GRE Reading Comprehension
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Source: XDF
The success of fluoride in combating dental decay is well established and, without a doubt, socially beneficial. However, fluoride's toxic properties have been known for a century. In humans excessive intake (for adults, over 4 milligrams per day) over many years can lead to skeletal fluorosis, a well-defined skeletal disorder, and in some plant species, fluoride is more toxic than ozone, sulfur dioxide, or pesticides.
Some important questions remain. For example, the precise lower limit at which the fluoride content of bone becomes toxic is still undetermined. And while fluoride intake from water and air can be evaluated relatively easily, it is much harder to estimate how much a given population ingests from foodstuffs because of the wide variations in individual eating habits and in fluoride concentrations in foodstuffs.
The passage suggests that it would be easier to calculate fluoride intake from food if
- A adequate diets were available for most people.
- B individual eating habits were more uniform
- C the fluoride content of food was more varied
- D more people were aware of the fluoride content of food
- E methods for measuring the fluoride content of food were more generally agreed on