Producing samples for the organization of proficiency tests. Study of the homogeneity of replicas produced from two atmosphere generation systems.

This article describes two atmosphere generation systems used for the production of replicas. The first, the Sputnic system, is based on the Sputnic air sampler developed by the National Institute of Occupational Health in Oslo (Norway). It is used to generate asbestos fibres or silica particles and allows the simultaneous production, by means of sampling on filters, of up to 114 replicas. The second is a multipurpose system that allows dust sampling on foams used with the CIP 10-R device. Twenty samples can be taken simultaneously. In total, 120 series of samples allowed characterization of the variability of the two generation systems used for the production of replicas loaded with asbestos fibres or silica dust. The coefficients of variation characterizing the dispersion of the filter loading in the Sputnic system are <10% for high densities asbestos fibre or silica dust samples. The coefficient of dispersion is on average higher when the asbestos fibre density is lower. The differences observed between the measurements taken on the different crowns of the Sputnic system are low and <2%. The results obtained with the multipurpose system show that replica dispersion is on average equal to 4%, which will allow proposal in the near future of a proficiency test dedicated to the quantitative analysis of crystalline silica on foams sampled with the CIP 10-R device.

Man-made vitreous fibers in office buildings in the Helsinki area.

Several sources of man-made vitreous fibers (MMVFs) may exist in an office environment causing irritation symptoms among occupants. In 258 office buildings, the occurrence and density of settled MMVFs on surfaces were measured by two sampling methods. Altogether, 1113 samples of settled dust were collected from surfaces with plastic bags and gelatine tape and were analyzed with a scanning electron microscope and a stereomicroscope, respectively. Tape samples from 68 buildings were collected from frequently cleaned (n = 162) and seldom cleaned (n = 57) room surfaces in 56 and 29 offices, respectively, and from supply air ducts (n = 24) in 10 offices. MMVFs longer than 20 microm were counted with a stereomicroscope. Irritation symptoms were recorded with a questionnaire. More than 60% of the surface dust and almost 90% of the samples collected from supply air ducts contained MMVFs. The density of MMVFs longer than 20 microm ranged from < 0.1 to 5 fiber cm(- 2). The mean density of the MMVFs was about two times higher on the seldom cleaned surfaces than on the frequently cleaned surfaces. The density was usually under 0.2 MMVF cm(- 2) in surface dust of offices without emission sources of MMVFs. The measurements combined with qualitative analysis of settled dust can help to localize relevant sources of fiber emissions. Altogether, in 40% of the buildings, several occupants had repeated irritation symptoms that were verified by occupational health care personnel.

Fiber analysis in lungs of residents of a Japanese town with endemic pleural plaques.

The authors analyzed various types of fibers in lung-tissue samples, which were obtained from 50 cases (46 surgical resections and 4 autopsies) at Kumamoto-Minami Hospital in Matsubase, where the occurrence of pleural plaques is endemic. Lung cancer necessitated surgical resection in 44 cases. Eleven of the 50 cases were residents of Matsubase; 15 resided in the region around the town, where the frequency of pleural plaques was slightly higher; and 24 cases lived in a region with normal plaque frequency. The number of anthophyllite fibers in the lungs of town residents was significantly higher than in residents of the region with normal plaque frequency. In 6 cases, the authors found accompanying pleural plaques, and the anthophyllite fiber count in the lungs in these cases was significantly higher than in cases without plaques. In addition, the anthophyllite fiber counts in 2 cases with severe plaques were significantly higher in 4 cases with only mild plaques. These results suggested that anthophyllite fiber might be responsible for the increased prevalence of pleural plaques in Matsubase. Even though the anthophyllite fibers were quite long (mean length = 25.1 microm), the width of most anthophyllite fibers were thick (mean diameter = 0.84 microm). Therefore, the aspect ratio of anthophyllite (mean = 38.7) was lower than that of amosite (mean = 81.8), which, in a previous report, was found predominantly in cases of pleural mesothelioma. Perhaps these differences in fiber size are related to the strength of the carcinogenicity to the pleura.