Since the 1960s, most drinking water provided by public water systems

Since the 1960s, most drinking water provided by public water systems has had fluoride added, because research has demonstrated that adding fluoride to drinking water significantly reduces the occurrence of dental cavities in the populations served by those systems. However, manufacturers now add fluoride to toothpaste in amounts sufficient to provide the same level of protection against dental cavities as that provided by fluoridated water. Therefore, public water systems could now save the money formerly spent on water fluoridation without impacting the rate of occurrence of dental cavities in the communities they serve.

Which of the following, if true, would most weaken the argument?


A. The savings realized by public water systems would not be passed on to their customers but would be used for maintenance of and improvements to the system.

B. The cost of adding fluoride to toothpaste is much less than the cost of adding fluoride to the water produced by public water systems.

C. Fluoride is a commodity traded throughout the world, and the availability and price of fluoride can vary substantially due to economic and political events.

D. Fluoride toothpaste has been widely available since 1980, and recent studies have found higher levels of dental cavities in communities with unfluoridated water than in communities with fluoridated water.

E. Fluoride is colorless, odorless, and tasteless when added to water, but flavorings are added to fluoride toothpaste to deliver a taste that most people describe as pleasant.