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I. Not applying standard to agriculture, construction or
maritime operations with the assumption that risks are not as
great or that interventions are not as feasible as with areas
of manufacturing and material handling is not consistent with
current science.
I feel fortunate to hold the rank of Associate Professor both
in the Biomedical Engineering Department in the College of Engineering
and in the Occupational and Environmental Health Department in
the College of Public Health at The University of Iowa. This
current position follows a variety of personal experiences that
includes jobs in agriculture and construction and a project in
the maritime environment.
As a teenager, I worked on a friend's farm for 4 months over
a period of 4 years primarily to help with haying in June. In
addition to handling string-bound hay bales in the field and
in the barn, I performed other tasks. Those tasks involved cleaning
and rebuilding horse stalls, handling animals, seated whole-body
jolt/vibration exposure (during tractor and vehicle operation),
equipment maintenance and repair, maintaining awkward postures,
handling feed sacks, exposure to uncertain footing, and digging
post-holes. Since my work on the farm, there has been a proliferation
of a new method to bale hay: in large rolls. From my perspective,
this decreases the need to handle manually bales of hay in the
field and in the barn. There has also been much work done to
improve tractor ride via jolt/vibration isolation and seat redesign.
During two summers of my college years, I worked in a carpentry/construction
crew. Tasks in that environment involved awkward postures, hand-arm
impact/vibration exposure, whole-body jolt/vibration exposure,
materials handling, bending-lifting-twisting, and uncertain footing.
Since my time on that crrew, nail guns have replaced many hammers
and prefabricated roof trusses have become commonplace.
In 1992, I conducted a study of part of a maritime operation:
a container-handling facility at a port in Norfolk, Virginia.
It was clear that ergonomic issues were present and involved:
whole-body jolt/vibration exposure while operating cranes and
terminal tractors, materials handing, and exertions in awkward
postures while handling lines and roping loads (securing loads
with ropes). From my own experience in handling small sail and
power boats, I believe that uncertain and slippery footing and
a moving or unstable base of support present ergonomic challenges
in the maritime environment. Using my recommendation to that
port facility, one of the three potential vendors of terminal
tractors created and sold an improved tractor design for the
port facility and the market in general. In this case, the improvement
was not only feasible, it was inexpensive and very welcome.
I would submit that the spirit of helping our fellow human-being
should hold here. If we know that there is a way to provide a
reasonable improvement in the workplace, don't we have an ethical
obligation to pursue that improvement? I also believe that the
economic forces of marketing and competition make it feasible
and profitable to address ergonomic issues in agriculture, construction
and maritime operations. If we as a nation choose to protect
people from ergonomic risk factors, we should reduce the risk
in general.
II. Exclusion of back supports from P.P.E. for standard
purposes does not allow for hierarchy of controls in combating
back injuries.
I have spent much time and effort since 1974, trying to understand
the way the lumbar spine works (curriculum vitae available upon
request). Many of the studies I have conducted or have contributed
to have had easily understood, mechanical cause and effect biomechanics
from many perspectives including how the lumbar spine interacts
with different types of internal or external mechanical interventions.
I have always believed that I could learn more about lumbar spine
biomechanics if I studied loads applied to it from different
sources (5, 6). This was my main motivation for evaluating lumbar
supports. This work has been some of the most challenging of
my career (1, 7). I have tried to understand back supports' effects
based on a mechanical hypothesis. The results of the experiments
point to another mechanism, a mechanism that strongly suggests
that lumbar supports, back belts, and sacro-iliac belts produce
a calming effect on the lumbar musculature's response to a sudden
load applied at the hands. As such, they can act as a barrier,
reducing the body's tendency to over-react to an applied sudden
load. As a barrier, they could be considered personal protective
equipment. So categorized, they would provide the flexibility
of more options for addressing an MSD problem/challenge.
III. My research strongly indicates that slips, trips and
falls should be included in a list of applicable MSDs.
In 1981, Manning and Shannon (3) and in 1984, Manning et al
(2), showed that slip events lead to back injuries and expressed
concern that this was a neglected research area in back injury
etiololgy. In 1987, Marras et al (4) showed that sudden, unexpected
loads applied at the hands lead to large over-compensations in
the back muscles. The pelvis acts as a foundation for the spine.
The orientation of the pelvis is affected not only by trunk muscles
located above the pelvis but also by muscles located below the
pelvis. Sudden events such as slips, trips and falls affect actions
of the leg and trunk muscles. In my opinion, these three papers
show that sudden loads and sudden movements of the body can place
the back at risk of injury, as they each describe conditions
that require the back muscles to respond rapidly to an imposed
load or movement.
IV. Sudden loading of the back frequently occurs as a first
event in injury to the back. As this occurs often during "accidents"
and back support studies have shown that a P.P.E. approach reduces
incidence and/or severity of lower back injury, "sudden
unexpected loading of the back" should be added to ergonomic
risk factors.
In 1981, Manning and Shannon (3) and in 1984, Manning et al
(2), showed that slip events are considered first events that
lead to back injuries and expressed concern that this was a neglected
research area in back injury etiology. When in 1987, Marras et
al (4) showed that sudden, unexpected loads applied at the hands
lead to large over-compensations in the back muscles, he showed
that the hazard is not necsssarily the load applied. The hazard
is the body's excessive reaction or over-compensation to the
applied load. The barrier needed is one that will reduce or eliminate
the body's excessive response. Udo et al (8, 9) present reasonable
evidence for use of back supports as P.P.E.
Udo et al (8) prospectively studied 60 male workers involved
in rice-carrying work (who had also experienced back pain) half
using a "lumbago" belt worn on the pelvis (thereby
minimizing motion restriction and risk of muscle atrophy) and
half without for 5.5 months. There was no significant difference
between the belt and non-belt groups in terms of age, findings
at the first lumbago examination, and total sum of work load.
To remove bias in the analysis, 16 pairs were matched by age,
classification of vehicle used and Total Lumbar Kinetic Pain
Scores. The belt group fared better than the non-belt group in
several ways:
- a.) The belt group had significant improvement in right and
left lateral bend pain and Total Lumbar Kinetic Pain score. They
also had a tendency toward improvement in forward flexion pain
and Lasegue test.
-
- b.) The belt group had a significantly higher rate of improved
subjects (50% versus 6.3% of the non-belt group).
-
- c.) On the rating of Total Lumbar Kinetic Pain Score or Total
Lumbar Tenderness Threshold Values, 56.3% of the belt-wearers
were improved versus 18.8% of the non-belt subjects.
-
- d.) Among the 28 in the belt group, degree of symptoms as
rated by the Total Lumbar Kinetic Pain Score or Total Lumbar
Tenderness Threshold Values were 33% for the "slight"
improvement grade, 77.8% for the "middle" grade, and
80% for the "high" grade.
-
- e.) Subjects with an incidence of acute lumbar sprain for
the investigation period were all from the non-belt group; the
incidence tended to decrease in the belt group.
-
Udo et al (9) prospectively studied 60 male workers involved
in crane work (who had also experienced back pain) 30 using a
"lumbago" belt worn on the pelvis (thereby minimizing
motion restriction and risk of muscle strophy) and 30 without
for 1 year. There was no significant difference between the groups
in age, length of service, body height, Broca index, low back
pain findings and crane-operating hours. The belt group fared
better than the non-belt group in several ways:
- a) The belt group had significant improvement in scores in
forward flexion pain, L4 right and L5 right lumbar tenderness
threshold values, total Lumbar Tenderness Threshold Values and
right Lasegue test.
-
- b) The rates of improvement in the Subjective Lumbago Evaluation
were 72.4% for the belt group, significantly higher than the
20.8% for the non-belt group. The rate of improvement in the
Total Lumbar Kinetic Pain Score or Total Lumbar Tenderness Threshold
Values was 58.6% higher for the belt group, significantly higher
than the 29.2% for the non-belt group.
-
- c.) The rate of improved subjects for Total Lumbar Kinetic
Pain Score or Total Lumbar Tenderness Threshold Values by degree
of lumbago in the belt group was 36.8% for the "slight"
improvement grade, 100% for the "medium" grade, and
100% for the "high" grade. The group that exhibitied
more than "medium" improvement significantly exceeded
that with "slight" improvement.
- The authors feel that these results prove the lumbago belt's
efficacy and expect it to be adopted for driving work.
-
V. There are scientific data to support defining elastic
back supports as P.P.E. (Page 66062 F4 of 29 CFR Part 1910).
Our data (7) have shown that back belts, sacro-iliac belts,
and back supports reduce over-compensation to sudden loads at
the hands, and hence provide a barrier to protect the individual.
The findings of Udo et al (8, 9) would justify using supports
worn low, on the pelvis as P.P.E.
VI. Reference to the NIOSH study on employees at Wal-Mart
stores is included in the proposed rules while reference to the
laboratory evaluation of back supports in Morgantown, West Virginia
was not included.
This author is eagerly awaiting the results of the laboratory
evaluation of back supports, conducted by NIOSH in Morgantown,
West Virginia. This sutudy, an important addition to NIOSH's
epidemiological research, will provide insight into the mechanism
by which back belts and back supports work.
Reference documentary evidence
- Chang H-T, Goel VK, Wilder DG, Pope MH, Kong W-Z: Development
of a thoracolumbar finite element model with soft tissues to
better understand the mechanisims of lumbosacral supports and
sacroiliac belts. Presentation# 162, International Society for
the Study of the Lumbar Spine, Brussels, Belgium, 9-13 June 1998.
- Manning DP, Mitchell RG, Blanchfield LP: Body movements and
events contributing to accidental and nonaccidental back injuries.
Spine, 9(7):734-739, 1984.
- Manning DP, Shannon HS: Slipping accidents causing low-back
pain in a gearbox factory. Spine, 6(1):70-72, 1981.
- Marras WS, Rangarajulu SL, Lavender SA: Trunk loading and
expectation. Ergonomics 30:551-562, 1987.
- Wilder DG, Aleksiev AR, Pope MH, Magnusson ML, Goel VK, Weinstein
JN, Lee S: Unexpected load and vibration as etiologic factors
in low back pain - biomechanics and time-frequency analysis.
International Society for the Study of the Lumbar Spine, Burlington,
24-28 June 1996.
- Wilder DG, Aleksiev A, Magnusson M, Pope MH, Spratt K, Goel
V: Muscular response to sudden load: A tool to evaluate fatigue
and rehabilitation. Spine 21(22):2628-2639, 1996 Nov. 15.
- Wilder DG, Lee JS, Pope MH, Magnusson ML, Goel VK: Back supports
and unexpected load. Eurpoean Spine Society Meeting, Kos, Greece,
10-13 September 1997.
- Udo H, Seo A, Koda S, Kurumatani N, Dejima M, Hisashige A,
Fujimura T, Matuura Y, Matumura K, Iki M: The effect of a preventive
belt on the incidence of low-back pain (Part II): Investigation
in rice-carrying work. J. Science of Labour 68(10):503-519, 1992.
- Udo H, Yoshinaga F, Tanida H, et al: The effect of a preventive
belt on the incidence of low-back pain (Part III): Investigation
in crane work. J. Science of Labour 69(1):10-21, 1993.
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