Practical Winery
58-D Paul Drive, San Rafael, CA 94903-2054
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email: Office@practicalwinery.com
Winegrowing

May / June 2000


CAL OSHA ergonomics standards:
What does it mean for vineyard employers?

James Meyers, University of California, Berkeley
John A Miles, University of California, Davis
Julia Faucett and Ira Janowitz, University of California, San Francisco,
Diane G Tejeda, University of California, Davis
Ed Eber, University of California, Co-op ext. Napa,
Rhonda Smith, University of California, Co-op ext. Sonoma
Linda Garcia, University of California, Co-op ext. Sonoma
California became the first state in the nation to implement regulation targeting ergonomics risk factors and repetitive motion injuries in 1997. The Cal/OSHA standard (GISO 5110, Repetitive Motion Injuries) became effective on July 3, 1997.

This regulation says that if two or more workers performing the same tasks have had diagnosed repetitive motion injuries (RMIs) in your workplace within the past 12 months, you must implement the three-step ergonomics program prescribed in the standard.

The program consists of 1) conducting a worksite evaluation for exposures causing RMIs; 2) taking steps to control exposures that have caused RMIs; and 3) implementing a training program that explains what RMIs are and the steps you are taking to control them. (This is a summary, see GISO 5110 for a complete statement of requirements.)

Is there a problem?
You might think from the popular news coverage that most jobs at risk for RMIs are related to manufacturing or clerical work. However, many jobs in agricultural workplaces have been found to involve the known risk factors and often have a very high incidence of RMIs.
The standard itself, as well as an updated history of litigation to date, is available on the Department of Industrial Relations (DIR) website, www.dir.ca.gov.

A team from the UC Agricultural Ergonomics Research Center has been investigating jobs in winegrape vineyard work (1997-1999). The UC team has worked with four Napa and Sonoma county vineyard operations and has focused on operations employing hand harvest. The results to date suggest that certain vineyard jobs create substantial risk for RMIs. In addition, the team found a high incidence of reported symptoms of RMIs.

While employers may not see many RMIs on their injury reports at this time, that may be due to worker outmigration. UC researchers suggest that because the winegrape workforce is trending toward stabilization, there is reason to believe that vineyard employers will see increasing numbers of RMIs in the future.

Before you start looking for a special consultant, some basic information and action on your part can go a long way toward improving your situation.

What is Ergonomics?
Ergonomics is the study of the "fit" between the physiology of the human body and the tasks it is asked to perform. Because of the way the body is built, it does some things efficiently and well, and others only with difficulty and stress.

Functions our bodies do not do well or do with stress are classified as "ergonomics risk factors" by ergonomists. Some of these include awkward postures (such as extreme forward bending or stooping), lifting and carrying heavy loads, and highly repetitive motions (such as pruning or harvesting).

These risk factors have been associated with the development of chronic injuries involving skeletal and soft tissues known as musculoskeletal disorders (MSDs) or repetitive motion injuries (RMIs). These injuries may affect muscles, tendons, joints, nerves and related soft tissues anywhere in the body. The lower back and upper extremities, including the neck and shoulders, are the most common sites. They are among the most frequently occurring and most costly of all workplace injuries.

Ergonomics risk factors in California winegrape production
According to an AgSafe study, California vineyard workers reported an overall non-fatal injury rate of about 4.3 per 100 workers per year in the 1981-1990 period. (AgSafe is a non-profit professional organization for persons interested in or working on safety issues in agriculture. For information, see their website: www.agsafe.org or call: 559-278-4404.) This is well above the average reported for other California workers of 3.5 per 100 workers. Of these reported injuries, 42% were sprains and strains (of which nearly half were back injuries). Overexertion was cited as a cause for some 23% overall. Together, these two factors indicate the presence of ergonomics risks.

The UC Agricultural Ergonomics Research Center team found significant evidence of MSDs in reviewing health records of three vineyard operations. They reviewed records for three vineyard operators representing 194 permanent vineyard workers. Records were available for 21/2 years for two vineyards and for 11/2 years for one. In Table I, 29 MSDs were defined for 28 employees. These MSDs represented 435 lost workdays. This suggests an incidence rate of 80 per 1,000 workers. In Table I, back injury is the most frequent MSD, and lifting during harvest and tractor/equipment is the most frequently reported cause.

The high proportion of back injuries suggests that jobs involving repetitive heavy lifting and bending and stooping are involved. No surprise then, that hand harvest shows up most often among reported causes.

The high proportion of these chronic injuries associated with tractors and equipment is harder to explain. The research team thinks it may be due to a combination of factors. Tractor operators are often more senior crew members who worked heavier jobs earlier in their careers.
Table I
Report MSDs among vineyard cooperators
Body Part # Reported Cause #
Back 20 Lifting (harvest) 6
Neck/Shoulder 3 Tractor/Equipment 6
Hand/Arm 3 Staking 3
Lower Ext. 3 Pruning 3
    Suckering 2
    All Other 8

Full-time equipment operators may be more subject to back injury because their muscles become less work hardened, meaning that the strain of hitching equipment, jumping to the ground, or even making long, awkward reaches can result in injury. While this suggested cause is still theory, it does warrant examining self-hitching equipment and conditioning for full-time drivers.

Evaluating vineyard jobs
Vineyard jobs were also screened for the presence of ergonomics risk factors. This was done with a checklist which assigns a numerical value to observed risk factors. Results are in Table II and clearly show that harvest jobs demonstrate the most severe ergonomic risk exposures in vineyard work.
Table II
Ergonomic risk factors in vineyard jobs
Job Checklist score
Harvest 25  
Hoeing/Weeding 19
Cutting Heads 17.6
Pruning 17.3
Pre-pruning 16.6
Staking 15.2
Planting 15
In order to better understand workers' exposures to these risk factors, supervisors were asked to estimate the numbers of workers performing specific jobs and the duration of the job task in the vineyard. Results are shown in Table III.
When the team looked for jobs that scored high on all lists, the jobs identified as having the greatest potential risk for MSD incidence were: harvest work, pruning, and weeding (especially with shovels). These jobs were re-evaluated to describe the specific risk factors that should have priority concern for prevention planning.
Table III
Vineyard job risk exposure
Task % of Workforce Duration
Harvest 90+% 6-8 weeks
Pruning 50-90% 8 - 10 weeks
Hand Weeding 50% Seasonal
Tractor Drivers 18% Seasonal
Staking 10-20% Occasional
A. Hand harvest risk factors
  1. Highly repetitive handgrip to cut grapes, average 25 to 50 cuts per minute depending on grape variety and yield density.
  2. Exertion of high force (up to 80 lbs) to lift and carry full tubs. Accelerative force is required to lift and dump the tubs.
  3. There are multiple awkward postures involved in the harvest task, including: shoulders and forearms to reach and cut grapes; forward bending of the trunk during cutting, full stoop to gather fallen grapes and pick up tubs; forward bending of the neck to see grapes for cutting.
  4. There is very high energy expenditure as the task is physically demanding (up to 52.7% of total aerobic capacity).
  5. There are long carries with heavy loads to put grapes in bins for transport.
B. Pruning risk factors
  1. Very high rate of repetitive cutting (36+ per min).
  2. Moderate force exertion to make cuts with hand shear (estimated 30 lbs).
  3. Awkward postures include: shoulder reaches and twisting of forearm and wrist to make cuts; use of pinch grip to hold vine for cutting; and sustained moderate forward bending of the trunk and neck to make cuts.
C. Hand weeding risk factors
  1. Very highly repetitive reaching and cutting motions with arms and upper body (50 to 60 per minute).
  2. Awkward postures include: severe forward bending and twisting of upper body to make cuts and effective backward bending of neck relative to body posture.
  3. Moderate forceful exertions by shoulder and arm are required to make cuts.
What to do about it?
The UC research team has completed trials with vineyard operators focusing on the use of lighter picking tubs for harvest and powered shears for pruning. Data are being tabulated, and results will be reported in a future report. The engineering group has also investigated a wide variety of hand-weeding tools, although so far without finding any to recommend highly.

Winegrape vineyard employers can get ahead of the problem of RMIs and implementation of the CAL OSHA ergonomics standard by taking some of the steps reported here. First, review your vineyard's OSHA Log 200 and first aid records to see if any reported RMIs can be associated with specific jobs. RMIs may be described by some of the following terms:
  • tendinitis (inflammation of a tendon),
  • bursitis (inflammation of the sack surrounding a joint),
  • carpal tunnel syndrome (pinched median nerve at the wrist),
  • cubital tunnel syndrome (pinched ulnar nerve at the elbow) and,
  • myalgia or muscle pain, which may also be referred to as muscle strain, tension neck, or neck and shoulder syndrome.
Also consider jobs associated with high incidence of sprain/strain injuries. Developing RMIs are often diagnosed as sprains or strains. This will give you a list of jobs you should consider as potential priorities for preventive action of some kind. Both you and your workers can begin to think about changes that might help and prove practical. Remember, if you have two or more RMIs reported for workers in the same job in a 12-month period, you are subject to the Cal/OSHA RMI standard.

Repetitive Motion Injuries standard
Employers subject to the RMI standard must implement an ergonomics program. In addition to identifying the jobs associated with RMIs, you must: 1) evaluate those jobs for ergonomics risk factors, 2) undertake some corrective action to control or reduce worker risk factor exposures involved, and 3) implement a worker training program. Note: The standard exempts employers with fewer than 10 workers.

Being subject to the standard requires that you also evaluate the jobs for ergonomics risk factors. The UC team has developed a very simple one-page check sheet for doing this, which is included in the UC Agricultural Research Center's pamphlet titled, "Ergonomics Programs in Agricultural Operations," (available free from the UC Agricultural Ergonomics Research Center, University of California, Davis, CA 95616). The third required element is to provide training for employees on ergonomics risk factors, repetitive motion injuries, and your ergonomics program.

The most difficult part of the RMI standard is its second element, requiring efforts to control or reduce employee risk factor exposure. However, it is through making changes in tools or job practices that these injuries can be successfully prevented.

For example, with highly repetitious jobs like hand harvest or pruning, the priority would be to eliminate or reduce repetitive hand work. No existing tool immediately lends itself to this in hand harvest, meaning that corrective action might involve something like frequent mini-breaks. In pruning, however, powered pruners almost completely eliminate this risk factor.

For repetitive heavy lifting, as in harvest, the priority objective would be to reduce the weight handled. For jobs involving awkward postures such as stooping to lift tubs, the priority would be to keep the loads off the ground, with a stand of some sort, for example.

Why should you be concerned about such measures if you aren't yet experiencing a high level of reported MSDs? Because they are there and developing in your workforce now. While the record of reported and diagnosed MSDs remains fairly low in many vineyard operations, this may be due to a variety of factors, including general youth of the workforce involved, worker outmigration, and workers' acceptance of the physical demands and aches and pains associated with the work. As the vineyard workforce continues to stabilize, it will also age and these injuries will begin to be recorded.

More important, by thinking the problems through, we can help workers become more efficient and less likely to suffer serious injury.

What next?
The most difficult task will be finding low-cost interventions that reduce risk factor exposures and help prevent RMIs. The research project reported here has moved to do just that with both the harvest and pruning jobs. The results of field trials of possible interventions for these jobs will be the subject of future reports.

This work was supported by National Institute for Occupational Safety and Health Agreement PHS-CCU912911-01.