Silag – the organisation

2017

In 2017 the working group changed its name to silag – swiss laboratory for particle analysis in tissues to accommodate future development.

1992-2020

The pneumoconiosis research in the pathology section of silag was disrupted due to changes of personnel. The intention of silag however was still to provide high-quality lung-dust analysis; therefore, an independent laboratory for sample preparation and lung-dust analysis was founded in 1992. Until 2020, the lab was hosted by the Institute of Geochemistry and Petrology at ETH Zurich. As administration, finances and human resources are in the hands of silag, continuity of the quality of sample preparation and analysis are guaranteed. The localisation of silag in the Institute of Geochemistry and Petrology offered several advantages like developing and testing new sample-preparation procedures as well as new analytical methods like particle and fibre analysis in bronchoalveolar lavage liquids in 2000.

1960-1992

Dust-related research in the inorganic domain lost its importance as soon as prevention measures against quartz dust exposure were implemented. Subsequently, improving the method for lung-dust analysis was the only activity in the inorganic domain. In the medical domain, especially in pathology, research on silicosis continued, but was extended towards other pneumoconioses. With increasing use of asbestos in the industry and with growing occurrence of asbestosis and mesothelioma, the focus of research was shifted towards asbestos-related diseases in the late seventies and early eighties.

Due to this diversification the working group changed its name in 1970 to

Zurich Working Group for the Study and Control of Pneumoconiosis in Switzerland (Zürcherische Arbeitsgemeinschaft zur Erforschung und Bekämpfung der Staublungen in der Schweiz). Figures 1 and 2 show how quartz-dominated research shifted to asbestos-dominated research.

Figure 1: Aim of analysis for lung-dust analysis in steps of 5 years. «Partikel» represents a wide variety of inorganic particles, except for quartz and rock dust, which are counted as «Quarz». Asbest = asbestos.

Figure 2: Diagnoses and number of dust analyses in steps of 5 years. SIL: silicosis, MIPN: mixed-dust pneumoconiosis, ASB: asbestosis, PM+PET: pleural and peritoneal mesothelioma, LuCa: lung cancer, «andere» includes aluminosis, Caplan’s syndrome, granulomatosis, graphite pneumoconiosis, talcosis, hard metal disease, welder’s- and rare earth lungs.

Since the establishment of the working group, silag received samples from all across Switzerland as well as from surrounding countries (Fig. 3). Changes in the kind of research at the University Hospital Zurich (USZ) in 1990 and 2012 subsequently lead to lower percentages of samples received from USZ.

Figure 3: Origin of the samples, sent to silag for lung-dust analysis. Ausland: foreign countries; InnerCH: cantons of UR, SZ, OW, NW, LU, and ZG; OstCH: GR, SG, TG, SH, GL, AR, and AI; ZentrumCH: cantons of BS, BL, BE, SO, and AG; WestCH: cantons of GE, VD, VS, FR, NE, and JU; restZH: canton of Zurich without USZ; USZ: University Hospital Zurich.

1945-1960

In 1944, silicosis, i.e., a quartz-related lung disease, was a severe occupational disease causing sorrow and high costs in Switzerland. Dust exposure and related adverse health effects are very complex and, therefore, experts from different fields founded the Zurich Working Group for the Study and Control of Silicosis in Switzerland (Zürcherische Arbeitsgruppe zur Erforschung und Bekämpfung der Silikose in der Schweiz) in 1945 to address dust exposure and the resulting health effects. The members (usually heads of an institute or clinic) agreed to support research projects of the working group with their staff or to support projects with their lab infrastructure. Thus pneumoconiosis research was organised in a decentralised way, guided by an advisory committee.

Since the early days of silag, medical doctors of the University Hospital Zurich (USZ), mineralogists and petrologists of the Swiss Federal Institute of Technology in Zurich (ETH Zurich), and medical doctors of the Swiss National Accident Insurance Fund (Suva) have participated in the working group. Representatives from the Federal Social Insurance Office (BSV), the Swiss Federal Laboratories for Materials Science and Technology (EMPA), the Swiss Geotechnical Commission (SGTK), the Institute of Forensic Medicine of University Zurich, and the Association of Swiss Civil Engineering Contractors joined in. For the first 15 years, the main focus of research was on silicosis.

The research was divided into two main domains: the inorganic domain and the medical domain:

inorganic domain

The projects in mineralogy and petrology described the formation of dust (concentration, processes, raw materials) at the work place. The characterisation of the dust (grain-size distribution and mineralogy) was also very important. The ultimate aim was to come up with technical means to prevent dust formation. At the same time, the first lung dust analyses were performed, and the results were compared with dust analyses from workplaces.

medical domain

The morphological description of pneumoconiosis was the main focus in pathology/anatomy. The pathological description was completed with the determination of grain size of alveolar dust. Lung diseases induced by organic compounds were also examined. The effects of different inorganic and sometimes organic substances were investigated in animal experiments. Another important task was the development of a reliable method for lung dust analysis.
The progression of silicosis, especially after termination of exposure, was of interest for the clinicians. The interaction with tuberculosis and related diseases such as chronic obstructive pulmonary disease (COPD) and cor pulmonale were investigated too. Moreover, pulmonary function testing (e.g., spirometry, blood gas analysis) was developed.

Radiological examination played a key role in the diagnostics of dust-related lung diseases.