One of my top questions has to do with the content of my metals and supplies, usually pertaining to nickle and lead, but occasionally zinc as well. Here is are details about each of these:
-None of my metals contain lead. The only products that contain lead at all are possibly some older stock of Swarovski™ Crystals which contain molecular bound lead and has shown to not be reactive or harmful to humans. Swarovski™ has recently created "Advanced Crystal" which is 100% lead free and any other materials must contain 0.009 % lead or less in reaction to the erroneous consumer image that any lead, even if bound, is harmful. I don't blame them. It is much easier to just say "nickel free" than to have to teach Chemistry 101 to customers.
-My products that contain nickel are nickel silver and all stainless steel unless specifically marked Nickel Free Grade 410 or Grade 430. Many grades of stainless steel, including those that fall under the umbrella category of "surgical steel" contain nickel (Grades 303, 304, 316L), but like the old Swarovski™ Crystals, it is bound and so it should not cause a reaction with consumers. The EU has enacted progressively stricter legislation about nickel content in consumer products including jewelry and any other products that come into contact with skin and products must pass a test to see if any nickle above very minute amounts leaches out over a period of time in order to claim "EU Complaint". As a humorous aside, some of the EU coins initially failed these tests! My belief is that nickel silver should not be used in piercings or for any customer with a know nickel allergy. Even though the nickel in surgical steel is bound and my background as a Chemical Engineer for almost 50 years tells me that surgical steel should not cause a reaction to consumers, my hands on experience shows me otherwise. So, my 2 grades of Nickel Free Stainless Steel, 410 and 430 should be selected for customers with a known nickel allergy or overall skin sensitivities (along with Surgical Grade Titanium and Niobium).
-While Zinc is a necessary mineral for humans, and even sold as a supplement there are toxic levels. The products that I sell that contain zinc are those that contain brass, both Rich Low and Yellow Brass. Yellow brass contain 30% zinc and Rich Low Brass is specifically called "rich low" because it has a lower zinc content (15%) - not for health concerns but to create a richer more golden tone. The main hazard for jewelry makers in relation to zinc is in soldering brass when potentially harmful zinc vapors can be released. Basic correct soldering techniques including proper ventilation avoids this problem.

If you have any further questions pertaining to the above, or anything else, please contact me.