Hand-transmitted vibration generated by a grinder is considered to be harmful to workers' health. It is found that balancing a grindstone can effectively attenuate vibration if the magnitude and direction of unbalance can be properly adjusted by use of a field balance detector. An effective automatic dynamic balancer consisting of a toroidal metal tube containing a number of steel balls which can circulate smoothly has been devised as a practical balancing device.
Noise measurements were performed in eight patients' rooms, three intensive care units (ICUs) and one operating theatre at a large hospital (1300 beds). Daytime and nighttime LAeq in patients' rooms and in ICUs were higher than the recommended standards. The measured noise levels could interfere with normal sleep and could be dangerous for patients at greatest risk. The laminar flow ventilation system was the main source of noise in the operating room. The LAeq recorded during a surgical procedure was sufficiently high to mask speech communication. The measurement of A-weighted sound pressure levels disclosed that staff activities were responsible for the loudest noises. Air-conditioning systems and electro-mechanical instruments were also important contributors to noise pollution in the hospital.
The comparative study on lead-induced inhibition of delta-aminolevulinic acid dehydratase (ALA-D) activity in both blood and liver and that on its restoration were performed using the mice which were given ad libitum a lead containing water (500 ppm as lead) for 30 days. The ALA-D inhibition in the liver was very mild compared with that in the blood, in spite of high accumulation of lead into the liver. The depressed ALA-D activity in both blood and liver was rapidly restored by means of the cessation of lead exposure. The gel filtration chromatography showed that the chromatographic ellution pattern of zinc from the supernatant of the liver homogenate corresponds well to that of protein-like substances of the supernatant. However, the lead-binding protein in the liver was not detected in mice exposed to lead for 30 days.
The effect of selenite administered at various time intervals after mercury treatment on the toxicity and renal content of mercuric mercury in mice was studied. A marked protective effect of selenite on growth depression and renal lesions caused by mercuric chloride was observed in mice receiving mercury and selenite simultaneously. However, growth depression was not protected by post administration of selenite at more than 20 min after mercury administration, and the renal lesions of mice receiving selenite at 1 hr after mercury administration were indistinguishable from those of mice receiving mercury alone. Selenite markedly depressed the renal accumulation of mercury administered simultaneously but seemed to be incapable of eliminating mercury which had already been de-posited there before selenite administration. These observations suggest that the protective effect of selenite on the acute renal toxicity of mercuric mercury was mainly due to reduction of renal mercury accumulation, rather than the elimination of mercury from the kidney.
The correlations between airborne concentration of mercury found and the clinical and biological manifestations in workers engaged in the manual manu-facture of mercury glass bubble relays has been studied. The workplace sampled was a small room in which there were five workers. Airborne mercury sampling was performed by using charcoal tubes and 3M mercury vapor monitors. Whole blood mercury concentration (HgB), ALA-D activity, free erythrocyte porphyrin IX (FEP), and the urinary output of mercury (HgU) were determined for each worker. Clinical examination revealed a tremor in the hands, a metallic taste and headaches. Workers with HgU higher than 400 μg/L were orally treated with N-acetyl-d, l-penicillamine, and temporary removal of them from exposure was re-commended. A very good linear correlation of environmental concentrations of mercury as time weighted average (TWA) between charcoal tubes and 3M monitors was found. The regression analysis for the results obtained as TWA and the biological parameters measured fit a logarithmic equation well, as well as the values obtained for HgB, ALA-D and HgU when they were compared.
The neurochemical effects of trimethyltin (TMT) intoxication were correlated with electron microscopic observations. Rats were injected intraperitone-ally with 1.0 mg TMT/kg body weight daily for 8 days. The administration of TMT diminished total lipid levels in all the regions of the brain. Phospholipids remained unaffected. However, cholesterol concentration was decreased in cerebral hemisphere and brain stem. Also, C/P ratio showed decrement in these regions. Moreover, esterified fatty acids were remarkably depleted in various brain regions. Interestingly, ganglioside contents showed depletion in the cerebellum and brain stem. Sulfhydryl radicals showed decreased levels in the brain stem only. Lipid peroxidation and lipase activity were elevated in the different regions of the brain. Furthermore, electron microscopic studies revealed remarkable accumulation of electron dense pigment bodies corresponding to the control.
A new type of determination method for ozone applicable for use in a personal dosimeter was developed utilizing the ozonolysis of trans-stilbene (t-stil-bene). Samples of gas containing ozone were introduced into a pyrex glass tube packed with glass beads coated with fine crystals of purified t-stilbene. Benzoic acid produced from the t-stilbene by ozone was determined by high performance liquid chromatography after dissolution into methanol and separation by filtration from the glass beads and unreacted t-stilbene. The amounts of benzoic acid detected were proportional to ozone concentrations in a range of 0.03 ppm to 0.6 ppm with a variation of 20%, and the detection limit was 0.01 ppm. No interference from nitrogen dioxide was detected. Though the influence of very high humidity was not negligible, the amounts of benzoic acid produced at a given humidity were proportional to the ozone concentrations. This method can therefore be used for monitoring ozone concentrations around 0.1 ppm which is the TLV recommeded by the Japan Association of Industrial Health.