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QAre there safety lic is exposed from base stations—can damage tis- Environmental Policy Act of 1969 (NEPA) standards for sue if the body cannot dissipate the resulting heat charges the FCC(among other federal agencies) exposure to the radio quickly enough.External body tissues,especially with evaluating the extent to which Commission- waves from base sta- corneas and testes,are most vulnerable because authorized facilities may have a significant impact tions? they lack enough blood circulation to quickly on the quality of the human environment.In carry away large amounts of heat. Intense thermal 1985,to perform its duty under NEPA, the FCC exposures can thus cause cataracts or temporary adopted a 1982 exposure standard (C95.1-1982) AYes. The Federal male sterility.7 Modest exposures to nonionizing promulgated by ANSI,the American National Communications fields,however,appear to be benign.Indeed,we " Standards Institute,the preeminent private scan- Commission, the federal ourselves generate low levels of microwave power.8 dard-coordinating body. Based on an extremely agency that licenses low risk of exposures in excess of the 1982 ANSI base stations, has At cellular frequencies,it takes power flux densi- standard,the FCC ties in the range of at least tens of milliwatts per categoricallyexcluded applica- adopted exposure limits square centimeter to cause measurable tissue dons for new or modified cellular base stations, for the RF fields from police and fire transmitters,etc. from having to base stations. Some warming.As we will see in greater detail below, demonstrate compliance with the standard. state and local govern- such power flux densities generally occur only ments and industry within feet or yards of a transmitting antenna.At In 1992,ANSI supplanted its 1982 standard with ground level,exposures from cellular base stations a 1991 RF-exposure standard drawn up by the standard-setting bodies are extremely low,one-thousandth or less of those Institute of Electrical and Electronic Engineers have also adopted exposure limits or that cause any measurable tissue warming. (IEEE),a prestigious professional society. In response,the FCC started an update of its envi- guidelines. There is some debate whether atherrnal exposures ronmental rules.The FCC proposes to adopt the —especially those involving nonionizing power 1992 ANSI standard as the most recent and com- flux densities significantly higher than those in prehensive of all the standards published since the public areas around base stations,but still too 1985,when the agency adopted the 1982 ANSI weak to cause tissue warming—can nonetheless standard.9 The FCC is also rethinking its categori- have any effects on tissue,such as the enhanced cal exclusion of various base-station and mobile- migration of calcium ions (calcium efflux).A radio facilities from scrutiny for compliance with minority of scientists believe so.Other scientists RF exposure limits.The FCC received many com- have been unable to reproduce claimed results in menta in the rule-making proceeding in the first their own laboratory experiments.Most of these four months of 1994.The great majority of the studies have nothing to do with health effects, comments favor replacing the 1982 ANSI stan- and the exposure levels are significantly above dard with the 1992 ANSI standard.'° those to the public from base stations. Note that this monograph discusses only exposures All of the standards under consideration by the to RF fields.The issue of exposure to electric and FCC share common elements.Each sets time- magnetic fields from high-tension lines is a separate averaged exposure limits,and all permissible expo- sures question altogether.Fields emanating from base are much less than those which cause the stations have frequencies of about 850 MHz, 14 slightest measurable thermal effects.The averag- ing times differ,but each standard allows continu- million times higher in frequency than those from power lines,which are at 60 Hz.Base-station fields, ous exposures that do not exceed a certain value. except when very close to the transmitting antennas, Also,permissible exposure levels vary with fre- are weak;at comparable distances,the fields from quency.The strictest limits occur in the frequency power lines are much,much stronger.So different range where the physical dimensions of human are the respective frequencies and field intensities bodies correspond to those of resonant antennas. that one simply cannot make any meaningful At these frequencies(roughly 30 to 300 MHz), the body can most efficiently absorb RF power comparisons. from ambient fields.Thermissible pe exposures at C. RF EXPOSURE LIMITS FOR BASE cellular frequencies under the various standards • STATIONS are comparable. The FCC,which licenses base stations and other The newer standards also have in common differ- civilian radio transmitters,has been active in con- ant tiers of exposure limits for occupational and general-public settings.The 1992 ANSI Standard trolling RF exposure.The National 18