We make a strong effort to avoid toxic materials when formulating our glass colors. We do not use Lead, Arsenic, Antimony, Cadmium, Hexavalent Chromium, Selenium, or Uranium in our glass batch. All glass is colored with metal oxides, and some batch ingredients are volatilized when the glass is superheated. I would strongly recommend using adequate ventilation when melting any glass. The Italian, German, or Chinese glass rods are also colored with metal oxides. Opaque greens are usually colored with Chromium, Opaque Reds, Oranges, and Yellows are colored with Cadmium Sulfate and Selenium. Some Rubino Oro glasses are up to 30% lead oxide. While silver is considered a non-toxic metal, inhalation of silver fumes is not healthy, nor is the inhalation of the products of combustion that are emitted from your torch. A good, simple test is to light a stick of incense and place it right next to your torch. The ventilation system should be capable of quickly removing the smoke away from you, and out a window or opening. Ideally, you should not be able to smell the incense at all. In summary, our glass is, in my opinion, substantially LESS toxic than most other lampworking glasses, and YES, you absolutely should have adequate forced air ventilation, (eg. A box fan in a window with your torch pointing at it) to be safe from respiratory hazards when working with hot glass and propane torches.