In California new legislation will require coffee shops to post warnings that acrylamide, a by-product of the roasting process, could be carcinogenic. This warning was based upon research done on mice who received large amounts of the compound. No research has documented the effect of acrylamide as a cancer risk in humans.
One of the most reliable sources that I use for information on foods is Consumer Lab. They recently published this statement.
“After a court in California suggested that coffee may require a warning label about acrylamide (a toxin that occurs with roasting), a new study indicates that amounts found in brewed coffee, including many popular brands, is low.”
This is not the final answer, but it is so reassuring that I am now drinking my daily cup without concern.