According to an Associated Press report, a state legislator from Maine has introduced a bill that would attach a warning label to cell phones. The proposed warnings would feature bold red text warning of the danger of brain cancer, and feature an image of a small brain. There's one small problem with all of this: there's little evidence that cell phones increase the risk of brain cancer.

The AP story provides a convenient way to look at a whole series of relevant issues: nonscientific policy initiatives, scientific consensus, and press reporting on contentious scientific issues. We'll start with the science.

Cell phones emit radiation in an area of the spectrum that isn't capable of rearranging the chemical bonds of biological systems unless intensely focused (which they're not). The energy is able to heat water, and that heat may influence biological systems. But there's no obvious connection between mild heating and any obvious health issues, meaning there's no clear mechanism linking cell phones with health problems.

In the absence of a mechanism, epidemiological studies might be used to identify a risk. Here, the literature is a bit more confused, as a few small studies have suggested associations between cell phone use and specific cancers (or, in one case, the location of the cancer and the side of the head that an individual typically holds the phone). So, it's possible for someone to read the literature and conclude there's some risk; that reading, however, would have to be very selective, as large population studies argue against it.

In the most recent example, published just this month, the records of national health services in Nordic countries were combed for instances of brain cancer. Although rates of some cancers have risen over the last 30 years, there was no change in the rate of increase since the boom in cell phone use of the 1990s. Studies like this one have led the majority of the scientific community to reach a consensus: any influence of cell phones on brain cancer rates has to take decades to be apparent, and cell phones simply haven't been in general use long enough for us to evaluate that risk.

As with any scientific consensus, there are dissenters, and the AP article features them prominently. These include the retired director of a cancer research institute, who bases his claims on unpublished data, and a report from an organization called the BioInitiative Working Group, which includes scientists who research this topic. The AP reporter, however, didn't appear to have bothered to evaluate the Bioinitiative document; doing so would have revealed a selective and, in some cases, misleading view of the current biomedical literature. In short, the report doesn't appear to be a reliable guide to the scientific literature, making its conclusions suspect.

Although the National Cancer Institute is given the final say (no apparent risks at this time), the article highlights one of the weaknesses of traditional reporting. In attempting to provide a sense of balance, it uncritically provides space to those who dissent from the prevailing consensus, which is likely to confuse those who haven't dug into the scientific literature.

(Presumably in an attempt to humanize the report, it also presents the opinion of a Maine cell phone user, even though there's no indication that the individual is in any way especially informed about the topic.)

As for the legislation in question, the person who introduced it (Democrat Andrea Boland, for the curious) apparently claims that numerous studies have established a link between cell phones and cancer, and wants the warning to target children and pregnant women. It's clear that the legislation is spectacularly ill-informed, but that hasn't stopped it from being introduced and promoted. Unless the bill is made an issue in an upcoming campaign, however, Boland is unlikely to face any difficulty for introducing something that runs counter to the best available evidence.

Boland's bill gets lumped in with another potential law, one being pushed by San Francisco mayor Gavin Newsom. In contrast to the Maine legislation, Newsom is promoting a law that would require cell phones sold in the city to carry an indication of the amount of radiation that their users are exposed to. Although that would almost certainly stoke unwarranted fears, it's actually a reasonable approach given the current state of the science. We can't currently know whether there are risks following decades of exposure; the bill would provide those who want to exercise caution with an opportunity to limit their exposure. Unfortunately, the AP terms that a "similar effort," despite the fact that its focus—informing cell phone buyers—is almost exactly the opposite of the Maine bill, which would misinform them.

At this point, neither of the efforts have passed. The Maine legislation is being introduced during the January session. Hopefully, other legislators will use the opportunity to educate its backers on understanding scientific evidence.

Journal of the National Cancer Institute, 2009. DOI: 10.1093/jnci/djp415