This is a proposal by a Subcommittee of the National Organic Standards Board (NOSB). Proposals are posted for public comment and 

then may be voted upon by the full Board. They are not final Board recommendations or NOP policy.

Revised June 20 2013

National Organic Standards Board

Livestock Subcommittee

Petitioned Material Proposal

Carbon Dioxide (CO2) for Use in Aquatic Plant Production

+

February 3, 2014

Summary of Proposed Action:

Synthetic carbon dioxide is proposed to be added to the National List at 205.609. 

Section 205.609 will contain a list of synthetic substances allowed in organic aquatic 

plant production.

Carbon dioxide is an inorganic compound composed of one carbon atom and two 

oxygen atoms. In nature, carbon dioxide occurs as a gas and comprises 0.03% of the 

Earth’s atmosphere. It is utilized by plants during photosynthesis and is produced by 

respiration by animals and plants. It is an important component of the carbon cycle and 

is also a well-known greenhouse gas. 

The petition is for the use of carbon dioxide to grow algae within contained systems 

such as ponds and tanks. Petitioned use is for synthetic carbon dioxide due to the 

difficulty in buyers determining the source of CO2. However there are naturally 

occurring sources of CO2 available in some parts of the country. 

CO2 gas is used in the culture of aquatic plants as a production aid for alkalinity 

adjustment and maintaining pH at levels essential for rapid and healthy growth of the 

algae. Most, if not all, algae species are sensitive to pH levels. Carbon dioxide is used 

to maintain desired pH levels in water. The addition of CO2 to water drives the pH value 

lower. Carbon dioxide is consumed by algae as cultures grow and can drive the pH 

level above the desired optimum. Since aquatic animals eliminate carbon dioxide as a 

metabolic product, the presence of aquatic animals in an algal culture reduces demand 

for carbon dioxide.

Carbon dioxide is available from natural sources and as a byproduct of various artificial 

sources. The most common operations from which commercially produced carbon 

dioxide is recovered are industrial plants which produce hydrogen or ammonia from 

natural gas, coal, or other hydrocarbon feedstock, and large-volume fermentation 

operations in which plant products are made into ethanol for human consumption, 

automotive fuel or industrial use. Breweries producing beer from various grain products 

are a traditional source. Corn-to-ethanol plants have been the most rapidly growing 

source of feed gas for CO2 recovery.

Carbon dioxide is allowed for use under all international organic standards that were 

researched in an August 2006 technical report including Canadian, CODEX, EEC 

Council and IFOAM. However, it should be noted that at the time of that technical 

report, organic standards were not in place for organic aquatic plant production, and the 

allowed uses of carbon dioxide were for processing aids, pest control and terrestrial 

plant production. 
This is a proposal by a Subcommittee of the National Organic Standards Board (NOSB). Proposals are posted for public comment and 

then may be voted upon by the full Board. They are not final Board recommendations or NOP policy.

Revised June 20 2013

While the petition is for synthetic carbon dioxide, the petitioner has made it clear that the 

reason for the request to include synthetic CO2 is because of the variable availability 

around the country, rather than because synthetic is the only source. 

Per the 1995 NOSB TAP review, CO2 poses little risk to the environment and was 

unanimously determined to be consistent with a system of sustainable agriculture. At 

that time, the petitioned use was for addition to the National List at 205.605 for use in 

organic handling. The present petition is for use in aquatic plant production and 

therefore should be evaluated with different considerations. It could be argued that 

production methods that require continued external inputs may not be sustainable. 

It should be noted that at the time of drafting this proposal there are no federal 

standards promulgated for aquatic plant or animal production and this proposal is based 

on NOSB recommendations of standards voted in 2007, 2008, and 2009.

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 

Substance Fails Criteria Category: [ ] Comments:

Subcommittee Action & Vote, including classification proposal (state actual motion):

Classification Motion: Motion to classify Carbon Dioxide, CAS # 124-38-9, as synthetic 

Motion by: Tracy Favre 

Seconded by: Joe Dickson

Yes: 5 No: 0 Absent: 2 Abstain: 0 Recuse: 0

Listing Motion: Motion to list CO2 at §205.609 with the following annotation: for use in 

contained systems such as tanks and ponds. 

Motion by: Tracy Favre 

Seconded by: Calvin Walker

Yes: 4 No: 1 Absent: 2 Abstain: 0 Recuse: 0

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

Notes: 

Minority Opinion: see end of document

Approved by Tracy Favre, Subcommittee Chair, to transmit to NOSB February 3, 2014
This is a proposal by a Subcommittee of the National Organic Standards Board (NOSB). Proposals are posted for public comment and 

then may be voted upon by the full Board. They are not final Board recommendations or NOP policy.

Revised June 20 2013

NOSB Evaluation Criteria for Substances Added To the National List: Crops

Category 1. Adverse impacts on humans or the environment? Carbon Dioxide for use in 

Aquatic Plant Production 

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 Carbon dioxide can be classified as either 

synthetic or non-synthetic depending 

upon source, and is a naturally occurring 

component of air. High concentrations 

can lower the pH of water, which could 

adversely affect the environment. 

However, good management practices 

would mitigate this possibility. (Petition 

2012).

2. Is there a probability of environmental 

contamination during, manufacture or 

disposal? [§6518(m)(3)]

X. Production of carbon dioxide is a byproduct of processes that have adverse 

effects on the environment. However, 

because CO2 is a by-product of these 

processes, these affects would occur 

regardless of CO2 production. (Aug 2006 

TR, lines 296-299). 

3. Are there any adverse impacts on 

biodiversity? (§205.200)

X Under good management practice carbon 

dioxide for use in aquatic plant production 

is self-limiting, as too much CO2

decreases plant production and lowers 

water pH. (Petition, 2012) So impacts to 

biodiversity are unlikely. 

4. Does the substance contain inerts 

classified by EPA as ‘inerts of 

toxicological concern’? [§6517 

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

X CO2 can exist in gaseous, liquid or solid 

forms but does not contain inerts. All 

manufacturing processes require 

purification (Aug 2006 TR, lines 188-189)

5. Is there potential for detrimental chemical 

interaction with other materials used in 

organic farming systems?

[§6518(m)(1)]

X High concentrations of CO2 will decrease 

water pH and make some nutrients biounavailable, but under normal good 

management practices, it is unlikely there 

would be detrimental chemical 

interactions. (Petitioner) See #3 above 

regarding self-limiting.

6. Is there a toxic or other adverse action of 

the material or its breakdown products?

[§6518(m)(2)]

X CO2 can be long-lived in the environment 

and therefore could contribute to climate 

change but otherwise poses no adverse 

action upon breakdown. 

7. Is there persistence or concentration of 

the material or breakdown products in 

the environment? [§6518(m)(2)]

X Carbon dioxide is a greenhouse gas (Aug 

2006 TR, line 299), however, under 

proper management for aquatic plant 

production, CO2 would be metabolized by 

aquatic plants. (Petitioner)
This is a proposal by a Subcommittee of the National Organic Standards Board (NOSB). Proposals are posted for public comment and 

then may be voted upon by the full Board. They are not final Board recommendations or NOP policy.

Revised June 20 2013

8. 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 At levels proposed for use by the 

petitioner, under normal good 

management practice, there is no 

demonstration of harmful effects to 

human health or the environment. In high 

concentrations in closed systems, there is 

a possibility of atmospheres dangerous 

for humans, but good management 

practices are likely to mitigate this 

possibility. Up to .05% is considered not 

harmful to humans. However, higher 

concentrations can be harmful. (Aug 

2006 TR, lines 306-307) No evidence 

was found indicating that carbon dioxide 

leaves residues on food. (Aug 2006 TR, 

lines 354-356). Carbon dioxide is on the 

list of FDA confirmed GRAS substances. 

(Aug 2006 TR, lines 348-349)

9. Are there adverse biological and 

chemical interactions in the agroecosystem? [§6518(m)(5)]

X On the contrary, good management of 

CO2 levels leads to increased plant 

production and biodiversity. Only at high 

concentrations could CO2 potentially have 

a negative impact. (Petitioner)

10. Are there detrimental physiological 

effects on soil organisms, crops, or 

livestock? [§6518(m)(5)]

X See comment above.

Category 2. Is the Substance Essential for Organic Production? Carbon Dioxide for Use in 

Aquatic Plant Production 

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

petition; regulatory agency; other)

1. Is the substance agricultural? [§6502(1)] X Carbon dioxide is an inorganic compound 

composed of one carbon atom and two 

oxygen atoms. In nature, carbon dioxide 

occurs as a gas and comprises 0.03% of 

the Earth’s atmosphere. It is utilized by 

plants during photosynthesis and is 

produced by respiration by animals and 

plants. It is an important component of 

the carbon cycle and is also a well known 

greenhouse gas. (Aug 2006 TR, lines 

17-21) Petitioned use is for synthetic 

Carbon Dioxide due to the difficulty in 

buyers determining the source of CO2. 

However, while non-agricultural, there are 

naturally occurring sources of CO2

available in some parts of the country. 

(Aug 2006 TR, lines 240-252)
This is a proposal by a Subcommittee of the National Organic Standards Board (NOSB). Proposals are posted for public comment and 

then may be voted upon by the full Board. They are not final Board recommendations or NOP policy.

Revised June 20 2013

2. Is the substance formulated or 

manufactured by a chemical process? 

[§6502(21)]

X There are numerous methods by which 

CO2 can be produced, including 

fermentation and as a by-product of oil 

and gas production. (Aug 2006 TR, lines 

226-229)

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 In some cases, CO2 production is a result 

of manufacturing processes, such as 

ethanol or oil and gas refining processes. 

(Aug 2006 TR, lines 178-201)

4. Is the substance created by naturally 

occurring biological processes? 

[§6502(21)]

X CO2 can result from metabolic process of 

plants and animals and from some 

fermentation processes. (Aug 2006 TR, 

lines 203-207, 234-238)

5. Is there a natural source of the 

substance? [§ 205.600(b)(1)]

X Naturally occurring CO2 does exist in 

deposits located in Mississippi, Colorado, 

and New Mexico, Utah, Wyoming and 

Washington, but transport of pressurized 

gas over long distances is not advised, 

and therefore may not be available in 

some parts of the country. (Aug 2006 

TR, lines 178-201)

6. Is there an organic substitute? 

[§205.600(b)(1)]

X Citric acid can be used in soil based 

operations but for aquatic environments, 

there is no known substitute. (Petitioner)

7. Is there a wholly natural substitute 

product?

[§6517(c)(1)(A)(ii)]

X Naturally occurring as a result of 

biological processes of animals, 

additionally natural sources of CO2 are 

available on a regional basis. (Petitioner)

8. Are there any alternative substances? 

[§6518(m)(6)]

X There are no known substitutes. While 

there are non-synthetic forms of 

carbonate such as sodium bicarbonate 

and sodium carbonate that can lower pH 

values in water, these substances do not 

lower pH to values below 8.5 that are 

necessary for most species of algae. For 

aquatic plant production, CO2 is essential 

for proper plant health and productivity. 

When aquatic plant production is paired 

with animal production, the requirement 

for additional CO2 is reduced. (Petitioner)

9. Are there other practices that would 

make the substance unnecessary? 

[§6518(m)(6)]

X See comment #8 above, however it is 

difficult to properly maintain water pH in 

aquatic plant production without the use 

of CO2 . Alkalinity and pH control is 

essential in the culture of aquatic 

systems. All, or virtually all, aquatic plants 

require carbon dioxide for healthy and 

rapid growth. There are no substitute 

substances, nor are there alternative 

culture methods. (Petitioner)

NOSB Evaluation Criteria for Substances Added To the National List Crops
This is a proposal by a Subcommittee of the National Organic Standards Board (NOSB). Proposals are posted for public comment and 

then may be voted upon by the full Board. They are not final Board recommendations or NOP policy.

Revised June 20 2013

Category 3. Is the substance compatible with organic production practices? Carbon Dioxide 

for Use in Aquatic Plant Production 

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 Per a 2005 TAP review, CO2 is 

consistent with organic farming and 

handling. CO2 is already listed on the 

National List for use in organic handling 

at 205.605. Carbon dioxide is allowed for 

use under all international organic 

standards that were researched including 

Canadian, CODEX, EEC Council and 

IFOAM. However, it should be noted that 

at the time of the technical report, organic 

standards were not in place for organic 

aquatic plant production, and the allowed 

uses of carbon dioxide were for 

processing aids, pest control and

terrestrial plant production (Aug 2006 TR, 

lines 127-171)

2. Is the substance compatible with a 

system of sustainable agriculture? 

[§6518(m)(7)]

X X Per the 1995 NOSB TAP review, CO2

poses little risk to the environment and 

was unanimously determined to be 

consistent with a system of sustainable 

agriculture. At that time, the petitioned 

use for or addition to the National List at 

205.605(b) for use in organic handling. 

The present petition is for use in aquatic 

plant production and therefore should be 

evaluated with different considerations. 

While the petition is for synthetic Carbon 

Dioxide, the petitioner has made it clear 

that the reason for the request to include 

synthetic CO2 is because of the variable 

availability around the country, rather 

than because synthetic is the only 

source. It could be argued that 

production methods that require 

continued external inputs may not be 

sustainable. 

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
This is a proposal by a Subcommittee of the National Organic Standards Board (NOSB). Proposals are posted for public comment and 

then may be voted upon by the full Board. They are not final Board recommendations or NOP policy.

Revised June 20 2013

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

toxins derived from bacteria X

pheromones, soaps, horticultural oils, 

fish emulsions, treated seed, vitamins 

and minerals

X

livestock parasiticides and medicines X

production aids including netting, tree 

wraps and seals, insect traps, sticky 

barriers, row covers, and equipment 

cleansers

X

Minority Opinion - Carbon Dioxide for Use in Aquatic Plant Production

February 23, 2014

A minority of the subcommittee suggests that it is appropriate to adopt an annotation for carbon 

dioxide in aquaculture, with a justification explaining the that the specific time frame of five (5) 

years for an expiration date allows the Board to monitor the use of the material, incentivize 

alternatives, update its scientific and essentiality review, and vote on the continuation of use 

pending the receipt of a petition requesting that use be continued.

Support for the annotation is based on the following justification: Since this petition is being 

considered in the absence of regulations defining acceptable practices in organic aquaculture, 

essentiality in particular cannot be judged at this time. Therefore, the NOSB needs to reconsider 

the approval in five (5) years at the least. Current consideration of the material has raised issues 

relating to health or environmental impacts; alternatives derived from natural sources; and 

compatibility with organic and sustainable agriculture.. The review in five (5) years provides an 

opportunity for the Board to reevaluate and vote for the continued or modified use of the 

material under the same standard of review that is used to approve the material initially. 

The NOSB Principles of Organic Production and Handling (adopted October 17, 2001) begin:

Organic agriculture is an ecological production management system that promotes and 

enhances biodiversity, biological cycles, and soil biological activity. It emphasizes the use of 

management practices in preference to the use of off-farm inputs, taking into account that 

regional conditions require locally adapted systems. These goals are met, where possible, 
This is a proposal by a Subcommittee of the National Organic Standards Board (NOSB). Proposals are posted for public comment and 

then may be voted upon by the full Board. They are not final Board recommendations or NOP policy.

Revised June 20 2013

through the use of cultural, biological, and mechanical methods, as opposed to using synthetic 

materials to fulfill specific functions within the system.

To provide a major component necessary for aquatic plant growth in the form of a synthetic 

chemical is inconsistent with organic principles.

The Crops Subcommittee received information that indicates that additions of synthetic carbon 

dioxide are not essential. An NOP survey of certifiers who certify organic aquatic plant 

production found that very few inputs were used. Sometimes natural alkali, carbon dioxide, and 

sodium bicarbonate were used. Integrated systems1 control pH and alkalinity, as well as other 

parameters, by balancing the organic components of the system.

While carbon dioxide may not seem very hazardous, the atmospheric concentration has 

reached the all-time high of 400ppm, elevating to extreme levels the threat of global climate 

change. Organic production may not be a large contributor, but the use of synthetic carbon 

dioxide, which is not captured, as opposed to using carbon dioxide produced by animals in the 

system, does contribute to the problem.

Finally, lacking an organic aquaculture policy for plant production introduces a further difficulty in 

creating the parameters necessary to establish systems that are compatible with the Organic 

Foods Production Act and resulting organic methods. Evaluating the use patterns of synthetic 

materials permitted on the National List outside of a defined policy on whole aquaculture 

systems for plants and animals runs contrary to organic process and practice because the use 

of a synthetic material must be evaluated relative to a practice norm in which no synthetics are 

added. 

The petitioner has indicated that carbon dioxide for use in organic production of aquatic plants 

would be used only in closed systems. We believe that use of this substance in closed systems 

with no discharge to natural water bodies is vital to be added to the motion for the carbon 

dioxide proposed recommendation.

 

1 See, for example, Siew-Moi Phang, 1992. Role of algae in livestock-fish integrated farming systems. 

Proceedings of the FAO/IPT Workshop on Integrated Livestock-Fish Production Systems, 16–20 

December 1991, Institute of Advanced Studies, University of Malaya, Kuala Lumpur, Malaysia.