National Organic Standards Board

Handling Subcommittee Petitioned Material Proposal 

Phosphoric Acid Annotation Change

February 1, 2022

Summary of Petition [Phosphoric Acid annotation change petition] 

This document reviews the petitioned annotation change of phosphoric acid, which is currently listed on 

the National List at §205.605(b): Phosphoric acid - cleaning of food-contact surfaces and equipment 

only.

Introduction

In 2019, Kemin Food Technologies petitioned the United States Department of Agriculture (USDA) 

National Organic Program (NOP) to amend the existing annotation of phosphoric acid on the National 

List to include use as a synthetic substance for organic processing and handling (USDA 2019, USDA 

2020a, USDA 2020b). This new petition requests the expansion of the use of phosphoric acid “as an 

acidifier to adjust pH of an extraction solvent to extract antioxidants or other target molecules from 

lamiaceae plants, provided the amount of acid used shall not exceed the minimum needed to lower pH 

to 2.5” (USDA 2020b).

Background

In 2002, Acadian Seaplants Limited petitioned the USDA NOP to expand the approved use of phosphoric 

acid within the National List to include production of organic aquatic plant extracts (USDA 2002). A 

technical report on phosphoric acid for organic processing was submitted in 2003 (USDA 2003). In 2004 

the NOP contacted the petitioner and stated that phosphoric acid did not need to be petitioned for use 

in plant extraction “because its use as a pH adjuster in aquatic plant extracts is currently not prohibited 

through the inclusion of “aquatic plant extracts” in section 205.601(j)(1) of the National Organic 

Standards” . In 2013 the NOP sent a memorandum to the National Organic Standards Board (NOSB) 

requesting a review on the use of phosphoric acid in plant extracts to ensure that this use is consistent 

with the context on the National List (NOP 2013). The petitioner subsequently withdrew the petition in 

January 2014. 

Use 

Phosphoric acid is used in organic handling and processing as a cleaning agent for “food contact surfaces 

and equipment,” as described in 7 CFR 205.605(b). Phosphoric acid has been approved for pH 

adjustment of some soil amendments (liquid fish products and squid byproducts) and as an equipment 

cleaner in both organic crop and livestock production. (7 CFR 205.601 and §205.603).

In addition to its appearance at 7 CFR 205.605, phosphoric acid has been used as an ingredient in plant 

extractions (USDA 2002, USDA 2019, USDA 2020a, USDA 2020b). When used in this manner, phosphoric 

acid acts as an acidifying agent and stabilizer to facilitate more efficient extraction of target compounds 

(Yoon et al. 2020). The petitioner is intending to use the substance in this manner, to extract target 

molecules, including but not limited to antioxidants, from various plant species of the lamiaceae family. 

In order to prepare the proper extraction solvent, tap water pH will be adjusted to lower pH.

The petitioner states, “This adjustment is critical to successful extraction because such low pH inhibits 

enzymatic oxidation that would otherwise destroy the target molecules. Regarding use of the extract, as 

consumer preferences begin to change and shift away from chemically sounding ingredients, consumers 

are looking to purchase and consume foods made with ingredients that come from natural sources. For 

food manufacturers, this means finding replacements for traditionally used synthetic ingredients, such 

NOSB Proposals and Discussion Documents April 2022 Page 31 of 152
as plant- based molecules. The petition is intended to be limited to extracting target molecules from 

plants of the lamiaceae family. The extracted target molecules may be subsequently blended with 

appropriate carriers for help in proper dispersal across the surface of finished food products. Application 

depends on the finished food matrix as different extracts have hydrophilic or lipophilic properties.” 

In addition to organic applications, phosphoric acid is a widely-used substance in conventional 

agriculture, with approximately 90% of wet process phosphoric acid used in the production of fertilizers 

(Shriver and Atkins 2008). Phosphoric acid has uses in food and beverage processing as a pH adjuster, 

flavor ingredient, and processing agent in dairy products (Wolke 2002, Gilmour 2019). Phosphoric acid is 

also a precursor to synthetic phosphates, which have a variety of uses including as fertilizers, 

surfactants, and detergents (Shriver and Atkins 2008). [TR 163-179]

Manufacture

Phosphoric acid is produced through two methods: the wet process, and the thermal process (EPA 1995, 

Gilmour 2019, Haghani and Daneshpazhuh 2020). Historically, the end-point use for the phosphoric acid 

was determined by its production method. High purity, technical and food grade phosphoric acid was 

produced by the thermal process (EPA 1995, Gilmour 2019). Lower purity phosphoric acid, primarily 

used in animal feed and fertilizer applications, was produced by the wet process (EPA 1995, Shriver and 

Atkins 2008, Gilmour 2019). Due to the expensive nature of the thermal process, there has been 

continued development of purification methods for wet process phosphoric acid, which now serve as 

the predominant method for the production of technical and food grade phosphoric acid (Gilmour 

2019).

Thermal Process

The thermal process is broken down into three major steps: combustion, hydration, and demisting 

(collection) (EPA 1995, Gilmour 2019). In the combustion step, elemental yellow phosphorus (P4) is 

reacted with oxygen gas, which oxidizes the phosphorous from its 0 to V oxidation state, as shown 

below in Equation 6 (EPA 1995, Gilmour 2019). The heat of combustion for phosphorus is highly 

endothermic and the reaction must be carried out at high temperatures (1650 – 2760 °C) (EPA 1995, 

Gilmour 2019).

P4 + 5 O2  2 P2O5

Equation 6

Once the elemental phosphorus is oxidized to P2O5, it undergoes the hydration process to form 

orthophosphoric acid, as shown below in Equation 7 (EPA 1995, Gilmour 2019). In this process P2O5 is 

generally reacted with water, although in some cases dilute solutions of phosphoric acid are used 

instead of water alone (EPA 1995). Once phosphoric acid has been produced, it is isolated in the 

demisting process. In this step, phosphoric acid is collected as a mist with high-pressure drop demisters. 

The thermal process produces phosphoric acid with P2O5 concentrations between 54 and 62%, which are 

sufficiently pure for use in technical and food grade applications (EPA 1995, Gilmour 2019).

2 P2O5 + 6 H2O 4 H3PO4

Equation 7

Wet Process

The wet process produces phosphoric acid from naturally occurring phosphate mineral sources 

(fluorapatite [Ca10(PO4)6F2] and hydroxyapatite [Ca10(PO4)6(OH)2]) (EPA 1995, Shriver and Atkins 2008, 

Gilmour 2019, Haghani and Daneshpazhuh 2020). Once mined, these minerals are converted to 

NOSB Proposals and Discussion Documents April 2022 Page 32 of 152
phosphoric acid in four main steps, as outlined in Figure 5 below (Gilmour 2019). The phosphate rock is 

prepped in the initial step by being milled and ground to increase its surface area (EPA 1995, Haghani 

and Daneshpazhuh 2020).

Figure 5

Once milled, the mineral phosphates are reacted with a strong mineral acid and converted to 

phosphoric acid, as shown in Equation 8 below (EPA 1995, Shriver and Atkins 2008, Gilmour 2019, 

Haghani and Daneshpazhuh 2020). While sulfuric acid is shown in both Figure 5 and Equation 8, other 

strong mineral acids [e.g., nitric acid (HNO3) and hydrochloric acid (HCl)] may also be used (Jin et al. 

2014, Haghani and Daneshpazhuh 2020). However, most commercial processes use sulfuric acid because 

it provides higher phosphoric acid yields, lower costs, and a solid form of calcium (Al-Fariss et al. 1992, 

EPA 1995, Shriver and Atkins 2008, Gilmour 2019). The specific reaction conditions dictate the type of 

calcium sulfate hydrate (CaSO4 • n H2O) formed, with lower temperatures favoring the formation of 

gypsum (CaSO4 • 2 H2O), as shown in Equation 8 (EPA 1995). The prevalence of fluorapatite among 

mineral phosphates also produces hydrofluoric acid (HF), as shown below in Equation 8.

Ca10(PO4)4F2 (s) + H2SO4 (aq) + 20 H2O (l)  6 H3PO4 (aq) + 10 [CaSO4 • 2 H2O](s) + 2 HF (aq)

Equation 8

The gypsum formed during the reaction with the mineral acid is removed via filtration. Once removed, 

the gypsum solids undergo several aqueous wash cycles to remove residual phosphoric acid from the 

solid surface, producing phosphoric acids yields of 99.9% (EPA 1995, Gilmour 2019). As shown previously 

in Figure 5, the aqueous gypsum washes are sent back to the reaction vessel to aid in the conversion of 

mineral phosphates (EPA 1995, Gilmour 2019). The presence of mineral silicon in the initial composition 

reacts with hydrofluoric acid to produce less reactive forms of silicon tetrafluoride (SiF4) and SiF6

2- ions, 

some of which are removed as solids with the gypsum (Gilmour 2019).

The phosphoric acid isolated following the filtration process is dilute, with P2O5 concentrations between 

26 – 30% (EPA 1995, Gilmour 2019). Vacuum evaporation is used to remove water and concentrate the 

phosphoric acid to 42 – 54% P2O5 (Gilmour 2019). Activated silica or clay is added during the 

concentration process to react with residual hydrofluoric acid. Silicon tetrafluoride isolated from the 

concentration step is hydrolyzed to fluorosilicic acid (H2SiF6), as shown in Figure 5 (Gilmour 2019).

Mineral impurities, including heavy metal contaminants, remain in phosphoric acid produced via the wet 

process, which have historically limited its use to agricultural fertilizer applications (EPA 1995, Shriver 

and Atkins 2008, Gilmour 2019, Haghani and Daneshpazhuh 2020). Wet process phosphoric acid results 

in concentrations of between 42 and 54% P2O5, which is largely unsuitable for technical applications 

(Gilmour 2019). The elemental phosphorous used in the thermal process can be purified via sublimation, 

resulting in no carry-over of heavy metal contaminants so that thermal phosphoric acid can be used in 

technical and food applications (Shriver and Atkins 2008). However, the thermal process is much more 

expensive and energy intensive than the wet process (~2000 °C vs ~80 °C) (EPA 1995, Gilmour 2019).

NOSB Proposals and Discussion Documents April 2022 Page 33 of 152
Wet process purification methods

Wet process phosphoric acid is commonly purified by crystallization or solvent extraction (Gilmour 

2019). Crystallization is a common purification technique, which is based on the differing solubilities of 

pure and impure mixtures, with pure substances selectively crystallizing at reduced temperatures (Pavia 

et al. 1995). When phosphoric acid is concentrated to 61% P2O5 or higher, it selectively forms 

hemihydrate crystals (H3PO4 • 1⁄2 H2O) when cooled to 8 – 12 °C (Gilmour 2019). The crystals are 

removed from the mixture and can be melted to undergo additional recrystallization cycles to improve 

purity, with each cycle yielding a 10 to 100 times increase in purity (Gilmour 2019).

Solvent extraction is another traditional purification method based on solubility. In solvent extraction, 

the target compound migrates between immiscible phases [usually aqueous (polar) and organic 

(nonpolar)] based on solubility (Pavia et al. 1995). The selectivity of phosphoric acid does not differ 

greatly compared to its impurities, requiring additional purification steps. Prior to solvent extraction, 

concentrated phosphoric acid undergoes precipitation with calcium or barium salts to remove sulfate 

(SO4

2-), sodium salts to remove fluorosilicates, and sulfides to remove arsenic (Shlewitt and Alibrahim 

2008, Gilmour 2019, Haghani and Daneshpazhuh 2020). Phosphoric acid extractions are performed in 

one or more extraction columns with many possible organic solvents, including alcohols, ethers, 

ketones, amines, and kerosene blends (Shlewitt and Alibrahim 2008, Jin et al. 2014, Gilmour 2019). 

Following extraction with an organic solvent, phosphoric acid is recovered with water. Residual organic 

solvents are removed via evaporation during the concentration of the recovered phosphoric acid from 

the aqueous solution (Shlewitt and Alibrahim 2008, Gilmour 2019). Solvent extraction of wet process 

phosphoric acid improves the purity of the substance from 42-54% P2O5 in the raw form to up to 97% 

P2O5 (Gilmour 2019). [TR 376-482]

International Acceptance

Canadian General Standards Board Permitted Substances List

Phosphoric acid is listed in the Organic Production Systems Permitted Substances List as an approved 

substance for pH adjustment of “fish meal, fish powder, fish wastes, hydrolysate, emulsions and 

solubles” that are used for “soil amendments and crop nutrition.” Phosphoric acid is also listed as a 

“cleaner, disinfectant and sanitizer permitted on organic product contact surfaces for which a removal 

event is mandatory [for use] on dairy equipment.” [TR 345-351]

European Economic Community (EEC) Council Regulation, EC No. 834/2007 and 889/2008

Phosphoric acid is not listed in EC No. 834/2007 or EC No. 889/2008. [TR 357-358]

CODEX Alimentarius Commission, Guidelines for the Production, Processing, Labelling and Marketing of 

Organically Produced Foods (CXG 32-1999)

Phosphoric acid is not listed in the CODEX. [TR 353-355]

International Federation of Organic Agriculture Movements (IFOAM) Norms

Phosphoric acid is listed in the IFOAM NORMS for organic production and processing as an “equipment 

cleanser and equipment disinfectant only for dairy equipment,” and as a “substance for pest and disease 

control and disinfection in livestock housing and equipment [for] dairy equipment.” [TR 364-367]

Japan Agricultural Standard (JAS) for Organic Production

Phosphoric acid is not listed in the JAS. [TR 360-361]

NOSB Proposals and Discussion Documents April 2022 Page 34 of 152
Summary of Review

The Subcommittee’s review and discussion were centered around the petitioner’s stated essentiality as 

the most effective acid for pH adjustment to prepare extraction solvents, as there are other acids on the 

National List that can be used for this purpose, along with the allowance on the crops list for a similar 

extraction process (e.g., pH adjustment of liquid fish products and squid byproducts). However, it was 

also noted that phosphoric acid isn’t allowed on the crops list for the extraction of aquatic plant extracts 

as the petition was withdrawn for this use. The Subcommittee further discussed the low negative impact 

on the environment and human health along with the fact that this material is already listed on the 

National List.

The NOSB is aware that this annotation change would be adding a synthetic substance for use in food. 

However, it does appear that due to the functionality of the petitioned use that it is unlikely for 

phosphoric acid to be present in the final food product. That said, the Subcommittee doesn’t fully 

understand exactly how and in what finished food products this is going to be used based on the 

petition. 

Category 1: Classification 

1. Substance is for: __X__ Handling _____ Livestock

2. For HANDLING and LIVESTOCK use: 

a. Is the substance _____ Agricultural or __X__ Non-Agricultural?

Describe reasoning for this decision using NOP 5033-2 as a guide: 

Phosphoric Acid is currently listed on the National List at §205.605(b).

b. If the substance is Non-agricultural, 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: 

Phosphoric Acid is currently listed on the National List at §205.605(b).

3. For LIVESTOCK: 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?

N/A

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)]

NOSB Proposals and Discussion Documents April 2022 Page 35 of 152
The petition states “Phosphoric Acid itself combines readily with many other chemicals and no known 

detrimental interactions within organic farming systems is known.” Additionally, this material is already 

listed twice on the National List, therefore the potential for detrimental chemical reactions seems 

unlikely. 

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)]

The petition states “In the process of phytochemical extraction, phosphoric acid combines with water to 

form an acidified extraction solution. Phosphoric acid in its original form will break down quickly in the 

environment, so there are no toxicity issues directly related to its breakdown products. In this process, 

phosphoric acid will be partially neutralized by the plant components, and after extraction, the matrix 

has a pH of about 5.0-6.0. Consequently, the phosphoric acid will no longer exist in its acid form and the 

resulting liquid will not be corrosive. Therefore, while raw and concentrated phosphoric acid might be 

toxic to aquatic environments, the process mitigates contaminant persistence and/or concentration in 

the environment.” 

The TR states that due to the low concentration in the extraction application, as well as the prevalence 

of phosphates throughput biology that the likelihood of toxicity and concentration in the environment 

are low.

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

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

When used as petitioned, phosphoric acid is used in low concentrations (1 - 3%), and is a source of 

phosphates for incorporation to biomolecules. The low concentration in extraction applications and the 

prevalence of phosphates throughout biology make phosphoric acid from plant extractions unlikely to 

be harmful to the environment or biodiversity.

However, the production of phosphoric acid does have the potential to be harmful to the environment. 

The thermal process for producing phosphoric acid is energy intensive and requires high temperatures. 

The high energy requirements of the thermal process may contribute to atmospheric CO2 levels if the 

energy is produced from fossil fuels. The thermal process also requires the treatment of combustion 

gases by scrubbers, cyclonic separators, mist eliminators, and electrostatic precipitators to prevent the 

release of phosphoric acid to the environment (EPA 1995, Gilmour 2019). The small size (< 3 μμm 

diameter) makes these phosphoric acid and phosphorus oxide (P2O5) particles difficult to capture, and 

contributes their release to the atmosphere at levels of “< 25 mg P2O5 per dry standard cubic meter of 

stack gas” (Gilmour 2019).

Wet process phosphoric acid is produced from chemical changes to mined mineral phosphates. There 

may be initial harm to the environment and biodiversity in the mining process. Once the minerals are 

isolated, hydrofluoric acid presents the most likely source of environmental harm (Shriver and Atkins 

2008). Hydrofluoric acid is removed as a solid or as fluorosilicic acid by reaction with silica sources. 

These include natural silicates present within the initial mineral, as well as activated silica and clay 

added during the manufacturing process (Shriver and Atkins 2008, Gilmour 2019). Additionally, 

scrubbers are used to remove gaseous fluorine compounds from concentration steps to prevent their 

release to the environment (EPA 1995).

NOSB Proposals and Discussion Documents April 2022 Page 36 of 152
In addition to the hazards from fluorine compounds, the gypsum produced may pose a hazard to the 

environment. Isolated gypsum may be used for other commercial applications if it is sufficiently pure 

(Gilmour 2019). In other cases, gypsum is left in gypsum stacks, or pumped out to sea (Gilmour 2019). 

However, the gypsum may also contain silicon fluorides, acids, and other impurities from the initial 

mineral source, which has resulted in its designation as a hazardous substance by the EPA in 40 CFR 

261.4. [TR 566-594]

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

§6518(m)(4)]. 

Concentrated phosphoric acid is corrosive and can result in burning and irritation of the eyes and skin on 

contact (Flomenbaum et al. 2002, NJDHSS 2004, Gilmour 2019). Phosphoric acid can desiccate epithelial 

cells, resulting in the drying and cracking of skin where long-term exposure occurs (Flomenbaum et al. 

2002, NJDHSS 2004). Inhalation of phosphoric acid may result in irritation to the nose, lungs, and throat 

and may induce coughing and wheezing (NJDHSS 2004, Gilmour 2019). Ingestion of phosphoric acid may 

damage gastric and esophageal mucus linings (Flomenbaum et al. 2002). 

Phosphoric acid is frequently used in food processing and production and is a common component of 

food and beverages (Wolke 2002). As described in Equations 2 – 4 in the “Composition of the 

Substance” section, phosphoric acid is the source of several phosphates, which are important 

components of biomolecules (e.g., ATP, DNA, etc.) (Shriver and Atkins 2008, Timberlake 2016, Gilmour 

2019). When used as petitioned, phosphoric acid is used in low concentrations (1 – 3%), making it

unlikely to be harmful to human health (Gilmour 2019). [TR 599-611]

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 petition states, “When stored, used and disposed of appropriately, Phosphoric acid use during 

phytochemical extraction will have no negative interactions with soil organisms, crops, or livestock.” 

Additionally Phosphoric acid is allowed at §205.601(j)(8) as a pH adjuster which makes the likelihood

that Phosphoric acid has negative physiological effects on soil organisms, crops, and livestock unlikely.

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

As previously stated, due to the low concentration in the extraction application, as well as the 

prevalence of phosphates throughput biology there doesn’t appear to be adverse impact on 

biodiversity. 

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)]

There are alternative methods to extract target molecules from plant material. One of the simplest ways 

to improve solvent extraction processes is to increase the solvent temperature (Pavia et al. 1995, 

NOSB Proposals and Discussion Documents April 2022 Page 37 of 152
Silberberg 2003). Increased temperature improves the solvation of most solids and liquids by disrupting 

the intermolecular forces that prevent the target molecule from entering the solution (Silberberg 2003).

Supercritical carbon dioxide extraction offers an alternative to acidic extractions. This extraction method 

uses temperatures and pressures that push the solvent beyond its critical point, so that it no longer 

exists as a liquid or gas (Silberberg 2003, Babovic et al. 2010). Carbon dioxide is the most common 

supercritical fluid used in extraction applications due to its low cost and the low temperatures and 

pressures required to reach supercritical conditions (31.1 °C and 7.38 MPa) (Babovic et al. 2010). The 

selectivity of supercritical fluids can be modulated by changing its temperature and pressure to target 

different classes of molecules.

Subcritical extractions offer another alternative to acidic extractions. In such applications, the solvent 

remains in liquid form, although conditions may approach the critical point of the solvent (Ibañez et al. 

2003). As with supercritical fluid extractions, the selectivity of the subcritical extractions can be 

manipulated by modifying temperature and pressure. Subcritical water extractions have been successful 

in the extraction of essential oils and antioxidants (Ibañez et al. 2003). However, some antioxidants and 

other compounds are sensitive to decomposition, and may not survive increased solvent temperatures 

or the high-pressure conditions needed in supercritical and subcritical extractions (Ibañez et al. 2003). 

[TR 616-634]

Many natural and currently allowed synthetic acids offer an alternative to phosphoric acid for plant 

extractions, such as acetic acid, citric acid, gibberellic acid, lactic acid, and tartaric acid (NOP 2016c). 

Polyprotic carboxylic acids (for example, ascorbic acid, citric acid, etc.) are also able to chelate positively 

charged species, facilitating improved extraction (Albuquerque et al. 2005). 

However, the strength of the acid is important in determining the effectiveness in the extraction of the 

target molecules. Carboxylic acids are weaker acids than phosphoric acid (pKa ~5 vs 2.15) meaning that 

they may be less effective in extracting some molecules, including anthocyanin antioxidants (Silberberg 

2003, Nicoué et al. 2007, Timberlake 2016). The target molecule and plant structure determine the 

optimal solvent conditions, although phosphoric acid solutions have been reported to be among the 

most effective for antioxidant extractions (Nicoué et al. 2007). [TR 640-650]

Alternatives to phosphoric acid are naturally acidic agricultural substances, including wine and vinegar. 

Both mixtures include natural acids that can provide an acidic extraction solution. However, as described 

in Evaluation Question 12, carboxylic acids are weaker than phosphoric acid and may be less effective in 

the extraction of some target molecules. Additionally, the complex mixture of compounds in wine and 

vinegar would make purification of the plant extracts more difficult. [TR 655-659]

Category 4: Additional criteria for synthetic substances used in Handling (does not apply to 

nonsynthetic or agricultural substances used in organic handling):

Describe how the petitioned substance meets or fails to meet each numbered criterion.

1. The substance cannot be produced from a natural source and there are no organic substitutes; 

(§205.600(b)(1)) 

Phosphoric acid is a synthetic substance that does not exist in nature. Therefore, there are no natural 

sources of phosphoric acid. [TR 500-501]

NOSB Proposals and Discussion Documents April 2022 Page 38 of 152
2. The substance's manufacture, use, and disposal do not have adverse effects on the environment 

and are done in a manner compatible with organic handling; (§205.600(b)(2)) 

The petition states, “There are many environmental consequences from the manufacture, misuse and 

disposal of phosphates in general and these cannot be separated out for phosphoric acid in particular. In 

figures from world phosphorus consumption in 1980, about 90% of phosphate consumption is for 

fertilizer, while 4.5% is for all detergents including other cleaners such as trisodium phosphate. There 

are extreme environmental impacts from mining of phosphate ore which occurs in many parts of the 

world. Worker safety is of prime concern in the wet-process acid and elemental phosphorous used in 

the thermal process because of high acidity, heat released upon neutralization and toxic gases released. 

Plants will be equipped with proper safety procedures and equipment to deal with these issues. 

The issues of phosphate pollution from disposal are discussed above, but in general the dilution of 

phosphoric acid will minimize disposal problems in the food processing or livestock facility.” 

The TR, as previously stated, indicates that the use of Phosphoric acid is relatively benign regarding its 

impact on the environment. However, it does state that thermal production process is energy intensive 

and uses high temperatures, which could contribute to CO2 levels if the energy is produced from fossil 

fuels. That said, as stated previously, due to the expensive nature of the thermal process, there has been 

continued development of purification methods for wet process phosphoric acid, which now serve as 

the predominant method for the production of technical and food grade phosphoric acid (Gilmour 

2019).

3. The nutritional quality of the food is maintained when the substance is used, and the substance, 

itself, or its breakdown products do not have an adverse effect on human health as defined by 

applicable Federal regulations; (§205.600(b)(3)

When used as petitioned, phosphoric acid will be used in the extraction of target molecules from plant 

material. The extraction of antioxidants and other compounds from the initial plant material will reduce 

the nutritional quality of the material from which they are extracted. However, the purpose of plant 

extracts is to improve the quality of other products to which they are added. (Nicoué et al. 2007, 

Proestos 2020). Phosphoric acid is a source of phosphates, which are important nutrients in human 

health, and can be found in many biomolecules, including ATP and DNA (Shriver and Atkins 2008, 

Timberlake 2016, Gilmour 2019). However, phosphoric acid is typically used in low concentrations (1 – 

3%) in extraction processes and is unlikely to contribute directly to improved nutritional quality. [TR 540-

547]

4. The substance's primary use is not as a preservative or to recreate or improve flavors, colors, 

textures, or nutritive value lost during processing, except where the replacement of nutrients is 

required by law; (§205.600(b)(4)) 

When used as petitioned, the primary function of phosphoric acid is to improve the extraction of target 

molecules, not to act as a preservative. However, in some cases, the addition of phosphoric acid 

stabilizes target molecules from decomposition, as described above in the “Action of the Substance” 

section.

Phosphoric acid is also used as an equipment sanitizer in organic agriculture in 7 CFR 205.605 and 

§205.603. The low pH of phosphoric acid solutions makes it an antimicrobial substance, as high acid 

content is not tolerated by microorganisms (Winniczuk and Parish 1997, Prado et al. 2015). The 

NOSB Proposals and Discussion Documents April 2022 Page 39 of 152
antimicrobial nature of phosphoric acid may result in some preservative characteristics if incorporated 

into food and beverage products (Winniczuk and Parish 1997). [TR 518-526]

When used as petitioned, the primary function of phosphoric acid is to improve the extraction of target 

molecules, not to improve or recreate flavors in processed food products. However, phosphoric acid has 

been used as a flavoring agent in conventional food and beverage production, as described above in the 

“Specific Uses of the Substance” and “Historical Use” sections. [TR 532-535] 

5. The substance is listed as generally recognized as safe (GRAS) by the Food and Drug 

Administration (FDA) when used in accordance with FDA's good manufacturing practices (GMP) 

and contains no residues of heavy metals or other contaminants in excess of tolerances set by 

FDA; (§205.600(b)(5)) 

As described in the “Approved Legal Uses of the Substance” section, the FDA has designated phosphoric 

acid generally recognized as safe (GRAS) for several uses. Phosphoric acid is listed as a “multiple purpose 

GRAS food substance” in 21 CFR 182. 1073, and as a GRAS “general purpose food additive” in 

§582.1073. Additionally, the FDA lists phosphoric acid as a substance used in the production of the GRAS 

substances monobasic ammonium phosphate in §184.1141, dibasic ammonium phosphate in 

§184.1141, magnesium phosphate in §184.1366, and hydrogen peroxide in §184.1366. [TR 507-512]

6. The substance is essential for the handling of organically produced agricultural products. 

(§205.600(b)(6)) 

The petition states, “Since effective extraction is a critical step in the ability to use biomolecules, the 

ultimately benefit of the applicable organic management program, and since phosphoric acid appears 

among the best and safest pH adjusters, this material seems compatible with an organic production and 

processing system.” 

7. In balancing the responses to the criteria in Categories 2, 3 and 4, is the substance compatible 

with a system of sustainable agriculture [§6518(m)(7)] and compatible with organic handling?

(see NOSB Recommendation, Compatibility with Organic Production and Handling, April 2004) 

The substance is compatible with a system of sustainable agriculture as phosphoric acid is already on the 

National List at §205.605(b) and is allowed as a pH adjuster of liquid fish products (§205.601(j)(8)).

Additionally, phosphoric acid doesn’t appear to have a negative impact on the environment or human 

health. Lastly, while there are other synthetic acids that are allowed (e.g., acetic acid, citric acid, 

gibberellic acid, lactic acid, and tartaric acid) as well as polyprotic carboxylic acids (for example, ascorbic 

acid, citric acid, etc.), these may not be as effective. 

Carboxylic acids are weaker acids than phosphoric acid (pKa ~5 vs 2.15) meaning that they may be less 

effective in extracting some molecules, including anthocyanin antioxidants (Silberberg 2003, Nicoué et 

al. 2007, Timberlake 2016). The target molecule and plant structure determine the optimal solvent 

conditions, although phosphoric acid solutions have been reported to be among the most effective for 

antioxidant extractions (Nicoué et al. 2007). [TR 646-650]

NOSB Proposals and Discussion Documents April 2022 Page 40 of 152
Questions to our Stakeholders

1. If the use of phosphoric acid is expanded through this petitioned annotation change will it perform 

an essential function that is different than other already listed acids?

2. What is the application of phosphoric acid in the finished food product (i.e., what does “The 

extracted target molecules may be subsequently blended with appropriate carriers for help in 

proper dispersal across the surface of finished food products” mean in an actual use case)? 

Subcommittee Vote:

National List Motion

Motion to amend the annotation of phosphoric acid to (underlined verbiage is the proposed addition)

“cleaning of food-contact surfaces and equipment, and as an acidifier to adjust pH of an extraction 

solvent to extract antioxidants or other target molecules from lamiaceae plants, provided the amount of 

acid used shall not exceed the minimum needed to lower pH to 2.5.” at § 205.605(b).

Motion by: Kyla Smith

Seconded by: Wood Turner

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

NOSB Proposals and Discussion Documents April 2022 Page 41 of 152