Alarming Precautions about Cell Phones
Kenneth R. Foster
The issue of health effects of cellular telephones took on a new urgency with the May 2000 report by an expert group chaired by Sir William Stewart. The British government formed this group to evaluate possible health effects of mobile telephones and make recommendations for public policy.
The Stewart Committee report cited a number of studies that reported effects, some involving cancer. For example, one group reported that radiofrequency (RF) exposure increased the incidence of lymphoma in Pim-1 mice (a strain that had been genetically engineered to be susceptible to the disease). However, the Committee noted that the study is difficult to interpret because the animal model has no human counterpart. Most other cancer studies, both animal and epidemiological, have been negative.
It also reviewed a variety of noncancer studies, including human studies that reported effects such as changes in reaction time, EEG, and sleep patterns. These effects were small and of no apparent health significance. I note that the studies can also be criticized on technical grounds.
The "balance of evidence," the Stewart Committee concluded, is that "exposures to RF energy below [present safety limits] do not cause health effects to the general population." But "it is not possible at present," they added, "to say that exposure to RF radiation . . . is totally without potential adverse health effects . . . "—as if one could ever prove the absolute safety of any technology.
It was not the science, however, that garnered headlines around the world, but the "precautionary" recommendations of the committee. These included proposals to avoid siting base stations so their "beam[s] of greatest intensity" fall on school property "without agreement from the school and parents," discouraging phone companies from marketing cellular phones to children, discouraging children from using cell phones "for nonessential calls," and providing the public with comparative information about specific absorption rates (SARS) from phones.
These precautionary recommendations raise many questions. A big one is how to use "precautionary" policies in a sensible way. In Europe, the term generally refers to the Precautionary Principle, which (by the Treaty on European Union) is the keystone of European environmental policy, yet remains ambiguous and elusive in meaning (Foster 2000). A recent commentary by the European Commission clarified the use of the Precautionary Principle by the European community, for example, the identification of a problem, the best possible scientific analysis of it, and a cost-benefit analysis—none of which the Stewart Committee provided. To my mind, it is inconsistent for a committee to make precautionary health recommendations for the public while concluding at the same time that the weight of evidence indicates the absence of public health problems from cell phones or base stations.
Also problematic is the Committee's recommendation against siting base stations so their "beams of greatest intensity" fall on school property. Typical cellular base stations use high-gain antennas. As one moves away from a base station, the RF signal level increases to reach a maximum at a distance perhaps 100 meters from the base station. However, the maximum is typically very broad, with half-power points ranging perhaps from 50 to 400 meters from the base station (the actual figures vary considerably in different base stations). Keeping such "beams of greatest intensity" away from schools creates compliance issues even for base stations located considerable distances from schools—even though the exposure levels are very far below the exposure guidelines that the Committee elsewhere recommended adopting. Considerably stronger RF fields may already be present from paging or other communications transmitters located near schools.
And how, exactly, can the public interpret the exposure (SAR) data from different handsets? Because of the "near field" nature of the problem, a user's actual exposure to RF energy from a cell phone depends very strongly on the distance and orientation of the phone with respect to the user's head. Also, in actual use, a phone's output is adoptively determined by the base station. None of these sources of availability are reflected in laboratory measurements of SAR. Nor can science provide any guidance about the aspects of the exposure a consumer should try to reduce. SAR is a measure of power deposition, and any presently unknown hazard of low-level RF energy is probably not thermal in nature.
The Stewart Committee, through its precautionary recommendations, creates a strong impression that a real health problem exists. That, on the basis of present evidence, is neither correct nor a useful service to the public.
Author: Kenneth R. Foster, PhD, is Professor of Bioengineering at the University of Pennsylvania. He is author of the book Phantom Risk (MIT Press 1993).