Since the early nineties, the use of devices that emit electromagnetic fields (EMF) has raised health concerns and, thus, prompted a lot of research on the biological effects of EMF. A critical study undertaken by MN Bates in 1991 gave new epidemiologic information which associated the cancer with extremely low frequency (ELF) EMFs. This research was concerned with the biological efficacy of ELF-EMFs, especially whether ELF-EMFs had any effect in relation to cancer in humans. In this blog, we will discuss the meaning of Bates’ results, the corresponding epidemiological studies, the biological processes involved in ELF-EMF exposure, and the broader consequences of this research on the health and safety of the general population.

Understanding Extremely Low Frequency (ELF) EMFs EMFs with a frequency range extending between 1 to 300 Hz falls under the classification of extremely low EMF’s. Such fields are a product of electrical power generation, transmission, and consumption which emanates in abundance owing to the contemporary systems. ELF EMF’s are mainly derived from power lines, electric tools, and industrial machinery. Not ionizing radiation, ELF EMF's are not capable of exerting energy that is sufficient to displace electrons encumbered in atoms which in essence means they do not break DNA like X-ray or gamma radiation. However, there is increasing evidence that chronic exposure to ELF-EMFs could still pose severe risks to human health including cancer. MN Bates’ 1991 Study: Key Findings Bates, M. N. in 1991 work was among the pioneer works to show epidemiological link between exposure to ELF EMF and cancer claims using echinoderm study. The research bred the possibility of investigate occupational and environmental ELF EMF exposures and its associated and probable risk factors for cancer development. Especially the work of this group was critical as they generated a sound quantification of biological effectiveness elicited by ELF EMF and addressed several plausible mechanisms of carcinogenesis induced by chronic exposure.

The major points in Bates’ 1991 study are:

1. Occupational Exposure and Cancer Yolanda: The study concluded that workers exposure to ELF-EMFs at the workplace had elevated risks of contracting some kinds of cancer, especially leukemia and brain cancer. Higher levels of these cancers were observed in workers exposed in industries like electrical utility, telecommunications and manufacturing. This association was much stronger in persons who had been exposed to very high magnetic field levels for several years.

2. Geographic Context and Cancer Risk: In addition, Bates evaluated the impact of ELF-EMF exposure in the environment, particularly in the homes. The study established that children’s leukemia was more frequent in children living close to high concentration of ELF EMF generators, such as high voltage power lines. The conclusions of the study added the reason why there was heightened interest and concern about the public health impact of the use of ELF EMFs in both occupational and non-occupational settings.
3. Epidemiologic Methods and Data Analysis: Bates used thorough epidemiologic methods to investigate the association between the exposure of ELF-EMF and the cancer. A case-control and cohort study designs were employed which are the common study designs employed in epidemiology in describing relationship between the risk factors and disease. Through such studies, it was possible for Bates to prove that the people more exposed to ELF-EMF were at a greater risk of developing cancer compared to non-exposed. The study also took into consideration the potential confounding factors like, age, sex and smoking status so as to be certain that other risk factors were not responsible for the observed associations.

Biological Mechanisms of ELF-EMF Carcinogenesis

Although the epidemiologic assertions made by Bates were persuasive, the biological mechanisms responsible for cancer susceptibility attributed to ELF-EMFs were not well ascertained in that particular moment. In any case, Bates’ investigation, as well as previous ones, assists in the understanding of several possible mechanisms of ELF-EMF carcinogenesis.

1. Bioenergetics challenge: Among the various theories, there is a suggestion that the bioenergetics of the cells might get disrupted, potentially leading to further activity of the ROS. These include a class of molecules such as reactive oxygen species that exhibit high activity and can damage important cellular structures such as DNA, proteins, and lipids. This is because chronic oxidative stress has been identified as a factor in the progression of many types of cancer due to its ability to affect DNA molecules and other features of cellular biology that are responsible for defining normal cell growth patterns. It has been demonstrated that exposure to ELF-EMFs enhances ROS levels in cells. This suggests a possible manner in which these fields may be able to assist in any formation of a tumor.
2. Structural changes to cellular elements: Towards putting cancer cells in check, there are normal biological responses that cause calcium-dependent growth and cell division processes to slow down, or for the programmed cell death to take place. In the absence of such healthy biological repressions, the non-apoptotic and continuous uncontrolled growth of cancer cells will occur. Though unresolved, Bates’ work triggered some hypotheses about possibilities of prolonged exposure to ELF-EMFs changing how ion specific channels in cells or embryos function in normal physiology and hence promoting abnormal growth of proliferative cells.
3. Melatonin Suppression: Another suggested mechanism is that exposure to electromagnetic fields of extremely low frequencies inhibits the synthesis of melatonin, which is a biological hormone regulating the sleep-wake cycle and is known for its anti-cancer effects. It has been reported that melatonin has a rather potent antioxidant effect on cells, inhibits cell proliferation of cancerous cells. According to Bates' study, a group of people who suffered from exposure to ELF-EMF’s of a high level, namely at night remained ill with a decreased level of melatonin which could compromise the body’s anti-cancer defense response. This hypothesis has been further confirmed by other studies which suggested that lower levels of melatonin raised the risk of the development of breast and several other types of cancer.

Public Health Implications

In light of the studies conducted by MN Bates in 1991 data for the study should be treated with a higher degree of concern especially at human resources and environment level towards ELF EMF exposure. The future trend for ever increasing dependence on the use of electric power emphasizes the need for identifying the threat level posed by ELF-EMF and its subsequent incorporation in the standards and regulations which are to be devised.

1. Occupational Health Guidelines: One of the immediate effects of the research done by Bates is the call for enhanced occupational health guidelines to be applied to employees working with ELF-EMFs. Those industries that involve a hefty operational level of ELF-EMF exposure like electrical utilities, manufacturing and telecommunications are supposed to take protective measures to limit the ELF-EMF exposure of its personnel. Such measures can entail the employment of shielding devices, the cutoff of the time period of exposure and periodic evaluation of the amount of EMF in a working environment.
2. Residential Exposure and Public Awareness: Bates’ results raise another concern that the public should know of the dangers associated with residence-related exposure to ELF-EMFs. Those people residing around the areas of electric’s transmission with high volts and other sources of ELF-EMFs need to be let know of the hazards especially for children. Concerned Public health agencies would have to set the guidelines that would bar people from being exposed to ELF-EMFs in their homes similar to that created for ionising radiation.
3. Further Research and Risk Assessment: Nevertheless, it should be recognized that, while the study of Bates provided an important epidemiologic evidence further research is necessary to be able to appreciate fully the biochemical processes involved in carcinogenesis and the risk posed by exposure levels. Such longitudinal studies whereby people are tracked up to a certain level and evaluated for their ELF-EMF exposure as well as laboratory studies that look into the EMF’s biological impacts will be essential in determining the safe level of EMF exposure to be implemented in guidelines.

Conclusion

The study by MN Bates in 1991 was a key advancement in the quest to prove the presence of a connection between cancer and extreme low frequency (ELF) EMFs. Exposure to ELF-EMFs and cancer, especially occupational and residential exposure, raised fundamental issues about the long-term desire to cut out ELF-EMF OS Bates' exposures accepted and raised significant points on safety. The details of the biological basis for ELF-EMF-induced carcinogenesis remain incompletely understood. But it has been clear from the work done by Bates that further studies are still needed and also policies should be put in place to help protect the population from further dangers of the ELFs. As long as the society sees the use of power and electronic devices, it will also be the case to deal with health issues related to ELF-EMFs.

References

Bates, M.N. (1991). Epidemiologic evidence linking extremely low frequency electromagnetic fields to cancer. American Journal of Epidemiology, 134(10), 923-936.

Kheifets, L., Sahl, J.D., Shimkhada, R., & Rees, M. (2006). The association between residential exposure to power-frequency electromagnetic fields and cancer: a review of the epidemiologic literature. Journal of Exposure Science and Environmental Epidemiology, 16(1), 3-19.

World Health Organization (WHO). (2007). Environmental Health Criteria 238: Extremely Low Frequency Fields. Geneva: WHO Press.

Schüz, J., & Ahlbom, A. (2008). Exposure to electromagnetic fields and the risk of childhood leukemia: a review. Radiation Protection Dosimetry, 132(2), 202-211.

Wertheimer, N., & Leeper, E. (1979). Electrical wiring configurations and childhood cancer. American Journal of Epidemiology, 109(3), 273-284.