Electromagnetic fields, previously implicated in triggering leukemia, brain tumors and breast cancer, may play a far more important role in Alzheimer’s disease, a USC researcher will report today.
Results from two new studies conducted in Finland and one in Los Angeles indicate that people with a high occupational exposure to EMFs are at least three times as likely to develop Alzheimer’s disease as those without significant exposure, Dr. Eugene Sobel is scheduled to report at the Fourth International Conference on Alzheimer’s Disease and Related Disorders in Minneapolis. In comparison, the cancer risk associated with EMFs is generally believed to be 1.5 to 1.8 times as high among those with occupational exposure.
Sobel and his colleagues also found that dressmakers and tailors were overrepresented among Alzheimer’s victims. Further study showed that industrial and home sewing machines produce much larger EMFs than other appliances and that people who use sewing machines regularly have the greatest exposure of any occupation--as much as three times that of electric power line and cable workers.
And unlike the case for leukemia and tumors, the researchers say they have a biological rationale for how the EMFs produce the suspected Alzheimer’s-related defects and animal evidence that supports their observations.
“This opens up a whole new frontier in terms of potential EMF effects,” said EMF expert Louis Slesin, editor of Microwave News. “EMF has long been a backwater area with a lot of skeptical people taking potshots at the research . . . . This could signal a major change in the way EMF health risks are addressed.”
Dr. James Mortimer of the Veterans Affairs Medical Center in Minneapolis said Sobel’s findings were very surprising. “Nobody ever even thought it (Alzheimer’s) was related to EMF. This is a much stronger finding than the link to leukemia.”
Alzheimer’s disease afflicts at least 2.5 million Americans and perhaps as many as 4 million, most over age 65.
It is characterized by memory loss, disorientation, depression and deterioration of bodily functions. It is ultimately fatal, causing about 100,000 deaths in the United States each year.
The cause of Alzheimer’s is still unknown. Genetics almost certainly plays a major role in its onset, experts say, but environmental factors may contribute as well. Most previous studies of environmental factors have focused on chemicals. Sobel’s findings offer entirely new possibilities.
The two Helsinki studies--conducted by USC with researchers from the Universities of Kuopio and Helsinki--and one in Los Angeles involved a total of 386 Alzheimer’s patients and 475 healthy control subjects. Subjects were divided into two categories--those with medium to high occupational exposure and those with low or no occupational exposure.
Those people with the higher occupational exposure to EMFs averaged three times as likely to develop Alzheimer’s as those with low exposure, Sobel reported. The relative risks were consistent in the three studies: 2.9, 3.1 and 3 times higher than the low exposure group.
Women were more susceptible to the effects of EMFs: in the three studies combined, women with the higher exposure had a relative risk of 3.8 compared to women with the lowest exposure. In one of the Finnish studies, those women with the highest exposure were 7.3 times as likely as women in the low exposure group to develop Alzheimer’s; in the other two studies, the relative risks were 3.3 and 4.2 times as great.
The study was an outgrowth of laboratory findings by one of Sobel’s co-authors, neurologist Zoreh Davanipour of Loma Linda University. Davanipour and her colleagues have found that EMFs increase the number of calcium ions (charged atoms) in nerve cells grown in the laboratory.
Calcium is extremely important in the cells because it is directly involved in many biological responses, especially communication among nerve cells. Sobel speculates that increased levels of calcium ions kill the cells. That finding suggests that EMFs could affect neurological diseases, a conclusion that the researchers said seems to be supported by the study results.
Some animal work also suggests that EMFs might damage the brain, although the mechanism proposed in that case is different from Davanipour’s. In the mid-1980s, physicists Henry Kues and Sam Koslov of Johns Hopkins University’s Applied Physics Laboratory in Laurel, Md., studied the effects of low levels of microwave radiation on the eyes of two different types of monkeys.
They found that persistent exposure to the radiation, at levels well below safety guidelines, damaged the cornea, apparently by opening the blood-brain barrier in the eyes. The blood-brain barrier is a tightly packed layer of cells on the inside of blood vessels in the brain that prevents microorganisms and many toxic chemicals in the blood from reaching delicate brain tissues.
Examination of the monkeys’ brain tissue by Dr. Linda Cork of Hopkins showed that it contained neurofibrillary tangles and other changes characteristic of Alzheimer’s disease. Koslov believes that opening the blood-brain barrier in the affected cells allowed toxic chemicals to leak in, eventually killing the cells and producing the tangles. The research was later abandoned for lack of funding, Koslov said.
In contrast, tumors have never been induced in animals by exposure to EMFs, Slesin said.
Sobel noted that he had spent five years studying the links between EMFs and cancer before abandoning the field in frustration because of the relatively low increased risks he had observed and the difficulties of reproducing those studies. He joined the current study at Davanipour’s urging, he said. “We’re really excited about this,” Sobel said. “It’s a very dramatic effect.”