Correction of an Error in Calculation in the Article "Frequency of Micronuclei in the Peripheral Blood and Bone Marrow of Cancer-Prone Mice Chronically Exposed to 2450 MHz Radiofrequency Radiation" (Radiat. Res. 147, 495-500, 1997)

Abstract

Upon re-examination of the data in our manuscript entitled Frequency of Micronuclei in the Peripheral Blood and Bone Marrow of Cancer-Prone Mice Chronically Exposed to 2450 MHz Radiofrequency Radiation, which appeared in the April 1997 issue of Radiation Research (Vol. 147, pages 495-500), we realized that an error was made in the statistical analysis. In the last column in Tables I and II, the group mean micronuclei was based on 1000 polychromatic erythrocytes (PCEs), but the calculation of the standard deviation was based on 2000 PCEs. When the correction is made using the same number of PCEs, the two-tailed Student's t test indicated that the difference between the mice chronically exposed to radiofrequency (RF) radiation and the sham-exposed mice is statistically significant for both peripheral blood and bone marrow in Table I, and not for either tissue in Table II. We apologize for the miscalculation. Having corrected the error, we wish to point out that, although the difference was statistically significant within this (one) experiment, the biological relevance must be put in proper perspective. The increase in the frequency of micronuclei in the 62 mice exposed to RF radiation, compared to the frequency in the 58 shamexposed mice, was only 1 additional micronucleus per 200 PCEs, or an increase of 0.05%. This is a very small change in a large number of animals exposed to RF radiation ov r a very long period (18 months). Based on this evidence alone, it would be premature to conclude that the RF radiation exposure acted as a weak mutagen. Furthermore, the statistical increase in the frequency of micronuclei was not correlated with an outcome of carcinogenesis. Neither the latent period nor the total number of tumors was reported to be different between the exposed and sham-exposed mice (Frei et al., manuscript in preparation), the same animals for which the micronucleus frequencies were determined. As one final point, and as pointed out in the paper, the incidences of micronuclei in both the mice exposed to RF radiation and the sham-exposed mice were all within the range of the spontaneous incidence of micronuclei reported for mice in the literature.