The government is adding viruses for the first time to its list of known or suspected causes of cancer, including hepatitis B and C (search) and a third virus that causes sexually transmitted diseases. Lead, X-rays and compounds in grilled meats also are joining the list.
But they were added to the list Monday only after officials decided to go beyond the report's historical focus on the occupational and environmental causes of cancer, said Dr. Christopher Portier, associate director of the National Toxicology Program, which prepared the latest update.
"We felt (the report) needed to be expanded to include other things in our general environment that can cause cancer," Portier said.
The list, which now identifies 246 known or suspected cancer-causing agents, is intended to give people who may or may not be exposed to any of the substances something to think about, he said.
Take X-rays, added to the "known" category. "This is simply to remind them that when they are making a decision about an X-ray to think about it and talk it over with your physician," Portier said.
But the American College of Radiology faulted the addition of X-rays and gamma rays, saying it was misleading and could prompt patients to avoid getting needed care.
"X-rays and gamma rays are not substances that the general public has access or exposure to and do not belong on a list of substances that pose a risk to people in the course of their normal, daily lives," Dr. James Borgstede, chairman of the radiology college's board of chancellors, said in a statement.
New to the suspected category are substances that form when meats are cooked or grilled at high temperatures. Studies suggest an increased cancer risk when foods containing them are eaten.
But "does that mean you have to throw out your barbecue grill?" asked Dr. Elizabeth Whelan, a critic of the list from the American Council on Science and Health, a consumer education group.
She said the "not consumer friendly" list should include information on the types of exposures and dosages that cause cancer, as well as on the health benefits of some of the substances identified, such as tamoxifen, the breast cancer treatment pill.
Lead, used to make lead-acid storage batteries, ammunition and cable coverings, and lead compounds, used in paint, glass and ceramics, in some cosmetics and as a fuel additive also joined the suspect list.
Portier said other agencies, such as the Environmental Protection Agency and the Food and Drug Administration, are responsible for determining exposure levels, dosages and other issues.
"We think everything on this list is, in fact, relevant to people's daily lives and the public health of the country," he said.
The Report on Carcinogens (search) — which federal law requires the health and human services secretary to update every two years — lists 58 "known" and 188 "reasonably anticipated" cancer-causing substances.
It was prepared by the National Toxicology Program of the National Institute for Environmental Health Sciences, and was last updated in December 2002.