Inhalation of dust, mist, or fumes containing beryllium can cause chronic beryllium disease, which restricts the exchange of oxygen between the lungs and the bloodstream. The International Agency for Research on Cancer (IARC) lists beryllium as a Group 1 human carcinogen. The National Toxicology Program (NTP) also lists beryllium as a carcinogen. Copper beryllium alloy containing less than 2.5% beryllium (in copper) is not designated as a carcinogen.