National Organic Standards Board

Crops Subcommittee

Petitioned Material Proposal

Potassium Hypochlorite

July 16, 2019

Summary of Petition 

[https://www.ams.usda.gov/sites/default/files/media/PotassiumHypochloriteRevisedPetition03262019.

pdf]: 

The petitioner is requesting potassium hypochlorite solution be included on the National List as follows: 

§ 205.601 Synthetic substances allowed for use in organic crop production: (2) Chlorine materials - For

pre-harvest use, residual chlorine levels in the water in direct crop contact or as water from cleaning

irrigation systems applied to soil must not exceed the maximum residual disinfectant limit under the

Safe Drinking Water Act, except that chlorine products may be used in edible sprout production

according to EPA label directions.

Potassium hypochlorite is produced by the reaction of chlorine with a solution of potassium hydroxide: 

Cl2 + 2 KOH → KCl + KClO + H2O 

Potassium hypochlorite (KOCl) is registered by EPA and is FDA approved. This material is approved for 

use in many agricultural applications. This product can address needs for irrigation equipment 

maintenance and to meet Food Safety Modernization Act (FSMA) requirements to provide sanitation to 

pre-harvest water for irrigation. The material can also incidentally provide a source of potassium for 

plants.

As described in the petition, potassium hypochlorite shares similar chemistry and uses as sodium 

hypochlorite (bleach), except for the replacement of sodium for potassium, potentially reducing issues 

with salinization of soils. At the request of the petitioner, the FDA reviewed this product in comparison 

to NaOCl. FDA found the substitution of potassium ions for sodium, in such applications as NaOCl 

solutions, would not raise new safety concerns. They also stated that a Food Contact Notification (FCN) 

would not be required to use KOCl in the same manner that NaOCl is permitted. KOCl is exempt from 

requirements for a food tolerance (https://www.federalregister.gov/documents/2011/03/02/2011-

4534/potassium-hypochlorite-exemption-from-the-requirement-of-a-tolerance) 

Like bleach and other chlorine sanitizing compounds currently on the National List, KOCl is a strong 

oxidant and can pose serious risks to human health if acute high exposure occurs or from chronic lower 

level exposures. It is a dermal, respiratory, ocular, and mucous membrane irritant. Bleach is a known 

asthmagen, and, given the similar chemistries and mechanism of action, KOCL is also likely to cause or 

exacerbate asthma. KOCL is toxic to fish and other aquatic organisms. Like bleach and other chlorine 

compounds, strict adherence to the label is required. Use of chlorine compounds in organic crop 

production, including calcium hypochlorite, sodium hypochlorite, and chlorine dioxide, were reviewed in 

a 2011 Technical Report (TR) 

(https://www.ams.usda.gov/sites/default/files/media/Chlorine%202%20TR%202011.pdf). Information 

in this TR is transferable to the KOCl.

Given the nearly identical chemistry and human and environmental risks to sodium and calcium 

hypochlorite, currently listed under (§ 205.601(2), and the potential benefit of avoiding application of 

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sodium to soils, the Crops Subcommittee recommends listing of KOCl for the treatment of irrigation 

water not to exceed the maximum residual disinfectant limit under the Safe Drinking Water Act. 

Summary of Review: 

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. 

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?

No.

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)]

When used in irrigation water and compliant with maximum residual disinfectant limit under the 

Safe Drinking Water Act [4 ppm free chlorine], the substance is unlikely to have detrimental 

chemical interactions with other materials used in organic farming systems.

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)]

Like bleach and other chlorine sanitizing compounds currently on the National List, KOCl is a 

strong oxidant and can pose serious risks to human health if acute high exposure occurs or from 

chronic lower level exposures. It is a dermal, respiratory, ocular, and mucous membrane irritant. 

Bleach is a known asthmagen, and, given the similar chemistries and mechanism of action, KOCL 

is also likely to cause or exacerbate asthma. KOCL is toxic to fish and other aquatic organisms. 

Like bleach and other chlorine compounds, strict adherence to the label is required. 

According to the petition, “...hypochlorite salts break down rapidly in to non-toxic compounds 

when exposed to sunlight. In seawater, chlorine levels decline rapidly: however, hypobromite 

(which is acutely toxic to aquatic organisms) is formed. Due to the presence of 65 ppm of 

bromide ion in seawater, hypochlorite salts form hypobromite salts. Hypobromite salts are very 

unstable to photolysis and rapidly break down back to bromide ion under the influence of ultra 

violet light [sunlight].

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

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

If the material is used according to label requirements, the probability of adverse environmental 

contamination is low. The petitioned use is in irrigation water, so the material will be directly 

released to the environment. The levels, generally 1-2 ppm and not to exceed 4 ppm, are 

consistent with drinking water standards and unlikely to pose a threat to human health or the 

environment. KOCl is not persistent. The major environmental risks are due to accidental 

releases of concentrated precursor material during manufacture (Cl2) or transport of finished 

product before dilution for irrigation purposes.

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

6518(m)(4)]. 

Like bleach and other chlorine sanitizing compounds currently on the National List, KOCl is a 

strong oxidant and can pose serious risks to human health if acute high exposure occurs or from 

chronic lower level exposures. It is a dermal, respiratory, ocular, and mucous membrane irritant. 

Bleach is a known asthmagen, and, given the similar chemistries and mechanism of action, KOCL 

is also likely to cause or exacerbate asthma. The threshold or duration of exposures that might 

result in long-term respiratory problems is unknown. Short low level term exposures may result 

in transitory respiratory and eye irritation. Like bleach and other chlorine compounds, strict 

adherence to the label is required and care must be taken to protect workers diluting material 

for irrigation use. 

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)] 

The application rate of 1-2 ppm, not to exceed free chlorine of 4 ppm, is consistent with drinking 

water standards for human. Use at this level in irrigation water is unlikely to have adverse 

biological and chemical interactions in the agroecosystem. Because KOCL substitutes potassium 

for sodium, it will not increase soil salinization.

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

Unlikely. 

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)]

Sodium and calcium hypochlorite can be used for the same purposes as the petitioned material. 

KOCl has the distinct benefit over NaOCL because it does not contain sodium and potassium and

is a plant nutrient. 

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

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

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Overall, yes. Like other chlorine compounds, KOCl poses human health and environmental 

concerns, reviewed in part in the chlorine materials 2011 TR. However, FSMA requires that 

irrigation water used during certain growing activities have an acceptable microbial water 

quality profile (MWQP) and KOCL can meet this need and can also reduce fouling of irrigation 

equipment. These purposes are consistent with allowed uses of other chlorine materials. KOCl 

provides another tool to meet these requirements, and avoids application of sodium to soils.

Classification Motion: 

 

Motion to classify potassium hypochlorite as synthetic

Motion by: Steve Ela 

Seconded by: Dan Seitz

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

National List Motion: 

Motion to add potassium hypochlorite at § 205.601(2): Chlorine materials - For use in water for 

irrigation purposes, residual chlorine levels in the water in direct crop contact or as water from 

cleaning irrigation systems applied to soil must not exceed the maximum residual disinfectant 

limit under the Safe Drinking Water Act.

Motion by: Steve Ela 

Seconded by: Rick Greenwood

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

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