Understanding Electric and Magnetic Fields

Wherever there’s electric power you'll find 60-hertz (power frequency) electric and magnetic fields (EMF). Do you have questions about the possible health effects of these fields? This site contains information and health studies about EMF.

The World Health Organization (WHO) concluded a review of the potential health implications of extremely low frequency (ELF) EMF, which includes power-frequency fields. Its conclusions and recommendations were presented in June 2007 in a report known as the Extremely Low Frequency Fields, Environmental Health Criteria Monograph No. 238.

The WHO report concluded that evidence for a link between ELF magnetic fields and childhood leukemia "is not strong enough to be considered causal but sufficiently strong to remain a concern." "Virtually all of the laboratory evidence and the mechanistic evidence fail to support" this reported association. For all other diseases, there is inadequate or no evidence of health effects at low exposure levels.

The report emphasized that, given the weakness of the evidence for health effects, the health benefits of exposure reduction are unclear and policies based on the adoption of arbitrary low exposure limits are not warranted.

In light of this situation, WHO made these and other recommendations:

• National authorities should implement communication programs with all stakeholders to enable informed decision-making, including how individuals can reduce their own exposure.
• Policy makers and community planners should implement very low-cost measures to reduce exposures when constructing new facilities and designing new equipment, including appliances.
• Policy makers should use existing international guidelines (833 and 9,000 milligauss) to establish standards for exposure to short-term, high-level ELF fields. These guidelines pertain to field levels that are virtually never encountered by the general public except from a few electric appliances.
• Government and industry should promote research to reduce the uncertainty of the scientific evidence on the health effects of ELF field exposure. Several recommended research projects are already under way through the Electric Power Research Institute, of which PG&E is a member.

See the full report and fact sheet.

In June 1999, the federal government completed a $60 million extremely low frequency, ELF, electric and magnetic field, EMF, research program managed by the National Institute of Environmental Health Sciences, NIEHS, and the Department of Energy, DOE. This program is known as the EMF Research And Public Information Dissemination, RAPID, Program. In its report to Congress, the NIEHS concluded:

The NIEHS believes the probability that ELF-EMF exposure is a genuine health hazard is currently small. The weak epidemiological associations and lack of any laboratory support for these associations provide only marginal, scientific support that exposure to this agent causes any degree of harm.

The NIEHS report also included the following conclusions:

It is our opinion that based on evidence to date, ELF-EMF exposure would not be listed in the "Report on Carcinogens" as an agent "reasonably anticipated to be a human carcinogen."

The NIEHS agrees that the associations reported for childhood leukemia and adult chronic lymphocytic leukemia cannot be dismissed easily as random or negative findings. The lack of positive findings in animals or in mechanistic studies weakens the belief that this association is actually due to ELF-EMF, but cannot completely discount the finding. The NIEHS also agrees with the conclusion that no other cancers or non-cancer health outcomes provide sufficient evidence of a risk to warrant concern.

Virtually all of the laboratory evidence in animals and humans, and most of the mechanistic work done in cells, fail to support a causal relationship between exposure to ELF-EMF at environmental levels and changes in biological function or disease status.

... the evidence suggests passive measures such as a continued emphasis on educating both the public and the regulated community on means aimed at reducing exposures are beneficial. NIEHS suggests that the power industry continue its current practice of siting power lines to reduce exposures and continue to explore ways to reduce the creation of magnetic fields around transmission and distribution lines without creating new hazards.

For information about the NIEHS EMF RAPID Program, or to obtain copies of its report, visit the EMF RAPID Program home page.

In May 1999, the National Research Council/ National Academy of Sciences, an independent scientific agency responsible for advising the federal government on science, technology, and medicine, released its evaluation of the scientific and technical content of research projects conducted under the U.S. EMF RAPID Program. It concluded that:

The results of the EMF-RAPID program do not support the contention that the use of electricity poses a major unrecognized public-health danger. Basic research on the effects of power-frequency magnetic fields on cells and animals should continue but a special research funding effort is not required. Investigators should compete for funding through traditional research-funding mechanisms. If future research on this subject is funded through such mechanisms, it should be limited to tests of well-defined mechanistic hypotheses or replications of reported positive effects. If carefully performed, such experiments will have value even if their results are negative. Special efforts should be made to communicate the conclusions of this effort to the general public....

For copies of the NRC/NAS report visit the National Academy Press web page.

In August 2004 the California Public Utilities Commission (CPUC) began a proceeding known as a "rulemaking" (R.04-08-020) to explore whether changes should be made to existing CPUC policies and rules concerning EMF from electric transmission lines and other utility facilities.

Through a series of hearings and conferences, the CPUC evaluated the results of its existing EMF mitigation policies and addressed possible improvements in implementation of these policies. The CPUC also explored whether new policies are warranted in light of recent scientific findings on the possible health effects of EMF exposure.

The CPUC completed the EMF rulemaking in January 2006 and presented these conclusions in Decision D.06-01-042:

• The CPUC affirmed its existing policy of requiring no-cost and low-cost mitigation measures to reduce EMF levels from new utility transmission lines and substation projects.
• The CPUC adopted rules and policies to improve utility design guidelines for reducing EMF, and called for a utility workshop to implement these policies and standardize design guidelines.
• Despite numerous studies, including one ordered by the CPUC and conducted by the California Department of Health Services, the CPUC stated, "we are unable to determine whether there is a significant scientifically verifiable relationship between EMF exposure and negative health consequences."
• The CPUC said it will "remain vigilant" regarding new scientific studies on EMF, and if these studies indicate negative EMF health impacts, the CPUC will reconsider its EMF policies and open a new rulemaking if necessary.

Since 1987, Pacific Gas and Electric Company has had a written company policy regarding electric and magnetic fields, EMF. The company has supported and funded medical, scientific and industry research on EMF for several years, and will continue such efforts. Company employees participated in an EMF occupational study with four other utilities that looked at the medical history of roughly 139,000 workers to see if magnetic field exposure contributed to brain cancer or leukemia. Please see the "What are the results from studies of electrical utility workers?" section of Frequently Asked Questions for more information about this study.

Pacific Gas and Electric Company will:

• Establish procedures to explicitly consider electric and magnetic field, EMF, exposure in the design of, planning for, and communications about new and upgraded facilities.
• Take reasonable steps to reduce EMF exposure in the design of new and upgraded facilities.
• Encourage a multi-industry effort to share responsibility for effectively addressing public concern about EMF exposure, while increasing overall energy efficiency.
• Work closely with employees and union leadership to continue review and implementation of EMF policies and procedures and provide employees with up-to-date information.
• Provide customers with up-to-date information on EMF and conduct measurements on request.
• Fund and actively participate in EMF research and work closely with government officials to resolve EMF issues.

NOTE: All of these policies have been implemented and are reviewed as new information becomes available.