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August 10, 2021 

MEMORANDUM TO THE NATIONAL ORGANIC STANDARDS BOARD

FROM: Jennifer Tucker, Ph.D. 

 Deputy Administrator

 National Organic Program 

SUBJECT: Research conducted on FDA’s classification of ion exchange resin 

Purpose

The purpose of this memorandum is to respond to the National Organic Standard Board’s 

(NOSB) request from the April 2021 meeting to provide information about the U.S. Food and 

Drug Administration’s (FDA) classification of resins used in the ion exchange process. The 

NOSB is reviewing ion exchange technology and its compatibility with organic production at the 

request of the National Organic Program (NOP) to address an inconsistency among certifiers. 

Definition

Ion exchange is a process used to purify or separate liquids. It is widely used in organic handling 

of various products, including organic juices. In the ion exchange process, a liquid solution is 

subjected to solid ion exchanger, typically a polymeric resin, that is used to exchange ions in the 

solution with those being held on the surface of the resin. The process is used to remove 

undesirable ions from solutions, such as decolorization, demineralization, and removal of 

contaminants. 

Background 

Consistent with NOP 3012, “Interim Instruction Material Review,” certifiers originally notified 

the National Organic Program (NOP) of discrepancies in how ion exchange materials are 

evaluated. Some certifiers only required the solutions used to recharge the ion exchange 

membranes to be on the National List at § 205.605, while others required all materials, including 

ion exchange membranes and resins, to be on the National List. 

NOP provided an initial clarification to certifying agents on May 7, 2019, instructing that 

nonagricultural substances (including but not limited to resins, membranes, and recharge 

materials) used in the ion-exchange process must be present on the National List. Originally, the 

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

however, based on feedback from certifiers, the NOP delayed the implementation date in order to 
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gather more information. As part of this process, the NOP requested that NOSB review the issue

on August 27, 20191

.

At the Spring 2021 meeting, the NOSB asked NOP to speak with the Food and Drug 

Administration (FDA), to learn how FDA classifies resins used in ion exchange. This request 

was made to help the NOSB reach a final proposal and/or recommendation on which exact 

components of the ion exchange process should be included on the National List. Specifically, 

the NOSB was interested to know if the resins used in ion exchange were considered ‘food 

contact substances’ or ‘secondary direct food additives’. Because food additives are listed on the 

National List, the NOSB believed this distinction would help determine if the resins should be 

listed or not.

FDA Definitions

On June 7, 2021, NOP staff met with scientists at the Center for Food Safety and Applied 

Nutrition within the FDA: Rachel Morissette, Ph.D., Regulatory Review Scientist, and Jeremy 

Mihalov, M.S., Chemist, both in the Division of Food Ingredients, Office of Food Additive

Safety; and Elizabeth Petro, Ph.D., Lead Consumer Safety Officer, Office of Food Additive 

Safety, Division of Food Contact Substances. FDA scientists explained that ion exchange resins 

can be classified both as food contact substances and secondary direct food additives and that 

resins are evaluated on a case-by-case basis.

Dr. Morissette defined ‘food additives’ as being present in the final product according to Section

201(s) of the Federal Food, Drug, and Cosmetic (FD&C) Act (codified in 21 U.S.C. Sec 321). As 

noted in FDA’s Guidance for Industry: Preparation of Food Contact Notifications 

(Administrative), in the past, FDA has informally characterized a food additive as being a ‘direct 

additive’ if it was intended to have a technical effect in food, a ‘secondary direct additive’ if it 

was intended to have a technical effect on food during food processing but not in the finished 

food as consumed, or an ‘indirect additive’ if it was intended to have a technical effect in a food 

contact material. Even though each of these types of food additives is listed in a separate section 

of 21 CFR (i.e., direct food additives are listed in 21 CFR Part 172, secondary direct food 

additives are listed in 21 CFR Part 173, and indirect food additives are listed in 21 CFR Parts 

175-178), no definitions for direct, secondary direct, or indirect food additive exist in the 

codified regulations or the statute. Examples of ‘secondary direct additives’ include: wire 

meshes, filters, defoamers, clarifying agents, and antimicrobial agents used on poultry carcasses. 

She explained that resins used for ion exchange purposes may be the subject of existing 

regulations (e.g., 21 CFR 173.25) or are evaluated through the food contact substance 

notification (FCN) process, which includes a safety review to identify any potential impacts on 

human health.

1 https://www.ams.usda.gov/sites/default/files/media/NOPNOSBIonExchangeJT.pdf
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Dr. Petro noted that the term ‘food contact substance’ is defined in section 409(h)(6) of the 

FD&C Act (21 U.S.C. 348(h)(6)) as ‘any substance 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.’ Food contact substances may also be food 

additives if, as a result of the intended use, they may reasonably be expected to become a 

component of food. Since the FDA Modernization Act of 1997, the FCN process has been the 

primary method by which FDA regulates food additives that are food contact substances. FDA 

has reviewed several FCNs for uses of ion exchange resins, including effective FCNs 531, 528, 

443, 325, 290, 157, 156, 74, 55, 52, and 45. Other examples of food contact substances include 

components of food packaging, wire meshes, filters, antimicrobial agents used in contact with 

poultry carcasses, and lubricants for food processing machinery.

Implications 

Based on the conversations with FDA, NOP would like the NOSB to note the following 

implications of using FDA’s definitions for “secondary direct food additives” and “food contact 

substances”:

• There is no clear nor consistent distinction between the two terms;

• If the NOSB refers to FDA’s definitions, it could result in substances that are not 

currently on the National List necessitating addition to the List (e.g. wire meshes and 

certain filters), or substances that are currently on the National List not needing to be on 

the List (e.g. antimicrobial agents used in contact with poultry carcasses).

Given the information received from FDA, it appears that caution is needed when considering 

FDA’s classification given the nuances of the criteria described above.

Request

Given the information above, the NOP requests the NOSB’s recommendation(s) on whether 

resins should be listed on the National List. We appreciate the Board’s work in considering this 

topic, as we all work towards increased consistency between certifiers on complex technical 

areas.

The allowance for current certifier practices remains in effect while the Board considers this 

topic.