Điện trường và từ trường (EMF)
In recent years, everyone from scientists to everyday people have questioned whether there’s a link between exposure to 60-hertz (power frequency) electric and magnetic fields (EMF) and serious health problems, including cancer. And no one is more concerned about it than all of us at SDG&E.
What Are Electric and Magnetic Fields?
Electric and magnetic fields (EMFs) are present wherever electricity flows — around appliances and powerlines, and in offices, schools, and homes.
- Electric fields are invisible lines of force created by voltage. Voltage is the electric force that causes current in a conductor, and are shielded by most materials.
- Magnetic fields are invisible lines of force created by current, movement of electrons in a conductor. They are not shielded by most materials such as lead, soil and concrete.
Can EMF Harm Your Health?
Electric and magnetic fields are present wherever electricity flows—around appliances and power lines, in offices and at schools and homes. Many researchers believe that if there is a risk of adverse health effects from usual residential exposures to EMF, it is probably just at the detection limit of human health studies; nonetheless, the possible risk warrants further investigation. The varying results from epidemiological studies, which looked at estimated EMF exposures and childhood leukemia, are consistent with a weak link. Laboratory studies, including studies investigating a possible mechanism for health effects (mechanistic studies), provide little or no evidence to support this weak link.
The results from many research studies have been evaluated by international, national and California EMF research programs to determine whether EMF poses any health risk. Given the uncertainty of the issue, the medical and scientific communities have been unable to conclude that usual residential exposures to EMF cause health effects, or to establish any standard or level of residential exposure that is known to be either safe or harmful. These conclusions remain unchanged by recent studies.
Cam kết của chúng tôi
Until research and the scientific community provide greater direction, SDG&E’s commitment includes the following measures:
- Maintaining an EMF Center staffed with informed representatives available to talk with customers about EMF issues
- Free measurements of magnetic fields
- Providing EMF health literature to the public.
- Supporting, funding, and monitoring EMF research
- Working to reduce fields associated with new and upgraded construction projects
Kết luận của Tổ chức Y tế Thế giới
The World Health Organization (WHO) completed a review of the potential health implications of extremely low frequency EMF, which includes power-frequency fields. Their conclusions and recommendations were presented in June 2007 in a report known as the Extremely Low Frequency Fields, Environmental Health Criteria Monograph No. 238.
Learn about the WHO report's conclusions and recommendations
Bạn có thể làm gì
In a situation of scientific uncertainty and public concern, WHO recommended that utilities explore “very low-cost” ways to reduce EMF exposure from new or upgraded facilities. SDG&E and other California public utilities have been pursuing no-cost and low-cost measures to reduce EMF levels from new utility transmission lines and substation projects.
You, too, may want to take no-cost and low-cost measures to reduce your EMF exposure at home and at work. Human studies have not produced a consensus about any health benefits from changing the way people use electric appliances. But, if you feel reducing your EMF exposure would be beneficial, you can increase your distance from electric appliances and/or limit the amount of time you use appliances at home or at work.
- For instance, you can place your electric clock away from the head of your bed. Increasing your distance from it and other appliances, such as televisions, computer monitors and microwave ovens, can reduce your EMF exposure.
- You can also reduce your EMF exposure by limiting the time you spend using personal appliances, such as hair dryers, electric razors, heating pads and electric blankets.
- You may also want to limit the time you spend using electric cooking appliances. You can locate the sources of EMF in your work environment and spend break time in lower-field areas.
It is not known whether such actions will have any impact on your health.
Thông tin thêm
Call SDG&E at 1-800-411-7343 to request a free information packet, home or business measurements or summaries of the reports listed in this brochure. You may also make an yêu cầu trực tuyến.
World Health Organization International EMF Project: Khám phá thêm tại who.int/health-topics/electromagnetic-fields for EMF information, including fact sheets, research completed and scientific journal articles.
National Institute of Environmental Health Sciences: Khám phá thêm tại niehs.nih.gov/health and click on Brochures & Fact Sheets, then select the Electric and Magnetic Fields booklet in English or the Campos Eléctricos y Magnéticos booklet in Spanish.
EPRI: EPRI is an independent non-profit energy research, development, and deployment organization that maintains a global research presence with trusted experts who collaborate with more than 450 companies in 45 countries, driving innovation to ensure the public has clean, safe, reliable, affordable, and equitable access to electricity across the globe.