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Mr. Chairman, Members of the Committee, it is an honor and
privilege to have the opportunity to share some of my concerns
about the terms and issues surrounding an ergonomic mandate to
avoid musculoskeletal problems at work. I am the Liberty Safe
Work Professor at the University of Aberdeen, Scotland and Director
of the Liberty Safe Work Centre. Prior to that I was an Endowed
Professor in the departments of Biomedical Engineering, Mechanical
Engineering, Orthopaedics and Preventive Medicine at the University
of Iowa as well as the Director of the Iowa Spine Research Centre.
I am privileged to have served as President of the International
Society for the Study of the Lumbar Spine and the American Society
of Biomechanics. I have spent my career doing spine research
and have over 300 publications to my credit. I have served on
the federally mandated public Health Services Agency for Health
Care Policy and Research (AHCPR) Panel of experts scientific
review for their 1994 Low Back Guideline.
I. Basic position on standard.
I commend OSHA on their initiative to develop the standard.
The overwhelming literature, much of which was cited by OSHA,
demonstrates a positive relationship between overloading of the
musculoskeletal tissues and injury. Laboratory studies clearly
show that excessive loads or repetitions will damage the tissues.
I believe we have a moral responsibility to prevent injuries
to so many working Americans. In addition, a disproportionate
number of injuries occur to working Americans in the lowest socio-economic
groups which includes many minority citizens. As important as
ergonomic changes are, OSHA has recognized that situations exist
in certain industries or operations where ergonomic changes are
not feasible. With your permission, Mr. Chairman, I will address
these issues.
II. Not applying standard to agriculture, construction
or maritime operations with the admission that LWD MSD injury
rates in these excluded industries could be as high as 10% of
the total on the basis that problems in these industries are
unique and that inadequate information on controls exist as compared
with areas of manufacturing and material handling is not consistent
with current science.
In fact, agriculture, construction or maritime operations
are at very high risk for all kinds of injuries. Aberdeen is
the centre of the North Sea off-shore industry, where the patient
census shows that the injury risk due to mechanical overload
is paricularly high. Agriculture and construction have, in addition
to the manual handling risk, exposure to uncertain footing and
vehicle vibration. There has also been much work done to improve
tractor and earthmoving equipment ride via jolt/vibration isolation
and seat redesign, but much remains to be done. A few years ago,
with my colleague David Wilder, we studied a large container-handling
facility at a port in Norfolk, Virginia. There was a high rate
of low back injuries but a progressive management with a desire
to cut the injury rate (and improve their bottom line). The ergonomic
issues involved: whole-body jolt/vibration exposure while operating
cranes and terminal tractors, materials handling, and exertions
in awkward postures while handling lines and roping loads under
uncertain and slippery footing and a moving or unstable base
of support. Using our recommendation to management regarding
the drivers, a vendor 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 relatively inexpensive, saved money and an improved product
was developed. Everyone was happy! For the other workers, a recommendation
was made to provide a back support, a point I will get to later.
I conclude that the economic forces of insurance, health-care
costs, marketing and competition make it feasible and profitable
to address ergonomic issues in agriculture, construction and
maritime operations. Prevention of injury is good business!
III. Slips, trips and falls should be included in a list
of applicable MSDs.
Slips, trips and falls represent some of the most common workplace
injuries. Often they occur in the occupations previously referred
to (agriculture, construction or maritime operations) but are
also present commonly in food preparation. This is an area where
ergonomic change may be beneficial by improvement of the coefficient
of friction of the floors. The inherent violence in a slip, trip
and fall can also overload the trunk (6, 7). Marras et al (8),
as well as our own group (12, 13) have demonstrated that sudden,
unexpected loads applied at the hands or directly to trunk or
by slipping lead to over-compensation of the back muscles. In
many cases the onset of back pain stems from an unanticipated
loading that occurs during the material handling task, for example:
when lifted objects stick together, when a multiple person lift
fails, when preventing an accident, or during a loss of footing
(slip). In these cases back supports can augment trunk stability
and ameliorate back loading.
IV. Exclusion of back supports from P.P.E. for standard
purposes precludes a hierarchy of controls in combating back
injuries.
Although back supports have been controversial, largely due
to a NIOSH review some years ago, recent data support their efficacy.
As mentioned earlier, the first approach should be one of ergonomics
to reduce the risk of injury. If an ergonomic solution is not
possible, then back supports coupled with proper education may
be the solution. The lumbar spine works as a column supported
by the trunk musculature. Biomechanics studies the loads applied
to the spine from different sources and in this context any changes
due to the use of back supports. This work, both from ourselves
and others, has suggested that back supports work through several
mechanisms. When used correctly, the back support helps to maintain
proper curvature and posture of the spine during lifting and
less muscle fatigue results. Back supports also partly reduce
the load on the spine. Lumbar supports clearly have a beneficial
role in reducing the tendency of the trunk to over-react to a
sudden load. Cholewicki et al (3) concluded that "trunk
stiffening due to a back support is a passive mechanism. These
findings are relevant to low back injury prevention and rehabilitation
strategies. Increased spine stability may provide greater protection
against injury following unexpected or sudden loading. As a passive
preventive measure that cannot be overridden by the employee,
they should be considered personal protective equipment (P.P.E.)
and thus provide the flexibility of more options for addressing
back problems.
V. Sudden loading of the back frequently occurs as a first
event in injury to the back.
As this occurs often during accidents and research has shown
that a P.P.E. approach reduces incidence and/or severity of low
back injury, sudden unexpected loading of the back should
be added to ergonomic risk factors.
Many back injuries occur in those whom we should be trying
particularly hard to protect our health care workers. The
primary cause of back injuries among nursing personnel is lifting
and transferring patients. The typical hospital staff nurse lifts
20 patients into bed and assists five to ten patients with transfers
from bed to chair during a shift. (1) In an Ohio study, the group
wearing support belts worked 22,243 hours and reported no back
injuries. Thus, they concluded that the use of back support belts
reduces the injury incident rate, at least in the short term.
As noted previously, slips, trips and falls are often the first
events that lead to back injuries (6,7). Sudden, unexpected loads
lead to large over-compensations in the back (8, 12, 13). The
injury occurs due to the body's excessive reaction or over-compensation
to the applied load a response that can be reduced by the
use of back supports as P.P.E.
There are now several prospective studies on back supports.
For example, Udo et al (9, 10) present compelling evidence for
use of back supports as P.P.E. Udo et al prospectively studied
males with low back pain involved in rice-carrying work (9) and
crane driving work (10). The belt-wearing group had significant
improvement in pain and clinical measures compared to the non-belt
group. Because of the success in the latter group the authors
recommended the belt as P.P.E. for driving work. Walsh and Schwartz
(11) studied randomly selected warehouse workers assigned to
one of three groups: a control group, a training group, and experimental
group that received training plus a back support. In the latter
group the days lost from work due to back injury decreased considerably.
Kraus et al (4) found that low-back injuries fell by about one-third
when all workers were required to wear back supports. Both men
and women workers, young and old, involved in low and high levels
of lifting benefited from wearing the back supports.
VI. There are scientific data to support defining elastic
back supports as P.P.E. (Page 66062 F4 of 29 CFR Part 1910).
The Lavender et al study (5) provides evidence that back supports
stiffened the torso through the reduction in the sagittal plane
motion. This study showed that a tensioned back support reduced
the forward bending in all subjects. Our data (12-14) have shown
that whilst back belts, sacro-iliac belts, and back supports
all reduce over-compensation to sudden loads at the hands, the
elastic back support worn low on the hips and tensioned was the
most effective. Each provided a barrier to protect the individual.
The findings of Udo et al (9, 10) and the other cited epidemiological
studies would justify using supports worn low, on the pelvis
as P.P.E.
VII. 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.
Reference to the unpublished Wal-Mart Stores study in the
proposed standard appears to predict an outcome not in evidence.
A laboratory evaluation of back supports, conducted by NIOSH
in Morgantown, West Virginia was recently concluded. This study,
an important addition to NIOSH's epidemiological research, provided
important insight into the mechanism by which back belts and
back supports work. Although the research is not yet published,
I served as an independent reviewer for NIOSH. The study provides
further laboratory evidence that back supports have a positive
mechanical effect on the trunk and parallel the other laboratory
studies cited earlier.
VIII. Summary
A brief summary of my key opinions follow:
- I commend OSHA on developing the standard.
- The overwhelming literature demonstrates a positive relationship
between overloading of the musculoskeletal tissues and injury.
- The standard should be applied to agriculture, construction
or maritime operations.
- Slips, trips and falls should be included in a list of applicable
MSDs.
- Back supports should not be excluded from P.P.E.
- Sudden loading of the back should be added to ergonomic risk
factors.
Thank you, Mr. Chairman, for the opportunity to talk to you
and for listening to my opinions on these vital topics.
Reference to documentary evidence
- Allen S K and Eilder K, Back Belts Pay Off for Nurses Occupational
Health & Safety 1996
- 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.
- Cholewicki J, Juluru K, Panjabi M.J., Radebold A, McGill
S.J. 1 : Lumbar spine stability can be augmented with an abdominal
belt and/or increased intra-abdominal pressure. Eur Spine J.
1999,8(5): 388-95.
- Kraus J., Brown K., McArthur D., Peek-Asa C. and Zhou L.,
Samaniego L. and Kraus C. Reduction of Acute Low Back Injuries
by Use of Back Supports, International Journal of Occupational
and Environmental Health, November 1996.
- Lavender, S.A., Shakeel, K., Andersson, G.B.J., Thomas, J.S.
Does a Lifting Belt Reduce the Spine Moments During Sudden Unexpected
Loading?
- Manning DP, Mitchell RG, Blanchfield LP: Body movements and
events contributing to accident 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): 7072, 1981.
- Marras WS, Rangarajulu SL, Lavender SA: Trunk loading and
expectation. Ergonomics 30:551-562, 1987.
- Udo H, Seo A, Koda S, Kurumatani N, Dejima M, Hisashige A,
Fujimura T, Jatuura Y, Matumura K, Iki J: 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.
- Walsh N.E. and Schwartz R.K. The Influence of Prophylactic
Orthoses on Abdominal Strength and Low Back Injury in the Workplace
American Journal of Physical Medicine and Rehabilitation, 1990,
pp. 245-250.
- 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, SprattK, 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 JH, Magnusson JL, Goel V: Back supports
and Unexpected load. European Spine Society Meeting, Kos, Greece,
10-13 September 1997.
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