---
kind: "section"
citation: "21 C.F.R. § 173.300"
title: "21"
number: "173.300"
heading: "Chlorine dioxide."
url: "https://uscodex.org/cfr/21/173.300"
---

# §173.300. Chlorine dioxide.


Chlorine dioxide (CAS Reg. No. 10049-04-4) may be safely used in food in accordance with the following prescribed conditions:

- (a)
  - (1) **The additive is generated by one of the following methods—**
    - (i) Treating an aqueous solution of sodium chlorite with either chlorine gas or a mixture of sodium hypochlorite and hydrochloric acid.
    - (ii) Treating an aqueous solution of sodium chlorate with hydrogen peroxide in the presence of sulfuric acid.
    - (iii) **Treating an aqueous solution of sodium chlorite by electrolysis.**
  - (2) The generator effluent contains at least 90 percent (by weight) of chlorine dioxide with respect to all chlorine species as determined by Method 4500-ClO2 E in the “Standard Methods for the Examination of Water and Wastewater,” 20th ed., 1998, or an equivalent method. Method 4500-ClO2 E (“Amperometric Method II”) is incorporated by reference in accordance with 5 U.S.C. [552(a)](/usc/5/552.md?p=a) and [1](/usc/5/1.md) CFR [part 51](/cfr/21/part51.md). You may obtain a copy from the Office of Food Additive Safety (HFS-200), Center for Food Safety and Applied Nutrition, Food and Drug Administration, 5001 Campus Dr., College Park, MD 20740, 240-402-1200, or the American Public Health Association, 800 I St. NW., Washington, DC 20001-3750. You may inspect a copy at the Dockets Management Staff (HFA-305), Food and Drug Administration, 5630 Fishers Lane, Rm. 1061, Rockville, MD 20852, 240-402-7500, between 9 a.m. and 4 p.m., Monday through Friday, or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.
- (b)
  - (1) The additive may be used as an antimicrobial agent in water used in poultry processing in an amount not to exceed 3 parts per million (ppm) residual chlorine dioxide as determined by Method 4500-ClO2 E, referenced in [paragraph (a)(2)](#a-2) of this section, or an equivalent method.
  - (2) The additive may be used as an antimicrobial agent in water used to wash fruits and vegetables that are not raw agricultural commodities in an amount not to exceed 3 ppm residual chlorine dioxide as determined by Method 4500-ClO2 E, referenced in [paragraph (a)(2)](#a-2) of this section, or an equivalent method. Treatment of the fruits and vegetables with chlorine dioxide shall be followed by a potable water rinse or by blanching, cooking, or canning.

## Notes

### Amendments

[60 FR 11900, Mar. 3, 1995. Redesignated at 61 FR 14245, Apr. 1, 1996, as amended at 61 FR 14480, Apr. 2, 1996; 63 FR 38747, July 20, 1998; 65 FR 34587, May 31, 2000; 70 FR 7396, Feb. 14, 2005; 81 FR 5592, Feb. 3, 2016; 88 FR 17723, Mar. 24, 2023]

### Authority

Authority: 21 U.S.C. 321, 342, 348.

### Source

Source: 42 FR 14526, Mar. 15, 1977, unless otherwise noted.

### Amendments

[60 FR 11900, Mar. 3, 1995. Redesignated at 61 FR 14245, Apr. 1, 1996, as amended at 61 FR 14480, Apr. 2, 1996; 63 FR 38747, July 20, 1998; 65 FR 34587, May 31, 2000; 70 FR 7396, Feb. 14, 2005; 81 FR 5592, Feb. 3, 2016; 88 FR 17723, Mar. 24, 2023]