Variation in urban and rural water fluoride levels in Ontario.

OBJECTIVE To compare levels of water fluoridation in urban and rural distribution systems in Ontario. METHODS A random sample of 17 urban and 17 rural municipalities was taken from a list of 445 municipalities. The Ontario Ministry of the Environment (MOE) website was used to identify the water treatment plants that supply these municipalities, and water quality reports published by each of these distribution systems for 2007 were collected. For municipal distribution systems without published reports, staff were contacted directly. RESULTS Far more urban distribution systems (82%) fluoridate their water compared with rural systems (18%). Most urban water suppliers (14 of 17) meet the 2000 MOE fluoride level standard of 0.5-0.8 mg/L, a range that includes the recently adopted Health Canada standard of 0.7 +/- 0.1 mg/L. Only 3 of 17 rural distributors artificially fluoridate their water and 11 of 16 supply suboptimal levels of fluoride. CONCLUSION Most Ontarians who live in rural areas receive levels of fluoride that are outside MOE standards. Urban water distribution systems that regulate their fluoride content are compliant with the range recommended in 2000. The communal water supplies of some rural residents of southwestern Ontario contain levels of natural fluoride that are well above the standard for artificially fluoridated water.