A pneumatic baby-rivetting hammer has often raised the problem in the indus-trial health. An isolator made by an air-cushion was applied to the hammer, by which the idea of a low-pass filter was examined. The attenuation characteristic on this isolator observed on a vibration table was very well and quite simple, be-cause a stable balance type was employed in mechanical structure of the isolator as compared with an isolator used in a rock-drill of leg-type (Part 2). The similar attenuation was also obtained from the practical test on the baby-rivetting hammer by using spectrum difference on the hammer without and with the isolator.
An acceleration measuring apparatus in Z direction with about 50 gr weight and a mechanical hand for simulating the human hand were constructed so as to measure isolation effectiveness of vibration isolation gloves. The glove, the acceleration measuring apparatus and the model hand were pressed in this order by an air-cylinder by about 1 kg/cm2 on a vibration table of electro-dynamic type. The vibra-tion frequency was swept from 10 to 1000 Hz in order to measure insertion loss of the glove. Thirteen samples of gloves commercially available were examined, but their isolation effectiveness could not be observed below about 200 Hz. The resonance frequency determined approximately from spring constant of the glove, the mass of the acceleration measuring apparatus and the first mass of the model hand (0.05+0.2kg) was quite important to estimate the cutoff frequency of the attenua-tion characteristic of the glove, namely, the gloves were non-effective below this resonance frequency but they showed attenuation near 12 dB/oct above this resonance. The force measurement was made to decide the vibration isolation effectiveness of the glove instead of acceleration measurement, so that the accuracy of the measurement was checked. The results agreed with those derived from the accel-eration measurement above the resonance frequency.
This report discribes the results of health examination of VCM workers in 1975 or 1976. All workers examined were healthy, and liver or spleen enlargement was not observed. By examining VCM workers, the measurement of blood catalase activity was ascertained to be seriously significant for VCM exposure, and it had been already found by us that the decrease of blood catalase activity in rats exposed with VCM occured corresponding to the concentration of VCM. The decrease of catalase activity in man was considered to be significant when the activity value was below 90%. When if the activity value was in normal range, the difference between the value and that obtained by following test should be taken into consideration. Effect of VCM on blood pressure has been discussed by some investigators. By our examination, rise of diastolic blood pressure was shown in some cases, but the rise should be explained by taking account of the results on catalase activity and blood platelets and so on. Although the activity of γ-GTP was an important factor for finding out the influence of VCM, it should be carefully treated by taking into account the other tests results when the increase was a little but not so large. Measurement of serum lipids such as triglycerides and free fatty acids etc. should be considered as a co-factor with the synthetic result of γ-GTP, blood platelets, reticulocytes, blood pressure and catalase activity. As the result of tracing examination of VCM workers for about one year, who have been exposed with VCM of 0.2 ppm or below for at least one year, it was assumed that serum proteins and surum bilirubin in Table 8 had been scarcely in-fluenced. Measurement of GOT, GPT and alkaline phosphtase (ALP) may be neces-sary for finding some disordered states of the liver, but not so serious for finding VCM influence in the first screening. As the screening test of VCM workers, blood catalase activity, γ-GTP, blood platelets, reticulocytes and blood pressure should be taken up, and the results of the tests should be considered synthetically and not independently. In the tests, since γ-GTP value increases by daily drinking and reduces fairly quickly by dis-continuation of drinking, the test must be carried out in an accustomed life-style, and the result should be carefully considered by making reference to the amount of drink if the worker drank habitually. The amount of VCM in the blood of workers was several ppb, and in 1976 it seemed to be less than that in 1975. In some workers, although the metabolic speed of VCM in the body has been considered to be rapid, VCM in the blood was detected after 48 hours apart from VCM works.
Cadmium (Cd), Cd fume and cadmium oxide (CdO) were more easily dissolved in protein and amino acid solution such as fetal calf serum, albumin, glycine or neutralized cysteine monohydrate solution than in water or Tyrode's solution. But, there was no difference in the dissolution of cadmium sulphite (CdS) between in the former solutions and in the latter. The solubility of Cd, CdO or Cd fume in albumin and glycine solution increased with increasing their concentration. When the Cd dissolved in protein or amino acid solution was added to the cul-tures, these dissolved Cd showed toxic action on the FM3A cells in proportion to the amount of Cd value irrespective of the sort of the solvent. On the column chromatographs by gel filtration on Sephadex G-200, the Cd dissolved in albumin solution or fetal calf serum coexisted with albumin fractions. In the case of the culture medium containing the Cd dissolved in albumin solution or fetal calf serum, the Cd was also associated with albumin fractions. When, however, metallothionein-Cd was added to the cultures, the Cd in the culture medium was combined mainly with metallothionein fractions and partly with albumin frac-tions and the Cd bound with thionein did not show the toxic action on the FM3A cells.