Unfortunately, I don’t have a proper source. When I saw this post, the warning from reddit came to my mind and from the answers here I was surprised how many people open drives.

I assume, it is per hard drive such a negligible amount, that it could theoretically matter over a long time if you open a lot but that there is probably not a single medical proven case and the warning from reddit was overly cautious.

Edit: I found the post and comment. The issue mentioned was the cobalt. https://www.reddit.com/r/pics/comments/17il3i3/comment/k6veo9c/?utm_source=share&utm_medium=web2x&context=3

Edit2: I went and searched a bit. This meta-analysis says they found no increased cancer risk for exposure to cobalt particles. https://www.sciencedirect.com/science/article/pii/S0273230021001288

I don’t want to ruin your fun, but the last time I saw a post like this on reddit, the top comment was: “Don’t open hard drives. They contain micro particles from wear and tear, that are as dangerous as asbestos.”

Edit: I found the post and comment. The issue mentioned was the cobalt. https://www.reddit.com/r/pics/comments/17il3i3/comment/k6veo9c/?utm_source=share&utm_medium=web2x&context=3

Edit2: I went and searched a bit. This meta-analysis says they found no increased cancer risk for exposure to cobalt particles. https://www.sciencedirect.com/science/article/pii/S0273230021001288