Document wq8YZ9jMXX5KD6En62pkpXNQJ

70 - OCCUPATIONAL ASBESTOS EXPOSURE crcrccsfccEKECCEt CKtKcsetieevMM In order to get any information about the question "who has been exposed to asbestos**, it is necessary to consider the different biological methods that can be used to answer this question. in principle the available methods 1. the demonstration of asbestos fibres in the human body or its excreta (e.9. sputum)^ 7, the demonstration of asbestos bodies (arrbestos fibres surrounded by pro tein and iron coating) in the human body or its excreta. Special attention should be given to the problem of the specificity of these bodies? 3. the demonstration either clinically cr at autopsy of pathological proces ses, which are considered to be p.-.th-.jne-or.ic, highly specific or highly suggestive of past asbestos exposure. To this group of processes belong esb^stosis, pleural plaques and several kinds of malignant tumours. hr;.*r. t> tesJU bres Only a limited number of studies on asbestos fibres in the human body or its excreta are available. Single fibres with a length less than 5pm and a diameter less than 3pm are too small to be recognised by the 1 ichtmicroscopc, but bundles of fibres can be seen by this method in some cases. In most cases these bundles or aggregates cf fibres are still too small to be seen by the 1 ightmicroscopc. This means that the 1 igh.tr.i croscopc can show only a small percentage of all fibres? a :.*.gative rsult does not prove the absence of asbestos. Phasc-contranvr.j cro: copy has a'so bi-vn used (Otto 1969) but the limitations mentioned tsve arc vilid for this method al so. As the mciphclogy with these r.'.uni f i cat i^ns is not specific, those methods are r.ot ipecific for asbestos, but they cun be used by those who only wish to have a total count of fibres of lengths greater than 5ym (bee 1974)(sec chapter IV). These 15mi U-.tirns c.re not present in the ca ^ crosccpy cc.;:.bi ned with ! :C tren <li f f racti on for example- .v ,, ey (1972, 1973). He studied lung tissue and slides of lung tissue cf mesothelioma pa tients and controls. In this last group which contains a mixture of contio) cases from Croat Britain, Sweden and the Netherlands he found asbestos fibres in 65 out of 135 cases. In 30 cases one of the amphiboles (probably croci- j i I i i do] to who asb asb gcr roc fro moa (mo and tio gro Nevferido> in . ice: on : j:-,3 : he the; }. fi b* vi) . > r-C *00] 0763 PfeODl TPFn RV PORn