Essential Guide to Allowed and Prohibited Substances for Organic Certification
- Joshua Brock
- Aug 12
- 12 min read
Understanding Allowed and Prohibited Substances
Using the wrong input could cost you roughly three years work. Whether you're currently farming organically or just considering the switch, understanding the National Organic Program’s (known to most simply as the NOP) “Allowed and Prohibited Substances Lists” is essential.
These lists, managed by the USDA, serve as the foundation for what inputs can and cannot be used on certified organic operations. But their importance extends beyond just organic farms — even conventional farmers benefit from knowing what’s on them, especially if they want to keep future organic certification options open.In our article, we’ll discuss the following topics;
(Use these links to skip to a specific section)
What Are the NOP Allowed and Prohibited Substances Lists?
The NOP, which falls under the authority and guidance of the USDA, regulates all organic agricultural products in the United States. In general, synthetic substances are prohibited unless specifically listed as allowed on the National List (going forward, also referred to as “the List”), while non-synthetic (natural) substances are allowed unless specifically prohibited.
The List ensures that organic production stays as natural and environmentally friendly as possible, while still allowing for a few necessary synthetic inputs — but only those that have been reviewed and approved.
Organic operations must have all substances, including those on the List, approved by their certifying agent before use in order to obtain or retain their organic certification. This is done by a USDA-accredited certifying agency during the farm or operator’s annual inspection.
Substances are evaluated for inclusion on the List based on criteria that include minimal adverse effects on human health and the environment, necessity for handling, and consistency with organic handling. Farmers, researchers, and the public can petition for a substance to be added or removed. Petitions are reviewed by the NOSB, which then votes and makes a recommendation to the NOP. Public comment periods are also part of the process.The List is dynamic and can be amended through rule making by the NOP, often in response to recommendations from the National Organic Standards Board (NOSB).
International Organic Standards
Across the globe, many other countries have their own unique organic certification organizations and standards:
European Union (EU): The EU uses a unified organic certification system with its distinctive green and white organic logo. However, individual EU countries may have additional voluntary certifications, such as AB in France and BIOSUISSE in Switzerland.
Japan: Japan has its Organic JAS logo, which focuses on soil health in its standards.
Canada: Canada uses the Canada Organic logo for its organic certification.
Australia: Australia's ACO certification considers factors like drought resilience and resource management.
Mexico: Mexico has its Organic Products Law (LPO) and the OTCO Transaction Certificate is required for products exported to Mexico from the U.S.
Who is the NOSB and What Is Their Role?
The National Organic Standards Board (NOSB) is a federal advisory board composed of 15 public volunteers appointed by the U.S. Secretary of Agriculture. They represent diverse stakeholders within the organic community, including farmers, handlers, retailers, environmentalists, consumers, scientists, and a USDA-accredited certifying agent. The NOSB is responsible for making recommendations on issues related to the production, handling, and processing of organic products and advising the NOP on substances allowed or prohibited in organic agriculture.
Established by the Organic Foods Production Act (OFPA), passed as part of the 1990 Farm Bill (also known as the Food, Agriculture, Conservation, and Trade Act of 1990), the NOSB's recommendations are crucial for shaping organic regulations and the organic certification process, particularly concerning the National List of Allowed and Prohibited Substances.
Additionally, the NOSB meets twice a year to discuss issues, review substances on the National List, and vote on proposals, which become recommendations to the USDA if approved by a two-thirds majority vote.
Why the Lists Matter to All Farmers
Even if you’re not currently certified organic, knowing what substances are allowed or prohibited can help you. These lists don’t just govern certification; they reflect broader trends in market demand, environmental sustainability, and demonstrate proper farm management.
Future-Proofing for Organic Certification
Many conventional farms consider transitioning to organic production — either on all or part of their acreage. But substances used today can affect eligibility down the road.
For instance, using a prohibited herbicide or non-approved livestock medication could trigger a reset of the 36-month transition clock, delaying certification and the ability to access organic price premiums. Staying aligned with NOP-compliant inputs now makes for a smoother and faster transition later.
Access to Premium Markets and Buyers
More buyers, especially grocery retailers and food companies, want transparency and sustainability — even from non-certified farms. Some processors, wholesalers, and co-ops give preference to suppliers who are “certification ready” or at least using NOP-compliant practices.
By voluntarily aligning with these lists, conventional farms can open doors to premium or specialty markets and diversify their revenue streams.
Reducing Environmental and Health Risks
The NOP List reflects a growing consensus on safer and more environmentally friendly inputs. Avoiding harsh synthetic chemicals and GMOs doesn’t just prepare a farm for organic — it often improves soil health, biodiversity, and water quality.
For livestock operations, using allowed natural treatments instead of routine antibiotics or growth hormones can lead to healthier animals and stronger consumer trust.
Consumer Expectations and Reputation
Even farms that aren’t seeking organic certification are increasingly being asked by customers — especially local, direct-to-consumer buyers — about their input practices. Being familiar with the NOP list allows you to respond knowledgeably and confidently to questions like:
“Do you spray Roundup?”
“Do your animals get antibiotics?”
“Do you use OMRI-listed products?”
Who or What is OMRI?
OMRI (Organic Materials Review Institute) is an independent, non-profit organization that provides product review and listing services for materials and inputs used in organic production, processing, and handling. Their primary function is to determine which input products (like fertilizers, pesticides, livestock care products, processing aids) are compliant with organic standards.
When a product is "OMRI Listed®", it means it has undergone a rigorous review process by OMRI to ensure it meets organic standards for its specific use. Their standards are based on the USDA's National Organic Program (NOP) and the Canada Organic Regime (COR) standards. OMRI does not certify organic food or fiber products; instead, it focuses on verifying the suitability of input products used in organic production.
In the end, being able to say your practices mirror or are aligned with organic standards, even without certification, can build consumer trust and loyalty.
Avoiding Costly Mistakes or Transition Delays
A common regret among transitioning farmers is realizing they used a prohibited input just before deciding to pursue organic certification. That one decision can lead to financial losses from delayed organic premiums, plus the extra work of soil remediation or reapplication. Some other common mistakes farmers make in this process:
Assuming all natural substances are allowed - While synthetic substances are generally prohibited unless specifically allowed, and natural substances are generally allowed unless specifically prohibited, there are exceptions. For example, vaccines for livestock are allowed synthetic substances, while arsenic, a natural substance, is prohibited.
Assuming all "organic"-labeled products are fully compliant - Some products may carry the "organic" label but still have restrictions on their use. Products with the OMRI seal are categorized as Allowed, Allowed with Restrictions, or Prohibited. Farmers must carefully check the restrictions for "Allowed with Restrictions" products and ensure their Organic System Plan (OSP) outlines how they will comply. For example, some pest control products require demonstration of using other preventative methods first.
Lack of buffer zone management - Crops harvested from buffer zones (areas bordering non-organic land) must be segregated and documented to avoid commingling with organic crops.
Split Operations and the NOP
It's not uncommon for some farms to include both organic and conventional fields within their operations. For farms that manage both organic and conventional acres (also known as ‘split operations’), understanding and correctly applying the NOP list is especially critical to avoid contamination or unintentional violations.
NOP regulations require split operations to clearly describe their management practices and physical barriers to prevent commingling and contamination of organic products in their Organic System Plan (OSP). While the regulations don't mandate a specific section for this within the OSP, USDA Agricultural Marketing Service (AMS) states that these operations must identify and address organic control points – the points where contamination or commingling could occur.
By consulting the NOP List now, conventional farmers can avoid missteps that would otherwise set them back years in the certification process.
Examples of What’s Allowed vs. Prohibited
Allowed
Specific synthetic substances, such as certain vaccines for livestock (e.g., to prevent pinkeye in horses) or peracetic acid for fire blight control, are allowed if they meet specific criteria for necessity, minimal adverse effects on human health and the environment, and consistency with organic handling.
The List also identifies non-organic ingredients that can be used in processed organic products, such as certain flavors, carnauba wax, and potassium lactate. There are six groups of allowed substances on the NOP List. We've broken them out for you with some of the more common examples of products that fall under each.
Synthetic Substances Allowed for Use in Organic Crop Production
These are exceptions to the general rule that synthetics are not allowed. These include:
Soil amendments and fertilizers (e.g., elemental sulfur, copper sulfate)
Pesticides and pest controls (e.g., pheromones, horticultural oils)
Plant disease control (e.g., streptomycin—though no longer allowed for fire blight in apples/pears)
Post-harvest handling substances (e.g., chlorine materials for disinfecting equipment)
Seed treatments (when organic versions are unavailable)
Non-Synthetic (Natural) Substances Allowed with Restrictions
While most natural substances are allowed, some are restricted or prohibited based on potential harm. Examples include:
Biological pesticides (e.g., Bacillus thuringiensis)
Botanical pesticides (e.g., neem oil, pyrethrins with restrictions)
Compost and manure (must follow specific application and treatment requirements)
Synthetic Substances Allowed for Use in Organic Livestock Production
These include substances used for:
Health care (e.g., electrolytes, aspirin, iodine, vaccines)
Parasiticides (e.g., moxidectin, but only with restrictions)
Feed additives (e.g., trace minerals and vitamins)
Non-Synthetic Substances for Livestock Production
Naturally derived products allowed in organic livestock, such as:
Herbal dewormers
Kaolin clay (for external parasite control)
Nonagricultural (Nonorganic) Substances Allowed in Processed Organic Foods ("§205.605")
Used in products labeled “organic” or “made with organic”, these include:
Food-grade additives (e.g., citric acid, ascorbic acid, enzymes)
Processing aids (e.g., filtering agents like diatomaceous earth)
Microorganisms and cultures (e.g., yeast)
Agricultural Ingredients Allowed in Processed Organic Foods When Organic Is Not Commercially Available ("§205.606")
These are agricultural ingredients that may be used only when the organic form is unavailable:
Color extracts (e.g., beet juice extract)
Starches and gums (e.g., rice starch, locust bean gum)
Whey protein concentrate, etc.
Examples, by category, of Allowed Substances on the NOP List
Category | Examples | Notes |
Synthetic (Crop) | Copper sulfate, pheromones | Allowed with restrictions |
Natural (Crop) | Neem oil, compost | Generally allowed |
Synthetic (Livestock) | Aspirin, iodine, vaccines | Some with limitations |
Natural (Livestock) | Kaolin clay, herbal remedies | Must not harm animals or the environment |
Nonagricultural (Processing) | Enzymes, citric acid | Food-grade level required |
Agricultural (Processing) | Colors, starches | Allowed if organic unavailable |
Prohibited
Prohibited natural substances in crop and livestock production include arsenic, lead salts, and rotenone. Certain prohibited non-organic ingredients in processed products cannot be used in the manufacture of organic processed products. These prohibitions are essential to uphold the principles of organic agriculture, which focus on ecological balance, biodiversity, and soil health.
Synthetic Substances Not on the National List
Default Rule: All synthetic substances are prohibited unless specifically allowed on the National List under §§205.601 (crops) or §205.603 (livestock).
Examples of prohibited synthetics:
Most synthetic herbicides, fungicides, and insecticides
Synthetic fertilizers (e.g., ammonium nitrate)
Sewage sludge (biosolids)
Genetically modified organisms (GMOs)
Natural Substances That Are Specifically Prohibited
While most natural substances are allowed, some are explicitly banned due to potential harm to human or environmental health.
Examples include:
Strychnine
Tobacco dust (nicotine sulfate)
Ash from manure burned as fuel
Arsenic and lead salts (historically used in pesticides)
Excluded Methods (GMOs & Gene Editing)
Any substance or input produced through excluded methods is prohibited. This includes:
Genetically modified organisms (GMOs)
Gene editing techniques (e.g., CRISPR)
Synthetic biology
Ionizing Radiation
The use of ionizing radiation (e.g., for food sterilization or seed treatment) is not allowed in organic agriculture.
Sewage Sludge
The application of sewage sludge (biosolids) as fertilizer is strictly prohibited, due to contamination risks from heavy metals, pathogens, and pharmaceuticals.
Synthetic Processing Aids and Additives
In organic food processing, synthetic non-agricultural substances and additives are prohibited unless listed in §205.605. This includes:
Artificial preservatives (e.g., BHA, BHT)
Artificial colors or flavors
Synthetic solvents or chemical processing aids
Inert Ingredients in Pesticides
Inerts used in pesticides must be approved by the EPA for food use and must be reviewed by the NOSB. Inerts not reviewed or approved are prohibited.
How Farmbrite Can Help
Farmbrite’s Inventory and Accounting features allow you to record all pertinent information regarding any inputs or amendments you purchased and use throughout the growing season. This includes all relevant details such as the vendor it was purchased from, price, amount/volume, lot tracking information (optional), among a variety of other information. You can also upload photos of the receipts as proof of purchase to provide during your annual inspection.
Common Allowed & Prohibited Substances on the NOP List
Category | Allowed Substances | Prohibited Substances |
Crops | ||
Natural pest control | Neem oil, pyrethrin (from chrysanthemum), beneficial insects, insecticidal soaps | Synthetic insecticides, such as malathion or chlorpyrifos |
Fertility inputs | Compost, green manure, rock phosphate, fish emulsion | Synthetic fertilizers made with urea, ammonium nitrate, or sewage sludge |
Weed management | Mulching, flame weeding, vinegar (acetic acid), plastic mulch (if removed after use) | Synthetic herbicides like glyphosate (Roundup), 2,4-D |
Fungicides | Copper sulfate (with restrictions), lime sulfur, sulfur | Synthetic fungicides like mancozeb, chlorothalonil |
Seeds | Organic, untreated, non-GMO seeds | GMO seeds, treated seeds with synthetic fungicides or pesticides |
Livestock | ||
Health treatments | Vaccines, herbal remedies, electrolytes, minerals | Antibiotics, synthetic parasiticides (except under emergency with withdrawal period), growth hormones |
Feed | Certified organic feed, minerals and vitamins (if approved) | Conventional feed, feed containing GMOs, animal by-products |
Living conditions | Use of natural bedding materials, outdoor access, pasture | Use of synthetic bedding with prohibited treatments, confinement systems with no outdoor access |
Sanitation | Lime, hydrogen peroxide, chlorine-based sanitizers (restricted use) | Unapproved synthetic disinfectants, bleaches with residues |
Processing | ||
Ingredients | Certified organic ingredients, non-organic ingredients only if listed and unavailable organically | Non-organic ingredients if organic alternatives exist, GMOs, artificial preservatives or flavors |
Processing aids | Enzymes, ascorbic acid, citric acid, pectin (non-amidated), baking soda | Sulfites (except for wine under certain labeling), nitrates/nitrites, synthetic processing aids not on the National List |
Packaging & Handling | Recyclable, non-toxic materials, BPA-free linings | Packaging with BPA, synthetic fungicides or fumigants for storage |
Notes:
Substances marked as allowed may still be restricted, meaning they must meet specific conditions or be used only when other methods fail.
The OMRI (Organic Materials Review Institute) label is often used to help verify if a product is compliant with NOP standards.
Always confirm with your certifier, as interpretations can vary slightly based on regional standards or new updates from the USDA.
How to Stay Compliant (or Prepare for Certification)
If your farm is planning to apply for organic certification — or you just want to align your practices — here are steps to ensure compliance with NOP substance requirements:
Read the National List Regularly - The list is updated periodically based on recommendations by the National Organic Standards Board (NOSB). New materials may be added or removed, so staying current is key.
Keep Records of All Inputs - Document every product you use — fertilizers, pest controls, livestock medications, cleaning agents — including brand names, ingredients, and application dates. This will be required during your organic inspection.
How Farmbrite Can Help
Farmbrite gives both crops and livestock farms the ability to record treatments to both your plants and animals. Under each category, when you navigate to either the appropriate plantings or livestock entry, there is a Treatments option. In the case of a crop, you can record the treatment type (fungus, herbicide, insecticide, etc.), the specific product used, the amount applied, the application method, and a number of additional criteria. At your annual inspection, using our Plantings History Report or the Livestock Treatments and Vaccinations History Report, you can provide a detailed list of all OMRI-approved materials you used throughout the growing season.
Buy from Approved Suppliers - Use products labeled “OMRI Listed” (Organic Materials Review Institute) or check with your certifier to ensure an input is compliant.
Consult Before You Spray or Spread - When in doubt, check with your organic certifier or technical advisor before using a new input. It’s much easier to prevent a violation than to correct one later.
Plan for the Transition Period - If your land has had prohibited substances applied, you’ll need a 36-month transition period before it qualifies for organic certification. Starting to follow the NOP lists now can get you closer to that goal.
Want to make sure your inputs are compliant? Download our free NOP Input Review Checklist or start tracking your farm’s inputs and substances with Farmbrite today! |
More Than Just Checking the Boxes
Understanding and adhering to the NOP Allowed and Prohibited Substances Lists isn’t just about checking boxes — it’s about building a healthier, more transparent, and sustainable farm system.
Whether you're organic, conventional, or somewhere in between, this knowledge empowers you to make choices that preserve your land, protect your buyers, and keep your future options open. If you're considering the shift to organic certification, familiarizing yourself with these lists is one of the best places to start.
If you're ready to put your farm on the right track to organic certification - or just better farm record management - we invite you to give Farmbrite a try. We have also have an extensive collection of blog articles and resources, as well as help articles and training videos to get you on your way.
Thanks for reading and Happy Farming!
Joshua, his wife Jenn, and their dog Rooster, live in PA. Joshua is the owner and operator of Hoffman Appalachian Farm where they grow Certified Naturally Grown hops. Joshua has over twelve years of experience in growing crops, including growing in an organic system. In his spare time he enjoys trail running, backpacking, and cycling.
