Translational toxicology in setting occupational exposure limits for dusts and hazard classification - a critical evaluation of a recent approach to translate dust overload findings from rats to humans.

Background: We analyze the scientific basis and methodology used by the German MAK Commission in their recommendations for exposure limits and carcinogen classification of "granular biopersistent particles without known specific toxicity" (GBS). These recommendations are under review at the European Union level. We examine the scientific assumptions in an attempt to reproduce the results.

Toxicological investigations on the respirable fraction of silicon carbide grain products by the in vitro vector model.

Increased lung cancer incidence with workers at the production site of crude silicon carbide (SiC) using the Acheson process has been reported. Several agents derived from the process were discussed as causative factors. Recently concern had been expressed about the presence of cleavage fragments (CFs) in commercial products fulfilling the WHO criteria for fibers.

Deposition behavior of inhaled nanostructured TiO2 in rats: fractions of particle diameter below 100 nm (nanoscale) and the slicing bias of transmission electron microscopy.

Context: In experimental studies with nanomaterials where translocation to secondary organs was observed, the particle sizes were smaller than 20 nm and were mostly produced by spark generators. Engineered nanostructured materials form microsize aggregates/agglomerates. Thus, it is unclear whether primary nanoparticles or their small aggregates/agglomerates occur in non-negligible concentrations after exposure to real-world materials in the lung.

Changes of tumor necrosis factor, surfactant protein A, and phospholipids in bronchoalveolar lavage fluid in the development and progression of coal workers' pneumoconiosis.

Objective: To evaluate the alterations of biomarkers in the development and progression of coal workers' pneumoconiosis (CWP).

Methods: The type and number of cells, and the levels of tumor necrosis factor-alpha (TNF-alpha), pulmonary surfactant protein, phospholipids and fibronectin in bronchoalveolar lavage fluid were assayed in 14 health active coal miners, 21 coal miners without CWP and 13 miners with CWP of 0/1 to 1/1.

Results: Compared to active coal miners without CWP (8.

Exposures to silica mixed dust and cohort mortality study in tin mines: exposure-response analysis and risk assessment of lung cancer.

Background: Mineral dusts that contain crystalline silica have been associated directly or indirectly with the development of pneumoconiosis or silicosis, non-malignant respiratory diseases, lung cancer, and other diseases. The health impacts on workers with silica mixed dust exposure in tin mines and dose-response relationships between cumulative dust exposure and the mortality from lung cancer are investigated.

Methods: A cohort of 7,837 workers registered in the employment records in 4 Chinese tin mines between 1972 and 1974 was identified for this study and the mortality follow-up was traced through 1994.

[Biological responses of tin mine particles and their association with adverse effects on health in tin mine].

Objective: To evaluate the biological and toxicity of tin mine particles mixed with crystalline silica using an in vitro test, and to compare to the pathogenesis of pneumoconiosis and lung cancer.

Methods: Respirable particle samples were sampled from four tin mines, in which elevated mortality of pneumoconiosis and lung cancer were reported in miners exposed to particles. Alveolar macrophages (AM) are considered as the target cells of primary dust effects.

Biological responses of workplace particles and their association with adverse health effects on miners.

Epidemiological research has demonstrated the relationship between exposure to quartz dust and an elevated risk of pneumoconiosis and possible elevated risk of cancer. The current study was designed to evaluate the biological responses of workplace particles containing crystalline silica using an in vitro cell test. Respirable particle samples were sampled from four tin mines, where the standardized mortality ratio (SMR) for pneumoconiosis was 51.

Variation of biological responses to different respirable quartz flours determined by a vector model.

Background: The hypothesis of widely differing lung damage due to commonly used types of quartz was studied in 16 samples of respirable quartzes (> 99% silica) from sites of the European quartz industry, using an in vitro test, the vector model. Two samples with high and 2 with low biological activities were identified and subsequently examined for their in vivo lung toxicity (inflammation, fibrosis, genotoxicity) and surface characteristics. Alveolar macrophages (AM) are considered the target cells of primary dust effects.

Relationship between the state of the surface of four commercial quartz flours and their biological activity in vitro and in vivo.

Four commercial quartz dusts (flours), two inflammogenic in vivo and activating macrophages in vitro (Qz 2/1-c and Qz 3/1-c) and two mostly inert (Qz 5/1-c and Qz 11/1-c), have been compared regarding their surface properties, in order to detect chemical differences which may account for their different biological behaviour. The following features have been examined: 1) extent of the amorphous fraction (heat associated alpha<-->beta transition of quartz) and its solubility in HF; 2) potential to cleave a carbon-hydrogen bond with consequent generation of carbon centred radicals (spin trapping technique, EPR); 3) evolution of surface functionalities upon heating (FTIR spectroscopy); 4) mechanisms of adsorption of water on dusts outgassed at 150 degrees and at 800 degrees C (adsorption calorimetry). HCl treated samples have also been examined.