U.S. health officials have endorsed a type of cigarette that will deliver very low levels of nicotine to help smokers overcome their addiction. The Food and Drug Administration say the cigarettes contain 95% less nicotine, but while the new products are safer than regular cigarettes,   there are no safe tobacco products and smoking remains the leading cause of preventable disease and death in the U.S., accounting for 480,000 deaths annually. The FDA says several studies show that when smokers switch to low-nicotine cigarettes they smoke less and are more likely to try quitting, but past efforts to sell low-nicotine products have failed.