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Use of the Term “Shock” in Swimming Pool, Hot Tubs, and Spa Products

June 21, 2007

The American Chemistry Council has requested clarification of the term “shock” on swimming pool, hot tubs, and spa labeling. Variations exist between consumers and professional groups concerning the definition of the term “shock” as it relates to swimming pools, hot tubs and spas. The Agency considers the definition of “shock” to imply pesticide control over microorganisms which requires FIFRA registration. EPA has determined that shock treatment and super-chlorination are terms usually used to describe claims to kill or control visible algae growth. Claims to kill, prevent or control algae or bacteria are pesticide claims. 

In previous years, EPA has taken enforcement actions involving the sale of unregistered products that were marketed to control algae and bacteria in swimming pools, hot tubs and spas. Previous Agency enforcement determinations have indicated that the term “shock” is inherently a pesticide claim. 

Under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), pesticide products must be registered with the Environmental Protection Agency (EPA) and bear EPA-approved labeling before they can be lawfully sold or distributed in the United States. These requirements reduce risk of misuse and screen out products that may present an unreasonable risk to public health and the environment. Products claiming to prevent, destroy, or repel pests, including bacteria and viruses, are considered pesticides.

Products that make claims for the prevention, removal, control, or elimination of algae or bacteria are considered pesticides. Products bearing implied or explicit public health claims against human pathogens are pesticides. The following are examples of pesticide labeling claims related to swimming pools, spas, and hot tubs:

  1. Shock.
  2. Super-chlorination.
  3. Non-chlorine Shock.
  4. Premium Grade Shock.
  5. Antibacterial.
  6. Bactericidal.
  7. Algicidal.
  8. Improves water quality through the reduction of microorganisms.
  9. Eliminates organic waste.
  10. Effectively reduces organic contamination.

Conversely, products that do not make direct or implied pesticide claims are not considered pesticides. If the product labeling does not state or imply that it prevents, destroys, controls, or eliminates pests or microorganisms, it may not require FIFRA registration. The following are examples of labeling claims that the Agency may consider to be acceptable as non-pesticidal provided no other pesticide claims appear on the product labeling or in conjunction with the marketing of the product in question:

  1. Oxidizer.
  2. Shock-oxidizer.
  3. Shocks non-living matter.
  4. Shocks non-living swimmer waste.
  5. This product is not intended to control microorganisms.
  6. This product does not sanitize or disinfect.
  7. Cleans swimming pools, hot tubs or spas.
  8. Clarifies cloudy water by oxidizing non-living organic and inorganic particles.
  9. This product improves water clarity.
  10. Oxidizes non-living swimmer waste.
  11. Clears cloudy water.
  12. Restores water clarity.
  13. Oxidizes non-living contaminants that cause cloudy water.
  14. Eliminates odors.
  15. Eliminates/Oxidizes/Controls/Reduces non-living organic waste.
  16. Eliminates/Oxidizes/Controls/Reduces non-living organic contaminants.

Statements which clarify the intent of the product are encouraged by the Agency. The Agency recommends inclusion of the following statements on the label of oxidizer or shock-oxidizer products: “This product is neither a sanitizer nor algicide. For control of microorganisms in pool, spa, or hot tub water, or algae control, use an EPA registered product.”

If you have questions concerning any of the criteria outlined in this letter, or are not sure if a product requires EPA registration, the Agency encourages you to request a written opinion from the Antimicrobials Division. For more information, contact the Antimicrobials Ombudsman (

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