WEAK EXTREMELY-LOW-FREQUENCY MAGNETIC-FIELD-INDUCED REGENERATION ANOMALIES IN THE PLANARIAN DUGESIA-TIGRINA

We recently reported that cephalic regeneration in the planarian Duges ia tigrina was significantly delayed in populations exposed continuous ly to combined parallel DC and AC magnetic fields. This effect was con sistent with hypotheses suggesting an underlying resonance phenomenon. We report here, in a parallel series of investigations on the same mo del system, that the incidence of regeneration anomalies presenting as tumor-like protuberances also increases significantly (P < .001) in a ssociation with exposure to weak 60 Hz magnetic fields, with peak inte nsities ranging between 1.0 and 80.0 mu T. These anomalies often culmi nate in the complete disaggregation of the organism. Similar to regene ration rate effects, the incidence of regeneration anomalies is specif ically dependent upon the planaria possessing a fixed orientation with respect to the applied magnetic field vectors. However, unlike the re generation rate effects, the AC magnetic field alone, in the absence o f any measurable DC field, is capable of producing these anomalies. Mo reover, the incidence of regeneration anomalies follows a clear dose-r esponse relationship as a function of AC magnetic field intensity, wit h the threshold for induced electric field intensity estimated at 5 mu V/m. The addition of either 51.1 or 78.4 mu T DC magnetic fields, app lied in parallel combination with the AC field, enhances the appearanc e of anomalies relative to the 60 Hz AC field alone, but only at certa in AC field intensities. Thus, whereas our previous study of regenerat ion rate effects appeared to involve exclusively resonance interaction s, the regeneration anomalies reported here appear to result primarily from Faraday induction coupling. These results together with those re ported previously point to two distinct physiological effects produced in regenerating planaria by exposure to weak extremely-low-frequency (ELF) magnetic fields. They further suggest that the planarian, which has recently been identified elsewhere as an excellent system for use in teratogenic investigations involving chemical teratogens, might be used similarly in teratogenic investigations involving ELF magnetic fi elds. (C) 1996 Wiley-Liss, Inc.