[Silicon carbide, occupational exposure, proposed MAC values]. / Weglik krzemu, narazenie zawodowe, propozycje NDS.

Occupational exposure to dust silicon carbide production and exploitation of its products was evaluated. Individual dosimetry was used to measure concentrations of total and respirable dusts; concentration of respirable mineral fibres was measured by means of light microscopy; the distribution of fiber length was analysed by employing a laser FM-7400; morphology of dust molecules was analysed in light and electron microscopes; x-ray diffraction and infrared spectrometry was used to identify dust mineral composition. Concentrations of total dust at workposts involved in silicon carbide production ranged between 5.0 and 14.0 mg/m3 (mean = 10.3 mg/m3); concentration of respirable fraction between 0.1 and 1.9 mg/m3 (mean = 1.1 mg/m3); and concentration of respirable mineral fibres between 0.42 and 1.04 f/cm3 (mean = 0.64 f/cm3). In the plants where SiC products were used the mean concentrations of total dust and respirable mineral fibres were about two times lower, and the concentrations of respirable fraction about five times lower. In the workpost air the presence of carborundum, mullite and cristobalite was revealed. A proposed MAC value for SiC dust (nonfibrous) containing less than 2% of free crystalline silica accounts for 10 mg/m3 for total dust.

[Evaluation of occupational exposure of workers engaged in mining of rock raw materials in the Sleza massif]. / Ocena narazenia zawodowego pracowników zatrudnionych przy wydobyciu surowców skalnych na obszarze masywu Slezy.

In two serpentinite mines and in a factory producing asphalt pavements using serpentinite, exposure to dusts and polycyclic aromatic hydrocarbons (WWA-fraction soluble in benzene) was assessed. In rock samples taken in the serpentinite mine and in dust samples from work posts crystalline phases were determined (using X-ray radiography and spectrometry in infrared). Also, morphology of dust particles was performed using electron microscopy. Both in the rock samples and in dust fibrous antigorite, a mineral of strong cancerogenic properties, was found. Total dust concentrations varied between 1.05 and 280 mg/m3, concentration of respirable mineral fibres from 0.01 to 3.56 fibre/cm3, and concentration of aromatic hydrocarbons varied between 266.7 and 850 micrograms/m3. The study will be continued concerning evaluation of biological effect of serpentinite in animal experiments and assessment of extraoccupational exposure of people living in the neighbourhood of serpentinite mines and plants processing this mineral.

[Fly ash and its biological effects. 3. Exposure to dust of workers in the energy-generating industry (power plants and thermoelectric power stations)]. / Popioly lotne i ich dzialanie biologiczne. 3. Narazenie na pyl pracowników zatrudnionych w zakladach energetyki (elektrowniach i elektrocieplowniach).

An evaluation of exposure to dust of workers employed at typical work-stands in power industry plants was made. Mean concentrations of respirable dust determined at 14 different work-posts range from 0.45 to 8.95 mg/m3, and of total dust from 1.55 to 85.0 mg/m3. Mean content of free crystalline silica in dust samples is less than 10%. At the work-stands where ash dust was encountered, the presence of respirable fibres at concentration below 0.2 fibre/cm3 was observed. In all ash samples alpha-quartz and mullite were found: in some of them also kaolinite and orthoclase were traced. Only at five out of all 14 work-stands examined mean concentration of respirable dust was lower than the hygienic standard value.

[Evaluation of working environment in the textile industry. IV. Dust concentration in the air of the flax spinning and weaving plants]. / Ocena srodowiska pracy w zakladach lniarskich. IV. Stçzenie pylu na stanowiskach pracy w przedzalniach i tkalniach lnu.

Evaluation of dust concentration in the air of spinning and weaving rooms was made by gravimetric sampling of dust in 3 flax plants, where short flax fibres (flax--tow) and long flax fibres were manufactured. Besides, the dispersion of dusts and concentration of free silica were determined. The highest concentration of dust (10 mg/m3) was found in hackling room, mixing mill, and the one where spreading machines are operated, while in the carding room it was - 7.0 mg/m3. In other shops the concentration was - 5.5 mg/m3. The dust in the air of spinning rooms contained 2.3% of free silica and 53% of its particles were smaller than 5 micrometers. In the weaving rooms it contained 1.6% of free silica and 57% particles were smaller than 5 micrometers. The geometric mean of dust concentration higher than MAC for vegetable dusts (4 mg/m3) was found in hackling mill, mixing mill and the one where spreading machines are operated.

[Biological and histological changes induced by cement dust]. / Zmiany biologiczne i histologiczne wywolane dzialaniem pylu cementu.

In animal experiments pneumoconiogenic properties of metallurgic and Portland cement dust, produced in Poland, were investigated. Experimental pneumoconiosis was developed by intratracheal single administration, to white rats, of 50 mg of dust suspended in 0.6 ml of NaCl physiological solution. The control groups were composed of animals to whom intratracheally physiological NaCl solution, TiO2 dust and two quartz dusts of varying fibrogenic properties--weak and mild, were administered. The content of crystalline silica, as determined chemically, was approx. 3% in both cement samples. X-ray diffraction did not show any content of crystalline phases in the cements, TiO2 dust contained rutile, whereas both quartz dusts contained about 100% alpha-quartz. After 3 months the animals were sacrificed. Wet lungs weight and hydroxyproline content in lungs were determined. In addition, mediastinal nodes and lungs were examined histologically. Cement dust was found to exhibit weak fibrogenic properties, not different significantly from fibrogenic properties of inert TiO2. Nevertheless increases in fibrogenic effect of cement dusts were significantly higher as compared to the control group (geometric mean hydroxyproline content in the control group was 2.52 +/- 0.06 mg, 4.50 +/- 0.09 in the Portland cement and 4.88 +/- 0.06 in metallurgic cement. Histological changes in lungs, due to cement effect are not progressive, expressing merely inflammatory reaction to dust. Nevertheless despite weak fibrogenic properties the cement dust provokes lesions of macrophages in lungs.

[Evaluation of work environment in the flax textile industry. V. Air microflora in the flax spinning and flax weaving rooms]. / Ocena srodowiska pracy w zakladach lniarskich. V. Mikroflora powietrza na stanowiskach pracy w przedzalniach i tkalniach lnu.

Microbiological air pollution in spinning and weaving rooms was determined by aspiration impinger using an aeroscop (Chirana, Czechoslovakia). The air samples were taken on Petri dishes with Bacto-broth-agar (Difco) or Bacto-blood-agar (Difco). After incubation at 37 degrees C for 24 h the number of bacterial or mould colonies and bacterial cells per 1 m3 of the air was calculated. The number of bacterial cells in flax spinning rooms ranged from 10.5 X 10(3) to 12,5 X 10(4), while in flax weaving rooms--from 2,4 X 10(3) to 10(4) per 1 m3 of air. In the examined samples of the air the bacterial pollution was found to dominate (45,1--95%). Gram-positive sporing bacteria were most frequently recognized. In the air of weaving rooms some moulds: Mucor sp., Circinella sp., Hormodendrum sp., Vetricillum sp., Aspergillus sp. and Penicillum sp. were also found (16.8--54%). It was observed that the microbiological air pollution in spinning and weaving rooms of flax industry was greater than in cotton industry. A wet technology of flax spinning promotes microbiological pollution in the air of this kind of workposts. A high level of mould cells in the air at workposts enhances the risk of workers' exposure to mycotoxins.

[Experimental silicosis. I. Fibrogenic effect of synthetic amorphous silica]. / Doswiadczalna pylica krzemowa. I. Dziallanie zwlokniajace syntetycznych krzemionek bezpostaciowych.

Fibrogenic properties of two dusts of synthetic hydrated amorphous silicas, Ze-O-Sil (French production) and Arsil (Polish production) were studied. Experimental silicosis was induced by intratracheal administration to rats of a single dust dose (50 mg in 0.6 ml NaCl). Fibrogenic properties were tested 3, 6, 9 months after administration of the dust. X-ray diffraction and chemical tests did not reveal any form of crystalline. Si02 in the composition of the investigated dusts. The dusts tested as compared with quartz, were characterized by a great solubility up to 211 mg/l, which made the dust excretion from the lungs easy; after 6 month-experiment approximately 1.2 mg of Arsil dust and about 28 mg of quartz dust residue was found. Fibrogenic properties of Arsil dust, represented by wet lungs weight increase and hydroxyproline content in lungs, were more pronounced than those of Ze-O-Sil. Hydroxyproline content 3 months after administration of Arsil, Ze-O-Sil, TiO2 and weak quartz amounted to 7.3 mg, 5.1 mg, 3.8 mg and 6.0 mg, respectively. Histological and ultrastructural investigations demonstrated that disseminated, multifocal granulomas were the basic reaction to both dusts; no clear histological signs of cytolytic action on the cells of dust granulomas were found. In the lungs no silicotic nodules or degeneration of changes were revealed. Neither biochemical tests nor histological examinations revealed a progressive development of fibrous connective tissue. In result of the studies the authors suggest 2 mg/m3 as a MAC value for Arsil dust instead of 10 mg/m3--the value which has been hitherto used.

[Experimental silicosis. II. Fibrogenic effect of natural amorphous silica]. / Doswiadczalna pylica krzemowa. II. Dzialanie zwlókniajace naturalnych krzemionek bezpostaciowych.

Fibrogenic effect of two natural amorphous silica dusts-diatomite from deposits near Leszczawka (Poland) and silica earth (from the USA) was tested on the rats. Pneumoconiosis was produced by intratracheal introduction of 50 mg dust, at a single dose. Fibrogenic effect was assessed after 3, 6 and 9 months after introduction of dust. Analysis of diatomite dust carried out with X-ray diffraction method showed the presence of quartz in a quantity not exceeding 5%, while in silica earth dust from the USA no silica critalline structures were found. Development of fibrogenic changes in lungs of the rats assessed with hydroxyproline (collagen) increase and weight increment of wet lungs was small. The increment of the indices was twice higher as compared with their increment found in the lungs of control animals but lower than in the rats which were given cristalline silica dusts. In histopathological examinations no progressive lung fibrosis was found though some signs of destruction and necrobiosis in some cells were noticed.