A well-received study that tested the effects of exposure from cell base station transmissions on self-identified sensitive individuals and control subjects has released more details to counter criticism: The University of Essex researchers reported that self-selected electromagnetically sensitive subjects were unable to determine when a base station signal was present or absent in double-blind tests, even though during "open" tests in which they were told correctly when a signal was absent or present these individuals exhibited physical and mental symptoms.

The researchers were criticized on a few grounds that they've now clarified; surprisingly, not all organizations that believe electromagnetic radiation can cause ill health thought the study was flawed. The primary critique was that 12 sensitive individual dropped out of the study before the double-blind portion. Critics suggested that those people were actually the true sensitives, and that the study was skewed against that point of view.

Researchers posted an extensive update on the matter in which they demonstrate that the characteristics of symptoms exhibited by the withdrawn subjects were very close to the 44 people who continued to the end. They note that five of the 12 withdrew because of their reaction to the exposure in the study, and two were excluded because they were taking medication that could have affected results. The first phase testing of these subjects was included in the final results, meaning that true sensitives, if they existed, didn't have markedly different symptoms from the subjects who completed the study.

Critics also pointed to the study's funding source, a joint effort by the mobile industry and UK government to research health effects. The researchers note in their FAQ that they their work was not subject to advance review after the grant was issued, nor did the funders have control over the release of results or their conclusions. The researchers note that their method of double-blind study removes results, too. That's true. With double-blind studies, you can critique the method by which bias was removed and information kept from participants and researchers during testing phases, and what's being tested--if the frequencies used or power levels involved don't match real-world conditions, for instance, that's a issue of the framing of the study and is a valid point of argument.

I contacted the research group, and on that last front, was told by Denise Wallace, a senior research officer, that the "power density used in our study 10 mW/m^2) was based on a recommendation from the National Radiological Protection Board" that's now part of the Health Protection Agency in Britain. These levels, therefore, are commensurate with what are considered safe levels found in the public sphere.

I asked Wallace whether the study results could be generalized to mobile phones themselves, as this study focused on the typically higher levels of power but more dispersed signal of base stations on "masts" or towers. She noted that their study was in line with other published double-blind studies that looked into matters such as human attention with GSM and continuous wave mobile phone signals present, and health effects from mobile phone usage on sensitive individuals.