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1.
Ann Occup Hyg ; 45(5): 365-70, 2001 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-11418086

RESUMO

The aim was to produce a radiolabelled fibre suitable for long-term carcinogenesis studies. To this end, we have successfully synthesised erionite fibres by a method adapted to incorporate (57)Co into the crystal framework. Morphologically the fibres are straight, of median length 2.5 microm, with 11% of fibres > 8 microm long, and median width 0.32 microm. These values are comparable to natural Oregon erionite. Autoradiography confirmed that the (57)Co was associated with the fibres themselves. The stability of the radiolabel in vivo was examined by instilling 1 mg of synthetic erionite into the lungs of F-344 rats. About half of the thoracic content of (57)Co was cleared in the first week, and over the following 5 weeks the remainder was cleared slowly with a half-time of 120 days. After 6 weeks the urinary excretion of (57)Co was only 0.054% of the initial lung content per day. This represented fibre dissolution plus any leaching of (57)Co from the fibres. It can be concluded that the (57)Co is bound into the erionite fibres with sufficient stability in vivo for studying their effects in relation to translocation to the pleura.


Assuntos
Zeolitas/síntese química , Animais , Autorradiografia , Fibras Minerais , Ratos , Ratos Endogâmicos F344
2.
Ann Occup Hyg ; 36(2): 115-29, 1992 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-1530229

RESUMO

Three grades of ceramic fibre have been examined for their composition, structures and biological effect in several in vitro assay systems. The fibres were examined in the 'as-manufactured' state and after heating at 1200 and 1400 degrees C. Devitrification of the fibres at 1200 degrees C probably gave mullite crystals on the surface and caused the formation of the high-temperature form of cristobalite and, in zirconia grade fibres, the high-temperature, tetragonal form of zirconia as well. Further heating changed surface structure and led to zircon production in the zirconia fibres. Heating reduced the affinity of the fibres for the surface of V79-4 cells and lowered fibre toxicity toward these cells and towards macrophage-like cells. These changes in toxicity were not due to a reduction in the fibrous nature of the materials although they did become more brittle and powders prepared from them contained more isometric particles than those from as-manufactured materials. This suggests that the devitrification occurring during the use of these materials in high-temperature environments will not necessarily enhance their adverse biological activities despite the production of one phase of crystalline silica.


Assuntos
Silicatos de Alumínio/química , Cerâmica/química , Temperatura Alta , Silicatos de Alumínio/toxicidade , Animais , Linhagem Celular , Células Cultivadas/efeitos dos fármacos , Cerâmica/toxicidade , Cricetinae , Cristalização , Camundongos , Relação Estrutura-Atividade , Propriedades de Superfície , Zircônio/química , Zircônio/toxicidade
3.
Ann Occup Hyg ; 36(2): 173-81, 1992 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-1530232

RESUMO

A small-scale study was carried out on friction and reinforcing materials containing Kevlar and glass fibres. Kevlar, an aramid fibre, and synthetic silicate fibres are being increasingly used in brake pads and shoes for cars and trucks. The fibre levels given out under abrasion in the laboratory were low. As a comparison, a brake pad containing asbestos was also tested and gave high levels of airborne fibres.


Assuntos
Amianto/análise , Poeira/análise , Automóveis , Filtros Microporos , Tamanho da Partícula
4.
IARC Sci Publ ; (90): 74-80, 1989.
Artigo em Inglês | MEDLINE | ID: mdl-2545619

RESUMO

A sample of erionite, a fibrous zeolite, was modified by milling to reduce the number and length of the fibres and by extraction with cyclohexane. The in vitro activities of this mineral were found to depend on the presence of long fibres. The erionite contained fewer of these fibres than the UICC asbestos samples but, unlike these materials, erionite can cause the transformation of C3H 10T1/2 cells. Erionite did not increase the activities of benzo[a]pyrene in this cell transformation assay. The cytotoxic activities of both asbestos and erionite have a similar dependence on the number of long fibres. Extraction with cyclohexane did not affect the activity of erionite.


Assuntos
Silicatos de Alumínio/toxicidade , Carcinógenos , Animais , Transformação Celular Neoplásica/etiologia , Células Cultivadas , Fibroblastos/patologia , Camundongos , Camundongos Endogâmicos C3H , Oregon , Tamanho da Partícula , Zeolitas
5.
IARC Sci Publ ; (90): 277-90, 1989.
Artigo em Inglês | MEDLINE | ID: mdl-2744827

RESUMO

The UK Health and Safety Executive, in conjunction with the Department of the Environment, has carried out a number of surveys of airborne asbestos fibre concentrations in buildings. All samples have been collected on membrane filters and analysed by analytical transmission electron microscopy. Four categories of buildings under normal occupation have been investigated; non-domestic buildings containing sprayed or trowelled asbestos, domestic buildings containing sprayed asbestos or asbestos plaster, buildings with warm air heaters containing asbestos and buildings without asbestos materials. A number of buildings have also been surveyed during and after the removal of asbestos materials. The choice of measurement indices and analytical procedures is reviewed, before measurements are compared in terms of the concentration of asbestos fibres greater than 5 microns long. The decision whether to remove asbestos from occupied buildings is discussed with reference to the associated cost and risk. In the present survey, management of undamaged asbestos appeared preferable to large-scale removal.


Assuntos
Poluentes Atmosféricos/análise , Amianto/análise , Arquitetura de Instituições de Saúde , Materiais de Construção , Reino Unido
6.
IARC Sci Publ ; (90): 319-22, 1989.
Artigo em Inglês | MEDLINE | ID: mdl-2744831

RESUMO

Levels of airborne man-made mineral fibres (MMMF) were measured during the insulation of lofts and after the disturbance of the insulation wools. Transmission electron microscopy was used for the analysis. Generally, the personal samples showed fibre levels of up to 0.7 f/ml, whereas static samples showed fibre levels of 0.05 f/ml in the lofts. Little contamination of living space occurred during these operations.


Assuntos
Poluentes Atmosféricos/análise , Substâncias Perigosas/análise , Habitação , Minerais/análise , Materiais de Construção , Microscopia Eletrônica de Varredura , Tamanho da Partícula , Reino Unido
8.
Br J Exp Pathol ; 67(2): 289-96, 1986 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-3011058

RESUMO

The in vitro activities of a highly carcinogenic potassium octatitanate fibre (Fybex) have been investigated. This material caused a low level of in vitro transformation in C3H10T1/2 cells and is thus more active in this assay than the UICC amphibole asbestos samples but less active than fibrous erionite. This ranking is in accord with carcinogenicity in vivo. However Fybex had no detectable activity in an assay for DNA damage based on the S1-nuclease sensitivity of the DNA from exposed cells. In that assay crocidolite asbestos was more active than either of the more carcinogenic dusts. It is suggested that the activities of amphibole asbestos in assays for genetic toxicity may depend on the production of free radicals via a catalytic reaction requiring the presence of transition elements which are either not present or only present at low concentrations in erionite or Fybex. This type of reaction may not be related to in vivo carcinogenicity. The action of fibrous dusts against macrophage-like cells, measured in this instance by the release of arachidonic acid, remains one of the best measures of biological activity.


Assuntos
Transformação Celular Neoplásica/efeitos dos fármacos , Titânio/farmacologia , Silicatos de Alumínio/farmacologia , Animais , Ácido Araquidônico , Ácidos Araquidônicos/metabolismo , Amianto/farmacologia , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , DNA/análise , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Camundongos , Zeolitas
9.
Am Ind Hyg Assoc J ; 46(5): 257-61, 1985 May.
Artigo em Inglês | MEDLINE | ID: mdl-4003277

RESUMO

A survey was conducted to determine the size distribution of airborne man-made mineral fibers in three factories using bulk materials which contain many fibers with diameters less than 0.3 micrometers. Personal samples were taken in two of the factories visited. In all the cases a full length and diameter distribution, determined by transmission electron microscopy, are presented. Median diameters ranged from 0.1 to 0.3 micrometers and, as a result, a substantial proportion of the fibers would not be detected using light microscopy or scanning electron microscopy even for fibers longer than 5 micrometers.


Assuntos
Poluentes Atmosféricos/análise , Minerais/análise , Microscopia Eletrônica , Tamanho da Partícula
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