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Anthrax spore decontamination using hydrogen peroxide and peroxyacetic acid

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Current as of July 2007

Bleach, chlorine dioxide, ethylene oxide, hydrogen peroxide and peroxyacetic acid, methyl bromide, paraformaldehyde and vaporized hydrogen peroxide were pesticides used in federal decontamination responses to the bioterrorism attacks of October 2001. These attacks involved the intentional placement of Bacillus anthracis spores (the causative agent of the disease anthrax) into letters addressed to various locations on the East Coast of the United States. More information about biological threats.

This page describes the Agency’s actions with regard to the chemicals used in the anthrax spore decontamination activities. EPA temporarily approved these pesticides for sale, distribution, and use based on the remediation action plans submitted for each specific site and only in accordance with the requirements of each crisis exemption under Section 18 of FIFRA. These chemicals were not intended for use by the general public.

What is hydrogen peroxide and peroxyacetic acid?

Hydrogen Peroxide is an oxidizing agent that is widely used as a disinfectant because of its reactive properties. In the home, hydrogen peroxide can be found in diluted form (3 percent); this formulation may be used to treat human cuts and scrapes. Hydrogen peroxide for industrial uses has a concentration of 30 percent or greater.

Peroxyacetic Acid is also an oxidizing agent. Often mixed with hydrogen peroxide, peroxyacetic acid is used as a disinfectant and sanitizer, and is usually applied as a spray, or as a mop-on solution.

Registration of pesticides containing hydrogen peroxide and peroxyacetic acid

EPA first registered hydrogen peroxide and peroxyacetic acid as antimicrobial pesticides in 1977 and 1985, respectively. Both chemicals are approved only for indoor use on hard, non-porous surfaces. Use sites include:

Responding to emergencies under FIFRA

Under Section 18 of FIFRA, the EPA "may exempt any Federal or State agency from any provision of this Act if the Administrator determines that emergency conditions exist which require such exemption." To respond as rapidly as possible to the bioterrorism attacks, the Agency decided in 2001 to develop and issue the crisis exemptions itself.

To obtain a crisis exemption from EPA for the unregistered use of a pesticide against anthrax, anyone who needed to use an antimicrobial product to inactivate Bacillus anthracis spores at contaminated sites had to submit:

  1. a written request to the Agency listing the antimicrobial product(s) to be used and describing how, when and where they would be used;
  2. data demonstrating efficacy of the product against bacillus spores; and
  3. remediation, sampling, and monitoring plans specific to the location of use.

Before issuing the exemption, EPA would review the request and the supporting information and then determine whether the product could be used safely and effectively (i.e., cause "no unreasonable adverse effects").

If during this review any data were found to be deficient or missing, or any adverse human health or environmental concerns were identified, EPA could deny the exemption request.

If a crisis exemption was issued and EPA determined that use of the product would be needed beyond the 15 day use period, EPA would complete an application for a public health exemption, allowing the crisis exemption to continue in effect until the application was either withdrawn or EPA issued a public health exemption.

Crisis exemptions for hydrogen peroxide and peroxyacetic acid

EPA reviewed data related to the safety and effectiveness of using hydrogen peroxide and peroxyacetic acid for inactivation of Bacillus anthracis spores. Published scientific data demonstrated that hydrogen peroxide and peroxyacetic acid would reduce bacterial spore populations under specific conditions including concentration, pH, and contact time.

EPA determined that the product could be used safely and effectively, and that no unreasonable adverse effects would occur from the requested uses.

Based on this review, EPA issued crisis exemptions for the limited sale, distribution, and use of four registered products containing both hydrogen peroxide and peroxyacetic acid

  1. "Oxonia Active" (EPA Registration Number 1677-129)
  2. "KX-6049" (EPA Registration Number 1677-158)
  3. Actril Cold Sterilant (EPA Registration Number 52252-7)
  4. Spor-Klenz Ready to Use (EPA Registration Number 52252-7-1043

EPA also issued a crisis exemption for the unregistered product Virex STF, which contains only hydrogen peroxide.

Under these crisis exemptions, the listed products could only be sold or distributed to employees of federal, state, or local government agencies, and the U.S. Postal Service for use in anthrax decontamination.

Use of hydrogen peroxide and peroxyacetic acid for decontamination

Applications of the five pesticide products mentioned above were limited to buildings or treatment sites identified by EPA or other federal, state, or local governmental authorities, or the United States Postal Service. Applications were conducted according to use instructions from federal, state, or local emergency response personnel following a plan that included the following steps:

These steps applied to facilities where the treated surfaces would be reused or the facility would be re-occupied. These steps did not necessarily apply to wastes or debris intended for disposal.

Because the products differed in formulation, the directions for use also differed. The specific conditions of use for these products follow:

Oxonia Active and KX-6049:

Actril Cold Sterilant and Spor-Klenz ready to use:

Virex STF:

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