[Relatedness of occupational exposure to whole-body vibration and health, principally back symptoms].
OBJECTIVE
DISCUSSION is continuing about whether or not to update the Occupational Exposure Limit for Whole Body Vibration exposure (OELWBV) which was established in 1975 as a part of the Recommendation of Occupational Exposure Limits (OEL), issued by the Japan Society for Occupational Health. The objectives of this study were to clarify the necessity of the update and the adverse health effects of whole-body vibration by reviewing the literature and to help to compile a for detailed revisions.


METHODS
Mainly referring to our preceding review, the current OELWBV exposure was examined. The relatedness of adverse health effects, principally back symptoms and occupational exposure to whole-body vibration (WBV) was examined by reviewing review papers, the original English papers referred to in those papers, and original English and Japanese references from 2002 to 2010 retrieved through a MEDLINE search.


RESULTS
The results show the necessity of updating the present OELWBV as soon as possible. The overwhelming majority of the literature consists of epidemiological studies showing the relatedness of WBV to back symptoms. Thirty epidemiological studies out of 28 literatures clearly show the presence of a relationship between WBV and back symptoms. Various indices of exposure to WBV and back symptoms show the dose response relationships. Among these, a few studies used A(sum)(8) (equivalent 8-hour r.m.s. acceleration value for the combined frequency-weighted vibration of three diagonal, that is x, y and z, axes) as the exposure index. All of these studies reported some dose-response relationship between WBV exposure and back symptoms.


CONCLUSIONS
Despite the clear presence or absence of a relationship between WBV and back symptoms, 0.5 m/s(2) seems to be the unconfirmed threshold of risk. Focusing on data of A(sum)(8), we suggest that the risk increases over the magnitude of 0.30 m/s(2). To clarify this, further epidemiological studies and others should focus on A(sum)(8) around 0.30 m/s(2).


CONCLUSIONS
The present OEL of WBV should be examined from the viewpoint of the risks of back symptoms referring to the epidemiological studies that show the larger risks of back symptoms in comparison with unexposed referent workers. We conclud that when updating the present OELWBV, A(sum)(8) should be taken into account for back symptoms, referring to the findings of epidemiological studies.
Division of Occupational and Environmental Health, Department of Social Medicine, Shiga University of Medical Science, Seta Tsukinowa-cho, Otsu, Shiga 520-2192, Japan.
Katsuo
K
Nishiyama
Noriaki
N
Harada
Hiroji
H
Tsujimura
Tatsuya
T
Ishitake
Hisataka
H
Sakakibara
Yasunao
Y
Matsumoto
D001416:Back Pain / Q000209:etiology*; D006801:Humans; D016273:Occupational Exposure; D020711:Threshold Limit Values; D014732:Vibration / Q000009:adverse effects*