Among the 7,000 or so different chemicals in cigarette smoke, more than 70 are known to be carcinogens. Most carcinogens promote cancer by damaging DNA and causing mutations. Illustration by Wenjing ...

JC Seneca watched as one of his workers poured finely chopped tobacco into a machine that feeds the tobacco into cigarette papers, rolls the papers and makes 2,300 cigarettes a minute. "These machines ...