Which authority sets the limits for the amount of ozone allowed in treatment plants?

The authority responsible for setting the limits for the amount of ozone allowed in treatment plants is the Environmental Protection Agency (EPA). The EPA establishes standards and regulations related to the use of ozone in drinking water treatment as part of its mission to protect public health and the environment. This includes guidelines for the safe use and application of ozone, a powerful oxidizing agent that can effectively eliminate pathogens and contaminants in water.

While the other agencies mentioned have their specific areas of oversight (the CDC focuses on public health issues, OSHA covers workplace safety, and the FDA is concerned with food and drug safety), the EPA is the relevant authority for water treatment concerning ozone levels. Therefore, the correct choice is linked to the EPA's regulatory role in ensuring that the ozone levels used in treatment do not pose a risk to public health or the aquatic environment.