National Organic Standards Board

Handling Subcommittee

Petitioned Material Proposal

Sodium chlorite, for the generation of chlorine dioxide gas

August 16, 2016

Summary of Petition (initial petition; petition addendum):

On October 8, 2015, the NOP received a petition to add chlorine dioxide (ClO2) (CAS #10049-04-4) dry 

gas to §205.605 (b) of the National List, nonagricultural (nonorganic) synthetic substances allowed as 

ingredients in or on processed products labeled as “organic” or “made with organic (specified 

ingredients or food group(s)).” The petition was revised November 30, 2015, revised again on December 

1, 2015 and forwarded to the Handling Subcommittee (HS) December 2, 2015.

This material is petitioned for use as an anti-microbial pesticide, sanitizer and/or disinfectant for fruits 

and vegetables. It is used for the direct treatment of fruits and vegetables during storage, transportation 

and food preparation applications with no requirement for post treatment rinse.

ClO2 gas is produced by impregnating zeolite with sodium chlorite and then activating the zeolite with a 

solid or liquid acid such as citric acid. An unspecified buffer is used.

ClO2 gas is used in post-harvest handling as a disinfectant to kill microorganisms. It is used in the direct 

treatment of vegetables, fruits and nuts to reduce spoilage and pathogenic organisms. In these 

applications the mode of ClO2 is a killing agent of these pathogenic organisms.

It is applied as a dry pure gas in closed containment. Treatment is done over several hours until the 

substance is completely consumed. ClO2 is converted to a chloride ion on the food products. In 

processing facilities, use of this material is used as an oxidizer, cleaner, deodorizing agent. It is applied as 

a dry pure gas at the point of need. Application rates vary and will convert to chloride ion when reacting 

with a wide variety of organic matter.

Summary of Review:

The HS’s initial review of the petition determined a need for revision by the petitioner. The HS found the 

initial petition sought to list a process rather than a material. If reviewed as petitioned, the HS would 

have reviewed several materials: sodium chlorite, zeolite acting as a carrier which is impregnated with 

sodium chlorite, acidic chlorine dioxide activators and related buffers. When used together as directed, 

these materials produce ClO2 gas.

The HS returned the petition to the petitioner April 18, 2016, with a request to revise to “sodium 

chlorite, for the generation of chlorine dioxide gas.” The HS believes a petition considering sodium 

chlorite for the particular use of gas generation is more consistent with how other sodium chlorite 

materials have been reviewed. It is very similar to the acidified sodium chlorite that is already on the list 

at 205.605(b), however that substance was petitioned as a solution, whereas this one is used as a 

fumigant gas. 

Therefore, the HS asked that the petitioner revise the petition to “sodium chlorite, for generation of 

chlorine dioxide gas.” If listed, certifiers and/or material review organizations will review the sodium 

chlorite product and the attendant components noted above. In its revision request, the HS also asked 
the petitioner if, as with use of other sodium chlorite materials, produce treated with ClO2 dry gas 

requires a potable water rinse sufficient that residual chlorine levels in the water shall not exceed the 

maximum residual disinfectant limit under the Safe Drinking Water Act.

The petitioner responded to the two HS requests above, resubmitting the petition as “sodium chlorite, 

for generation of chlorine dioxide gas.” In response to the question regarding need for a post-treatment 

potable water rinse, the petitioner noted that ClO2 gas rapidly reacts with produce surfaces and 

residues of concern, primarily ClO2 or chlorite ion, do not persist. Gas applications are different than 

water solution applications and precautionary potable rinses are not required1

.

Because of this material’s intended use as killing agent for pathogenic organisms, the petitioner’s 

formulated product is EPA registered. While the petitioner notes the target use of ClO2 gas is for 

vegetables and fruit, the EPA label for the formulated product only allows for use on stored potatoes. It 

is likely the petitioner seeks EPA allowance for broader use on fruit and vegetables as evidenced by their 

formulated product name “FruitGard®.”

As noted, acidified sodium chlorite is already listed at 205.605(b) and at the April 2016 NOSB meeting, 

the Board voted unanimously to add hypochlorous acid to 205.605(b). Like acidified sodium chlorite and 

hypochlorous acid, ClO2 gas has the potential to offer handling operations a material that has strong 

antimicrobial properties and is compatible with the fundamental principles of organic production.

Category 1: Classification 

1. Substance is for: X Handling 

2. For HANDLING and LIVESTOCK use:

a. Is the substance _____ Agricultural or X Non-Agricultural?

 Describe reasoning for this decision using NOP 5033-2 as a guide:

The substance is a mineral.

b. If the substance is Non-agricultural, is the substance _____ Non-synthetic or 

 X Synthetic? 

Is the substance formulated or manufactured by a process that chemically changes a 

substance extracted from naturally occurring plant, animal, or mineral sources? [OFPA 

§6502(21)] If so, describe, using NOP 5033-1 as a guide: 

The substance is not manufactured, produced or extracted from a natural source.

3. For LIVESTOCK: Reference to appropriate OFPA category

Is the substance used in production, and does it contain an active synthetic ingredient in the 

following categories: [§6517(c)(1)(B)(i)]; copper and sulfur compounds; toxins derived from 

bacteria; pheromones, soaps, horticultural oils, fish emulsions, treated seed, vitamins and 

minerals; livestock parasiticides and medicines and production aids including netting, tree wraps 

and seals, insect traps, sticky barriers, row covers, and equipment cleansers; or (ii) is used in 

production and contains synthetic inert ingredients that are not classified by the Administrator 

of the Environmental Protection Agency as inerts of toxicological concern? N/A

 1 Smith, D.J. et al. Chloroxyanion residues in cantaloupe and tomatoes after chlorine dioxide gas sanitation. Journal of 

Agricultural and Food Chemistry, 2015, 63, 9640-9649.
Category 2: Adverse Impacts 

1. What is the potential for the substance to have detrimental chemical interactions with other 

materials used in organic farming systems? [§6518(m)(1)]

ClO2 gas is a known oxidizer. However, when used as prescribed in the petition, there are no 

known interactions with other substances used in organic production.

2. What is the toxicity and mode of action of the substance and of its breakdown products or any 

contaminants, and their persistence and areas of concentration in the environment? 

[§6518(m)(2)]

ClO2 gas is not persistent and not a known bio-accumulative substance. When used in the 

intended use in an enclosed environment and allowed to degrade to ClO2 or the chlorite ion, 

there is no toxicity.

3. Describe the probability of environmental contamination during manufacture, use, misuse or 

disposal of such substance? [§6518(m)(3)]

Manufacturing sodium chlorite produces some byproducts, such as chlorine dioxide, which 

cannot be immediately released into the environment. This petition is for the use of sodium 

chlorite as chlorine dioxide gas. As noted above, if used as intended, the substance degrades to 

ClO2 or chlorite ions.

4. Discuss the effect of the substance on human health. [§6517 (c)(1)(A)(i); §6517 (c)(2)(A)(i); 

§6518(m)(4)].

As noted in the petition, the primary concern of exposure to the substance is acute toxicity 

related to inhalation where the substance is a known irritant to eyes and mucal membranes. 

Severe exposure (beyond amounts available by petitioned product) can result in chemically 

induced pneumonia and or death. However, if used as intended, the substance degrades to ClO2 

or chlorite ions.

5. Discuss any effects the substance may have on biological and chemical interactions in the 

agroecosystem, including the physiological effects of the substance on soil organisms (including 

the salt index and solubility of the soil), crops and livestock. [§6518(m)(5)] 

When used according to the petitioned use, applied at low levels and in secure conditions, the 

substance does not have adverse impacts in the agroecosystem.

6. Are there any adverse impacts on biodiversity? (§205.200)

When used according to the petitioned use, applied at low levels and in secure conditions, the 

substance does not have adverse impacts on biodiversity.

Category 3: Alternatives/Compatibility

1. Are there alternatives to using the substance? Evaluate alternative practices as well as nonsynthetic and synthetic available materials. [§6518(m)(6)]
There are some fluid alternatives such as sodium hypochlorite or chlorine dioxide in liquid form, 

the latter of which is already listed on the National List. However, presently there are no antimicrobial pesticides, sanitizers or disinfectants in gas form on the National List.

2. For Livestock substances, and Nonsynthetic substances used in Handling: In balancing the 

responses to the criteria above, is the substance compatible with a system of sustainable 

agriculture? [§6518(m)(7)]

N/A

Category 4: Additional criteria for synthetic substances used in Handling (does not apply to 

nonsynthetic or agricultural substances used in organic handling):

Describe how the petitioned substance meets or fails to meet each numbered criterion.

1. The substance cannot be produced from a natural source and there are no organic substitutes; 

(§205.600(b)(1))

The substance is a mineral not derived from a natural mined source.

2. The substance's manufacture, use, and disposal do not have adverse effects on the environment 

and are done in a manner compatible with organic handling; (§205.600(b)(2))

When used as intended, the substance degrades to ClO2 or chlorite ions that have no adverse 

effects on the environment.

3. The nutritional quality of the food is maintained when the substance is used, and the substance, 

itself, or its breakdown products do not have an adverse effect on human health as defined by 

applicable Federal regulations; (§205.600(b)(3)

Neither the nutritional quality of the food nor human health is impacted with use of ClO2 gas or 

its breakdown products of ClO2 or chlorite ions.

4. The substance's primary use is not as a preservative or to recreate or improve flavors, colors, 

textures, or nutritive value lost during processing, except where the replacement of nutrients is 

required by law; (§205.600(b)(4))

The petitioner describes the preservative qualities in the use of this substance. However, the 

preservative qualities are secondary to its primary action, which is a disinfectant used to kill 

microorganisms.

5. The substance is listed as generally recognized as safe (GRAS) by the Food and Drug 

Administration (FDA) when used in accordance with FDA's good manufacturing practices (GMP) 

and contains no residues of heavy metals or other contaminants in excess of tolerances set by 

FDA; (§205.600(b)(5))

Sodium chlorite, for the generation of ClO2 gas does not appear in the FDA GRAS inventory. 
However, ClO2 generated using sodium chlorite in calcined or sulfated kaolin clay2

, and ClO2 

generated from particles composed of sodium polyphosphate, magnesium sulfate, sodium 

silicate and sodium chlorite that are incorporated into low density polyethylene (LDPE) foodpackaging films appear in the FDA GRAS inventory3

.

6. The substance is essential for the handling of organically produced agricultural products. 

(§205.600(b)(6))

While other sanitizers and disinfectant substances appear on the National List, none are 

currently present in gas form. As a gas form, ClO2 reacts rapidly and completely thereby 

reducing or negating the need for de-chlorination of waste water streams. Liquid forms of ClO2 

mainly treat the rinse waters and are not as effective in treating microorganisms on produce. 

Dry gas applications appear to have greater effectiveness in penetrating coarse or porous 

produce. The use of ClO2 in gas form stands to reduce water usage.

7. In balancing the responses to the criteria in Categories 2, 3 and 4, is the substance compatible 

with a system of sustainable agriculture [§6518(m)(7)] and compatible with organic handling?

(see NOSB Recommendation, Compatibility with Organic Production and Handling, April 2004) 

Like acidified sodium chlorite and hypochlorous acid, ClO2 gas has the potential to offer 

handling operations a material that has strong antimicrobial properties and is compatible with 

the fundamental principles of organic production.

Category 5: Additional criteria for agricultural substances used in Handling (review of commercial 

unavailability of organic sources):

1. Is the comparative description as to why the non-organic form of the material /substance is 

necessary for use in organic handling provided? 

N/A

2. Does the current and historical industry information, research, or evidence provided explain how 

or why the material /substance cannot be obtained organically in the appropriate form to fulfill an 

essential function in a system of organic handling?

N/A

3. Does the current and historical industry information, research, or evidence provided explain how 

or why the material /substance cannot be obtained organically in the appropriate quality to fulfill 

an essential function in a system of organic handling?

N/A

4. Does the current and historical industry information, research, or evidence provided explain how 

or why the material /substance cannot be obtained organically in the appropriate quantity to fulfill 

 2 Tarantino, FDA Agency Response Letter GRAS Notice No. GRN 000161, 2005.

3 Rulis, FDA Agency Response Letter GRAS Notice No. GRN 000062, 2001.
an essential function in a system of organic handling?

N/A

5. Does the industry information about unavailability include (but is not limited to) the following?:

Regions of production (including factors such as climate and number of regions);

a. Number of suppliers and amount produced;

N/A

b. Current and historical supplies related to weather events such as hurricanes, floods, and 

droughts that may temporarily halt production or destroy crops or supplies;

N/A

c. Trade-related issues such as evidence of hoarding, war, trade barriers, or civil unrest that 

may temporarily restrict supplies; or

N/A

d. Other issues which may present a challenge to a consistent supply?

N/A

6. In balancing the responses to the criteria in Categories 2, 3 and 5, is the substance compatible with 

a system of sustainable agriculture [§6518(m)(7)] and compatible with organic handling? (see 

NOSB Recommendation, Compatibility with Organic Production and Handling, April 2004) 

N/A

Classification Motion: 

Motion to classify sodium chlorite, for the generation of chlorine dioxide gas as nonagricultural,

synthetic.

Motion by: Scott Rice

Seconded by: Jean Richardson

Yes: 7 No: 0 Abstain: 0 Absent: 1 Recuse: 0 

National List Motion: 

Motion to add sodium chlorite, for the generation of chlorine dioxide gas as petitioned at 

205.605(b)

Motion by: Scott Rice

Seconded by: Ashley Swaffar

Yes: 7 No: 0 Abstain: 0 Absent: 1 Recuse: 0