Health & Science

Beware of heavy cell phone use

Do cell phones cause brain cancer? Scientists still can’t say for sure, but the latest study has found that heavy use of cell phones does increase the risk of cancer. The new study, a 10-year project by the World Health Organization’s International Agency for Research on Cancer, studied 12,000 people—some in good health, and some with either of two types of brain cancer. The results found no connection between moderate cell phone use and the risk of glioma or meningioma tumors. But for the heaviest users, there was up to a 40 percent higher incidence of these cancers. The cell phone industry, which helped pay for the study, proclaimed that the results proved that normal cell phone use is safe, but some scientists and consumer advocates say the study’s analysis was badly flawed. Because the period studied was 2000 to 2004, heavy users were defined as those who used their phone for half an hour a day—relatively little by today’s standards. Teens, known to be heavy phone users, weren’t studied, nor were people who’d used a cell phone for 15 years or more. “At the very least, the risks are greater than many believed only a few years ago,” Louis Slesin, the editor of Microwave News, tells The New York Times. Scientists involved in the study agreed that further research is needed.

The creeping smog

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Kudzu, the invasive vine that has taken over more than 7 million acres of the U.S., does more than just hog real estate; it also contributes to air pollution, a new study has found. Kudzu is a legume, a member of the pea family, and like its kin it moves nitrogen from the air into the soil. There, microbes turn it into nitrous oxide—a pollutant found in auto exhaust. In the air, chemical reactions turn nitrous oxide into ozone. Kudzu is so widespread and fast-growing, say researchers at Columbia University, that areas with a lot of kudzu—mostly in the Southeastern U.S.—have twice the amount of nitrous oxide in the air. Using a computer model, researchers estimated that kudzu can lead to a 35 percent increase in the number of days that ozone levels exceed EPA safe limits. “The changes you can’t see in a kudzu invasion,” researcher Jonathan Hickman tells Nature.com, “are just as dramatic as the ones you can.”

Life gets easier later

They don’t call them the golden years for nothing. A recent study by researchers at Stony Brook University found that after age 50, people feel consistently happier, less stressed, and less worried than their counterparts in the full bloom of youth, says Scientific American. That finding emerged from a Gallup survey of 350,000 Americans from all parts of the country. The results showed that happiness and enjoyment declined between ages 20 and 50, but increased steadily after 50. Worry and stress start rising in the 20s, but fall off sharply after age 50. The patterns were similar for men and women, and held regardless of whether a person was employed, married, or had children in the house. Older people may be “more effective at regulating their emotions than younger adults,” says psychiatrist and study author Arthur Stone, or they may simply forget negative experiences more quickly. Whatever the reason, says Stone, “If you were to do a survey and say, ‘How many of you would like to be 25 again?’ you don’t get a lot of takers.”

New dads get sad, too

New mothers aren’t alone in their susceptibility to postpartum depression; fathers suffer from it, too, and at the same rate as women, scientists have found. Psychologists at the Eastern Virginia Medical School reviewed 43 studies, involving 28,000 dads in the U.S. and other developed countries, that looked at depression during the first year of fatherhood. The rates were surprisingly high: Fourteen percent of American men exhibited signs of postpartum depression, and 25 percent did in the three to six months after childbirth. Sleep deprivation, a decline in sexual intimacy, and the stress of juggling work and new home responsibilities may combine to produce the baby blues, researchers tell the Los Angeles Times. “We are expecting dads to be more involved in parenting than we ever have before,” said University of California at Berkeley researcher Will Courtenay, a psychotherapist who studies paternal depression. “Most dads are welcoming of that, but they don’t have any models about what a dad is supposed to do. That creates uncertainty, and that uncertainty can lead to anxiety and depression.”