Children exposed to cell phones before and after birth were 50% more likely to have emotional or behavior problems by the age of 7, compared with kids who were not exposed to the phones, according to a new study of 28,745 children. The same authors of the new study reached similar conclusions in a previous study conducted in 2008.
The children in the current study were all enrolled in the Danish National Birth Cohort, a large-scale study of 100,000 Danish children born between 1996 and 2002. Researchers from the School of Public Health at the University of California, Los Angeles, used data from surveys that the mothers of the children filled out; questionnaires included standard tests for emotional or behavior problems in children, as well with hyperactivity, inattention and inability to get along with other kids. (More on Time.com: Cell-Phone Safety: What the FCC Didn’t Test)
The surveys also asked about the families’ lifestyle, the parents’ mental and health histories and cell-phone use in parents and kids. In addition, there were questions about whether mothers breast-fed and how much time mothers spent with their child each day. The investigators used these factors to estimate the level of attention mothers paid to their kids and to address the question of parental influence on behavior: moms who spend all day talking on their cell phones during pregnancy or early childhood may not be paying enough attention to their kids, which can result in episodes of acting out.
About half of the kids in the study had no exposure to cell phones. (More on Time.com: 6 Common Sources of Radiation In Your Life)
After analyzing the data, the researchers found that 18 percent of the children were exposed to cell phones before and after birth, up from 10 percent in the 2008 study, and 35 percent of seven-year-olds were using a cell phone, up from 30.5 percent in 2008. Virtually none of the children in either study used a cell phone for more than an hour a week.
Compared to children with no exposure to cell phones, those exposed both before and after birth were 50 percent more likely to display behavior problems, the study found. Children exposed to cell phones in the womb, but not after they were born, showed a 40 percent higher risk of borderline behavior problems. And those not exposed to cell phones before birth, but who were using them by age seven, were 20 percent more likely to have behavior problems.
One expert on child development who was not involved in the study commented favorably on its design.
“The study’s methodology was rigorous and responsible. The researchers took into account as many possible variables as they could, given the limitations of the data set,” said Dr. Andrew Adesman, chief of developmental and behavioral pediatrics at the Steven and Alexandra Cohen Children’s Medical Center of New York in New Hyde Park.
Though alarming, the research is far from conclusive. “Although it is premature to interpret these results as causal,” wrote lead author Leeka Kheifets in the study, which was published online on Dec. 6 in the Journal of Epidemiology and Community Health, “we are concerned that early exposure to cell phones could carry a risk, which, if real, would be of public health concern given the widespread use of the technology.” (More on Time.com: Cell Phones and Cancer: A Scientist’s Persuasive New Book)
The data add to the growing concern over the health risks of cell-phone use, which have focused mainly on brain tumors and cancer — risks that some researchers think may be higher in children.
The links between radiation from cell phones and health problems have not yet been proven conclusively. But for parents and other consumers who are worried about the potential effects, it’s easy to lessen your exposure: don’t hold your phone close to your body when you’re using it or carrying it around. Use headsets or the phone’s speaker to talk, and keep your phone in a holster, belt clip or in your bag, not in a shirt or pants pocket.