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S.
Tanaka, C.F. Estill, S.C. Shannon and P. Millard
NIOSH Education and Information Division
Annually from late July through early September, thousands
of seasonal workers harvest wild blueberries in Maine and
the eastern Provinces of Canada. Maine's crop in 1993 was
approximately 65 million pounds. The harvesting is mostly
done by manual raking through the low lying bush (height <
10 inches). In response to reports of tendinitis among blueberry
rakers, we conducted a survey in August, 1993, consisting
of a symptom questionnaire, physical examinations of the hands
and wrists, and an ergonomic assessment of raking.
The participants were 134 rakers who volunteered on-site;
73% were males, compared to 74% among the total 1300 rakers
hired by this company. The median age of our participants
was 30, compared to 28 for all rakers. Children (age 12 to
18) were 10% among the participants and 16% among all rakers.
Participants reported moderate to severe pain in the back
(13.5%), in the hand/wrist (12.0%), and in the elbow (7.5%).
On screening physical examinations, 9.8% had some hand/wrist
pain accompanied by a positive Phalen's or Tinel's test (suggesting
carpal tunnel syndrome), or a positive Finkelstein's test
(suggesting de Quervain's disease - tenosynovitis of the abductor
pollicis longus and the extensor pollicis brevis). Since the
survey was conducted in late August, some rakers might have
left work because of pain.
Ergonomic analysis of raking revealed that rakers worked
mostly in stooped posture and frequently carried loaded buckets
(up to 28 pounds each). The metal rakes, shaped like a deep
dustpan with the handle attached inward, varied in size (14
to 24 inches wide) and weight (2.6 to 4.6 pounds). The typical
raking motion involved constant firm grip on the handle, ulnar
deviation of the wrist initially to insert the tines into
the bush, followed by radial deviation and lifting of the
rake to separate berries. The force of this lifting was estimated
to he 87 ñ 17.5 newtons, and the motion was repeated 32 ñ
13 times/min.
These forceful and repetitive motions would cause friction
on the tenosynovium and explain a high incidence of tendinitis.
Many seasonal workers depend on income from this work, which
nonetheless needs to be performed without adverse health effects.
Ergonomic recommendations such as keeping the wrist in a neutral
position (to avoid deviations) and an initial period of slow
raking (work hardening) might reduce the incidence of tendinitis.
Some efforts are underway to improve the design of the rake.
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and Reproduction Information: Information in NASD does not represent
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NASD Review: 04/2002
This research abstract
was extracted from a portion of the proceedings of "Agricultural
Safety and Health: Detection, Prevention and Intervention,"
a conference presented by the Ohio State University and the
Ohio Department of Health, sponsored by the Centers for Disease
Control/National Institute for Occupational Safety and Health.
The authors noted above are from: NIOSH,
Cincinnati, OH; NIOSH, Cincinnati, OH; Maine Dept. of Human
Services, Augusta, ME; and Maine Dept. of Human Services,
Augusta, ME respectively.
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