Abstract
We show that a logical error is contained in some epidemiologic papers which intend to verify the hypothesis that there is an association between magnetic fields of power lines and childhood leukemia: for instance, the Swedish paper by Feychting and Ahlbom in 1993 showed us leukemia association related to calculated magnetic fields in one-family houses but apartment ones, from the results obtained from the stratified analyses according to type of building; this was contradictory to their premise that exposure assessment was claculated magnetic fields irrespective of type of building. However, the authors described in conlusion that their hypothesis could be verified. Nevertheless it needed to be supplemented by some data, as was customary in epidemiologic analysis, not to miss any possible causes of cancer. Our views are as follows: related engineers would be hard to accept the procedure, which needs the supplementary data, because it is employed at the auther (s)'s will for the scheduled verification of the hypothesis; it would be natural to suppose that the hypothesis could not be verified.
