National Organic Standards Board 

Crops Subcommittee 

Petitioned Material Proposal 

Chitosan for Plant Disease Control 

June 1, 2021 

Summary of Petition: 

Chitosan has been petitioned for use in organic crop production for addition to the National List at 

§205.601(j)(4) for plant disease control. The NOSB requested a technical review (TR) of chitosan since 

the last one was from 2004 when there was a petition for its use as an adhesive adjuvant. Much of the 

material in the current analysis comes from the TR received by the NOP in July 2020. Chitosan is a 

copolymer composed of two different chemical subunits that repeat in particular order: glucoseamine 

and N-acetyleglucosamine. It is derived from chitin which is structurally similar to cellulose. The 

petitioner stated that chitosan is an alternative to sulfur-based pesticides, which can be phytotoxic to 

plants. The petitioner bases the request on chitosan's antimicrobial properties as well as its role in plant 

defense signaling pathways. 

Most commercial chitin, from which chitosan is derived, is produced from shrimp, prawn, and crab 

waste. Chitin forms structures that strengthen cell walls, insect skeletons, crustacean shells, and internal 

mollusk body parts. The manufacture of chitosan uses relatively large amounts of corrosive chemicals, 

notably sodium hydroxide and hydrochloric acid. That said, relatively little chitosan is produced. Only 

2000 metric tons of chitosan are produced each year while 70 million tons of sodium hydroxide are 

produced for use in all types of industrial processes. In contrast to the chemicals used to isolate and 

synthesize the material, chitosan is produced from chitin, a food related marine biowaste and is thus, 

part of a recycling process. However, as part of an industry that requires the use of sodium hydroxide 

and hydrochloric acid, considerable energy is consumed producing these products with concomitant 

production of chlorine gas, carbon dioxide, carbon monoxide, freon and mercury. 

Chitosan has a variety of potential uses. It is a registered pesticide (OPP No. 128930) that is used in crop 

production as a plant growth enhancer and plant defense booster (EPA 2003). Chitosan is applied to 

treat field crops, ornamentals, turf, home gardens, and nurseries. It is also listed as an animal feed 

component in the Official Publication of the Association of Animal Feed Control Officials. The State of 

Oregon has approved the use of chitosan in unrestricted amounts as a soil amendment (fertilizer). 

Chitosan was recommended to be added to the National List in 2005 as an adjuvant although it was 

already present on EPA List 4, and therefore would have been redundant. Chitosan also has a variety of 

other uses that include as a flocculant allowed for precipitating proteins during animal food production, 

a plant growth regulator in or on wheat, and as a seed treatment for specific crops. The FDA also allows 

chitosan produced from the fungus Aspergillus niger as a secondary direct food ingredient in alcoholic 

beverages. 

Chitosan is not toxic as demonstrated in acute toxicity studies in mice, rats and rabbits and is naturally 

occurring in the environment in large concentrations. EPA exempted chitosan from the requirement for 

a tolerance limit due to its low toxicity and abundance in the environment. As mentioned in the 

summary above, EPA states that chitosan is not expected to harm people, pets, wildlife, or the 

environment when used according to label direction. 

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Summary of Review: 

A survey of regulations for organic production from a number of countries and international 

organizations indicates that chitosan is not included within the Canadian Organic standards as an 

allowed material. CODEX Alimentarius does not include chitosan within the Codes guidelines. European 

Economic Community (EEC) Council Regulation shows that chitosan hydrochloride is allowed for pest 

and disease management under European Union organic regulations but may not be used as an 

herbicide. 

Category 1: Classification 

1. For CROP use: 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 petition describes the process of producing chitosan from chitin as proprietary so the exact 

process they use is unknown. Generally, however, chitosan is produced from chitin by using 

dilute sodium hydroxide to separate and extract chitin from shells or acids for demineralization, 

but a more concentrated solution is required to effectively deacetylate chitin to form chitosan at 

a range of 40 to 60% concentration. Chitin can also be converted into chitosan using a high-heat 

process or a lower temperature process using enzymatic conversion 

2. 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? 

The petitioner is requesting that chitosan be added to 7 CFR 205.601(j)(4) as a synthetic 

substance allowed for use in organic crop production as a plant disease control. 

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)] 

Based on information in the 2020 Technical Report, the application of chitosan as an active 

ingredient in pesticidal products is unlikely to be harmful to the environment. It occurs naturally 

in quantities exceeding what would be used in organic crop production and it degrades into 

substances that are non-toxic and readily used as nutrients. 

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)] 

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Due to the variety of results found in different studies it is likely that chitosan has multiple 

antibacterial modes of action. One hypothesis is that positively charged chitosan binds to 

negatively charged cell surface molecules. Another hypothesis is that smaller chitosan 

molecules move through cell walls and inhibit gene transcription. There is also another 

thought that chitosan chelates essential nutrients making them unavailable to bacteria. 

Chitosan can also initiate systemic resistance in plants and may act directly between host 

and pathogen to block the growth of the pathogen itself. Since chitosan is used at low levels 

and is degraded by soil microorganisms the is expected to be no increase in the environment. 

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

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

Because of the low toxicity of chitosan, the misuse of the product or its disposal are expected to 

have minimal effects on the environment. Both chlorine and sodium hydroxide are used in 

production of chitosan, and are toxic in the environment if not contained in transport. 

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

§6518(m)(4)]. 

According to numerous sources as reported in the Technical Report chitosan is nearly non-toxic 

to humans and most other animals and its degradation products do not cause side effects in the 

body (US EPA). 

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)] 

Pesticide studies about the use of chitosan as an active ingredient have shown that there might 

be temporary changes to soil microbial communities. Being a large polymer with numerous 

reactive sites, it is difficult to characterize all possible chemical interactions involving chitosan. 

the Technical Report found studies that chitosan can limit the ability of some microorganisms to 

absorb nutrients, but it can also act as a chelator. It has been suggested because of this, it might 

be used as a material to improve the anionic exchange capacity of soils to limit the leaching of 

anionic nutrients and improve nutrient delivery to plants 

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

At the rates this substance is applied, no adverse impacts on biodiversity are expected. 

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)] 

As the Technical Report emphasizes, good farming practices, including suppressive soils, 

creating unfavorable conditions for pathogens, managing disease vectors such as aphids, 

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sterilizing soils with heat and planting resistant cultivars reduce the need to use disease control 

substances. Also, there are more than 200 products listed by OMRI for use as plant disease 

control. Some do contain synthetic active ingredients, but many contain nonsynthetic active 

ingredients such as bacteria, microorganism extracts, botanical substances, oils, and natural 

acids. 

2. In balancing the responses to the criteria above, is the substance compatible with a system of 

sustainable agriculture? [§6518(m)(7)] 

Chitosan is a relatively benign product and also has the advantage of taking a waste stream of 

seafood shells and converting them to a useful recycled product. Both chlorine and sodium 

hydroxide are energy-intensive, toxic chemicals used in the production of chitosan, and must be 

considered. Additionally, chitosan is classified as synthetic, and the Subcommittee questions 

whether there is a need for an additional synthetic plant disease control product on the National 

List. The Crops Subcommittee is divided on whether chitosan should be added to the National 

List. 

Classification Motion: 

Motion to classify chitosan as synthetic 

Motion by: Rick Greenwood 

Seconded by: Brian Caldwell 

Yes: 8 No: 0 Abstain: 0 Absent: 0 Recuse: 0 

National List Motion: 

Motion to add chitosan to the National List at 205.601(j)(4) for plant disease control 

Motion by: Rick Greenwood 

Seconded by: Steve Ela 

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

Approved by Rick Greenwood, Crop Subcommittee Chair, to transmit to NOP June 1, 2021. 

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