A study says radiation doesn't cause cancer in kids—but watchdog groups say reporters have misunderstood the results
The results of an unprecedented study published yesterday in the Journal of The National Cancer Institute have been rocketing around the Internet: "Study Sees No Cellphone-Cancer Ties"; "Cellphones don't increase cancer risk in kids, study says"; "Cellphones, kids and cancer: Don't worry, be happy?". Less attention, however, has been paid to the fact that at least two prominent environmental health groups believe the study is fundamentally flawed. In the words of the Environmental Working Group, "Although parents are likely feeling reassured by the first media headlines about a new Swiss study of brain tumor risk in children using cell phones, the findings are actually quite troubling."
The new report, spearheaded by lead author Martin Roosli of the Swiss Tropical and Public Health Institute, presents the results of a case-control study of 352 brain cancer patients diagnosed between 2004 and 2008 and 646 control subjects, all of them ages seven to 19 and residing in Denmark, Norway, Sweden, or Switzerland. In-person interviews with a parent present were used to estimate each person's cell phone use, and phone company records, when available, were used to confirm the data. As John D. Boice and Robert E. Tarone of the International Epidemiology Institute write in an op-ed accompanying the study, "Consistent with virtually all studies of adults exposed to radio frequency waves, no convincing evidence was found that children who use cell phones are at higher risk of developing a brain tumor than children who do not regularly use cell phones."
Boice and Tarone add that there "were no consistent exposure-response relations for any of the metrics evaluated, whether by time since first phone use, cumulative duration of calls, cumulative number of calls, or location of the brain tumor with respect to ear (side of the head) most often used during calls."
Case closed, right? Maybe not. Both the Environmental Working Group (EWG) and the Environmental Health Trust (EHT) have taken up arms against the study's results, arguing that poor data and methodological flaws render the findings problematic. Among the organizations' complaints:
- Failure to examine the consequences of long-term use. The EWG points out that only 5 percent of the participants in the study had used cell phones for more than five years. In the words of EHT president Devra Davis, "Given the restricted time-frame of the JNCI study, the absence of brain tumor risk from cell phones in children and adolescents is precisely what is expected." She adds, "If you asked whether people who had smoked only four years had an increased lung cancer risk, you would come up empty-handed." According to the EWG, studies of adults have found statistically significant increases in cancer risk only in people who have used cell phones for more than 10 years.
- Weak definition of "regular" phone use. The researchers defined "regular" phone users as "all subjects who had an average of at least one call per week for at least 6 months." The EWG argues that "[a]s nearly every cell phone user would affirm, one call a week is an extraordinarily low, and hardly typical, frequency of use," making it hard to generalize the results of the study to people in the real world, who presumably use cell phones more often.
- Media coverage ignores small but significant red flags. The EWG draws attention to a sentence from the study that indicates that when the researchers looked at the relatively small number of patients for whom phone company data were available, they found a "statistically significant trend of increasing risk with increasing time since first subscription." In other words, the greater the amount of time the children and adolescents had had their phones, the more likely they were to be at risk.
It is hard to know who's correct, but one thing is certain: The EWG and EHT are right to point out that most accounts of the cell phone study paint a rosy picture and don't spend much time addressing their criticisms. Even Boice and Tarone seem to imply that the discussion isn't over: "it will be debated," they write, "whether and at what level additional research funds should be spent in assessing health effects associated with nonionizing radiation." And, they add, "it is impossible to prove a non-effect."