Ever since I started working with metals I've always wondered about the safety considerations. I've handled and been exposed to metals of all kinds for years and haven't worried as much about them as I have of chemicals, insecticides and food additives. It seems like there are more people with allergies than ever before. Many times they don't know what's causing the allergies.
Long ago a doctor told me that showing symptoms of allergies is sort of like a bucket filling with water - when it gets overfilled it finally runs out. Same thing with allergies - when we are exposed to enough allergens for enough time- eventually our bucket runs over and we get the symptoms -runny nose , hives, itchy eyes, etc.
I believe in trying to avoid allergic reactions or lung and tissue damage by using whatever safety equipment we can use to limit our exposure.
Since I make metal dust when I saw, grind, sand or polish I try to either wear a mask or use a shield. I have a nice plastic shield that has a hole in the back that a shop vac hose attaches to. When I use my foredom tool to grind or polish I hold it in the shield to protect my lungs and my eyes. I also wash my hands often and especially before eating after handling metals.
MSDS sheets can be requested from whomever you buy your supplies from- they describe any and all hazards and issues that can happen from any materials they contain. I work mostly with gold, silver and copper alloys but if you use base metals (like nickel silver, sometimes called german silver), or plated materials, these could contain lead (toxic), cadmium or nickel (an allergan) you should know what you are working with and what hazards it presents. The new laws regarding items for children under twelve are there just for this reason. That cheap unknown imported metal might be a hazard that you hadn't even considered.