A study of white finger in the gas industry.

Abstract

Men engaged in breaking or reinstating road surfaces are exposed to vibration from mechanical tools. In view of the lack of epidemiological information on vibration white finger in such a population, a survey was carried out to identify the prevalence of symptoms of white finger in a sample of men using these tools in the gas industry and to compare the prevalence with that found in a control group not occupationally exposed to vibration. Altogether 905 men (97%) in the gas industry and 552 men (92%) in the control group were interviewed, using a questionnaire from which the presence or absence of white finger symptoms from all causes was noted. The prevalence of white finger was 9.6% in the group exposed to vibration at work compared with 9.5% in the control group. The prevalence in the former group when adjusted for age differences between the survey and control populations was 12.2%, but this difference did not reach statistical significance. In case the approach of comparing prevalences of white finger from all causes might have obscured any contributory effect of vibration, the prevalence of white finger was examined in relation to the number of years vibrating tools had been used, this being the only measure of exposure to vibration available. No direct association was found between the prevalence of symptoms and number of years vibrating tools had been used. In view of this and the absence of a significant excess of white finger symptoms in the group using vibratory tools, the authors conclude that vibration white finger is not a special problem in the gas industry. Nevertheless, experimental tests carried out on the different types of roadbreakers used in the industry and on different road surfaces indicate that the vibration levels exceed the standards advocated in the draft international standard DIS 5349 (1979) at the lower end of the frequency spectrum. That no particular problem has been found may be due to the relatively short exposures to vibration experienced by the operators or the fact that they are able to grip the tools lightly, or even, possibly, that the standards suggested in DIS 5349 do not accurately reflect the risk of vibration white finger when they are exceeded at the lower end of the frequency spectrum for vibrating tools such as roadbreakers.

Frequency Weighting for Vibration-induced White Finger Compatible with Exposure-response Models

“…For both the pavement breaker and motorcycle populations, the observed raw prevalence of white fingers was statistically indistinguishable from that of the respective control group. The lack of statistical significance for the operators of pavement beakers even though a difference in raw prevalence from controls of 0.1% was observed, which increased to 2.7% when adjusted for the age difference between exposed workers and controls 21) , suggests the exposed population was bifurcated. The presumed deviation from a normal distribution could well indicate the presence of "low" and "high" exposure subgroups.…”

“…The need to resolve differences in prevalence as small as 0.1% in order to establish the threshold for the onset of VWF led to this requirement. The gas industry controls, however, were not manual workers but persons working outdoors reading gas meters or collecting charges for gas delivery 21) , and hence their suitability for a control group may be challenged. The prevalence of white fingers recorded from these non manual workers was similar to that observed in other non vibration-exposed male Caucasian populations (typically from 6 to 10%) 49) , hence qualifying them for this application.…”

“…This group size is estimated to permit a difference in prevalence of 0.1% to be detected with 95% confidence in a two-sided test 50) , and assumes that the standard deviation for the prevalence of Raynaud's phenomenon in population studies is 1% (see, for example, reference 49). There are two well-documented exposures that may then be considered, one of which contained a "low" and "high" exposed subgroup 21,[51][52][53][54] . The epidemiologic data for these populations are summarized in Table 5, and involved either gas maintenance/construction workers operating pavement breakers or postmen delivering mail by motorcycle.…”

“…Studies of the prevalence or latency of VWF (i.e., time of exposure prior to the onset of white fingers) have reported agreement with the prediction of the health risk as well as overestimation and underestimation of the risk 18,19) . The health risk appears to be overestimated for power tools such as rock drills, pavement breakers, sand rammers and impact wrenches, (e.g., see references 2,4,[20][21][22][23] , and underestimated for riveting tools and some grinders and chain saws (e.g., see references [24][25][26] . The discrepancies, whether real or unsubstantiated 27) , have been attributed in the literature to one or more considerations used to characterize the exposure: 1) employing a frequency weighting function that progressively reduces the contribution to the hazard from accelerations at increasing frequencies; 2) restricting the upper frequency limit of the acceleration used to predict the hazard to 1400 Hz, and 3) ignoring temporal details of the acceleration waveform, such as the crest factor (e.g.…”

To compare the efficacy and safety of nifedipine sustained release with Ginkgo biloba extract to treat patients with primary Raynaud’s phenomenon in South Korea; Korean Raynaud study (KOARA study)

“…According to population based surveys of various ethnic groups, the prevalence of unusual sensitive to cold on fingers is 12%, RP in the healthy population is 3% to 5% [3]. Also, the prevalence of RP is reported 9.5% in labor group [4], in women 15.6-30% [5,6], and 11-21% in general practice setting [7]; 70-89% of RP is Primary Raynaud's phenomenon of unknown origin [2,8]. Thus, the exact prevalence of primary RP is unknown, but primary RP is a common clinical disorder, especially in general practice setting.…”