I am shocked, SHOCKED at the incredible lack of scientific knowledge displayed in this thread!
The critical consideration that arises from the original question "are tubes considered hazardous waste?" has been completely ignored!
Let's put on our thinking caps, people. We call them "tubes," but actually they are "VACUUM tubes." Once the glass envelope containing the vacuum has been broken or otherwise compromised, the vacuum is released directly into the environment!
We're all familiar with the saying "Nature abhors a vacuum," aren't we? Can you name anything else Nature abhors? No? I thought not.
I rest my case.
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