Document MJpNeXaqQd5jbKV3VyNz7GYo7

- 12} - they rely too heavily on assumptions, e.g. similar distribution of fibre lengths in occupational and ambient air; similar respiratory volume; it is clear that a simple extension of the principles of campling within factories to the general environment is inappropriate, both because of the very much lower concentrations in air and water, and the need to identify positively the typo of mineral er.d sire distribution 0/ fibres; they compare an environmental quality standard for preventing malignancy with an occupational permissible lir.it for preventing asbestosisj - in sampling air (and water) in the ambient envi ronr-c-nt the ratio of as bestos to other fibrous particle''- may be too low to permit neglecting the non-asbestos minerals, as is normally done in the factory and the mine. Nevertheless they both indicate that ambient air exposure of the general public, except in case of para-occupational and neighbourhood exposure, is an or.V.-r of two or three maqni tudes spin) 1 er than i n wcl 1 control 1 cd industry. It svvms possible that a factor of 1000 or more piay be large enough to reduce 1' risk of tumours to a negligible level compart-! to other risks. The conclusion given before that it is not possible to core to a quanti tative assessment of the risk of malignancies for the general public, is not contradicted by the two approaches mentioned. . 3 r. 1972 the hdvisory ComrsJ t tce_ on Asbestos Cancers to the pi rector of the Jj.i..-notional Agency for Kcsearch on Cancer (1ARC 1973) discussed the follow ing qn-r.Mion: "is there evidence of an increased risk of mcsothclial cancers at low levels of exposure to asbestos, such as have been encountered by the gi.n.r.i 1 population in urban areas?" The answor was: "There is evidence of a:. O'jboc i at j on of mesothcliol tumours with air pollution in t.hc neighbourhood of crocidolite mines and of factories using mixtures of asbestos fibre 7 n*/ evidence- relates to conditions many years ago. Thorc is evidence 01 no ex'-c*:?- risk of mesotheliomas from asbestos ait pollution which has existed in If '- neighbourhood of ebrysotile and amosite miner-. There arc- reported dif fer. i.-'-cw between urban and rural areas, the causes of which have not been es tablished. There is no evidence of a risk to the general public at present" The data discussed in this report, not available at the time of the byon Confei wt.ee* in 1972, have not brought conclusive evidence that the conclusion of the Advisory Committee has to be changed. This report has stressed that fto&i os]* PROmiCF.n FY FORD