Tap water in Canton is now treated with fluorine to prevent tooth decay. It has a fluorine content of 0.9 mg./litre.* * *Northeast China's Liaotung Peninsula reports excellent harvests of edible...
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Tap water in Canton is now treated with fluorine to prevent tooth decay. It has a fluorine content of 0.9 mg./litre.* * *Northeast China's Liaotung Peninsula reports excellent harvests of edible...