If you want something "official", then within the United States (and Canada, I believe), and it's a FIPS 140-2 algorithm (as SHA-1 is), then what comes to mind is the NIST Cryptographic Module Validation Program (CMVP). You can tell what's been validated by looking at the list of Validated FIPS 140-1 and FIPS 140-2 Cryptographic Modules.
A prerequisite to CMVP validation is Cryptographic Algorithm Validation Program (CAVP). That conformance testing will verify that your implementation complies with FIPS 180-4's definition of SHA-1 by using The Secure Hash Algorithm Validation System (SHAVS). All testing is done by a testing laboratory.
Be prepared to break out your checkbook - official validation testing isn't free, though it sounds like you haven't been looking at the full CMVP validation, so it might not be as expensive, particularly for only SHA-1.
P.S. is there any particular reason you're not starting with a SHA-2 family function (SHA-224, SHA-256, SHA-384, or SHA-512)? See NIST SP 800-131A - SHA-1 is deprecated or disallowed for almost all uses at this time, and if you're in the U.S., and you're doing medical work, you're likely bound by HIPAA and HITECH - using a fading hash standard seems pointless for new development - you don't want to have to go through the validation process a second time if SHA-1 is now, or becomes in the future, disallowed for whatever purpose you're using it for.