Statistics do not support claims that low frequency electromagnetic fields from power lines, electrical appliances, etc., cause leukemia or any other form of cancer, says the Physics Division's Dave Jackson, who is also a UC Berkeley physics professor.
In a paper appearing in the April 15 issue of the "Proceedings of the National Academy of Sciences", Jackson examines historical data on the generation and consumption of electrical power since 1900, and compares it to corresponding data on cancer death and incidence rates.
"The conclusions from the data are that there cannot be any significant cause of cancer from the use of electricity in society," Jackson says. "There is no evidence to support the claim that stray low frequency (50 or 60 hertz) electromagnetic fields cause leukemia."
The data examined by Jackson showed that while the amount of electrical power generated and consumed in this country since the turn of the century has increased enormously, the age-adjusted cancer death rate for the population as a whole shows only a slight rise. Furthermore, when respiratory cancers, caused mainly by the use of tobacco, are subtracted, the remaining death rate from cancers has actually declined since 1940 -- a period when per capita residential use of electric power increased twentyfold.
The issue has been raised in recent years as to whether stray low frequency electromagnetic fields from overhead electrical power lines, transformers, or even household wiring and appliances are hazardous to human health. Claims have been made that such radiation can cause cancer, especially leukemia. Research on the subject has been inconclusive.
"I wanted to look at the problem in a pragmatic way," Jackson says, "in order to establish whether there is likely to be any appreciable threat to most people from the stray fields inevitably present in our increasing reliance on electrical devices for work and play."
Jackson worked from statistics collected from a variety of sources, including the U.S. Department of Energy, the Bureau of the Census, the National Center for Health Statistics, and the Office of Technology Assessment. As a measure of potentially threatening electromagnetic fields, he looked not only at the per capita residential power consumption, but also at the total electric power generation per capita in this country, which increased by 350 times, from 32,000 watt hours per year in 1902, to 11.2 million watt hours per year in 1990.
"Power generation includes the losses in transmission," says Jackson, "a component of the electricity distribution system brought into question by those who suspect some cause and effect."
Jackson notes that the early data on cancer are on cancer death rates and not incidence rates of newly diagnosed cancers. Reliable national data on trends in cancer incidence have only been available since the late 1960s. However, even these data show only a small (0.9 percent per year) increase in total incidence rate, and, if anything, a decrease in the incidence of leukemia. Furthermore, most of this increase is attributable to forms of cancer for which there are known causes other than electromagnetic fields.
Jackson says his conclusions will not come as a surprise to scientists who have been studying the issue. The broad consensus has been that the hazards posed by low frequency electromagnetic fields are insignificant and that any possible risk is confined to very small segments of the population which might possibly be particularly susceptible for one reason or another.
"The average person has nothing to fear about sleeping next to an electric radio or alarm clock, using a household appliance, or walking under a high-tension power line," Jackson says.