Which organization regulates fluoride levels in bottled water?

The Federal Drug Administration (FDA) is the organization responsible for regulating fluoride levels in bottled water. This regulation falls under the FDA's oversight of food and beverages, which includes bottled water as a category. Bottled water is classified as a food product, and the FDA establishes standards to ensure safety, including permissible levels of various substances such as fluoride.

In contrast, the Centers for Disease Control and Prevention (CDC) focuses on public health and disease prevention but does not directly set regulations for bottled water. The Environmental Protection Agency (EPA) regulates drinking water standards for public water systems, while the World Health Organization (WHO) provides international guidelines and recommendations but is not a regulatory body in the same sense as the FDA. Thus, the FDA's role in regulating the quality and safety of bottled water makes it the correct answer for this question.