As many as two-thirds of cancers are caused by lifestyle choices like smoking, bad diet and not getting enough exercise, according to a U.S. presidential panel of cancer advisers. However, many avoidable cancers result from pollution, radon in the soil and medical imaging scans, they said. Little is known about the risk, if any, posed by cellphones, so the panel advised people to consider wearing headsets and limiting themselves to quick calls. The American Cancer Society said the report didn’t focus enough on known risks that cause most cases of cancer, like tobacco, obesity, infections, alcohol, hormones and sunlight, Reuters reports, calling it “most provocative when it restates hypotheses as if they were established facts. For example, its conclusion that ‘the true burden of environmentally (pollution) induced cancer has been grossly underestimated’ does not represent scientific consensus. Rather, it reflects one side of a scientific debate that has continued for almost 30 years,” the group’s Dr. Michael Thun said in a statement.