Public concerns on possible health risks from residential exposures to low-strength, low-frequency electric and magnetic fields became a major focus of scientists and government officials. In 1991, the National Academy of Sciences (NAS) was asked by the United States of America Congress to review the researches conducted on the effects from exposure to electromagnetic fields and determine whether the scientific basis was sufficient to assess health risks from such exposures (Miller et al., 1996; Moulder, 2006).
Overview
Health Effects
According to studies (ELF Electric & magnetic fields: health effects & exposure guidelines, n.d.), biological material being affected by electromagnetic fields depends on the frequency of the source. It usually acts as waves but at times, it acts like particles especially at high frequencies. The particle nature of electromagnetic energy is important because it is the energy per particle (or photons) that determines what biological effects electromagnetic energy will have (Possible health effects of exposure to residential electric and magnetic fields, 1997). These photons are believed to have abilities to break chemical bonds (called ionization) because it has enough energy (Moulder, 2006).
The ionizing and non-ionizing characteristics of electromagnetic fields and biological effects lead to researches on its possible carcinogenic effects to humans. The International Agency for Research on Cancer (IARC) is the one responsible for cancer research for the World Health Organization. IARC reported in 2001 that “overall, extremely low frequency magnetic fields were evaluated as possibly carcinogenic to humans, based on the statistical association of higher level residential extremely low frequency (ELF) magnetic fields and increased risk for childhood leukemia (Miller, et al., 1996; Repacholi, 1998).” However, studies are still underway to determine if ELF exposure can influence cancer promotion or co-promotion (Electric and magnetic fields, 2003).
Laboratory studies on humans exposed to intense electric and magnetic fields produced no observed changes in blood pressure, body temperature, sleep, appetite or physical functions (Electric and magnetic fields, 2003). Other studies showed mood and behavior unchanged in human subjects (Repacholi, 1998).
The use of cardiac pacemakers and other implanted electromedical devices was also reported to be affected by strong electromagnetic fields (Repacholi, 1998). WHO then suggested manufacturers of such devices to manufacture less susceptible electromedical devices to EMI. These fields were shown to cause electromagnetic interference (EMI) and may be more of a threat than a benefit to the patient. It was suggested that these patients must consult their doctor for possible susceptibility to EMI.
Environmental Effects
The electromagnetic fields were known to lower the dielectric constant of the water due to the resultant partial or complete destruction of the hydrogen-bonded network (Moulder, 2006; Electric and magnetic fields, 2003). In addition to the breakage of hydrogen bonds, electromagnetic fields may perturb in the gas/liquid interface and produce reactive oxygen species (Electric and magnetic fields, 2003). These changes in hydrogen bonding may effect carbon dioxide hydration resulting in pH changes. This consequently decreases the quality of soil and affects agriculture and economic output, especially on areas highly dependent on agriculture as source of living. It also affects ground water, thus, affects public health of the community dependent on it.
Power lines Siting
Which is safer: power lines constructed underground or overhead? Many aspects should be considered when putting up power lines. If health risk is the more focus though scientific evidence is not strong enough, power lines should be underground in crowded areas like rural or cities. On areas where agriculture is critical, powerlines should be overhead to avoid effects on water quality since this is scientifically supported. But considering government management and budget, it is more economical to put powerlines overhead due to easy access and earlier repair in cases of problems or emergencies. At present, Grade A copper priced at 50 U.S. cents per ton (Copper, n.d.). The per capita income demand for copper in North America in year 2000 was 12 kg (Copper, n.d.). It is therefore important to have an effective system of health information and communication among scientists, governments, industry and the public because it can help raise general awareness to deal with exposure to ELF fields and reduce any mistrust and fears.
Conclusion
The researches on effects of electromagnetic fields have shown interactions between fields and biological systems can occur. But based on risk assessment performed in many studies, significant adverse interactions at ambient fields to which human and animals are typically exposed remains unclear and insufficient. The research does hold out the possibility of a risk, but it is expected that research efforts that are currently underway will likely address this concern. Many researches have been done that provided the present established exposure limit values. These are now used to provide protection against the acute hazards that can result from high intensity exposure levels. These studies along with future researches will determine if there is a need for lowering the limits to provide protection against the consequences of chronic low level exposure.
References
- Base Metals (n.d.) Copper [Internet].
- BC Hydro. (2003) Electric and magnetic fields [Internet]. British Colombia, BC Hydro. Available from: <http://www.bchydro.com/> [Accessed 11 January 2007].
- Commission on Life Sciences (1997) Possible health effects of exposure to residential electric and magnetic fields [Internet]. Commission on Life Sciences (CLS). Available from: <http://books.nap.edu/openbook.php> [Accessed 11 January 2007].
- Department of Labour (n.d.) ELF Electric & Magnetic Fields: Health Effects & Exposure Guidelines [Internet]. Radiation Safety Unit, Department of Labour. Saskatchewan, Canada.
- Miller, A.B., To, T., Agnew, D.A., Wall, C., and Green, L.M. (1996) Leukemia following occupational exposure to 60 – Hz electric and magnetic fields among Ontario electric utility workers, American Journal of Epidemiology, 144(2) July, pp. 150-60.
- Moulder, J.E. (2006) Questions and answers on EMF and its effects: What’s new? [Internet]. Version 10.1.1 (August).
- Repacholi, M. (1998) Electromagnetic fields and public health: extremely low frequency (ELF) [Internet]. World Health Organization (WHO). Geneva, WHO.