Document Yry4YjbxxQ2xmgV5zEExJ1a2k

intake water* The average background level of asbestos fibre concentrations In the water distribution systems in the Great L-ake Basin was 1.6 x 10^ fibre/ liter and 90% of the areas tested-.at <3 x 10 fibre/1. of the various Canadian studies# only at Ottawa and Toronto were samples taken by different investigators at different times. Ratios between the counts ranged from about 2 to 14. Ratios in samples taken at Niagara Tails and Thun* dcr Bay in different years ranged from about 1 to 5. Variability of the counts was within a factor of 2 or 3. Comparison of the effects of filtration in a water treatment plant are available for Windsor. 3n Windsor the reduction was as much as 90%. Fang (1975) recorded up to 99.8% rcmoyel by flocculation using 10 ppm fcrrichloride and 1 ppm polyelectrolytc at pH * 7.6. Continued drinking water sampling programs of the Canada Centre for In land Waters produced additional results.in Nay- 1974. In the Northern Ontario mining/milling area at Timmins (Natogani River) untreated water had a concen tration of 3.78 x 10^ and treated water 0.761 x 10^ fibres/1. At the Union treatment plant in Leamington on Lake Erie values were 2.17 end 5.15 x 306 (untreated) and 0.957 x 10 (treated). The American Waterworks Association Research foundation published "h study of the problem of asbestos in water* in September 3974 (13). A facsimile of report no. E404-79 Of the Dohn-Manville Research and Engineering Centre con cerning the removal of chrysotile fibre from the inner walls of asbestos cement pipe by potable water in water systems has been incorporated. Two municipal systems were selected: Malvern, Pennsylvania and Glendolc, Arizona. Beth sys tems utilised well water sources. The Malvern well v:as drilled in a serpentine rock belt containing chrysotile fibre while the Glendale system was outside any scrpentinc-bcaring area. Table 6 gives some characteristics and data sum mary. Statistical analyses of the fibre level data Faulted In an average of all well site samples for Malvern of 0.04 ug/l and 0.C05 ;.g/L for Glendale. There war. a 90 percent probability of an increase in fibre level between the well site and the domestic cite at both Malvern and Glendale. It was also shown * that t) the amc is pi< at Ma2< From % cxposei Table \ bipeds; diam3 eng area vate wate pipe wate tote Calc alke dj f t pH !\VCi <9/ Avoi <9/s The f Cj 1 ;? Ovc: f.'cm % appro: I *001 0751 PRODUCED BY FORD