Document DDaq5qx0NyrZGwBMgE3nKVd0d

103 intestinal cancers in the general public by ingestion of asbestos fibres from drinking water. 4. There are no numerical data defining a dose-response relationship with re gard to peritoneal roc3thnllcr.'.&, neither on the proportion Of lon9 to short fibres in potable water. The risk for the general population can not adequately be assessed. However, there it no evidence of increased prevalence of peritoneal mesothelioma jn relation to the use of asbestos cement pipes fov drinking water, already in use for over 40 years in USA and Buropv. Nor has there been evidence of excess gastrointestinal tu mours in the population of Asbestos and Thetford in Canada, where the water and certainly the ambient air was contaminated for several years. However, the usage of asbestos cemcnt.'pjpes is so widespread that it is hardly possible any more to find a large enough control group of subjects who have not drunV. water transported through such pipes (Elzengo et al 1914) . Because gar.trointestir.al tumours are much less specific as regards causative asbestos exposure than for example pleural mesotheliomas, epi demiological studies have tc> be based upon large groups out of the general population. Because of this low specificity any relationship with asbes tos in drinking water will be very difficult to prove or to disprove. The approach mentioned in 3 above (extraj>ol&tion from occupational to pub lic health) is based upon the assumption that the distribution of fibre length and diameter in both situations is comparable. However, this may be seriously questioned; relatively many more short fibres are present in true environmental exposure. This review of studies on the potential risks of ingested asbestos sup ports the conclusions arrived at by the lARC-Working Conference on Biological Effects of asbestos (1973), that such evidence as there is dics noi indicate any.i.ncr^eased^j_i_sk resulting from asbestos fibres present in water. be\/X*Qes, food and in the fluids used for administration of drugs. There is a potential health hazard, not associated with (para-)occupationel or neighbourhood exposure, but as such directly relevant for public health: parenteral administrati on. Sclikoff (1973b) pointed to a potential risk in allergy desensitiration treatment: a syringe found widely useful is constructed with an asbestos-filled plunger, and therefore loose fibres may be injected eooi 0796 PRODUCED BY FORD