Does heavy use of cell phones pose a risk of cancer? This question has provoked controversy for many years. A new study in rats now adds to those concerns. Its data linked long-term, intense exposure to radiation from cell phones with an increased risk of cancer in the heart or brain. The results have yet to be confirmed, the authors note. Moreover, they add, it’s not yet clear what the findings may mean in terms of human health. Indeed, although the rat study found a link between cell-phone radiation and cancer, it offers no clues to why such a link might exist, notes Jonathan Samet. He teaches preventative medicine and directs the Institute for Global Health at the University of Southern California in Los Angeles. Still, he calls the new study’s findings “significant.” They could lead to studies probing how cell-phone radiation might cause cancer, he says. Phone signals are relayed between cell towers and cell phones via radio waves. This radiofrequency — or RF — radiation is a type known as non-ionizing. Unlike X-rays and alpha particles, non-ionizing radiation does not deposit enough energy into cells to release electrons from atoms or molecules, producing ions. So it tends to be far less harmful than ionizing radiation, such as X-rays. But that does not mean radio waves might not cause harm. In very large doses this radiation will heat the body and cause tissue damage. But it’s not yet known what much lower RF levels might do, such as those from cell-phone use. Five years ago, the World Health Organization’s International Agency for Research on Cancer, or IARC, concluded that cell-phone use “is possibly carcinogenic.” That means it might cause cancer. Its conclusion was based on what little research data were available at that time. But notice that IARC was not certain. It said only that phone use might “possibly” cause cancer. So scientists at the National Toxicology Program, or NTP, investigated further. The scientists exposed rats to the same types of radiation emitted by U.S. cell phones. The cancers in these rats resembled those seen in some human studies that had probed harm from cell phone use. For this reason, NTP says its findings appear to support IARC’s conclusion that heavy cell-phone use might be harmful.【小题】(1) In Jonathan Samet’s view, the new study in rats is very valuable because _________. A.it links cell phone radiation with an increased risk of cancer in the heart or brain B.it confirms the association between frequent use of cell phones and a risk of cancer C.it has found why heavy use of cell phones leads to an increase of risk of cancer D.it can push researchers to explore how radiation from cell phones leads to cancer 【小题】(2) Radiation from cell phones is comparatively safe in that __________. A.in fact it comes from X-rays B.it has nothing to do with ionizing C.it releases much electrons D.it doesn’t produce alpha particles 【小题】(3) According to IARC’s conclusion we may learn that __________. A.it’s very reasonable to use cell phones B.people should avoid using cell phones C.it deserves our caution to use cell phones D.we can use cell phones ignoring their harm

Does heavy use of cell phones pose a risk of cancer? This question has provoked controversy for many years. A new study in rats now adds to those concerns. Its data linked long-term, intense exposure to radiation from cell phones with an increased risk of cancer in the heart or brain. The results have yet to be confirmed, the authors note. Moreover, they add, it’s not yet clear what the findings may mean in terms of human health. Indeed, although the rat study found a link between cell-phone radiation and cancer, it offers no clues to why such a link might exist, notes Jonathan Samet. He teaches preventative medicine and directs the Institute for Global Health at the University of Southern California in Los Angeles. Still, he calls the new study’s findings “significant.” They could lead to studies probing how cell-phone radiation might cause cancer, he says. Phone signals are relayed between cell towers and cell phones via radio waves. This radiofrequency — or RF — radiation is a type known as non-ionizing. Unlike X-rays and alpha particles, non-ionizing radiation does not deposit enough energy into cells to release electrons from atoms or molecules, producing ions. So it tends to be far less harmful than ionizing radiation, such as X-rays. But that does not mean radio waves might not cause harm. In very large doses this radiation will heat the body and cause tissue damage. But it’s not yet known what much lower RF levels might do, such as those from cell-phone use. Five years ago, the World Health Organization’s International Agency for Research on Cancer, or IARC, concluded that cell-phone use “is possibly carcinogenic.” That means it might cause cancer. Its conclusion was based on what little research data were available at that time. But notice that IARC was not certain. It said only that phone use might “possibly” cause cancer. So scientists at the National Toxicology Program, or NTP, investigated further. The scientists exposed rats to the same types of radiation emitted by U.S. cell phones. The cancers in these rats resembled those seen in some human studies that had probed harm from cell phone use. For this reason, NTP says its findings appear to support IARC’s conclusion that heavy cell-phone use might be harmful.【小题】(1) In Jonathan Samet’s view, the new study in rats is very valuable because _________.  A.it links cell phone radiation with an increased risk of cancer in the heart or brain  B.it confirms the association between frequent use of cell phones and a risk of cancer  C.it has found why heavy use of cell phones leads to an increase of risk of cancer  D.it can push researchers to explore how radiation from cell phones leads to cancer 【小题】(2) Radiation from cell phones is comparatively safe in that __________.  A.in fact it comes from X-rays  B.it has nothing to do with ionizing  C.it releases much electrons  D.it doesn’t produce alpha particles 【小题】(3) According to IARC’s conclusion we may learn that __________.  A.it’s very reasonable to use cell phones  B.people should avoid using cell phones  C.it deserves our caution to use cell phones  D.we can use cell phones ignoring their harm