Intra-individual variation of skin temperature recovery rate after cold water immersion among Japanese bush-cutter operators.

Recovery rates of skin temperature after cold water immersion tests and other measurements were recorded from 1978 to 1989 to assess the effects of vibration due to the use of bush-cutters on the health of 42 road-maintenance workers having an average age of 51.7 years. Their work and health conditions were controlled and checked systematically, and the incidence of white finger in 1989 was 2%. The recovery rate as well as the initial skin temperature was influenced greatly by ambient temperature and thus direct assessment of the changes in recovery rate had little value. The intra-individual variation in recovery rates among 6 examinations ranged widely from 6.7 to 55.7%. Subjects with large variation in the recovery rate showed better results in recovery rate, skin temperature, and vibratory sensation than those with little variation. Individuals with large variation tend to respond well to changes in ambient temperature and to suspension and resumption in the use of bush-cutters, indicating the elasticity of their peripheral circulatory system.