Under the Federal Food, Drug, and Cosmetic Act (FD&C Act), a substance is legally a “drug” if it’s intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease in humans or animals — and marketing a “new drug” without FDA approval is prohibited. That legal definition turns on intended use, not just chemical identity. A compound labeled and sold strictly for laboratory or research use — not intended for human or veterinary consumption — falls outside that new-drug approval requirement, which is exactly why research-chemical suppliers, including the Signal Library’s own compounds, carry that specific “research use only” language rather than dosing instructions or health claims.

The FD&C Act’s new-drug approval process exists to ensure that anything marketed for treating or preventing disease in people has been through a formal safety and efficacy review. Research chemicals sit outside that process specifically because they aren’t being marketed for that use — they’re intended for laboratory and in-vitro research, where a different set of institutional and scientific safeguards apply instead of FDA drug approval. That’s the legal logic behind every “research use only, not for human consumption” disclaimer you’ll see across the Signal Library and Stack Science’s other pages.