Questions and Answers About EMF Electric and Magnetic Fields Associated with the Use of Electrical Power.
January 1995.

Human Health Studies

Q. What about the Swedish cancer study of people living near transmission lines?

A. In late 1992, researchers in Sweden reported results of a study of cancer in people living near high- voltage transmission lines. The Swedish study generated a great deal of interest among scientist, the public, and the news media. Relative risk for leukemia increased in Swedish children who lived within 50 m (164 ft) of a transmission line. The risk was found also to increase progressively as the calculated average annual 50-Hz magnetic field increased in strength. However, the risk calculations were based on very small numbers of cases (see summary below).

The Swedish researchers concluded that their study provides additional evidence for a possible link between magnetic fields and childhood leukemia. However, scientists have expressed differing opinions about this study. Some scientists believe the study is important because it is based on magnetic field levels presumed to have existed around the time the cancers were diagnosed. Others are skeptical because of the small numbers of cancer cases and because no cancer association was seen with present-day magnetic field levels measured in the home.

There are about 70 new cases of childhood leukemia per year in Sweden. The National Electrical Safety Board of Sweden estimates that if, as this study suggests, living overhead transmission lines increases a child's risk of developing leukemia, then approximately two children per year in Sweden would develop leukemia as a result of living near such power lines.

SUMMARY OF SWEDISH RESIDENTIAL CANCER STUDY

• Cancer cases (from 1960-85) and controls selected form the 500,000 people who had lived on property within 300 m (984 ft.) of 220- and 400 - kV lines.

• Magnetic field exposure was estimated by (1) in-home measurement, (2) dwelling distance form lines, and (3) calculated average annual magnetic field before and near time of cancer diagnosis.

• The relative risk of child leukemia was 1.50 for calculated fields of 1 to 2.9 mG (based on four leukemia cases), and 3.80 for fields above 3 mG (based on seven cases). The trend for increasing risk with increasing field strength was statistically significant.

• No cancer association was found with present-day in-home magnetic field measurements.

• For homes with 50m (164 ft.) of transmission lines (six cases), relative risk for child leukemia was 2.90, which was on the borderline of statistical significance.

• Excess leukemia risks were found only in one-family homes. There were no elevated risks for other types of child cancers.

• Control for possible effects of air pollution and socioeconomic status did not change study results.

• Adults with highest cumulative exposures to power-line EMFs had twice the risk of developing acute myeloid leukemia.

  Source: Feychting & Ahlbom 1992, 1993.