This page lists the principal epidemiological studies of female breast cancer and magnetic fields. See also an overall summary of the evidence on breast cancer and summaries of what review groups have said about it. We also provide the abstracts of the principal residential and occupational studies.
Studies of residential exposure
Three early studies were Wertheimer et al 1982, McDowall et al 1986, and Schreiber et al 1993. Of these, certainly Wertheimer et al suggested an association (for pre-menopausal women).
These were followed up by three large, thorough studies in the USA and one in Norway. The three US studies were uniformly negative and the Norwegian study largely so. These studies were:
Davis et al 2002
see abstract
- Conducted in Seattle
- approximately 800 cases
- exposure assessment by 48 hour measurements
- Odds ratio per 0.1 µT exposure: 1.04 (95% confidence interval 0.97-1.12)
London et al 2003
see abstract
- Conducted in Los Angeles
- approximately 700 cases (350 with measurements)
- exposure assessment by 7 day measurement
- Odds ratio per 0.1 µT exposure for night-time exposure: 1.0 (95% confidence interval 0.94-1.07)
Schoenfeld et al 2003
see abstract
- Conducted in Long island
- approximately 600 cases
- exposure assessment by 24-hour measurement
- Odds ratio for exposure >0.172 µT: 0.97 (95% confidence interval 0.69-1.4)
Kliukiens et al 2004
see abstract
- Conducted in Norway
- approximately 2000 cases
- exposure assessment by calculated field from high-voltage power lines plus occupational exposure
- Odds ratio for combined residential and occupational exposure: 1.3 (95% confidence interval 0.8-2.1)
Note that this is only a summary, most of the studies looked at risks in different subgroups (such as women of different ages) and for different measures of exposure (such as nighttime only or 24 hour).
Studies of occupational exposures
With studies of occupational exposure, there is a similar pattern. Some of the earlier studies suggested risks, but later, larger studies with better methodologies have been more negative.
The earlier studies were reviewed by Kheifets and Matkin 1999. The two more recent studies are Loomis et al 1994 (in the USA) and Forssen et al 2005 (in Sweden).
