What do OMRI, FIFRA 25(b) and EU organic actually mean?
These three mean different things and none is a safety rating. What each covers, what it attaches to, and why a certification on the active does not transfer to the formulated product.
The short answer
They are three different things, they attach to different objects, and none of them is a safety rating. Two describe eligibility for use in organic systems; one describes exemption from federal pesticide registration. A product can hold one and not the others.
FIFRA 25(b) — a registration exemption, not an approval
The US EPA maintains a list of active ingredients eligible for the minimum-risk exemption under FIFRA section 25(b). Eligibility of the active is necessary but not sufficient: the exemption applies to a complete formulated product meeting every condition of the rule, including that all inert ingredients appear on the permitted-inerts list, that the label carries no pesticidal claims beyond those allowed, and that the actives and inerts are named.
So an active appearing on that list does not make a product exempt. Exempt status has to be established product by product. And exemption is not an EPA endorsement of efficacy or safety — it is a decision not to require registration.
OMRI — attaches to a product, and only while listed
OMRI reviews specific formulated products against the USDA National Organic Program standards and lists those that comply. The listing attaches to the product, not to the compound, and it is current only while the listing is maintained.
This is why a compound page never says an active is OMRI-listed. Where a specific Vegalab product holds a current listing, that is stated on that product's page. Where you need to confirm it, the OMRI listing itself is the record.
EU organic — a different framework again
EU organic production operates under its own regulation with its own annexes of permitted inputs, and compliance there is not conferred by a US listing or by 25(b) eligibility. A product acceptable in one framework may be unusable in another.
Registration, permitted uses and claims all vary by jurisdiction. Nothing here should be read as approval in your country.
What none of them tells you
None of the three is a toxicity rating. A product can be eligible for organic use and still be harmful to fish, toxic to cats, or an irritant in concentrate — the aquatic and cat pages on this site are about exactly such materials. Read the safety sections and the label, not the certification mark.
"Natural", "chemical-free" and "non-toxic" are marketing terms with no fixed regulatory meaning. Treat them as claims requiring support, not as certifications.
When to get advice
Check with your certifier before using any input in a certified system — the certifier's decision governs, not the manufacturer's description. Ask a Vegalab agronomist which registrations apply in your market.