Chlorine Dioxide

CHLORINE dioxide shall only be used for remediation for water quality issues when the AQUATIC VENUE is closed and BATHERS are not present.

CHLORINE dioxide is not presently registered by the U.S. EPA for any use in recreational water. Since it is not registered, the use of chlorine dioxide as an antimicrobial treatment (e.g. disinfectant, sanitizer, algaecide, slimicide, biofilm control agent) in recreational water, or any market claims that implies chlorine dioxide provides any biological control in recreational water is a violation of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). Chlorine dioxide has been granted registration by the U.S. EPA as an antimicrobial for other applications, including drinking water. One product was previously registered as a slimicide for use in PHMB-treated recreational water but that registration has since been dropped. The U.S. EPA Registration Eligibility Document (RED) on chlorine dioxide is available from the US EPA website at http://www.epa.gov/oppsrrd1/REDs/CHLORINE_dioxide_red.pdf. The U.S. EPA posts PDF copies of accepted product labels on the National Pesticide Information Retrieval System website (http://ppis.ceris.purdue.edu/#). Product claims for uses and concentration may be verified by reading the PDF of the U.S. EPA stamped and accepted copy of the product use directions at this website. Chlorine dioxide has the potential to be an alternative remediation tool, but it has not yet been approved by EPA for this use and can be hazardous unless appropriate SAFETY protocols are included. CDC has determined that chlorine dioxide can be used instead of HYPERCHLORINATION for rapid inactivation of Cryptosporidium (3-log inactivation in 105 to 128 minutes) and that this effect was synergistically enhanced with a FREE CHLORINE RESIDUAL in place.³⁷⁵ This suggest chlorine dioxide might be very useful in remediating contaminated AQUATIC VENUES in the absence of BATHERS. Potential for Using Chlorine Dioxide in the Future During the drafting of this section of the MAHC, several members of the MAHC had interest in using chlorine dioxide as a remedial treatment for Cryptosporidium and Legionella. Recommendations for this were not pursued because of the status of chlorine dioxide under FIFRA. Published studies, including the EPA Alternate Disinfection Manual for drinking water shows that chlorine dioxide may be a very rapid remedial treatment for these life-threatening pathogens. If the registration status of chlorine dioxide changes, the MAHC suggests that chlorine dioxide use should be reconsidered. Provisions for Emergency Use of Chlorine Dioxide Even though chlorine dioxide is not presently registered for use in recreational water, it is possible to use it under Section 18 of FIFRA. An example of this would be the remediation of a Legionella-contaminated health club SPA where other treatments were proven to be ineffective. More information on emergency exemptions can be found on the U.S. EPA website at http://www.epa.gov/opprd001/section18/. Because of the lack of existing use directions and potential for occupational exposure, it is strongly suggested that a certified industrial hygienist be included in developing emergency treatment plans.