Cigarette smoke contains thousands of compounds, including 69 known to be carcinogens, chemicals that are directly involved in causing cancer. Carcinogens can result in tumors by damaging the genome or disrupting the cell's metabolic processes. Other new entries in the official list of smoking-caused diseases include Type 2 diabetes, rheumatoid arthritis, erectile dysfunction, macular degeneration that can blind older people, and cleft palate birth defects.