GMM FDA GRAS Certification: Three Core Dimensions Explained

At its core, GRAS status signifies that a substance is generally recognized as safe under its intended conditions of use, based on the consensus of qualified experts. For GMM-derived substances, however, the key question lies in whether the genetic modification introduces any new safety risks. The FDA's evaluation logic for GMMs therefore revolves around a comprehensive, end-to-end safety assessment—from the origin of the production strain to the safety of the final product for human consumption. 

REACH24H has synthesized this assessment framework into the following three core dimensions:

Strain and Genetic Modification – The Safety Foundation

This pillar constitutes the starting point of the GMM safety assessment and is also the stage most susceptible to evidentiary gaps. A complete and coherent chain of evidence must be established, encompassing the recipient strain, genetic elements, modification procedures, and the final production strain.

• Safety Assessment of the Recipient Strain: Core documentation should include taxonomic identification of the production organism (confirmed to the species level through phenotypic, genotypic, and gene sequencing analyses), historical use data, and screening reports for genes associated with virulence, antimicrobial resistance, and toxin production. Preference should be given to strains with a well-documented history of safe use. For example, Escherichia coli K-12 derivatives, such as DH1 and MG1655, which account for over 70% of production strains used in HMOs manufacturing, are characterized by their non-pathogenicity and well-characterized genetic backgrounds, substantially reducing the regulatory complexity of the safety assessment.

• Transparent Characterization of Genetic Modifications: The origin (donor organism safety), function (mechanism of action of the target gene and regulatory sequences), and structure (nucleotide sequence and deduced amino acid sequence) of all inserted or deleted sequences must be clearly documented. Of particular importance is the need to exclude any homology between the newly expressed proteins and known toxins or allergens through comprehensive bioinformatics analyses.

• Safety Assessment of the Production Strain: Core documentation for the production strain should include a strain identification report, a whole genome sequencing (WGS) report, screening analyses for virulence, antimicrobial resistance, and toxin-associated genes, and bioinformatics allergenicity and toxicity assessments of any heterologous proteins. Additionally, experimental data from at least five consecutive passages must be provided to verify the stability of transgene integration and the consistency of expression product profiles, ensuring that the production strain does not exhibit gene loss or mutation during large-scale fermentation.

Closed-Loop Risk Control – Manufacturing Process and Final Product Safety

The FDA's evaluation of GMM-derived products extends beyond the production strain itself, placing equal emphasis on the intrinsic link between process controllability and end-product safety.

• Full Traceability of the Manufacturing Process: A detailed process flow diagram must be submitted, covering raw material specifications, fermentation parameters (temperature, humidity, aeration rate), purification steps (e.g., chromatographic and filtration parameters), and inactivation procedures (where viable organisms are involved). Particular attention should be given to demonstrating how horizontal gene transfer is prevented and how GMM residues are effectively removed throughout the downstream processing chain.

• Control of Residues and Impurities in the Final Product: Three core analytical assessments are essential to demonstrate product purity and safety:In addition, impurity specifications must be established for heavy metals, residual solvents, fermentation by-products, and other potential contaminants, with corresponding analytical test reports provided for each batch.

• Residual Foreign DNA: Detection of target genes, marker genes, and other specific nucleotide sequences to confirm their absence in the final product.

• Viable Cell Residues: Confirmation that no viable GMM cells are present in the final product, with data generated from at least three non-consecutive production batches.

• Residual Heterologous Proteins: Verification that no exogenous proteins are carried through to the final product, thereby mitigating risks of allergic reactions, toxicity, or immunogenicity.

Scientific Substantiation Framework – Integrating Toxicology and Safety Data

The safety assessment for GMM-derived substances must integrate toxicological studies with other relevant safety data to construct a comprehensive and scientifically defensible substantiation framework.

• Data Quality Requirements: Toxicological studies should be conducted in compliance with Good Laboratory Practice (GLP) and, where possible, follow OECD test guidelines to ensure data reproducibility and traceability. Core toxicological datasets typically include:

• Three genotoxicity assays: Ames test, in vitro chromosomal aberration test, and in vitro micronucleus test;

• Subchronic toxicity study: 90-day oral toxicity study in rodents; and

• Allergenicity assessment: Bioinformatics sequence homology searches against known allergens, complemented where appropriate by in vitro sensitization testing.

• Core Risk Assessment Logic: The toxicological dataset is used to establish the No-Observed-Adverse-Effect Level (NOAEL) for the substance. A safety factor of 100 or greater (comprising 10-fold for interspecies differences and 10-fold for interindividual variability) is then applied to derive a safe intake level (e.g., ADI). This health-based guidance value is subsequently compared with the estimated daily intake (EDI) from the dietary exposure assessment to support the overall safety conclusion for the intended conditions of use.

To further assist industry applicants in navigating the regulatory landscape, REACH24H has also summarized the key differences in documentation requirements for GMM-derived novel products across the United States, the European Union, and China.

Compared with the regulatory frameworks in China and the EU, the U.S. GRAS notification pathway for GMM-derived products does not mandate the following studies as a prerequisite for submission:

• Testing for GMM residues in manufacturing waste streams (i.e., "three wastes"—wastewater, waste gas, and solid waste);

• Pathogenicity, antimicrobial resistance, or toxigenicity testing of the production strain;

• Cytotoxicity assays; and

• Teratogenicity (developmental toxicity) studies.

For the latter, the need for teratogenicity testing is determined on a case-by-case basis, depending on the nature of the substance and its intended conditions of use.

Overall, while the U.S. FDA's safety assessment framework for GMM-derived products is guided by its published guidance documents, it adopts a more flexible, science-driven approach compared to the more prescriptive, itemized testing requirements imposed by Chinese and EU regulations.

REACH24H advises industry applicants to plan ahead and develop a robust, transparent, and scientifically defensible data package for their GMM-derived products. A well-structured dossier, grounded in sound scientific reasoning and aligned with FDA expectations, is essential for achieving a successful GRAS determination and unlocking global market access.

How to Obtain GRAS Status?

In principle, any individual or organization may pursue a GRAS determination for a substance through either of the following two pathways:

• Self-Affirmed GRAS: This pathway involves convening a panel of qualified experts to evaluate the available safety data and conclude that the substance is GRAS under its intended conditions of use. The resulting GRAS determination is documented in a self-affirmed GRAS dossier, which is not submitted to the FDA and remains confidential to the notifier.

• FDA Notified GRAS: This pathway involves the preparation of a comprehensive GRAS dossier, which is then submitted to the FDA for formal review. The FDA evaluates the submission and issues a response, typically in the form of a "no questions letter" if the agency concurs with the GRAS determination.

It should be noted that an FDA GRAS notification generally incorporates the conclusions and expert opinions of the qualified expert panel that were originally developed for the self-affirmed GRAS determination.

In brief, a Self-Affirmed GRAS notification enables the substance to be marketed in the United States, while an FDA GRAS notification offers greater advantages in terms of market communication and consumer acceptance. However, the FDA notification pathway typically requires a longer review timeline. Companies may choose between the two options based on their specific market strategies and product launch plans.