THE EFFECTS OF 50 HZ MAGNETIC-FIELD EXPOSURE ON DIMETHYLBENZ(ALPHA)ANTHRACENE INDUCED THYMIC LYMPHOMA LEUKEMIA IN MICE/

Several epidemiological investigations have suggested an increased inc idence of lymphoma, leukemia, and brain tumor in residents living near power transmission lines. However, some observers failed to confirm s uch a positive correlation. To evaluate the effects of extremely low f requency (ELF) magnetic fields on leukemogenesis, an experimental anim al model was used, in which thymic lymphoma/leukemia was induced by di methylbenz(alpha)anthracene (DMBA) injected subcutaneously into the in terscapular region of newborn mice within 24 h after birth. Beginning at the second week of age, 165 mice were exposed to 50 Hz magnetic fie ld at 1 mT, 3 h/day, 6 days/week for 16 weeks, and 155 animals exposed to sham conditions. All surviving animals were killed by cervical dis location at the age of 32 weeks and were examined pathologically. The results showed that the incidences of advanced thymic lymphoma, compli cated with lymphomatous leukemia, were 21.8 and 23.9% in the two group s, respectively, without statistically significant differences. But de nse metastatic infiltration by lymphoma cells into liver in the held e xposure group greater (50%) than that in the sham-exposure group (16.2 %) was observed (chi(2) = 9.847, P < 0.01). To determine whether ELF a cts as a tumor promoter, further experiments are required. (C) 1997 Wi ley-Liss, Inc.