industry, even fairly elaborate or relatively expensive innovations can be used without negatively effecting production costs. Unlike the nursery owners, who had to be cautious about the effects changes might have on their comparatively smaller profit margin, the vineyard owners were able to consider a variety of experimental devices--one example being smaller bins, which the owners purchased for their harvesters--without rejecting the idea due to concern about the costs. This fact may make this sector of California’s agriculture unique but it has allowed the engineers to develop some ideas that might not be considered in other settings. For example, cooperating owners recently experimented with an innovation and, to encourage the workers to try this new method, they suspended the production incentive by guaranteeing that all workers would earn at least the same amount they had earned on the previous day. This practice could have proved expensive for the vineyard owner but it did permit the workers to try out a new method without sacrificing their income.

At this point in the study, there is considerable accumulated data about pain symptoms. For some workers, this data has been collected every three months using the Spanish language questionnaire. Although this data has not yet been analyzed, eventually, it should allow researchers to examine the effect of the innovations on the kind of complaints that can be precursors of cumulative work-related musculoskeletal disorders.

Summary and Conclusions

The results of this study should generate concern about the group of manual labor agricultural field jobs and the contribution that identifiable ergonomic risk factors make to the overall reported injury rates. There is substantial evidence from the study that WRMDs and their symptoms occur among wine grape vineyard workers. There is also evidence of significant ergonomic risk factors, commonly associated with the development of these disorders, in the jobs identified and analyzed in this study.

This sample of vineyards was not randomized and is not fully generalized to the overall wine grape industry. But the WRMDs incidence rate is considerably above the Healthy People 2000 target rate and more than double the rate observed in the nurseries where the previous study was done. The study results confirm years of anecdotal evidence that field agricultural jobs are physically demanding and take a physical toll. The results also confirm a belief that the large number of sprain/strain injuries and overexertion injuries, predictive of long-term WRMDs, may be redressed by reducing risk factors with low cost, non-labor displacing measures.

It is time to take another look at many of the routine jobs and tasks in agriculture which are, at present, largely assumed to be immutable. It is time to give ergonomic risk factor reduction a new priority.