National Organic Standards Board

Crops Subcommittee

Petitioned Material Proposal

Potassium Sorbate as an active ingredient for plant disease and insect control/suppression

August 1, 2023

Summary of Petition:

Potassium sorbate, referred to as KS throughout the 2023 technical report (TR), is being petitioned for 

use as an active ingredient for plant disease and insect control/suppression in field and greenhouse 

applications. The petition states that potassium sorbate will be an effective tool in a crop diseaseresistance program with its contact mode of action and that it is not suspected to contribute to the 

phytotoxicity of crops. 

The petition identifies the substance as 100% food-grade KS with no ancillary substances. The proposed 

end-use fungicide/insecticide contains 45% KS, with the remaining 55% comprised of the inert 

ingredients’ urea and citric acid, both appearing on the 2004 EPA List 4A: Inerts of Minimal Concern. 

With KS as an active ingredient, the end-use product would be used to target crop disease and insects 

such as powdery mildew, downy mildew, and whiteflies, on many crops, including grapes, cucurbits, 

roses, stone fruit, pome fruit, nuts, solanaceae vegetables, and cannabaceae plants.

Summary of Review:

KS is petitioned for addition to the National List at 7 CFR 205.601(e) for use as an insecticide and at 

7 CFR 205.601(i) for use as a plant disease control. KS currently is on FIFRA’s (Federal Insecticide, 

Fungicide Rodenticide Act) list 25(b), which is for active and inert ingredients (of chemicals) that are 

considered a minimum risk, and therefore, do not require an EPA registration number and are exempt 

from EPA regulations on efficacy and toxicity. KS is generally recognized as safe (GRAS) by the Food and 

Drug Administration (FDA). 

KS has been petitioned unsuccessfully three times for inclusion on the National List. KS is not 

internationally approved for the petitioned use.

 

1. 1995, seed treatment, production aid 7 USC 6517(c)(1)(B)(1)

a. Petitioned (sorbic acids and its salts) for use in food processing 

b. Conclusion: sorbic acid was synthetic and not compatible with organic processing or 

handling

2. 2002 Crops, 205.601: 

a. Petitioned for use in seed film coating as a preservative. 

i. Potassium sorbate is a weak acid antimicrobial known to cause resistance and is 

used in the food industry. 

ii. Conclusion: potassium sorbate was not allowed as a synthetic substance for use 

as a preservative, as more information was needed for justification.

3. 2002 Livestock, 205.603: 

a. Petitioned for use in organic livestock production as a mold inhibitor (preservation in 

aloe vera - aloe vera can be used as an alternative for antibiotics when treating 

livestock)

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i. Conclusion: Additional information on the ingredients in the manufacturing of 

potassium sorbate is questioned. 

KS used as an active ingredient would function in a contact mode of action form. Many alternative 

products and cultural practices exist. The petition states that the degradation products (sorbic acid and 

potassium hydroxide) are more hazardous than the product itself. 

In food additives, sorbic acid interacts negatively with nitrite and is known to create direct-acting 

mutagens and genotoxic agents. The extent of these interactions in field conditions is unknown. The TR 

indicates that limited information on KS, as petitioned, exists. Thus, there needs to be more available 

information regarding the potential interactions of KS with other crop production inputs. (TR 579-583). 

In addition, the TR indicates that there was little to no information on KS as petitioned to understand its 

chemical interactions or its use in conventional crop pesticide application (TR 579-581), how KS interacts 

with soil organisms, the use of KS as a foliar spray on growing crops (TR 758-759), and persistence of KS 

in the environment or its by-products (TR 468-470), thus in many cases the TR leverages information 

that was available regarding KS as a post-harvest treatment and/or as a conventional food additive (TR 

74, 470-472, 857-862). 

Note: The board is reviewing the substance potassium sorbate; however, the formulation of the finished 

product provided in the petition elicited concerns from stakeholders. If the petitioned substance is 

approved and added to the national list, then a material review organization will need to further review 

the complete composition of formulated products as this is outside of the Board’s jurisdiction. 

Comments centered around the inerts in the finished product; urea and citric acid. Both of these 

substances have pesticidal actions, and urea is a synthetic substance not on the National List for use as 

an active ingredient. The evaluation of urea as an active ingredient is outside the scope of this review. 

Citric acid is a nonsynthetic substance so it would be allowed as an active (not the same level of concern 

as urea which is synthetic).

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. 

Potassium sorbate is not explicitly listed anywhere in the Organic Foods Production Act of 1990 (OFPA) 

nor the USDA organic regulations at 7 CFR 205. It is implicitly on the National List as an inert ingredient 

of minimal concern on the National List at 205.601(m)(1) and 205.603(e)(1).

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 

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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 potassium sorbate be used as an active ingredient for plant disease and 

insect control/suppression under the following conditions:

1. § 205.601(e): Synthetic substances allowed for use in organic crop production – as insecticides

2. § 205.601(i): Synthetic substances allowed for use in organic crop production – as plant disease 

control

Note: The TR states that KS is one of the most common food preservatives; In contrast, most food 

preservation with KS occurs as part of food processing; it is the application during crop production and 

post-harvest handling of raw agricultural commodities that are considered within the scope of the 

current petition. Post-harvest use would have to be annotated explicitly for any KS listed at 205.601 

according to the National Organic Program (NOP) Guidance 5023. (TR 99-103) 

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)]

Potassium sorbate, due to its antimicrobial properties, has been historically used in the food processing 

industry as a preservative and is used in a wide range of food products, including meats, cheeses, baked 

goods, fresh and fermented vegetables, dried fruit, fish, processed food, and carbonated beverages. 

There is little historical use of KS in organic agricultural production. 

The TR notes that before receiving the 25(b) exemption, potassium sorbate was used as an active 

ingredient in several EPA-registered pesticides. The last of these registrations was canceled in 1989. KS is 

also on the 2004 EPA List 4A – Minimal risk inert ingredients. Thus, it is currently permitted as an inert 

ingredient in combination with permitted active ingredients in pesticide formulations used in organic 

crop production according to 205.601 (m) (1) (TR 206-213).

Two notable points were brought up in the TR relating to KS (and/or sorbic acid used to make KS):

 

1. Processed food products with sorbate and nitrite preservatives may form mutagens and 

genotoxic agents under certain conditions. 

a. In vitro studies on bone marrow chromosomes of mice showed that the combination of 

sorbic acid and nitrite creates a synergistic effect, severely affecting the spindle 

apparatus and chromosomal structure.

b. Research on how these two substances would interact with humans and the field 

environment is unavailable. 

 2. Ames test and rec-assay mutagenicity found DNA-damaging activity when combined with KS, 

ascorbic acid, and iron salts. (TR 585-597).

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

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

Few studies in the literature report on using KS as a crop fungicide. Thus, information regarding its 

persistence or that of its by-products in the environment is limited. (TR 467-468).

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The TR states that crystalline KS is relatively stable; its behavior in solutions and foods depends on 

factors like temperature, pH, food combination, water activity, packaging, and various metals and other 

additives. (TR474-477). The presence of KS in natural environments after its commercial use is 

considered safe. KS has a contact mode of action. 

The TR notes that since KS inhibits microorganisms from colonizing a “new” substrate, KS is an effective 

antimicrobial. However, this bacteriostatic effect is likely to be overwhelmed in a natural community, 

where microorganisms can quickly degrade KS into readily metabolized compounds such as sorbitol, 

potassium, and sorbic acid. (TR 454-457). In general, sorbic acid and its salts have been considered 

compounds of low ecotoxicity. 

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

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

KS is a potassium salt of sorbic acid. Sorbic acid (synthetically manufactured using ketene and 

crotonaldehyde) is neutralized with potassium hydroxide (manufactured through chemical synthesis) to 

yield potassium sorbate, the petitioned substance. Several methods are described for isolating the KS 

solid, including filtration, centrifugation spraying, or crystallization of KS and subsequent distillation. The 

petition states that the source of potassium sorbate is food grade and manufactured in a closed system, 

waste disposal certified, and chlorine-free production with multiple accreditations such as Food Safety 

System Certification, HACCP, and ISO 9001. 

Potassium hydroxide (KOH) is considered a category-one hazardous substance under the Clean Water 

Act due to its impact on pH and potassium levels in wastewater. Although KOH itself may be corrosive in 

solid form and is listed as a hazardous substance under the Clean Water Act, it is considered a GRAS 

substance when produced with good manufacturing practice and currently appears on the National List 

at 205.605(b)(26) for use in processed products. 

KS and its by-products are disposed of by landfilling in closed containers or incarceration. The TR states 

that KS has no potential for environmental accumulation. 

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

§6518(m)(4)].

Potassium sorbate is listed as Generally Recognized as Safe (GRAS) by the U.S. Food and Drug 

Administration (US FDA) at 183.3640, with the only specification being that it be used according to good 

manufacturing practices (GMPs). The TR states that KS and its residues are exempt from the 

requirement of a tolerance in food per 40 CFR 180.1233. 

Since minimal data is available on potassium sorbate as petitioned, the TR provides information 

regarding other uses of KS (food preservation, cosmetics, personal care products, washing and cleaning 

products, pharmaceuticals, and other manufactured industrial products) and not necessarily for the 

petitioned use. 

The current TR discusses the consumption of processed products that use KS as a food additive. Most of 

the KS is dispelled when consumed, however 12.6% is retained (studies on rats) by internal organs, 

skeletal muscles, and other body parts (TR 516-519). An increased KS intake (>25mg/kg) may lead to 

cytotoxic and genotoxic effects by producing mutagenic compounds and inducing chromosome 

aberrations and DNA breakage (cancers and diabetes mellitus). Wide use of KS in food, cosmetics, 

cleaners, etc., could lead to higher-than-normal buildup. 

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On the contrary, the petition references the 2002 Technical Advisory Panel Review (TAP) that was 

contracted to support earlier reviews of KS. The TAP states that potassium sorbate is the potassium salt 

of an unsaturated fatty acid, which participates in the normal fat metabolism in the human body and 

will be oxidated into carbon dioxide and water finally. It will not be accumulated in the human body. The 

2002 TAP states that KS is safe and has the lowest allergenic potential of all food preservatives. 

The petition states that although allergic reactions to KS can be described as unusual: There was a 

reported incident of severe rashes by a worker in a dairy plant who had repeated occupational 

exposure. The petition also states that KS is a category 2B serious eye damage/eye irritation health 

hazard with a WARNING signal word. As petitioned to be used in the OR-159-B end-use product with KS 

at 45%, KS is classified by OSHA Hazard Communication Standards as not hazardous. 

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)]. 

Few studies are found in the literature that report on the use of KS as a crop fungicide, thus, information 

regarding its persistence or that of its by-products in the environment resulting from this use is limited. 

No studies on KS used to control the target organism identified on the petitioned product’s label were 

found to expound on its potential effects on soil microbial communities. (TR 467-470). One public 

commenter mentioned, “the petition does not provide sufficient information for the evaluation of 

Potassium sorbate against some of the required evaluation criteria: Potassium sorbate is used as a 

preservative in processing, raising the issue of potential for impacts on soil microbes. However, the 

petition presents speculation instead of providing clear information about the mechanisms and levels of 

Potassium sorbate’s impacts on soil microbes, stating, “Sorbic acid should inhibit the growth of soil 

bacteria and fungi.” 

For crops: The TR mentions KS being tested for phytotoxicity in cotton in the 1970s. The treatments 

caused a reduction in the primary root elongation at three different concentrations and showed that the 

KS severely affected the dry weight of cotton seedling shoots and roots (TR 606-608). The TR mentions 

that further field research is needed on any possible adverse effects that KS could have on the bacterial 

communities necessary for healthy soil and optimal microbe-plant interactions, as early testing 

demonstrated that KS addition slightly increased the pH of the soil and soil pH is essential in bacterial 

community structure and diversity (TR 618-620). 

For Livestock: The TR mentions that when KS was petitioned in 2002 for use in livestock, one Technical 

Advisory Panel (TAP) reviewer stated that one should determine directly at what level KS, as an antibacterial, will interfere with ruminant metabolism. The TR noted that future research that identifies the 

concentrations of KS affecting the ruminant microbiome is needed (TR 633-637). 

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

KS antimicrobial properties and characteristics could alter the microbiome in the soil. The petition states 

that it is reasonable to expect that it would inhibit the growth of soil microorganisms, and additionally, 

that a significant number of organisms regarded as beneficial are suppressed. 

The TR mentions that further field research is needed on any possible adverse effects that KS could have 

on the bacterial communities necessary for healthy soil and optimal microbe-plant interactions (TR 618-

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620), as early testing demonstrated that KS addition slightly increased the pH of the soil and soil pH is 

essential in bacterial community structure and diversity.

In general, sorbic acid and KS are considered compounds of low ecotoxicity. However, the TR states that 

high concentrations of KS can impair photosynthetic functions in algae, negatively affect the microbiome 

of fishes, inhibit mycelial growth in fungi, and affect the soil pH (TR 615, 617, 669).

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)]

 

The petition states that KS is necessary as an organic input pesticide active ingredient because it has a 

contact mode of action where organic crop farmers in the US can use the petitioned product in a disease 

resistance management program rotating with fungicides with different modes of action. The petition 

includes testing data showing efficacy on powdery mildew, downy mildew, and white fly, and observed 

no phytotoxicity even at double the use rate on the crops tested. No other trials on the effectiveness of 

KS were found. 

The petition discusses efficacy, indicating that KS is comparable to conventional pesticides and carries a 

higher efficacy rate than other allowed organic or natural actives. The petition included research 

regarding in vitro efficacy of eight food additives as possible alternatives to synthetic fungicides for 

controlling soil-borne pathogens. Also included in the petition is a breakdown of a comparison study of 

the efficacy of potassium salts against soil-borne and air-borne fungi reviewing KS and potassium 

bicarbonate (active ingredient listed on 7 CFR 205.601i(9)). According to the petition, in tests done at 

Michigan State University, KS significantly outperformed potassium bicarbonate and sulfur in controlling 

downy mildew, an important, difficult-to-control grape disease. Few other published pesticide trials 

have been done with this material. However, the petition also notes that there are currently nonsynthetic and natural substances that could be used in place of potassium sorbate.

 

A literature review for KS uncovered limited information on use as a foliar spray for growing crops (TR 

758-759). The TR indicates that over 750 biological controls were approved for use as crop pests, weeds, 

and disease controls under NOP standards on the OMRI Products List (OMRI 2022) (TR 764-765). The 

petition states that searching in the OMRI database under the “Crop Pest, Weed, and Disease Control” 

keyword “fungicide” yields 464 fungicide products that are OMRI approved. The TR indicated that there 

were over 500 pesticides formulated with plant-derived active ingredients on the OMRI Products List 

(OMRI, 2022). Fixed coppers and copper sulfate, potassium silicate, lime sulfur, hydrogen peroxide, 

horticultural oils, potassium bicarbonate, and polyoxin D zinc salt are all alternative products. 

In terms of cultural practices, applying a systems-based approach and deploying preventive practices 

and ecological processes to promote beneficial microbial diversity in the soil and biodiversity to attract 

beneficial insects, as well as cover cropping, crop rotations, and cropping schedules, are examples of 

management practices that can also assist in insect and disease mitigation. 

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

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

KS is already used in organic crop production as an inert ingredient in accordance with § 205.601(m)(1) - 

EPA List 4—Inerts of Minimal Concern. 

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As petitioned, KS is not approved to be used internationally. However, it is permitted under the 

European Economic Community Council Regulations as a preservative in organic livestock feed. KS has 

been petitioned twice, in crops as a seed treatment and once in livestock as a mold inhibitor, and was 

not added to the national list due to reasons discussed in the summary of the review section. In 

addition, KS is not made from renewable resources, the materials used to produce KS are not recyclable, 

do not complement the use of natural and biological controls, and many alternative substances and 

practices exist currently. 

As the TR states in several places, more research is needed to understand the impacts of allowing KS to 

be used as an active ingredient for insect and plant disease control; therefore, an abundance of caution 

needs to be considered. 

2023 Spring Meeting Discussion Summary: 

The Board reviewed and discussed the discussion document, the TR, and public comments for the 

petitioned substance, KS. Many community members, including certifiers and advocacy groups, have 

concerns with potassium sorbate due to the limited information available, efficacy data, essentiality, 

environmental impact, and effects on health. Farmers tended to be in favor of this product as well as 

grower groups. However, several farmers encouraged more research and supported listing potassium 

sorbate only if it meets OFPA criteria. Several groups favoring this substance noted that potassium 

sorbate is already allowed since it's on the National List as an approved inert ingredient. One additional 

public comment of note stated that the, "We know we need tools in this area. We're just not sure if this 

is the right tool for the situation". 

Oral and written public comments introduced additional background regarding the history of KS as a 

registered pesticide until 1989. The NOSB discussed whether potassium can be a part of an integrated 

pest management program (IPM), whether its efficacious and available alternatives. The petition 

provided limited information regarding efficacy, and the Crops Subcommittee has not been able to 

verify the data with independent studies. 

 

New Information from Petitioner Summary: 

At the Spring 2023 NOSB meeting, the NOSB requested additional information from the community 

comparing the use of KS in conventional production, efficacy, effects on health, and environmental 

impact. The petitioner provided additional information in July 2023. A few notable items are as follows:

1. Conventional Products Using KS as an Active: 

a. Since KS is listed at FIFRA 25(b), US EPA does not monitor products under this category. 

b. Registration is required at the state level; currently, no database exists.

2. KS as a Fungicide: 

a. KS end-use product depends on the spray solution being between a pH of 4.5 and 5. 

b. Additional Efficacy Data was made available by the petitioner, who stated, “KS is 

comparable to conventional and organic certified active ingredients.”

c. The petitioner mentioned that KS could reduce the dependency on copper and sulfur 

products.

1. KS as an Insecticide:

a. The limited exploratory insect trials conducted by Oro Agri show that KS will suppress 

whiteflies. 

b. Insect suppression may be selective and variable due to a possible indirect mode of 

action (MOA).

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i. Note: observed suppression may be indirect via induced plant health due to the 

bio-available potassium supplied by KS.

2. Health and Environmental Concerns:

a. The petitioner stated, “Due to the regulatory status and extensive regulatory review of 

KS to date, we have reason to believe that the industry will conduct little to no research 

to add to the health and environmental data already available for KS.” 

b. The EPA continues to monitor KS as a preservative/antioxidant on the Safer Chemical 

Ingredients List (SCIL)

i. KS is a “green circle” ingredient, verified as low concern. 

c. The petitioned use of KS is for foliar application with no tolerance requirement. Little 

interaction with the soil is expected.

Question for stakeholders: At the Spring 2023 NOSB meeting the Crops Subcommittee asked the 

following question and is re-asking for the Fall 2023 meeting.

1. Is there any additional known research available to understand KS’s potential and efficacy if 

used as an insecticide or plant disease control?

Subcommittee Vote:

1. Motion to classify potassium sorbate as synthetic 

Motion by: Amy Bruch 

Seconded by: Mindee Jeffery

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

2. Motion to add potassium sorbate to the National List at § 205.601(e): Synthetic substances allowed 

for use in organic crop production – as insecticides

Motion by: Amy Bruch 

Seconded by: Logan Petrey

Yes: 1 No: 5 Abstain: 1 Recuse: 0 Absent: 1

3. Motion to add potassium sorbate to the National List at § 205.601(i): Synthetic substances allowed 

for use in organic crop production – as plant disease control

Motion by: Amy Bruch

Seconded by: Brian Caldwell

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

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