What Have The Studies Of Cancer In People Living Near Power Lines EMF Found
EFFECTS OF 60-Hz EMFs REPORTED IN SOME LABORATORY STUDIES
Changes in functions of cells and tissues
Decrease in the hormone melatonin
Alterations of immune system
Accelerated tumor growth
Changes in biorhythms
Changes in human brain activity and heart rate
Of children ages 14 and under, in the United States, about 14 in 100,000 develop some form of cancer each year. Almost one-third of these cases are acute lymphocytic leukemia, the most common form of leukemia in children. For childood leukemia victims, chances of survival are about 60%. To date, 14 studies have analyzed a possible association between proximity to power lines and various types of childhood cancer. Of these, eight have reported positive associations between proximity to power lines and some form(s) of cancer. Four of the 14 studies showed a statistically significant association with leukemia.
The first study to report an association between power lines and cancer was conducted in 1979 in Denver by Dr. Nancy Wertheimer and Ed Leeper. They found that children who had died from cancer were 2 to 3 times more likely to have lived within 40 m (131 ft) of a high-current power line than were the other children studied. Exposure to magnetic fields was identified as a possible factor in this finding. Magnetic fields were not measured in the homes. Instead, the researchers devised a substitute method to estimate the magnetic fields produced by the power lines. The estimate was based on the size and number of power line wires and the distance between the power lines and the home.
A second Denver study in 1988, and a 1991 study in Los Angeles, also found significant associations between living near high-current power lines and childhood cancer incidence. The L.A. study found an association with leukemia but did not look at all cancers The 1988 Denver study found an association with all cancer incidence. When leukemia was analyzed separately, the risk was elevated but not statistically significant. In neither of these two studies were the associations found to be statistically significant when magnetic fields were measured in the home and used in the analysis. Studies in Sweden (1992) and Mexico (1993) have found increased leukemia incidence for children living near transmission lines. A 1993 Danish study, like the 1988 Denver study, found an association for incidence of all childhood cancers but not specifically leukemia. A Finnish study found an association with central nervous system tumors in boys. Eight studies have examined risk of cancer for adults living near power lines. Of these, two found significant studies involving cancer in people living near power lines.
Is there something significant about the 2-mG magnetic field level? A. The significance of 2 mG is as a boundary to define the exposed group in some studies, not as a safety threshold. Some experiments with cells have reported effects at field levels as low as 2 mG but there is no laboratory evidence for adverse human health effects at this level. A typical American home has a background magnetic field level (away from any appliances) that ranges from 0.5 mG to 4 mG, with an average value of 0.9