We thought copper salts were benign until we recently started linking them to dopamine neuron death. Too much of anything absorbed into the body is rarely a good thing.
I think it's tempting to get into kitchen chemistry but you can very quickly find yourself playing with things that should not be in your home. Having a baby has made me question a lot of my home experiments and made me realize how sloppy I was.
Very small amounts of nickel are beneficial for the bacteria inhabiting the gut.
Great amounts that are absorbed into the blood would do no good. For many people, mainly for women, nickel may be an allergen, which is why nickel is not recommended for jewels or piercings or anything else that stays in contact with the skin.
Maybe not a project for the kids but any adult wearing gloves should be just fine. I've been having fun painting graphite lubricant in urethane onto PLA 3D prints and nickel acetate electroplating them.
