van den Heuvel et al., 2004), a deg

van den Heuvel et al., 2004), a degree of satisfaction with leisure
time activities (Thorbjornsson et al.,1998; Van Nieuwenhuyse et al.,
2004), night shift work (Eriksen et al., 2004), high job insecurity
(Lee et al., 2008), and work stress (Oksuz, 2006).
Rubber tapping is an important occupation in Asia especially in
Thailand, Indonesia, Malaysia, India, and Sri Lanka, with approximately
1.2 million workers in the southern part of Thailand in the
year 2009. However, a previous report revealed that rubber tapping
is a high risk occupation for developing MSDs. Rubber tappers were
reported to have a high prevalence (55%) of low back pain followed
by carpal tunnel syndrome (19%) (Bensa-ard et al., 2004). MSDs
among rubber tappers may relate to possible ergonomic problems
from working such as an awkward work posture and highly
repetitive work.
Rubber taping is the process by which natural rubber is
collected. When the circumference of the tree trunk reaches
50 cm, the tapping can be begun. Normally, the tree is divided into
two or three sections circumferentially. One section can be cut for
about 5 years and then the next section is begun. The tapping level
is usually started at a height of 150 cm above the ground and then
moves down nearly to ground level and then the next part of the
tree trunk is started at a level of 150 cm again. A special sharp
tapping knife is used to cut the tree bark downward at a 30  angle
along a left to right oblique curve that cuts through the latex
vessels. In performing rubber tapping (Fig. 1.), the rubber tapper’s
forearm, lower arms, and wrists must maintain a degree of flexion,
while the trunk posture is in a degree of forward bending and
laterally twisted which depends on the height of the tapping level.
This work task often involves rubber tappers being in ergonomically
awkward activities, such as the repetitive tapping movement
which is often repeated hundreds of times per day in awkward
postures of the upper limbs, neck, trunk, and legs. These ergonomic
problems may be a cause of MSDs in rubber tappers.
However, our literature review shows that the ergonomic risk
assessment of rubber tapping work and the associationwith MSDs
has never been evaluated. Currently, the Rapid Upper Limb
Assessment (RULA) is commonly used tool for evaluating ergonomic
risk of work-related MSDs due to work posture, muscle use,
and forces exerted on the upper arms, lower arms, neck, trunk, and
legs (McAtamney and Nigel Corlett, 1993; Cook and Kothiyal, 1998;
Massaccesi et al., 2003; Pourmahabadian and Azam, 2006) which
is linked to job charecteristics and physical demand of rubber
tappers.
To effectively address MSDs problems among rubber tappers,
this study aimed to evaluate the prevalence of musculoskeletal
disorders and ergonomic risk levels of rubber tapping postures, and
also to identify ergonomic factors influencing low back pain among