A new study from the University of Kent has found that Britons who live in areas with higher water fluoride levels are significantly more likely to develop thyroid problems.The debate has long raged on about whether adding fluoride to drinking water is a boost or a bane. The US Centers for Disease Control has dubbed water fluoridation one of the ten greatest public health achievements of the 20th century, due to its cavity-reducing properties and measurable improvement of the nation's dental health.…