Document Qg7jzr8XYKqDDd74NX22q9nkv

Industrial Hygiene Digest March. 1963 hydrocortisone was discontinued, however, the size of nodules returned close to control level. Histological differences were noted between control and treated nodules after 150 days. These differences (disorganization and cellularity of treated nodules) suggest a continuation of the ,-arly inflammatory response in hydrocortisone treated lesions. There are 13 references to the subject. -- Authors' summary 265 Asbestosis in Experimental Animals. J. C. Wagner. Brit. J. Ind. Med. 1-12 (Jan. 1963). Previous animal experiments with asbestos dusts have been almost entirely confined to chrysotile asbestos. It was, therefore, decided to investigate the effects ofmill dusts from the three types of asbestos that are produced commercially in South Africa, namely chrysotile, amosite, and crocidolite. Chrysotile and amosite samples were relatively pure while in con trast the crocidolite dust was found to consist mainly of iron stone and silica and contained less than 10% of asbestos fiber. Guinea pigs, Vervet monkeys, and rabbits were exposed to these dusts. The results were assessed on histological criteria. It was found that, in all three species of animals, the amosite dust produced more marked lesions than the chrysotile and that these lesions occurred at an earlier period. It was not possible to compare these lesions with those caused by the crocidolite dust, owing to its impure nature. It was noted, however, that this dust caused severe lesions in guinea pigs and monkeys and that the animals in this group succumbed more readily to respiratory infections. -- Author's abst. Ibb Arc Pleural Calcifications Pathognomonic for Asbestosis? M. Anspach. Intern. Arch. Gewerbepathol. Gewerbehyg. _19> 108-120 (1962). German. The occurrence of pleural calcifications was studied during a mass x-ray survey of the Dresden area in 1960. All films showing such calcifications were noted except those ob viously arising from pleurisy, empyema or chest injury. It was found that the distribution of the cases was not uniform but was concentrated largely in one or two districts in Dresden itself and to a much less extent in some other areas. The areas involved were mostly those in which asbestos works were or had been situated. The patients whose films showed plaques numbered 244; they were divided into 5 groups. In 77. 78% of patients the action of asbestos dust was con firmed as the cause of calcification. In 11.54% no cause could be assigned, and in 10.68% pul monary or pleural diseases were the cause. From these results it is concluded that pleural calcifications cannot be regarded as pathognomonic for asbestosis. There must be in addition proof of exposure to asbestos dust. -- Cond. from Bull. Hyg. PHYSICAL ASPECTS OF THE ENVIRONMENT J67 A Vehicle for Use as an Audiology Unit. W. R. Lee, J. E. J. John and F. Fowweather. Brit. J. Ind. Med. 0, 57-62 (Jan. 1963). Reliable measurement of hearing by audiometry requires quiet surroundings for which suggested criteria exist. When field studies of hearing are carried out it is frequently most practicable to use a vehicle in which these desired sound levels are obtained. It was decided to incorporate in the design of this vehicle a consulting room and a waiting room so that the patient could adjust to the surroundings for what is essentially a psychological test. Ventilation is effected by input and extractor fans. As a basis for the acoustic design the sound-levels in typical situations where the van was to be used were determined. From these it is possible to estimate the attenuation required. The walls and roof of the vehicle are of solid construction with a surface density of 5 lb./sq. ft. , and the floor has a surface density of 6 lb./sq. ft. A commercially made booth is suspended on resilent mountings inside the consulting room. The ' * 03121193 20.