Cancer and Power Lines--an Uncertain Connection : Health: A 1979 study linked magnetic fields with childhood disease. But the issue is far from settled.
When a 1979 study indicated that childhood cancer rates were higher in families living near high-current electric power lines, scornful utility officials and many scientists insisted that electromagnetic fields from power lines couldn’t possibly affect human health.
But a follow-up study supported the findings, concluding that children living near high-current lines were 1.5 to 2 times more likely than others to get cancer. Other studies have found that workers in electrical jobs--such as utility linemen, power station operators and electricians--have higher rates for brain cancer, leukemia and lymphoma, the same cancers implicated in the childhood studies.
Still, the issue is far from settled. There are ambiguities in much of the research, and other studies have found no link between illness and electric and magnetic (EM) fields. Nor does anyone know the mechanism by which these fields, even weak ones, may cause harm.
The controversy is especially perplexing because few things seem more benign or indispensable than electricity, and it is hard for some scientists to envision demons lurking in electric wires.
Robert Adair, a Yale University physics professor and leading doubter, said investigating the effects of EM fields is like looking for “werewolves. . . . When someone tells you a leaf fell on an elephant and broke his back, you’re skeptical,” he said.
Nevertheless, a growing number of lawmakers and even utility executives are calling for more research on potential health effects and ways to reduce exposure.
And what began as concern about power lines now includes electric blankets and video display terminals, which also expose users to EM fields. Amid the uncertainties, some experts are advocating “prudent avoidance,” or limiting exposure to fields in cheap and simple ways.
The issue is creating concern in communities throughout the country, where the mere suggestion of power line hazards may devalue property. Parents fret over schools that were built in the shadow of transmission towers to take advantage of cheap land. And neighbors are battling new transmission lines and electrical distributing stations, like the one the Los Angeles Department of Water and Power wants to build in Arleta.
In a draft report released earlier this month, the U.S. Environmental Protection Agency described fields “from power lines and perhaps other sources in the home as a possible, but not proven, cause of cancer in humans.”
The EPA and other federal health agencies have been criticized for investing too little in EM health research, much of which is funded by utilities. Citing austerity budgets and other priorities, the EPA dropped its own research program a few years ago.
The situation is pathetic, said Dr. David O. Carpenter, dean of the School of Public Health at the State University of New York at Albany. “I think . . . there really are some hazards here,” but “the federal government has simply not been a player of any major import.”
Other experts say that the risk, if there is one, seems small compared to hazards like cigarettes, alcohol and asbestos.
Childhood cancer, for example, is mercifully rare, striking about one child in 10,000 per year. If, as some studies suggest, the risk doubles for children living near high-current lines, the risk climbs to two chances in 10,000.
Even with such slim odds, however, EM fields could emerge as one of society’s more significant involuntary risks. Carpenter, former head of a New York state program of EM fields research, has estimated that fields could account for 20% to 30% of childhood cancers, or up to 2,000 per year, as well as 4,000 adult cancers annually in the United States.
“The stakes are really high on this,” Ken Henderson, director of compliance for the California Public Utilities Commission, recently told a meeting of utility officials. “If damages are proved,” he said, “society increasingly demands that someone pay,” and utilities are seen as having the “deepest pockets around.”
Utilities do not look forward to the prospect of retrofitting the nation’s electric power grid--which some say would reduce the problem--at a cost in the billions of dollars.
“I think in hindsight, we should have come in with more research money sooner,” said Jack Sahl, senior research scientist with Southern California Edison. But “it’s not like the health departments . . . were saying that we ought to be really pushing this hard.”
The press also paid less attention to this than to other cancer scares. “A lot of this information isn’t that new,” but “the institutions in society that would normally warn you about this haven’t,” said Louis Slesin, editor of the Microwave News, a newsletter that provided steady coverage of the issue.
Humans have always been exposed to electromagnetic energy, from the Earth’s static magnetic field to the fields produced by bursts of lightning. Brain, muscle and nerve tissues produce electric currents as part of their normal function.
But fields created by the electric power grid, and the gadgets it runs, have altered the electromagnetic environment.
Every wire or appliance that carries electric current produces electric and magnetic fields--invisible lines of force that radiate outward and fall off sharply with distance from their source.
Fields associated with electrical power are called 60 cycle, or 60 Hertz, fields because they are produced by alternating current that flows back and forth, reversing direction 60 times per second.
These extremely low-frequency fields are at the far end of an electromagnetic spectrum. Toward the other end are radar and microwaves, which oscillate at frequencies in the billions of cycles per second.
Higher still on the frequency spectrum are ultraviolet, X-rays, and gamma rays--called ionizing radiation because their high-energy waves actually tear apart--or ionize--atoms of living cells, damaging genetic material and creating a risk of cancer.
Until recently, it was believed that EM radiation could affect living cells in only two ways: either by ionization or heating tissue, as microwaves do. Since fields induced in the body by power lines and appliances are weaker than fields produced by the body itself, they were thought to have no biological effect.
However, by the 1970s some scientists had demonstrated changes in the function of cells exposed to low-frequency fields. And from Eastern Europe came reports of stress and sexual dysfunction among workers at electric power switchyards.
But the watershed was the 1979 study indicating a higher rate of childhood cancer in homes near high-current power lines. The Denver-based study was done by Nancy Wertheimer and Ed Leeper, a pair of obscure researchers working with their own funds.
“It was a joke between us for quite a long time,” said Wertheimer, adding that she and Leeper spent “two years before we published trying to make the findings go away, because we thought it was an accident somehow.” Nine years later, a second Denver study, led by epidemiologist David Savitz, found childhood cancer rates were 1.5 to 2 times above average for children living near high-current lines.
Meanwhile, EM fields were implicated in various occupational studies. For example, a 1982 USC study found that white males in Los Angeles County with electrical occupations had leukemia rates 29% above average.
The same year, a study found that leukemia mortality in Washington state from 1950 through 1979 was 37% higher than average among workers in electrical occupations.
A 1988 study found that utility workers in east Texas were 13 times more likely to develop brain tumors than other workers. A 1989 study in Los Angeles County found rates of astrocytoma, a type of brain cancer, were 4.3 times greater for men with over five years in electrical work, and 10 times greater for those with more than 10 years of experience.
Another study has found elevated cancer rates in the children of workers in electrical occupations, suggesting that fields may affect the sperm.
Many appliances generate strong EM fields, but in most cases the use is sporadic and field strengths drop sharply with distance.
But electric blankets can expose users to high fields for hours at a time. A study published last May found higher cancer rates among children whose mothers used electric blankets during pregnancy. An earlier study linked electric blanket use during pregnancy to higher risk of miscarriage.
Two more studies found no link between electric blanket use and leukemia and testicular cancer, respectively. Another study found no connection between EM fields and an acute form of leukemia.
The ubiquitous video display terminal has also stirred concern, because it exposes users to fields that are weak, yet of similar strength to those implicated in the childhood cancer studies. A 1988 study found higher rates of miscarriage and birth defects among Northern California women who used computer terminals more than 20 hours per week during their first trimester of pregnancy. Other studies concluded that VDTs are probably safe to use during pregnancy.
In the laboratory, scientists have shown that EM fields alter basic cellular functions, like protein synthesis and production of hormones involved in immune response. Some have theorized that fields create weak currents around cell membranes that alter biochemical signals, possibly interfering with the cancer-fighting function of the immune system.
“There is a body of laboratory evidence, there is a body of epidemiological evidence, and the two are coming together in a very remarkable way,” said Dr. W. Ross Adey, associate chief of staff at the Pettis Memorial Veterans Administration Medical Center in Loma Linda.
Others say that overstates the case. They point to contradictory studies that found no elevated cancer risk with EM fields, as well as flaws in studies that suggested a link. For example, most of these studies included few, if any, measurements to show that workers and children living near power lines actually had higher exposure.
The Savitz findings in Denver illustrate some of the difficulties in interpreting the research. His childhood cancer data not only indicated a link with power lines, but with maternal smoking, failure of mothers to breast feed, and higher auto traffic near the home.
If there is a hazard, reducing it will be a daunting task. In general, exposure from power lines can be lessened by raising tower heights and expanding rights of way, or by “phasing” lines--arraying them in such a way that fields cancel each other.
However, field strengths may also depend on wiring and the way the power is grounded in the home. And it’s uncertain what aspects of fields should be controlled--whether the risk would be in magnetic or electric fields or both, and results from chronic exposure to weak fields or transient peaks in field strengths.
Consequently, utility officials and electronics manufacturers contend that regulations are premature. “I understand we are all under tremendous pressure from our customers and our clients to do something, even if it’s wrong,” said Kirby C. Holte, a consulting scientist with Southern California Edison. “We simply don’t know what to regulate, and whatever we do, we will probably be wrong given all the opportunities to be wrong.”
Currently three states are sponsoring EM fields research, including a three-year, $2-million program in California. No results have been reported as yet from that study, which began in 1989. And the Electric Power Research Institute, a utility industry group based in Palo Alto, is spending $6 million on EM fields research, more than all federal agencies combined.
Utilities have won praise for their effort, but many officials are uneasy about the fact that they dominate the research.
“I would not want to rely upon research funded by the Electric Power Research Institute for the definitive word on the health effects of electromagnetic radiation,” said Rep. George Brown (D-Colton). “It’s just too obvious a conflict of interest.”
Congress next year is expected to consider bills to increase federal funding and put a centralized research program under authority of a single federal agency or interagency committee.
The Large Public Power Council, representing the Los Angeles DWP and other publicly owned utilities, also is calling for a federally controlled research fund to which utilities would contribute. “Let’s pool this money and utilize a federal agency to oversee a national study,” said Bernard V. Palk, the DWP’s assistant chief engineer for power.
“There is an urgency to get out ahead of this thing and make sure the research is done,” said Dr. Raymond Neutra, chief of special epidemiological studies for the California Department of Health Services.