Some are. Most aren't.
It's common practice for seed growers to help the plants die down quickly once the seeds are formed to make harvest easier. This isn't always done with the same standards as food seeds. To avoid this, organic seeds are the way to go.
Inoculation or other treatment may also be an issue.
And seeds for seed don't have to have the same storage standard as seed for food. Rodent urine or stuff to diswade rodents are possible, but less likely.
That said, most small scale, locally grown and processed, organic seed companies would normally be safe. Nice thing about small companies like that is we can call them up and ask.
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I wonder if a germination test and note with the seeds saying how old and the test results would help? Education opertunities for seed library members to learn about the benefits of germination testing?