By inquiring of sufferers from Raynaud's phenomenon in chain saw operators as to the period from the beginning of chain saw use to the first appearance of that phenomenon, we found that accumulated number of sufferers n at the time tincreases with time according to the equation: n=a log t+b, where, n is accumulated number of sufferers from Raynand's phenomenon at the time t, t is elapsed time from the beginning of chain saw use to the first appearance of Raynaud's phenomenon (in years), and a and b are constants. On the hypothesis that the sufferer's group consists of two sub-groups, which are supposed to exist by mathematical analysis but not yet identified, we set up two logarithmic equations for them respectively. Sum of n of both sub-groups at the time t fits farely well the observed number.

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Evaluation of the concentration of mercury element in the human hair has interested investigators for the purpose of estimating the inhalation of mercury vapours or the intake of mercury element with foods. However, for the measurement of its content in the hair, it is necessary to wash the hair in order to remove its surface contamination. This study was made to see how extensively the mercury element in the hair is modified by the adsorption of environmental contaminants and to see if detergents could be found that would remove the mercury adsorbed on the hair. The procedure used was to place samples of hair in solutions of radioactive mercury and in radioactive mercury vapours. After several hours the samples were removed from the solurions and from the container which was filled with mercury vapours, washed and then rinsed. Ater that, the mercury in the hair and the mercury in detergent solutions was measured by neutron activation analysis. Radioactivity remaining on the hair after washing was measured by a multichannel pulse height analyzer. Mercuty element was found to be easily adsorbed on the hair and was removed by solutions containing KI, NK₄I, KCN and KBr. However, these solutions were found to remove even the mercury in the hair which was necessarily to be measured. Moreover, the mercury adsorbed on the hair was shown only at the surface of the hair by autoradiography. It can be concluded that an adequate method for washing the hair in order to measure the concentration of mercury element would consist of a solution of non-ionic surface active agent -Nonion- with 0.1M EDTA at pH 9.0 and of shaking for 10 minutes. After then, it is better to rinse with acetone for a few minutes. Besides, it might be useful to wash with a KI 1% solution since the hair is suspected of mercuty contamination.

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