Nonlinear dynamical law governs magnetic field induced changes in lymphoidphenotype

The results of many different types of animal and human studies dealing wit h the biological effects of exposure to low frequency electromagnetic field s (EMFs) have consistently been both positive and negative. We addressed th e question of why this pattern had occurred so commonly in biological studi es involving exposure to EMFs and hypothesized that it stemmed from the pre valent use of a linear model to characterize what are inherently nonlinear input-output relationships. The hypothesis was tested by analyzing biologic al data using a novel statistical procedure that could be adjusted to detec t either nonlinear or linear effects. The reliability of the procedure was established using positive and negative controls and by comparison with the results obtained from sampling a known nonlinear system. In four independe nt experiments, male and female mice were exposed continuously to 0.1 or 0. 5 mT, 60 Hz, for 175 days, and the effect on 20 immune parameters was measu red using flow cytometry and functional assays. In each experiment, EMF exp osure resulted in statistically significant changes in lymphoid phenotype w hen and only when the response of the animals to the fields was analyzed as if it were governed by nonlinear laws. Our results suggest that the patter n of inconsistency in the EMF bioeffects studies is an artifact resulting f rom an incorrect choice of the conceptual model for the relation between th e field and the biological effect it causally determines. (C) 2001 Wiley-Li ss, Inc.