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

Human Health Studies

Q. What have the studies of cancer in people living near power lines found?

A. 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 (see p. 34).

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.

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Summary of Residential Power-Line Cancer Studies

Study	Location	Leukemia	Other Cancers
Child Cancer Studies
Wertheimer & Leeper '79	Denver	OR = 2.35*	All Cancer OR = 2.22*
Fulton et al. '80	Rhode Island	OR = 1.09	Not Studied
Tomenius '86	Sweden	OR = 0.30	CNS Tumors OR = 3.70*
Savitz et al. '88	Denver	OR = 1.54	All Cancer OR = 1.53*
Coleman et al. '89	U.K.	OR = 1.50	Not Studied
Lin & Lu '89	Taiwan	OR = 1.31	All Cancer OR = 1.30
Myers et al. '90	U.K.	OR = I .14**	All Cancer OR = 0.98
London et al. '91	Los Angeles	OR = 2.15t	Not Studied
Lowenthal et al. '91	Australia	O/E = 2.00	.
Feychting & Ahlbom '93	Sweden	OR = 3.80*	All Cancer OR = 1.30
Olsen et al. '93	Denmark	OR = 1.50	All Cancer OR = 5.60
Petridou et al. '93	Greece	OR = I .19	Not Studied
Verkasalo '93	Finland	SIR = 1.60	All Cancer SIR = 1.50,
.	.	.	CNS Tumors in Boys, SIR = 4.20*
Fajardo-Gutierrez et al. '93	Mexico	OR = 2.63*	Not Studied
Adult Cancer Studies
Wertheimer & Leeper ‘82	Denver	OR = 1.00	All Cancer OR = 1.28*
McDowall ‘86	U.K.	SMR = 143	Lung Cancer SMR = 215*
Severson et al ‘88	Seattle	OR = 0.80	Not Studied
Coleman et al. ‘89	U.K.	OR = 0.90	Not Studied
Youngson et al. ‘91	U.K.	Leukemia & Lymphoma OR = 1.29
Eriksson & Karlsson ‘92	Sweden	Not Studied	Multiple Myeloma OR = 0.94
Feychting & Ahlbom ‘92	Sweden	OR = 1.00	(Leukemia Subtypes OR = 1.70)
Schreiber et al. ‘93	The Netherlands	No Cases	All Cancer SMR = 85,
.	.	.	Hodgkins Disease SMR=469

Notes: This table is intended to summarize briefly some of the selected, often-cited results of the residential cancer studies. Consult the full papers for details (see References, p. 56).

OR = Odds Ratio. An OR of 1.00 means no increased or decreased risk.
SMR = Standardized Mortality Ratio. An SMR of 100 means no increased or decreased risk.
SIR = Standardized Incidence Ratio. An SIR of 1.00 means no increased or decreased risk.
CNS = Central nervous system.
O/E = Observed number of cases divided by the expected number of cases.
* The number is statistically significant (greater than expected by chance), p. 11.
** For nonsolid tumors, which includes leukemia and lymphomas.

Although often characterized this way, these diverse studies can't simply be "added up" to determine weight of evidence or to reach a conclusion about health effects because many types of studies are included in these lists. Also, many studies that reported no statistically significant elevations in risk did report elevated risks (above 1.00). The risks in some cases may not be reported as "significant" because of small sample sizes. For studies included as significant, some found only one or a few significant risks out of several that had been calculated. When many risks are calculated, some can be "significant" due to chance. It is also worth noting that studies which report positive associations tend to receive more publicity than do studies which find no association.