National Organic Standards Board

Livestock Subcommittee Petitioned Material Proposal 

Acidified Sodium Chlorite (ASC), Sodium Chlorite, Acidified

January 27, 2014 

Summary of Proposed Action:

Sodium Chlorite, Acidified - Acidified Sodium Chlorite, (ASC) - CAS#13898-47-0 (Chlorous 

Acid), 7758-19-2 (Sodium Chlorite) – is a synthetic substance petitioned to be added to the 

National List at 205.603(a) as a disinfectant, sanitizer and medical treatment, and at 205.603(b) 

for use as a topical treatment, for the intended use on organic livestock as a pre and post teat 

dip. 

The Livestock Subcommittee proposes to recommend this material be added to the National 

List.

Background:

The Petition, dated 4/30/12, was received by the NOSB, and a Technical Report was requested. 

The Technical Report was received in May 2013 and the Livestock subcommittee developed a 

Proposal with recommendation not to list this materials based on issues of non-essentiality - 

Proposal and Recommendation dated August 30, 2013. 

Acidified sodium chlorite was considered at the NOSB meeting in April 2014 and tabled based 

on public comment and returned to the subcommittee for further review.

ASC was reviewed but no revisions were made - Proposal and Recommendation dated January 

7th, 2014.

On July 29 2014 and July 31 2014 the Petitioner submitted further detailed and lengthy 

documentation, with References, to address concerns raised by the NOSB and the public.

On January 7 2015 the subcommittee, as part of Sunset Review of Iodine, received a Technical 

Report on Iodine, an ingredient common in teat dips. This report provides comparative data on 

ASC and other teat dips.

Discussion:

Preventive health care is an essential part of organic farming, and mastitis prevention through 

clean milking parlors and clean animals is always of paramount importance on a dairy farm. 

Organic farmers cannot use antibiotics and thus the use of pre-milking and post milking teat 

dips is a normal practice and may be the most critical factor in preventing mastitis. Mastitis is 

caused by several commonly found bacteria. Mastitis causes inflammation and infection and is 

painful to the animal. There are several teat dips available on the market, but some may be 

more irritating to the animal than others, and some bacteria may become resistant, and thus a 

broader array of teat dip ingredient choices for organic farmers seems essential.

Research indicates that alternative practices to teat dipping/spraying or udder washing are not 

advised, as the exclusion of a disinfecting step from a mastitis control program would 

significantly increase the likelihood of infection. 

Acidified Sodium Chlorite (ASC) was petitioned for use as a pre and post teat dip treatment in 

organic livestock production. ASC, also listed as Sodium Chlorite, Acidified, is currently on the 

Page 207 of 249
National List as an allowed disinfectant for direct food contact under 205.605(b). After reviewing 

the ASC petition, along with the Technical Evaluation Report prepared for the NOSB in 2013, 

the NOSB found that ASC satisfies the criteria related to impact on humans and the 

environment, and is compatible with organic agriculture. However, in preparation for a vote on 

ASC at the spring 2014 NOSB meeting, the Livestock Subcommittee had unanimously 

recommended not adding ASC to the National List because of current alternatives available and 

a lack of written comments from organic dairy producers in support of listing ASC, leading the 

Subcommittee to believe ASC did not meet the essentiality criteria. However, at the spring 2014 

NOSB meeting the NOSB received a number of public comments indicating a strong need for 

ASC as an effective alternative teat dip that could be used in cases of microbiological resistance 

to teat dips currently listed. Therefore, the NOSB voted to table ASC at the spring 2014 meeting 

in order to further review ASC. 

The Livestock Subcommittee has reviewed the additional data provided by the petitioner in 

summer of 2014, and reviewed all written and oral public comment. In addition, as part of the 

Sunset Review process, the Livestock subcommittee has been reviewing iodine, in both its 

primary molecular form and in the various complexed iodophor forms. Iodine is widely used in 

teat dips. As part of this iodine review the subcommittee requested a Technical Report for 

Iodine. This report, received on January 7th 2015, provides some recent research information 

and comparative data on iodine based teat dips and on teat dips whose primary ingredient is 

acidified sodium chlorite.

The following is excerpted from the Iodine Technical Report in its discussion of Alternatives to 

Iodine in teat dips: 

“Information regarding the availability of natural, non-synthetic agricultural commodities 

or products that could substitute for iodine and iodophor disinfectants is limited. Nisin, a 

naturally occurring antimicrobial protein known as a bacteriocin, has been incorporated into preand post-milking teat dips and is highly effective against Gram-positive as well as Gramnegative bacteria (citation provided). Formulated products containing nisin, .... are currently 

available for mastitis prevention (citation provided). Nisin naturally present in milk is also 

instrumental in preventing milk spoilage due to bacterial contamination (citation provided). The 

antimicrobial mode of action for nisin involves lysis of the cytoplasmic membrane phospholipid 

components (citation provided). 

Nisin, generally considered a natural product, is not listed as a prohibited non-synthetic 

substance in organic livestock production (7 CFR 205.604). However, the NOSB classified nisin 

as synthetic during their 1995 review of the substance for organic processing (USDA, 1995a). 

Nisin was not recommended for inclusion on the National List for use in the processing of food 

labeled as “organic” and “made with organic ingredients” (USDA, 1995b; OMRI, 2014).

Small-scale milk producers use homemade udder washes containing lavender essential oil, 

water, and apple cider vinegar (i.e., acetic acid) as the active antimicrobial agent (citation 

provided). Other procedures for pre- and post-milking treatments include an udder wash (warm 

water or warm water with a splash of vinegar) in combination with a teat dip (1 part vinegar, 1 

part water, plus 3–4 drops Tea Tree oil per ounce). Naturally-derived acids (e.g., lactic acid) 

may be used as standalone germicides or further activated through the synergistic interaction 

with hydrogen peroxide to provide a bactericidal teat cleansing treatment (citation provided). In 

addition to the natural substances mentioned above, a small number of synthetic substances 

are currently allowed as disinfectants, topical treatments, and external parasiticides in organic 

livestock production (7 CFR 205.603 (a) and (b)... “. Iodine TR, 2015, 723-744.

Page 208 of 249
“Suppliers of livestock and dairy products have indicated that iodine is traditionally the 

preferred germicide used as a teat dip for mastitis prevention. Recent natural disasters in Japan 

and water shortages in Chile led to increasing prices for iodophor products and resultant interest 

in alternative teat dips (citation provided). ........ Animal health researchers recently found that 

acidified sodium chlorite (ASC)-chlorine dioxide solutions are equally effective in preventing new 

intramammary infections (IMI) in lactating dairy cows naturally exposed to mastitis pathogens 

when compared to an established iodophor teat dip product (citation provided). Alternatively, the 

results of experimental challenge studies (cows intentionally exposed to mastitis pathogens) 

suggest that ASC may actually provide enhanced antimicrobial activity against the mastitis 

bacteria Staphylococcus aureus and Streptococcus agalactiae relative to a commercial 

iodophor (citation provided). These studies also indicate that the tested ASC products had no 

deleterious effects on teat condition. Further, ASC components exhibit minimal persistence in 

the environment and are highly unlikely to contaminate the milk from treated animals (USDA, 

2013). Commercial ASC teat dips are being increasingly used in conventional dairies. (iodine 

TR, 2015, 761-776).”

ASC thus appears to be a potentially important ingredient in teat dips and the Livestock 

subcommittee recommends its addition to the National List as petitioned.

Evaluation Criteria (see attached checklist for criteria in each category)

 Criteria Satisfied? 

1. Impact on Humans and Environment x Yes No ☐ N/A 

2. Essential & Availability Criteria x Yes No ☐ N/A

 3. Compatibility & Consistency x Yes No ☐ N/A

Subcommittee Action & Vote

Classification Motion: Motion to classify Acidified Sodium Chlorite (CAS # 7758-19-2 

(sodium chlorite) and CAS # 14998-27-7 (chlorous acid)) as synthetic. 

Motion by: Jean Richardson

Seconded by: Francis Thicke 

Yes: 5 No: 0 Abstain: 0 Absent: 3 Recuse: 0

Listing Motion: Motion to list Acidified Sodium Chlorite (CAS #s 13898-47-0 (Chlorous 

Acid), 7758-19-2 (Sodium Chlorite)) at §205.603(a) and 205.603(b) of the National List 

annotated as follows: Acidified Sodium Chlorite, allowed for use on organic livestock as a 

pre and post teat dip treatment. 

Motion by: Jean Richardson

Seconded by: Francis Thicke 

Yes: 4 No: 1 Abstain: 0 Absent: 3 Recuse: 0 

 Basis for annotation: x To meet criteria above ☐ Other regulatory criteria ☐ Citation 

 Approved by Tracy Favre, Subcommittee Chair, to transmit to NOSB January 27, 2015

Page 209 of 249
NOSB Evaluation Criteria for Substances Added To the National List: Livestock

Category 1. Adverse impacts on humans or the environment? Acidified Sodium Chlorite

Question Yes No N/A Comments/Documentation (TAP; 

petition; regulatory agency; other)

1. Is there a probability of environmental 

contamination during use or misuse,? 

[§6518(m)(3)]

x Risk is minimal. TR page 9, lines 359-

369. 

2. Is there a probability of environmental 

contamination during manufacture or 

disposal? [§6518(m)(3)]

x TR page 9, lines 359-390.

3. Does the substance contain inerts 

classified by EPA as ‘inerts of 

toxicological concern’? [§6517 

(c)(1)(B)(ii)]

x

4. Is there potential for detrimental chemical 

interaction with other materials used in 

organic farming systems?

[§6518(m)(1)]

x As petitioned, substance does not 

interact with the agroecosystem. TR page 

10 lines 410-411.

5. Is there a toxic or other adverse action of 

the material or its breakdown products?

[§6518(m)(2)]

x Breakdown products are citric acid, salt 

and water (2009 handling 

recommendation). 

6. Is there persistence or concentration of 

the material or breakdown products in 

the environment? [§6518(m)(2)]

x When used as petitioned, SCA and its 

components exhibit minimal likelihood of 

persistence in the environment. TR page 

7 lines 296-298. 

7. Would the use of the substance be 

harmful to human health or the 

environment? [§6517 (c)(1)(A)(i); §6517 

(c)(2)(A)(i); §6518(m)(4)]

x “When used as petitioned, acidified 

sodium chlorite and its component 

chemicals exhibit minimal likelihood of 

persistence or accumulation in the 

environment.” TR page 10, lines 436-428. 

The material is both GRAS and on the 

USDA National List for handling. 

8. Are there adverse biological and 

chemical interactions in the agroecosystem, including biodiversity? 

[§6518(m)(5)]

x As petitioned, substance does not 

interact with the agroecosystem. TR page 

10 lines 410-411.

9. Are there detrimental physiological 

effects on soil organisms, crop- s, or 

livestock? [§6518(m)(5)]

x As petitioned, substance does not 

interact with the agroecosystem. TR page 

10 lines 410-411.

Category 2. Is the Substance Essential for Organic Production: Acidified Sodium Chlorite

Question Yes No N/A Comments/Documentation (TAP; 

petition; regulatory agency; other)

1. Is the substance agricultural? [§6502(1)] x TR page 7, lines 280-293.

Page 210 of 249
2. Is the substance formulated or 

manufactured by a chemical process? 

[§6502(21)]

x TR page 6, lines 222-279

3. Is the substance formulated or 

manufactured by a process that 

chemically changes a substance 

extracted from naturally occurring plant, 

animal, or mineral sources? 

[§6502(21)]

x The substance is synthetically produced. 

TR page 7, lines 280-293.

4. Is the substance created by naturally 

occurring biological processes? 

[§6502(21)]

x The substance is synthetically produced. 

TR page 7, lines 280-293.

5. Is there a natural source of the 

substance? [§ 205.600(b)(1)]

x TR page 7. 

6. Is there an organic substitute? 

[§205.600(b)(1)]

x Nisin, a natural material that may be a 

substitute, is not authorized for use as a 

teat dip due to earlier rejection by NOSB 

as an antibiotic . A number of essential 

oils and organic acids may also be used 

as teat dips. TR page 12, lines 503-514

7. Is there a wholly natural substitute 

product?

[§6517(c)(1)(A)(ii)]

x See above. 

8. Are there any alternative substances? 

[§6518(m)(6)]

x There are a number of alternative 

substances, including iodine, alcohols, 

chlorine materials, hydrogen peroxide, 

chlorhexadine and certain essential oils 

may function as alternatives. TR 524-539

At the spring 2014 NOSB meeting, 

comments from dairy industry 

representatives indicated that there was a 

need for another effective teat dip to be 

available to organic dairy producers as a 

substitute in cases of microbiological 

resistance to teat dips on the National 

List.

9. Are there other practices that would 

make the substance unnecessary? 

[§6518(m)(6)]

x Teat dips are critical in commercial dairy 

production to prevent mastitis. TR page 

12.

Page 211 of 249
NOSB Evaluation Criteria for Substances Added To the National List: Livestock

Category 3. Is the substance compatible with organic production practices? Acidified Sodium 

Chlorite

Question Yes No N/A Comments/Documentation (TAP; 

petition; regulatory agency; other)

1. Is the substance consistent with organic 

farming and handling? 

[§6517(c)(1)(A)(iii); 6517(c)(2)(A)(ii)]

x TR, petition. Substance is already 

allowed for use in handling in direct food 

contact.

2. Is the substance compatible with a 

system of sustainable agriculture? 

[§6518(m)(7)]

x

3. If used in livestock feed or pet food, Is 

the nutritional quality of the food 

maintained with the substance? 

[§205.600(b)(3)]

x

4. If used in livestock feed or pet food, Is 

the primary use as a preservative? 

[§205.600(b)(4)]

x

5. If used in livestock feed or pet food, Is 

the primary use to recreate or improve 

flavors, colors, textures, or nutritive value 

lost in processing (except when required 

by law)? [§205.600(b)(4)]

x

6. 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

x TR page 6, lines 210-221

toxins derived from bacteria x TR page 6, lines 210-221

pheromones, soaps, horticultural oils, 

fish emulsions, treated seed, vitamins 

and minerals

x TR page 6, lines 210-221

livestock parasiticides and medicines x TR page 6, lines 210-221

production aids including netting, tree 

wraps and seals, insect traps, sticky 

barriers, row covers, and equipment 

cleansers

x TR page 6, lines 210-221

Page 212 of 249