National Organic Standards Board 

Handling Subcommittee Proposal

Review of the Ion Exchange Filtration Process and Materials Used 

August 4, 2020 

Background: 

In an August 27, 2019, memo the National Organic Program requested the NOSB provide 

recommendations related to the process of ion exchange filtration in the handling of organic products. 

It has become clear that there is inconsistency between certifiers in how they approve or disapprove 

this type of process. Some certifiers require only the solutions that are used to recharge the ion 

exchange membranes be on the National List at § 205.605. Others require that all materials, including 

ion exchange membranes and resins be on the National List. 

The National Organic Program provided clarification to certifying agents in an email sent on May 7, 

2019, that nonagricultural substances used in the ion-exchange process must be present on the National 

List. This would include, but is not limited to, resins, membranes and recharge materials. Originally, the 

NOP asked all operations to come into compliance with the statement above by May 1, 2020. However, 

in response to requests for clarification of NOP’s rationale, as well as requests to extend the timeline for 

implementation, the NOP delayed the implementation date in order to gather more information and 

requested that NOSB review the issue. 

Manufacturers and certifiers who wish to continue allowance of the ion exchange process disagree with 

some of the findings of the NOP on this complex issue. The different opinions of the need for resins, 

recharge materials and membranes to be present on the National List, as well as how they interact with 

each other and the liquid run through the process, is complicated and the NOP therefore asked the 

NOSB to take on this issue. 

A simplified summary of ion exchange, provided in the past from OMRI is as follows: 

Ion exchange is based on the principle that a solid mass with immobilized charges can attract 

the mobile ions of the opposite charge in a fluid media. In practice, this involves a column that is 

like a large pipe packed with an exchanger, which may be in the form of beads, crystals, gels, or 

granules. The fluid can pass through, but the ions in solution will be pulled out and held to the 

exchanger. The process chemically changes the resulting fluid. 

Techniques used to produce various sweeteners offer a good example of how the process 

works. Minerals, salts, proteins and color bodies occur naturally in grape juice, cane juice, beet 

juice, and corn syrup. The refinement process seeks to remove these "impurities". They are also 

naturally present or—in case of color bodies—are formed between naturally present 

components during heating. These can be removed by a number of techniques. Some are 

physical, some are chemical, and some use both. However, the use of synthetic cross-linked 

polymeric resins—such as styrene-divinylbenzene (S-DVB)—to remove certain constituents of 

liquids based on their chemical properties is a chemical process. The liquified sweetener stream 

chemically reacts with the ions present on the ion exchange resin to purify and concentrate the 

desired sugar (Cantor and Spitz, 1956). 

Other processing aids that are considered secondary food additives required petitions in order 

to be considered. In addition to the filtering / clarifying / fining agents mentioned above, these 

also included the boiler water additives, antifoaming agents, and certain enzymes. Other 

additives that are considered ‘de minimis’ in conventional processing—such as disinfectants and 

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atmospheric gases—also required petitions, reviews, and recommendations to be added to the 

National List. Ion exchange resins are known to leak from columns and thus become incidental 

additives in the food. 

Subcommittee Review: 

The question before the Handling Subcommittee essentially boils down to whether only the recharge 

materials for the resins must be on the National List or whether both the resins and recharge material 

must be reviewed and added to the List. 

The 2020 Technical Review (TR) provides a thorough review of ion exchange filtration and should be 

referred to for details on this process. It is clear that there is widespread use of ion exchange filtration 

in organic processing whether it be for removal of off-tastes, heavy metals, or clarification of the final 

product, among others. Alternatives to ion exchange filtration are not generally available. 

As noted in the 2020 TR, ion exchange filtration differs from physical filtration processes in that there is 

an actual chemical change in the ensuing product – ions (either cations or anions depending on the resin 

and desired outcome) that were present on the resin have been substituted in the final product while 

ions that were initially found in the product are left attached to the resin. This is not just a physical 

removal of material or a reaction whereby another material is used to help process the initial substance 

and then removed after that process. The 2020 TR cites various research articles and states: 

...ion exchange filtration requires the replacement of bound ions (ions initially present in the 

filtration material) by others with the same charge and requires electroneutrality... 

...ion exchange filtration is based on the principle that if an ion is removed from the treated 

substance by the filtration material, it is replaced by an ion of the same charge that began in the 

filtration material (e.g., removal of positive ion from treated substance is replaced by a different 

positive ion from the filtration material). The ion exchange process is a result of electrostatic 

attractions between the ion of interest (ion to be removed from the treated substance) and the 

charged functional groups incorporated into the filtration material. 

The final product, by passing through the ion exchange filter, does have a different ionic makeup than 

the initial product. In the case of removing “hardness” from water, the substitution of sodium for the 

original calcium in the water does not change that it is still water, per se, but it can change how that 

interacts with other materials. Thus, it seems difficult to argue that ion exchange filtration does not 

cause a chemical change in the final product, even though the chemical change may be beneficial. 

There is a different ionic makeup in the final product as compared to the initial product and the final 

product may behave slightly differently than the initial product. 

The next question is whether the ion exchange membranes and resins are secondary food additives or 

food contact surfaces. If they are food contact surfaces, then, based on past NOP guidance, they may be 

used unless explicitly prohibited. If they are secondary food additives, then they must appear on the 

National List. It is beyond the capacity of NOSB members to investigate the nuances of FDA rules and 

regulations. The NOSB received a number of public comments from our Spring 2020 discussion 

document with a number of viewpoints, however the comments from the Organic Trade Association 

gave the most details of FDA rule history on this topic: 

In a policy statement issued on December 12, 2002, after consultation with FDA, NOP clarified 

which substances are subject to review and recommendation by NOSB for inclusion on the 

National List. According to the policy, substances that are listed in 21 CFR Part 173 as secondary 

direct food additives are subject to review, unless the substances are classified by the FDA as a 

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food contact substance. In 2002, FDA clarified that ion exchange resins were food contact 

substances, therefore ion exchange resins under the 2002 policy were not subject to the 

National List process. The 2002 food contact substance policy was archived when the NOP 

Handbook was created; however it has never been formally rescinded and remains in use by 

some certifiers. 

FDA references are as follows: 

• Ion exchange resins and membranes are listed in 21 CFR Part 173 as secondary direct food 

additives, which are substances that have a technical effect in food during processing but 

not in the finished food. 

• According to FDA guidance, some secondary direct food additives also meet the definition of 

a food contact substance, which is any substance that is intended for use as a component of 

materials used in manufacturing, packing, packaging, transporting, or holding food if such 

use is not intended to have any technical effect in such food. 

• Prior to 1997, FDA regulated ion exchange resins under 21 CFR 173.25. Once Congress 

established the term “food contact substance” in the Federal Food, Drug, and Cosmetic Act 

and initiated the Food Contact Notification Program (FCN) in 1999, all ion exchange petitions 

were converted to this approval method. There was no need to alter or change prior 

approvals under § 173.25, so they were left as is. Since that time, FDA has directed all new 

approvals of ion exchange resins through its FCN program. This clearly reflects FDA’s stance 

that they are food contact substances. 

• FDA maintains a database of approved Food Contact Substances, which include ion 

exchange resins that have been classified and approved by FDA as food contact substances. 

Additionally, Ingredion submitted comments that echoed the comments from the Organic Trade 

Association: 

The regulatory classification for ion exchange resins is both a food contact substance AND a 

secondary direct food additive. https://www.fda.gov/foodjfood-ingredientspackaging/foodingredient-packaging-terms: 

• Food Contact Substance (FCS) - Section 409 of the FD&C Act defines an FCS as any 

substance that is intended for use as a component of materials used in manufacturing, 

packing, packaging, transporting, or holding food if such use of the substance is not 

intended to have any technical effect in such food. 

• Secondary Direct Food Additive (SDFA) - This term is in the title of 21 CFR 173, which 

was created during recodification of the food additive regulations in 1977. A secondary 

direct food additive has a technical effect in food during processing but not in the 

finished food (e.g., processing aid). Some secondary direct food additives also meet the 

definition of a food contact substance. 

There were no other comments received that contradicted that materials could be listed as both a 

secondary direct food additive and food contact surface. It would seem that, even though a material 

might be listed both ways, the fact that they are listed by FDA as a food contact surface, exempts those 

materials from needing to be reviewed by the NOSB and placed on the National List. 

Finally, there is the question of whether the resins or membranes themselves contribute to a change in 

the final organic product or whether, as food contact substances, they are simply a structure that holds 

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the ions to be exchanged. The 2020 TR states that there are studies that demonstrate that the resins do 

degrade over time, however that degradation is generally in terms of their loss of resin activity or 

efficiency or capacity. In other words, the resins are simply not as good at holding ions to be exchanged 

and thus need to be recharged sooner than they would when they were new. In some cases, this loss of 

efficacy may be because of a loss of functional groups that were originally present, however the 

citations referenced in the TR note that this loss seems to primarily occur during the recharge process. 

Thus, the loss of those functional groups would not be into an organic product, but rather into the 

recharge material. The 2020 TR further states that there were no published studies on the human 

health effects of the degradation of the resins found by the TR writers. Based on the findings of the TR 

and no public comments that provided scientific evidence that the resins degrade and cause changes in 

the final product it would seem that the resins act in the capacity of food contact surfaces and not 

primarily as direct food additives. 

Subcommittee Recommendation: 

The inherent nature of ion exchange leads us to the conclusion that recharge materials used to recharge 

ion exchange resins must be on the National List if they are used in the processing of organic product. 

These recharge materials leave ions on the resins and those ions will ultimately end up in the final 

organic product. The public comments received at the Spring 2020 NOSB meeting support this 

recommendation. 

There is less consensus on the question of whether the resins or membranes themselves must be 

reviewed and included on the National List. From comments received, the resins and membranes 

appear to be classified as food contact substances. There was no compelling evidence in the 2020 TR or 

public comments that the resins or membranes degrade and alter the final organic product. Based on 

this review, it is the recommendation of the NOSB that the recharge materials, but not the resins or 

membranes themselves, must be reviewed and included on the National List. 

Subcommittee vote: 

Motion to approve the recommendation on ion exchange materials 

Motion by: Steve Ela 

Seconded by: Scott Rice 

Yes: 6 No: 0 Absent: 1 Abstain: 0 Recuse: 0 

Approved by Asa Bradman, Handling Subcommittee Chair, to transmit to NOP August 13, 2020 

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