Breast cancer and electromagnetic fields--a review

Improved Swallow Outcomes with Early Intervention using Combined Swallow Therapy in Advanced Oropharyngeal Carcinoma

Objective

To evaluate the impact of early intervention using combined swallow therapy, consisting of traditional swallow exercises and transcutaneous neuromuscular electrical stimulation, on patients with advanced oropharyngeal squamous cell carcinoma.

Methods

A cohort study of 60 prospectively enrolled patients was performed. Thirty patients with advanced oropharyngeal squamous cell carcinoma starting combined swallow therapy two weeks after surgery that continued throughout chemoradiotherapy were compared with a matched cohort of 30 patients starting combined swallow therapy after cancer treatment completion. Gastrostomy tube status, modified barium swallow, and Functional Oral Intake Scale scores were assessed before and after therapy.

Results

Both cohorts demonstrated a statistically significant improvement in Functional Oral Intake Scale scores. All patients in the early intervention cohort discontinued gastrostomy tube use, compared with one-third in the control cohort, with greater improvements in Functional Oral Intake Scale scores. The tongue base was the site of greatest improvement in the early intervention group.

Conclusion

Early initiation of combined swallow therapy may optimise swallow outcomes in patients with advanced oropharyngeal squamous cell carcinoma.

Changes in pyramidal and granular neuron numbers in the rat hippocampus 7 days after exposure to a continuous 900-MHz electromagnetic field during early and mid-adolescence

The aim of this study was to investigate qualitative and quantitative changes in pyramidal and granule neurons in the male rat hippocampus after exposure to a continuous 900-megahertz (MHz) electromagnetic field (EMF) for 25 days during early and mid-adolescence. Three-week-old (21 day) healthy Sprague Dawley male rats were divided equally into control (CON), pseudo-exposed (PEX) and EMF groups. EMF rats were exposed to a 900-MHz EMF in an EMF-application cage, while the PEX rats were placed in the same cage without being exposed to EMF. No procedure was performed in CON. EMF was applied for 1 h/day, every day for 25 days. Following the 900-MHz EMF and pseudo-exposed applications, behavioral tests were performed for seven days. Then, all animals were euthanized and their brains were removed. Following histological tissue procedures, sections were taken from tissues and stained with toluidine blue. The optical fractionation technique was performed to estimate the pyramidal neuron numbers in the CA1, CA2-3 and hilus regions of the hippocampus and granule neuron numbers in the dentate gyrus region. Our findings indicated that the number of pyramidal and granule neurons in the hippocampus of the EMF group was statistically higher than PEX. Furthermore, the histopathological results showed that the cytoplasm of pyramidal (in the hilus, CA1, CA2 and CA3 region) and granular (in the dentate gyrus region) cells at the hippocampus were disrupted, as evident by intensive staining around cytoplasm and some artifacts were detected in the EMF group. In addition, statistical comparisons of the mean body weights and brain weights of the study groups revealed no significant differences. There was no statistically significant difference between the PEX and EMF groups in terms of temperature (p > 0.05) or humidity (p > 0.05) in the cages. In conclusion, higher numbers of both pyramidal and granule neurons were found in the male rat hippocampus after continuous 900-MHz EMF treatment.

The effects of a continuous 1-h a day 900-MHz electromagnetic field applied throughout early and mid-adolescence on hippocampus morphology and learning behavior in late adolescent male rats

The purpose of this study was to investigate hippocampus morphology and changes in learning behavior in male rats in late adolescence exposed to the effect of a continuous 1-h a day 900-megahertz (MHz) electromagnetic field (EMF). Twenty-four male Sprague Dawley rats aged 3-weeks were divided equally into control, sham and EMF groups. EMF group rats were exposed to a 900-MHz EMF inside an EMF cage, while the sham group rats were placed in the same cage but were not exposed to such an effect. No procedure was performed on the control group. Following 25-day application of EMF, passive avoidance, 8-arm radial maze and Y-maze tests were applied to determine rats' learning and memory performances. Open field and rotarod tests were applied to assess locomotor activity. At the end of the tests, the animals' brains were removed. Sections were taken and stained with toluidine blue. The regions of the hippocampus were subjected to histopathological evaluation. At histopathological examination, impairments of pyramidal and granular cell structures were observed in the EMF group hippocampus. No significant change was observed in learning, memory or locomotor behavior in any group. In conclusion, 900-MHz EMF applied in early and mid-adolescence causes no changes in learning, memory or locomotor behavior.

Chemical Exposures in the Workplace

Occupational health nurses need to be aware of the current science on breast cancer risks in the workplace because they are risk communicators for employees and their families. Occupational health nurses can serve as advocates for necessary research ultimately leading to risk reduction and prevention strategies in the workplace. Current research suggests exposure to organic solvents, metals, acid mists, sterilizing agents (ethylene oxide), some pesticides, light at night (shift work), and tobacco smoke increases breast cancer risk among women in occupational settings. Animal cancer bioassays conducted by the National Toxicology Program indicate more than 40 chemicals can induce mammary tumors, and most of these are still in production. A variety of occupations worldwide, including health care providers and metal, textile, dye, rubber, and plastic manufacturing workers, have been identified as having some evidence of higher breast cancer risk. Although some chemical exposures are suspected to affect breast cancer risk, estimates of or actual exposures to these chemicals in the workplace often have not been determined. Research needed to better identify breast cancer risks in occupational settings includes monitoring breast cancer incidence in occupations with exposures to suspected carcinogens, characterizing chemical exposures by job type and task, determining whether potential gender differences affect chemical exposures, and using molecular approaches to identify gene-environment interactions.

Occupational exposure and risk of breast cancer

Breast cancer is a multifactorial disease and the most commonly diagnosed cancer in women. Traditional risk factors for breast cancer include reproductive status, genetic mutations, family history and lifestyle. However, increasing evidence has identified an association between breast cancer and occupational factors, including environmental stimuli. Epidemiological and experimental studies demonstrated that ionizing and non-ionizing radiation exposure, night-shift work, pesticides, polycyclic aromatic hydrocarbons and metals are defined environmental factors for breast cancer, particularly at young ages. However, the mechanisms by which occupational factors can promote breast cancer initiation and progression remains to be elucidated. Furthermore, the evaluation of occupational factors for breast cancer, particularly in the workplace, also remains to be explained. The present review summarizes the occupational risk factors and the associated mechanisms involved in breast cancer development, in order to highlight new environmental exposures that could be correlated to breast cancer and to provide new insights for breast cancer prevention in the occupational settings. Furthermore, this review suggests that there is a requirement to include, through multidisciplinary approaches, different occupational exposure risks among those associated with breast cancer development. Finally, the design of new epigenetic biomarkers may be useful to identify the workers that are more susceptible to develop breast cancer.

[Night work, shift work: Breast cancer risk factor?]

OBJECTIVE

The aim of this review was to determine the link between night/shift work and breast cancer.

METHODS

The analysed articles were taken from the PUBMED database between 1996 and 2015. The keywords used were "breast cancer risk", "night work" and "shift work". In total, 25 articles were selected.

RESULTS

Night/shift workers are more at risk to develop a breast cancer (relative risk (RR) between 1.09; 95% CI: 1.02-1.20 and 1.48; 95% CI: 1.36-1.61 in the meta-analyses). However, this risk is not found by some cohort and case-control studies. The circadian rhythm disruption, responsible of disorderliness of melatonin secretion, could be one of the mechanisms involved in the increase of that risk. Hormonal status of night/shift workers, their geographic origin, their lifestyle and their vitamin D deficiency appear as other mechanisms potentially responsible for increased risk of cancer in this professional population. Moreover, a dose-effect connection may exist, with an increase of the risk with the number of years of night/shift work.

CONCLUSION

Night/shift work is associated with a moderate increased risk of breast cancer, especially among women who worked over 20 years. Recommendations concerning the breast monitoring in this population could be diffused. The benefit of melatonin supplementation remains to be assessed.

Electromagnetic fields, oxidative stress, and neurodegeneration

Electromagnetic fields (EMFs) originating both from both natural and manmade sources permeate our environment. As people are continuously exposed to EMFs in everyday life, it is a matter of great debate whether they can be harmful to human health. On the basis of two decades of epidemiological studies, an increased risk for childhood leukemia associated with Extremely Low Frequency fields has been consistently assessed, inducing the International Agency for Research on Cancer to insert them in the 2B section of carcinogens in 2001. EMFs interaction with biological systems may cause oxidative stress under certain circumstances. Since free radicals are essential for brain physiological processes and pathological degeneration, research focusing on the possible influence of the EMFs-driven oxidative stress is still in progress, especially in the light of recent studies suggesting that EMFs may contribute to the etiology of neurodegenerative disorders. This review synthesizes the emerging evidences about this topic, highlighting the wide data uncertainty that still characterizes the EMFs effect on oxidative stress modulation, as both pro-oxidant and neuroprotective effects have been documented. Care should be taken to avoid methodological limitations and to determine the patho-physiological relevance of any alteration found in EMFs-exposed biological system.

Risk factors for breast cancer, including occupational exposures

The knowledge on the etiology of breast cancer has advanced substantially in recent years, and several etiological factors are now firmly established. However, very few new discoveries have been made in relation to occupational risk factors. The International Agency for Research on Cancer has evaluated over 900 different exposures or agents to-date to determine whether they are carcinogenic to humans. These evaluations are published as a series of Monographs (www.iarc.fr). For breast cancer the following substances have been classified as "carcinogenic to humans" (Group 1): alcoholic beverages, exposure to diethylstilbestrol, estrogen-progestogen contraceptives, estrogen-progestogen hormone replacement therapy and exposure to X-radiation and gamma-radiation (in special populations such as atomic bomb survivors, medical patients, and in-utero exposure). Ethylene oxide is also classified as a Group 1 carcinogen, although the evidence for carcinogenicity in epidemiologic studies, and specifically for the human breast, is limited. The classification "probably carcinogenic to humans" (Group 2A) includes estrogen hormone replacement therapy, tobacco smoking, and shift work involving circadian disruption, including work as a flight attendant. If the association between shift work and breast cancer, the most common female cancer, is confirmed, shift work could become the leading cause of occupational cancer in women.

Histopathological and ultrastructural studies on the effects of electromagnetic fields on the liver of preincubated white Leghorn chicken embryo

There are several reports indicating a linkage between exposures to 50-60 Hz electromagnetic fields and abnormalities in the early stages of embryonic development of chicken embryos. The present study was designed to demonstrate whether electromagnetic fields could be an environmental factor invoking histopathological and ultra-structural changes in livers of preincubated chicken embryos exposed to EMFs. Following other researchers and our previous results from different groups of Developmental Biology at the Animal Sciences, Faculty of Biological Sciences, Shahid-Beheshti University, effects of most effective intensities (1.33, 2.66, 5.52, and 7.32 mT) of electromagnetic fields (EMFs, 50 Hz ) on livers of pre-incubated white leghorn chicken embryos were investigated . 150 healthy, fresh, and fertilized eggs (55-65 gr) were divided into 6 groups of experimental(1-4, n = 30), control (n = 60), and sham (n = 50). Experimental eggs (inside coil) were exposed to 4 different intensities (1.33, 2.66, 5.52, and 7.32 mT). Sham groups were located inside same coil, with no exposure, for 24 h before incubation. Control, sham, and experimental groups (1-4) were then incubated in an incubator (38 +/- 0.5 degrees C, 60% humidity) for 17 days. At the end of this period, livers of experimental, sham, and control groups were processed for light and transmission electrom microscopes (TEM and SEM) studies. So, livers of 17-day old chicken embryos were removed by C-sections, fixed in formalin 10%, stained with H&E and reticulin, and studied under light microscope. Others were prepared for electron microscopes (TEM and SEM) investigations. Morphological observations indicated exencephalic embryos, embryos with asymmetrical faces, crossed beak, shorter upper beak, deformed hind limbs, gastroschesis, anophthalmia, and microphthalmia. H&E and reticulin stainings, TEMS, and SEMs studies indicated EMFs would create hepato-cytes with fibrotic bands, severe steatohepatitis, vacuolizations, swollen and extremely electron-dense mitochondria, reduced invisible cristae, crystalized mitochondria with degenerated cristae, myelin-like figures, macrophages engulfing adjacent cells, dentated nuclei, nuclei with irregular envelopes, degenerated hepatocytes, abnormal lipid accumulations, lipid droplets pushing hepatocytes' nuclei to the corner of the cells, abundant cellular infiltrations cellular infiltrations inside sinusoid and around central veins, disrupted reticulin plexus, and release of chromatin into cytosol,, with partially regular water layers. An elevated oxyradical generation and, subsequently, cell membrane disruptions were the reasons for electromagnetic fields inducing cell damages.

Racial differences in follow-up of abnormal mammography findings among economically disadvantaged women

BACKGROUND

In the United States, and particularly in South Carolina, African-American women suffer disproportionately higher mortality rates from breast cancer than European-American women. The timeliness of patient adherence to the follow-up of mammographic abnormalities may influence prognosis and survival. The objective of the current investigation was to examine racial differences in the completion and completion time of a diagnostic workup after the finding of a suspicious breast abnormality.

METHODS

Study participants of the Best Chance Network, a statewide service program that provides free mammography screening to economically disadvantaged and medically underserved women, were included in the study. Racial differences in tumor characteristics and adherence to recommended workup were tested using chi-square tests and t tests. Logistic and Cox regression modeling was used to assess the relation between workup completion and other factors among African-American women and European-American women.

RESULTS

Completion of the workup was associated with the number of previous procedures and income, and no significant differences were noted by race. The amount of time to completion of the workup was influenced by previous procedures, income, and race. After accounting for completion time, African-American women were 12% less likely than European-American women to complete the recommended workup (hazard ratio, 0.88; P=.01).

CONCLUSIONS

The results from this study established a racial disparity in the time to completion of a diagnostic workup among Best Chance Network participants. These findings highlight the importance of understanding the factors associated with delays in and adherence to completing the recommended workup when breast abnormalities are detected in mammograms.

A biomonitoring study of genotoxic risk to workers of transformers and distribution line stations

A cytogenetic monitoring study was carried out on a group of workers from transformer and distribution line stations in the Bursa province of Turkey, to investigate the genotoxic risk of occupational exposure to extremely low frequency electric (ELF) and magnetic fields (EMF). Cytogenetic analysis, namely chromosomal aberrations (CAs) and micronucleus (MN) tests were performed on a strictly selected group of 55 workers and compared to 17 controls. CA and MN frequencies in electrical workers appeared significantly higher than in controls (p < 0.001, 0.05, respectively). The frequency of CA in exposed groups were significantly enhanced with the years of exposure (p < 0.01). The effect of smoking on the level of CA and MN was not significant in the control and exposure groups. The results of this study demonstrated that a significant induction of cytogenetic damage in peripheral lymphocytes of workers engaged to occupational exposure to ELMF in electric transformer and distribution stations.

Chronic prenatal exposure to the 900 megahertz electromagnetic field induces pyramidal cell loss in the hippocampus of newborn rats

Widespread use of mobile phones which are a major source of electromagnetic fields might affect living organisms. However, there has been no investigation concerning prenatal exposure to electromagnetic fields or their roles in the development of the pyramidal cells of the cornu ammonis in postnatal life. Two groups of pregnant rats, a control group and an experimental group, that were exposed to an electromagnetic field were used. For obtaining electromagnetic field offspring, the pregnant rats were exposed to 900 megahertz electromagnetic fields during the 1–19th gestation days. There were no actions performed on the control group during the same period. The offspring rats were spontaneously delivered—control group ( n = 6) and electromagnetic field group ( n = 6). Offspring were sacrificed for stereological analyses at the end of the 4th week. Pyramidal cell number in rat cornu ammonis was estimated using the optical fractionator technique. It was found that 900 megahertz of electromagnetic field significantly reduced the total pyramidal cell number in the cornu ammonis of the electromagnetic field group ( P < 0.001). Therefore, although its exact mechanism is not clear, it is suggested that pyramidal cell loss in the cornu ammonis could be due to the 900 megahertz electromagnetic field exposure in the prenatal period.

Cell Activating Capacity of 50 Hz Magnetic Fields to Release Reactive Oxygen Intermediates in Human Umbilical Cord Blood-derived Monocytes and in Mono Mac 6 Cells

The aim of this study was to investigate the mechanism of cell activation induced by extremely low frequency magnetic fields (ELF-MF) (50 Hz) in human cells. We examined the production of free radicals in human umbilical cord blood-derived monocytes and in human Mono Mac 6 cells. The release of superoxide radical anions was analyzed using nitroblue tetrazolium chloride and the total of reactive oxygen species (ROS) was detected using dihydrorhodamine 123. Our results show a significant increase of superoxide radical anion production up-to 1.4 fold as well as an increase in ROS release up-to 1.2 fold upon exposure of monocytes to 1 mT ELF-MF (45 min). Mono Mac 6 cells exhibit higher superoxide radical anion and ROS production up-to 1.4 and 1.5 fold, respectively. These results indicate that Mono Mac 6 cells are more sensitive to ELF-MF than monocytes. Using diphenyleneiodonium chloride (DPI) a specific inhibitor for the NADPH oxidase, the MF-effect was not inhibited in Mono Mac 6 cells. Therefore, we suggest that ELF-MF exposure induces the activation of NADH oxidase in these cells. However, the MF-effect was inhibited by DPI in monocytes, indicating the activation of the NADPH oxidase after exposure to ELF-MF.

Review of the etiology of breast cancer with special attention to organochlorines as potential endocrine disruptors

Breast cancer is the most frequently diagnosed cancer among Canadian women, accounting for about 30% of all new cancer cases each year. Although the incidence of breast cancer has increased over the past 50 years, the cause of this rise is unknown. Risk factors for breast cancer may be classified into four broad categories: (1) genetic/familial, (2) reproductive/hormonal, (3) lifestyle, and (4) environmental. Established risk factors for breast cancer include older age, later age at first full-term pregnancy, no full-term pregnancies, postmenopausal obesity, and genetic factors. However, these known risk factors cannot account for the majority of cases. In the early 1990s, it was suggested that exposure to some environmental chemicals such as organochlorine compounds may play a causal role in the etiology of breast cancer through estrogen-related pathways. The relationship between organochlorines and breast cancer risk has been studied extensively in the past decade and more, and at this point there is no clear evidence to support a causal role of most organochlorine pesticides in the etiology of human breast cancer, but more evidence is needed to assess risk associated with polychlorinated biphenyls (PCBs). Future studies need to consider the combined effects of exposures, concentrate on vulnerable groups such as those with higher levels of exposure, only consider exposures occurring during the most etiologically relevant time periods, and more thoroughly consider gene-environment interactions.

Occupation and breast cancer risk among Shanghai women in a population-based cohort study

INTRODUCTION

A total of 74,942 female subjects were recruited in a population-based cohort study in Shanghai, China between 1997 and 2000. We examined the relationship between occupation and breast cancer risk.

METHODS

Cases were 586 women previously diagnosed with breast cancer at baseline and 438 women newly diagnosed with breast cancer during follow-up through December 2004. Eight controls were randomly selected for each case from cancer-free cohort members and frequency-matched to the cases by year of birth and age at diagnosis. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) of breast cancer risk associated with occupations, adjusting for established breast cancer risk factors.

RESULTS

In the prevalent breast cancer data analysis, increased risks of breast cancer were associated with technicians in engineering/agriculture/forestry (OR = 1.6, CI: 1.0-2.4), teaching personnel (OR = 1.5, CI:1.1-2.0), tailoring/sewing workers (OR = 1.6, CI:1.0-2.7), and examiners/measurers/testers (OR = 1.5, CI:1.1-2.1) among those who started the jobs at least 20 years ago. Among incident breast cancer cases, significantly increased risks were associated with medical/health care workers (OR = 1.4, CI:1.0-2.0), administrative clerical workers (OR = 1.5, CI:1.0-2.4), postal/telecommunication workers (OR = 2.2, CI:1.0-5.5), and odd-job workers (OR = 1.7, CI:1.1-2.8) among those who started the jobs at least 20 years ago. The excess risks were found in both prevalent and incident cases for postal/telecommunication workers and purchasing/marketing personnel, although ORs reached only marginal significance.

CONCLUSIONS

This study suggests that white-collar professionals and several production occupations may be associated with an increased risk of breast cancer.

Use of electric blankets and association with prevalence of endometrial cancer

The objective of this study was to assess the relationship between electric blanket use and prevalence of endometrial cancer for women. Information relating to women enrolled in the Women's Health Initiative Observational Data Set (n=93 676) used to test the relationship factors associated with endometrial cancer included older age at screening, younger age at last menstrual period, region of domicile (highest prevalence in the South), less than a high school education, lower income, body mass index >25 kg/m, low parity, unopposed use of estrogen, never use of estrogen plus progesterone, past alcohol use, higher percentage of daily calories from fat and any electric blanket use. Following a univariate identification of factors significantly related to endometrial cancer, stepwise logistic regression analysis was performed for those factors with P values of less than 0.001 in the univariate analysis. Using electric blankets was associated with a 15% higher prevalence of endometrial cancer than never having used electric blankets (odds ratio=1.15, 95% confidence interval: 1.03-1.27). After controlling for variables significantly associated with endometrial cancer, use of electric blankets for 20 years or more was associated with 36% higher prevalence of endometrial cancer (odds ratio=1.36, 95% confidence interval: 1.16-1.59). Although we were unable to determine the duration of electric blanket use before diagnosis of endometrial cancer, we found that women using electric blankets for 20 years or more had a significantly higher prevalence.

Residential magnetic fields, medication use, and the risk of breast cancer

BACKGROUND

Exposure to 60-Hz magnetic fields may increase breast cancer risk by suppressing the nocturnal production of melatonin. The use of medications associated with reduced melatonin levels could modify this relationship.

METHODS

We recontacted participants in a population-based case-control study of residential magnetic field exposure and breast cancer risk and interviewed them regarding medication use during the 10 years before diagnosis. Cases were diagnosed between November 1992 and March 1995, and magnetic field levels were measured in the home at diagnosis. We obtained medication use information by telephone interview from 558 cases and 588 controls.

RESULTS

Breast cancer risk was not associated with exposure to residential magnetic fields, regardless of medication use.

CONCLUSIONS

These results support previous findings that magnetic field exposure does not increase breast cancer risk.

Lack of promotion of mammary, lung and skin tumorigenesis by 20 kHz triangular magnetic fields

In order to evaluate possible tumorigenic effects of a 20 kHz intermediate frequency triangular magnetic field (IF), a frequency emitted from TV and PC monitors at 6.25 microT rms, which is the regulated exposure limit of magnetic field for the public in Korea, mammary tumors were produced in female Sprague-Dawley rats by oral intubation of dimethylbenz(a)anthracene (DMBA), lung tumors in ICR mice by scapular region injection of benzo(a)pyrene (BP), and skin tumors in female ICR mice by topical application of DMBA and tetradecanoylphorbol ester (TPA). IF was applied 8 h/day for 14 weeks beginning the day after DMBA treatment for mammary tumor experiment, for 6 weeks after weaning for lung tumor, and for 20 weeks beginning 1 week after DMBA application for skin tumor experiment. For skin tumors, TPA was applied once a week for 19 weeks. Results showed no significant differences in tumor incidence, mean tumor number and volume, and histological patterns between IF magnetic-field exposed and sham control rats in the above three tumor models. Therefore, we conclude that within the limitation or number of animals and the experimental conditions, 20 kHz IF triangular magnetic field exposure of 6.25 microT does not appear to be a strong co-tumorigenic agent in the chosen murine mammary, lung and skin models.

Risk of breast cancer after night- and shift work: current evidence and ongoing studies in Denmark

Breast cancer is the most frequent cancer among women, and the number is increasing worldwide. This tumour is strongly associated with Western lifestyle, but the specific risk factors behind this observation are not well known. Exposure to light-at-night, including disturbance of the circadian rhythm, possibly mediated via the melatonin synthesis and clock genes, has been suggested as a contributing cause of breast cancer. Since shift- and night-time work is prevalent and increasing in modern societies, this exposure may be of public health concern, and contribute to the continuing elevation in breast cancer risk. Until now only few epidemiological studies have evaluated breast cancer risk after shift and night work. Although these studies are all suffering from methodological problems, especially concerning assessment of light exposure, results have consistently shown an increase in risk associated with night and shift work. Good opportunities for epidemiological cancer research exist in Denmark, and several studies on different aspects of breast cancer, work schedules, light exposure and melatonin levels are ongoing in order to further examine different aspects of this issue.

Exposure to light-at-night increases the growth of DMBA-induced mammary adenocarcinomas in rats

In order to assess whether light exposure at night influences the growth of mammary tumors, as well as the role of melatonin in this process, female rats bearing DMBA-induced mammary adenocarcinomas were exposed to different lighting environments. Animals exposed to light-at-night, especially those under a constant dim light during the darkness phase, showed: (a) significantly higher rates of tumor growth as well as lower survival than controls, (b) higher concentration of serum estradiol, and (c) lower nocturnal excretion of 6-sulfatoxymelatonin, without there being differences between nocturnal and diurnal levels. These results suggest that circadian and endocrine disruption induced by light pollution, could induce the growth of mammary tumors.

Power Frequency Magnetic Fields Increase Cell Proliferation in the Mammary Gland of Female Fischer 344 Rats but Not Various Other Rat Strains or Substrains

Epidemiological data have raised concerns about the relationship between exposure to power frequency magnetic fields (MFs) and breast cancer. We have shown previously that 50-Hz MFs at microtesla flux densities enhance mammary gland tumor development and growth in the 7,12-dimethylbenz[a]anthracene (DMBA) model of breast cancer in female Sprague-Dawley (SD) rats. We also demonstrated that MF exposure results in an enhanced proliferative activity of the mammary epithelium of SD rats, which is a likely explanation for the cocarcinogenic or tumor-promoting effects of MF exposure in the DMBA model. Comparison of different SD substrains indicated that the genetic background plays a pivotal role in these effects of MF exposure. This prompted us to compare the effects of MF exposure (100 microT, 2 weeks) on cell proliferation in the mammary gland in eight different strains and substrains of outbred and inbred rats. Proliferation of epithelial cells in the mammary tissue and adjacent skin was examined by labeling proliferating cells with bromodeoxyuridine (BrdU). In addition to the MF-sensitive SD substrain (SD1) previously used in our experiments, Fischer 344 rats were the only strain in which MF exposure significantly enhanced BrdU labeling in the mammary epithelium, indicating a marked increase in cell proliferation. The MF-induced increase in BrdU labeling in Fischer 344 rats was similar to that seen after DMBA application. Furthermore, whole mount analysis of mammary tissue from Fischer 344 rats demonstrated that MF exposure increased the number of terminal end buds, i.e. the site of origin of mammary carcinomas. By comparison with MF-insensitive inbred rat strains, Fischer 344 rats may serve to evaluate the genetic factors underlying sensitivity to cocarcinogenic or tumor-promoting effects of MF exposure.

Biomedical evidence of influence of geopathic zones on the human body: scientifically traceable effects and ways of harmonization

BACKGROUND

Empiric knowledge of the existence of geopathic zones ('water veins' etc) is probably as old as humankind. It has often been tried to experimentally detect direct influences on the body. However, so far, there have been no publications in accepted biomedical journals. The target of this study was to verify influences of 2 different zones above ground on the human body and to test a device for which pilot studies have indicated a potential harmonizing effect in this context.

MATERIALS AND METHODS

Using a randomized, non-clinical, double-blinded trial design, 52 persons were tested with a gas discharge visualization (GDV) system whilst staying on 2 zones with or without the Geowave device (Geowave-Research, Salzburg, Austria). The 2 zones investigated had been dowsed by experienced professional dowsers and labeled with black dots in a non-persuasive manner, thereby blindly representing areas of geopathy or more neutral zones. The main analytical parameter was the GDV glow image area (area of glow). Complementary calculated parameters were spatial fractality, corona projections and corona diagrams.

RESULTS

In the geopathic zone, the detected areas of glow were statistically significantly smaller than in the more neutral zone. With the Geowave blindly mounted in an adjacent room of the above story, a marked increase of the glow image area was found in both zones. The corona projections showed well-recognizable points of body energy deficits in the geopathic zone, mostly associated with the lymphatic system, the cardiovascular system and the pineal gland, which were -- to a distinctly lesser degree -- also present in the more neutral zone. The device tested yielded compensation or harmonization in both zones in most of the test persons.

CONCLUSION

The significant differences in the physical area of glow parameter, which were also noticed for the complementary parameters analyzed, lead to the conclusion that the 2 different zones within the same room (geopathic vs. more neutral zone) exerted different influences on the human body, which may have caused a geopathic stress phenomenon. As a result, individually different retardation of the immune system and other organs may occur. The device tested in both zones showed harmonizing effects, which may help to compensate some influences of geopathy and possibility also superimposed stressors derived from certain other sources, such as technical electromagnetic fields.

Extremely low frequency electromagnetic fields as effectors of cellular responses in vitro: Possible immune cell activation

There is presently an intense discussion if electromagnetic field (EMF) exposure has consequences for human health. This include exposure to structures and appliances that emit in the extremely low frequency (ELF) range of the electromagnetic spectrum, as well as emission coming from communication devices using the radiofrequency part of the spectrum. Biological effects of such exposures have been noted frequently, although the implication for specific health effects is not that clear. The basic interaction mechanism(s) between such fields and living matter is unknown. Numerous hypotheses have been suggested, although none is convincingly supported by experimental data. Various cellular components, processes, and systems can be affected by EMF exposure. Since it is unlikely that EMF can induce DNA damage directly, most studies have examined EMF effects on the cell membrane level, general and specific gene expression, and signal transduction pathways. In addition, a large number of studies have been performed regarding cell proliferation, cell cycle regulation, cell differentiation, metabolism, and various physiological characteristics of cells. Although 50/60 Hz EMF do not directly lead to genotoxic effects, it is possible that certain cellular processes altered by exposure to EMF indirectly affect the structure of DNA causing strand breaks and other chromosomal aberrations. The aim of this article is to present a hypothesis of a possible initial cellular event affected by exposure to ELF EMF, an event which is compatible with the multitude of effects observed after exposure. Based on an extensive literature review, we suggest that ELF EMF exposure is able to perform such activation by means of increasing levels of free radicals. Such a general activation is compatible with the diverse nature of observed effects. Free radicals are intermediates in natural processes like mitochondrial metabolism and are also a key feature of phagocytosis. Free radical release is inducible by ionizing radiation or phorbol ester treatment, both leading to genomic instability. EMF might be a stimulus to induce an "activated state" of the cell such as phagocytosis, which then enhances the release of free radicals, in turn leading to genotoxic events. We envisage that EMF exposure can cause both acute and chronic effects that are mediated by increased free radical levels: (1) Direct activation of, for example macrophages (or other cells) by short-term exposure to EMF leads to phagocytosis (or other cell specific responses) and consequently, free radical production. This pathway may be utilized to positively influence certain aspects of the immune response, and could be useful for specific therapeutic applications. (2) EMF-induced macrophage (cell) activation includes direct stimulation of free radical production. (3) An increase in the lifetime of free radicals by EMF leads to persistently elevated free radical concentrations. In general, reactions in which radicals are involved become more frequent, increasing the possibility of DNA damage. (4) Long-term EMF exposure leads to a chronically increased level of free radicals, subsequently causing an inhibition of the effects of the pineal gland hormone melatonin. Taken together, these EMF induced reactions could lead to a higher incidence of DNA damage and therefore, to an increased risk of tumour development. While the effects on melatonin and the extension of the lifetime of radicals can explain the link between EMF exposure and the incidence of for example leukaemia, the two additional mechanisms described here specifically for mouse macrophages, can explain the possible correlation between immune cell system stimulation and EMF exposure.

The Effect of Environment on Breast Cancer Risk

Environmental factors are believed to explain a large proportion of breast cancer incidence. Known risk factors for breast cancer, which are related to the reproductive life of women, and other factors, such as inheritance and socioeconomic status, explain only about half of the breast cancer cases in the US. Ionizing radiation is a well established environmental risk factor for breast cancer. Chemicals that induce mammary cancer in rodents have served as leads for studies in humans, but occupational and environmental exposure to these chemicals have for the most part lacked association with breast cancer risk. However, there is recent evidence in rats that cadmium at very low doses acts as an estrogen mimic, indicating a need to investigate the effects of metals on breast cancer risk. Studies suggest that circadian rhythm disruption is linked with breast cancer, but too few studies have been done to be conclusive. Over the years, cigarette smoking as a risk factor for breast cancer has remained controversial. However, recent research has found passive smoke exposure to be associated with increased breast cancer risk, which is hypothesized to be accounted for on the basis of an antiestrogenic effect of smoking. Solar radiation has been noted to be associated with reduced breast cancer, supporting the hypothesis that vitamin D plays a protective role in reducing this risk. Although, most of the environmental factors discussed in this review have not been convincingly found to influence breast cancer risk, research suggests that environmental exposure in combination with genetic pre-disposition, age at exposure, and hormonal milieu have a cumulative effect on breast cancer risk.

Significant Differences in the Effects of Magnetic Field Exposure on 7,12-Dimethylbenz(a)anthracene-Induced Mammary Carcinogenesis in Two Substrains of Sprague-Dawley Rats

We have shown previously (S. Thun-Battersby et al., Cancer Res., 59: 3627-3633, 1999) that power-line frequency (50-Hz) magnetic fields (MFs) at micro T-flux densities enhance mammary gland tumor development and growth in the 7,12-dimethylbenz(a)anthracene (DMBA) model of breast cancer in female Sprague-Dawley (SD) rats. We also demonstrated that MF exposure results in an enhanced proliferative activity of the mammary epithelium of SD rats (M. Fedrowitz et al., Cancer Res., 62: 1356-1363, 2002), which is a likely explanation for the cocarcinogenic or tumor-promoting effects of MF exposure in the DMBA model. However, in contrast with our data, in a similar study conducted by Battelle in the United States, no evidence for a cocarcinogenic or tumor-promoting effect of MF exposure was found in the DMBA model in SD rats (L. E. Anderson et al., Carcinogenesis, 20: 1615-1620, 1999). Probably the most important difference between our and the Battelle studies was the use of different substrains of SD rats; the United States rats were much more susceptible to DMBA than the rats used in our studies. This prompted us to compare different substrains of SD outbred rats in our laboratory in respect to MF effects on cell proliferation in the mammary gland, susceptibility to DMBA-induced mammary cancer, and MF effects on mammary tumor development and growth in the DMBA model. The SD substrain (termed "SD1") used in all of our previous studies was considered MF-sensitive and used for comparison with another substrain ("SD2") obtained from the same breeder. In contrast with SD1 rats, no enhanced cell proliferation was determined after MF exposure in SD2 rats. MF exposure significantly increased mammary tumor development and growth in SD1 but not SD2 rats. These data indicate that the genetic background plays a pivotal role in effects of MF exposure. Different strains or substrains of rats may serve to evaluate the genetic factors underlying sensitivity to cocarcinogenic or tumor-promoting effects of MF exposure.

Occupational exposures to extremely low frequency magnetic fields and postmenopausal breast cancer

BACKGROUND

The association between occupational exposure to extremely low frequency magnetic fields (ELF-MF) and risk of postmenopausal breast cancer was assessed in a case-control study.

METHODS

Breast cancer cases were compared to cancer controls. Interviewers elicited information on risk factors and on lifetime work history. Industrial hygienists assigned to each job average duration of exposure to ELF-MF at four levels of intensities ("none," <0.2 microT; "low," 0.2-<0.5microT; "medium," 0.5-<1microT; "high," > or =1-10microT). Unconditional logistic regression was used to estimate adjusted odds ratios (OR) and 95% confidence intervals (95% CI).

RESULTS

A total number of 608 cases and 667 controls participated. Adjusting for accepted breast cancer risk factors, we found an OR of 1.13 for lifetime occupational exposure to ELF-MF at medium or high intensities. Risks were larger for exposures before age 35 (OR = 1.40), and statistically significant for exposures before 35 among cases with progesterone receptor positive tumors (OR = 1.56, 95% CI=1.02-2.39).

CONCLUSIONS

There appears to be a small increased risk for breast cancer among postmenopausal women exposed occupationally to ELF-MF.

Micronucleus induction in cells co-exposed in vitro to 50 Hz magnetic field and benzene, 1,4-benzenediol (hydroquinone) or 1,2,4-benzenetriol☆

The generation, transmission (e.g. power lines, transformers, service wires, and electrical panels), and use (e.g. home appliances, such as electric blankets, shavers, and televisions) of electrical energy is associated with the production of weak electric and magnetic fields (EMF) which oscillate 50 (Europe) or 60 (USA) times per second (power-line frequency), falling in the extremely-low frequency (ELF) region of the electromagnetic spectrum. Epidemiological reports suggest a possible association between exposure to ELF-EMF and an increased risk of cancer (e.g. childhood acute leukaemia). Benzene is an established human leukomogen. This xenobiotic, which is unlikely to be the ultimate carcinogen, is metabolized in the liver to its primary metabolite phenol, which is hydroxylated to hydroquinone (1,4-benzenediol) and 1,2,4-benzenetriol. In this in vitro approach, to test the genotoxic and / or co-genotoxic potency of ELF-EMF, the cytokinesis block micronucleus (MN) method with Jurkat cells has been used. A 50 Hz magnetic field (MF) of 5 mT field strength was applied for different length of time (from 1 to 24 h), either alone or with benzene, 1,4-benzenediol, or 1,2,4-benzenetriol. Our preliminary results show that, after 24 h exposure, the frequency of micronucleated cells in MF-exposed cultures is 1.9 fold higher than in sham-exposed (control) cultures. Benzene exposure does not show any cytogenetic activity, whereas 1,4-benzenediol or 1,2,4-benzenetriol alone significantly affect the number of MN in Jurkat cells, as compared to untreated cultures. Moreover, co-exposure to ELF-MF does not seem to affect the frequency of micronuclei induced by benzene, 1,4-benzenediol, or 1,2,4-benzenetriol.

Head-only exposure to GSM 900-MHz electromagnetic fields does not alter rat’s memory in spatial and non-spatial tasks

Over the last decade, exposure to high frequency (2450 MHz) electromagnetic fields (EMFs) has been found to induce performance deficit in rodents in spatial memory tasks. As concern was expressed about potential biological effects of mobile communication microwaves, studies testing the effects of signals such as GSM were required. In a previous study, using head-only exposure to 900 MHz GSM EMF, we could not demonstrate any behavioural deficit in two simple learning tasks. The present study aimed at extending these results with more complex spatial learning tasks and a non-spatial task. In a first experiment, rats were trained in a radial-arm maze with a 10-s confinement between each visited arm. In a second experiment, a 15-min intra-trial delay was introduced after four visited arms. In a third experiment, non-spatial memory was tested in an object recognition task. In all experiments, performance of the head-only exposed rats (1 and 3.5 W/kg) was compared with that of sham and control rats. In the first experiment, a slightly improved performance was found after 3.5 W/kg exposure, a result that was not observed in the delay-task. In the third experiment, although some effects on exploratory activity were found, recognition memory was unaffected in exposed rats. Altogether, this set of experiments provides no evidence indicating that spatial and non-spatial memory can be affected by a 45-min head-only exposure to 900 MHz GSM EMF.

Electric Blanket Use and Breast Cancer on Long Island

BACKGROUND

Exposure to electromagnetic fields (EMF) has been hypothesized to increase the risk of breast cancer by inhibiting the normal nocturnal rise in melatonin levels.

METHODS

Information on electric blanket use was collected in a large, 2-stage, population-based, case-control investigation of breast cancer, The Long Island Breast Cancer Study Project (LIBCSP) and the EMF and Breast Cancer on Long Island Study (EBCLIS). The LIBCSP used a comprehensive questionnaire, including questions about electric appliance use, with responses available on 1354 cases diagnosed between mid-1996 and mid-1997 and 1426 control subjects. EBCLIS enrolled 576 cases and 585 control subjects who had participated in the LIBCSP and who had lived in their current homes for at least 15 years. EBCLIS participants were interviewed to obtain additional information on EMF exposures, including detailed questions on electric blanket use.

RESULTS

Analyses of both the EBCLIS and the LIBCSP groups showed no association with breast cancer for ever-use of electric blankets, current or former use, use directly on the body, or use throughout the night in either pre- or postmenopausal women (range of adjusted odds ratios for ever vs. never use: 0.9-1.2). Furthermore, there was no trend in risk with increased duration of use, frequency of use, or other indicators of more intense exposure to EMF. Electric blanket use was not associated with hormone receptor status of the tumor.

CONCLUSIONS

The results of this large investigation are consistent with those of most previous studies, and do not support the hypothesis that electric blanket use is associated with increased breast cancer risk.

Wire coding in the EMF and Breast Cancer on Long Island Study: relationship to magnetic fields

The Electromagnetic Fields and Breast Cancer on Long Island Study (EBCLIS) is a large population-based case-control study investigating possible associations between magnetic fields and breast cancer, and includes a comprehensive set of in-home measurements. We investigated the reproducibility of wire codes, their relation to 24-h measurements of residential magnetic fields, and potential influences, such as housing characteristics, in homes of the 1161 EBCLIS participants. Replicate wire coding was performed in homes originally categorized as having very high current configurations (VHCC) in the Wertheimer-Leeper (W-L) wire coding scheme, and a random sample of other homes (235 residences). Reproducibility was very high, with a kappa statistic of 0.83 (95% confidence interval (CI)=0.77-0.89) for the five-category W-L wire codes and 0.91 (95% CI=0.86-0.95) for the three-category Kaune-Savitz (K-S) codes. As levels of W-L and K-S wire codes increased, the mean and median 24-h levels of broadband and harmonic fields in the residences also increased, indicating an association between wire codes and magnetic fields measurements. Regions of Long Island with the highest percentage of homes built before 1950 had the highest percentage of higher current configuration homes, as well as the highest average 24-h broadband and harmonic measurements. Adjustment for age of the home and region did not affect the relation between wire codes and measured magnetic fields. Our results indicate that: (a). a high reproducibility in wire coding was achieved, (b). wire codes were correlated with magnetic fields, and (c). wire code levels were related to the age of the home. The high level of reproducibility suggests that, in our case-control analyses, there will be minimal bias due to misclassification of wire code categories. Results also suggest that wire codes are a proxy measure, to some degree, for current in-home magnetic field measurements in this study.

Immunomodulatory effects of L-carnitine and q10 in mouse spleen exposed to low-frequency high-intensity magnetic field

In the current study, we have investigated the bioeffects of repeated exposure to low-frequency (50 Hz) high-intensity (20 mT; 200 G) electromagnetic field (EMF) on some immune parameters in mice. The animals were exposed to EMF daily for 30 min three times per week for 2 weeks. We also studied the possible immunomodulatory effects of two anti-radical substances known to have non-specific immunostimulant effects namely, L-carnitine (200 mg/kg body weight i.p.) and Q10 (200 mg/kg body weight, p.o.). Both drugs were given 1 h prior to each EMF exposure. Immune endpoints included total body weight, spleen/body weight ratio, splenocytes viability, total and differential white blood cell (WBCs; lymphocytes, monocytes, neutrophils) counts, as well as the lymphocyte proliferation induced by the mitogens; phytohaemagglutinin (PHA), concanavalin-A (Con-A) and lipoploysaccharide (LPS). Magnetic field decreased splenocyte viability, WBCs count, as well as mitogens-induced lymphocyte proliferation. L-carnitine, but not Q10 could ameliorate the adverse effects of EMF on the vast majority of the immune parameters tested, suggesting a possible immunoprotective role of L-carnitine under the current experimental conditions.

Environmental risk factors for breast cancer among African-American women

There are few unequivocably established environmental carcinogens for breast cancer in women. Nevertheless, environmental factors are believed to explain much of the international variation in breast cancer risk and possibly differences among racial/ethnic groups. Along with lifestyle, some adverse exposures may be higher in minority racial/ethnic groups and in underserved populations that experience higher ambient contamination. Associations have been found between environmental agents and breast cancer in subgroups of women who can be identified by common susceptibility traits as well as by timing of exposures at certain milestones of reproductive life. Susceptibility can be defined by social, environmental, and genetic modalities-factors that may predominate in certain racial/ethnic groups but that also transcend racial/ethnic boundaries. For example, genes involved in transcription and estrogen metabolism have rapid variants that are more prevalent among African-Americans, yet risk accompanying metabolic changes from these genes will prevail in all racial/ethnic groups. Lack of reliable exposure assessment remains a principal obstacle to elucidating the role of environmental exposures in breast cancer. Resources must be identified and consolidated that will enable scientists to improve exposure assessment and to assemble studies of sufficient size to address questions regarding exposure, susceptibility, and vulnerability factors in breast cancer. Breast cancer studies should be expanded to examine combinations of chemicals as well as competing or complementary exposures such as endogenous hormones, dietary intake, and behavioral factors.

Occupations and breast cancer risk among Chinese women in urban Shanghai

BACKGROUND

Although, an elevated risk of breast cancer has been suggested for a number of occupations, many earlier studies were limited by selection biases, the incomplete assessment of job histories, and the inability to control for confounding.

METHODS

We examined the relationship between occupational history and breast cancer risk using data from a population-based case-control study of 1,458 cases and 1,556 age-matched controls (90% response rate) conducted in Shanghai, China. Unconditional logistic regression models were used to derive odds ratios (ORs) and 95% confidence intervals (95% CIs) of breast cancer risk associated with occupations and duration of employment adjusting for non-occupational risk factors.

RESULTS

The following occupations were found to be associated with an increased risk of breast cancer: laboratory technicians (OR 9.94, 95% CI 1.20-82.37), telephone and telegraph operators (OR 4.63, 95% CI 1.85-11.59), leather and fur processors (OR 3.25, 95% CI 1.11-9.53), and glass-manufacturing workers (OR 2.08, 95% CI 1.14-3.82). A dose-response pattern for years of employment was observed for leather and fur processors (P = 0.02) and glass-manufacturing workers (P = 0.01). Stratified analyses also revealed dose-response relationships between the risk of breast cancer and years of employment as inspector and product analysts among pre-menopausal women (P = 0.02), and as farmers among post-menopausal women (P = 0.04).

CONCLUSIONS

This study found that several occupations are associated with an increased risk of breast cancer among women. Studies examining various occupational exposures in these high-risk occupations are warranted to identify carcinogens that may play a role in the increased breast cancer risk.

The DC electrical-field-induced Ca2+ response and growth stimulation of multicellular tumor spheroids are mediated by ATP release and purinergic receptor stimulation

It has been demonstrated that adenosine 5′-triphosphate (ATP) is actively secreted by cells, thereby eliciting Ca2+-dependent signal transduction cascades in an autocrine and paracrine manner. In the present study the effects of direct current (DC) electrical fields on ATP release, the intracellular Ca2+ concentration [Ca2+]i and growth of multicellular prostate tumor spheroids were investigated. Treatment of multicellular tumor spheroids by a single DC electrical field pulse with a field strength of 750 Vm-1 for 60 seconds resulted in a transient Ca2+ response, activation of c-Fos and growth stimulation. The initial [Ca2+]i signal was elicited at the anode-facing side of the spheroid and spread with a velocity of approximately 12 μm per second across the spheroid surface. The electrical-field-evoked Ca2+ response as well as c-Fos activation and growth stimulation of tumor spheroids were inhibited by pretreatment with the anion channel blockers NPPB, niflumic acid and tamoxifen. Furthermore, the Ca2+ response elicited by electrical field treatment was abolished following purinergic receptor desensitivation by repetitive treatment of tumor spheroids with ATP and pretreatment with the purinergic receptor antagonist suramin as well as with apyrase. Electrical field treatment of tumor spheroids resulted in release of ATP into the supernatant as evaluated by luciferin/luciferase bioluminescence. ATP release was efficiently inhibited in the presence of anion channel blockers. Our data suggest that electrical field treatment of multicellular tumor spheroids results in ATP release, which concomitantly activates purinergic receptors, elicits a Ca2+ wave spreading through the tumor spheroid tissue and stimulates tumor growth.

Residential magnetic fields and the risk of breast cancer

Chronic exposure to 60-Hz magnetic fields may increase the risk of breast cancer by suppressing the normal nocturnal production of melatonin. This population-based case-control study investigated whether such exposure is associated with an increased risk of breast cancer in women aged 20-74 years from the greater Seattle, Washington, area. Cases were diagnosed between November 1992 and March 1995 (n = 813); controls were identified by random digit dialing and were frequency matched by 5-year age groups (n = 793). Exposure was estimated using magnetic field measurements in the home at diagnosis, wiring configuration of all homes occupied in the 10 years prior to diagnosis, and self-reported measures of at-home electric appliance use. Odds ratios and 95% confidence intervals were estimated using conditional logistic regression with adjustment for other potential risk factors. Risk did not increase with measured nighttime bedroom magnetic field level, wiring configuration of the home at diagnosis, weighted summary wire codes of all homes occupied 5 and 10 years prior to diagnosis, or reported use of common household appliances, including bed-warming devices. These data do not support the hypothesis that exposure to residential magnetic fields is associated with an increased risk of developing breast cancer.

Does head-only exposure to GSM-900 electromagnetic fields affect the performance of rats in spatial learning tasks?

The rapid expansion of mobile communication has generated intense interest, but has also fuelled ongoing concerns. In both humans and animals, radiofrequency radiations are suspected to affect cognitive functions. More specifically, several studies performed in rodents have suggested that spatial learning can be impaired by electromagnetic field exposure. However, none of these previous studies have simulated the common conditions of GSM mobile phones use. This study is the first using a head-only exposure system emitting a 900-MHz GSM electromagnetic field (pulsed at 217 Hz). The two behavioural tasks that were evaluated here have been used previously to demonstrate performance deficits in spatial learning after electromagnetic field exposure: a classical radial maze elimination task and a spatial navigation task in an open-field arena (dry-land version of the Morris water maze). The performances of rats exposed for 45 min to a 900-MHz electromagnetic field (1 and 3.5 W/kg) were compared to those of sham-exposed and cage-control rats. There were no differences among exposed, sham, and cage-control rats in the two spatial learning tasks. The discussion focuses on the potential reasons that led previous studies to conclude that learning deficits do occur after electromagnetic field exposure.

Epidemiology and aetiological factors of male breast cancer: a ten years retrospective study in eastern Turkey

The aim of this study was to assess the epidemiological and aetiological factors of male breast carcinoma in eastern Turkey. For this purpose we evaluated breast carcinoma patients admitted to our regional hospital from 1990 to 2000. A total of 196 patients were admitted during that time, 11 of whom were male (5%). The average age at presentation was 60.7 +/- 7.5. Infiltrating ductal carcinoma was the most frequent histopathological type; lobular carcinoma was detected in only one of our cases. Right-sided male breast carcinoma was seen in 7 of 11 cases, left-sided in four cases. We detected gynaecomastia in two patients. Other factors were excessive alcohol consumption for 35 years in one patient, family history in one patient and exposure to electromagnetic fields (EMFs) and light at night in four patients. We demonstrated no risk factor in the other three cases. Of the patients in our study, the youngest was 45 years old--the patient with post-pubertal gynaecomastia. The overall rate of male breast carcinoma seen among people who had worked for the Turkish Institution of Electricity in eastern Turkey was 0.3%. In our study we demonstrated a close relation between exposure to EMFs and light at night and male breast carcinoma in eastern Turkey. We also supposed that not only exposure to EMFs but also the duration of the exposure could affect the risk of development of male breast carcinoma.

Electric blanket or mattress cover use and breast cancer incidence in women 50-79 years of age

Previous research has demonstrated inconsistent associations between electromagnetic radiation, especially from electric blanket use, and breast cancer. Breast cancer risk according to electric blanket or mattress cover use was examined as part of a multicenter population-based case-control study. Breast cancer patients 50-79 years of age (N = 1949) were identified from statewide tumor registries in Massachusetts, New Hampshire, and Wisconsin from the period June 1994 to July 1995. Women of similar age were randomly selected from population lists as controls. Information regarding electric blanket and mattress cover use and breast cancer risk factors was obtained through telephone interviews. After adjustment for age, body mass index, and other breast cancer risk factors, the risk of breast cancer was similar among ever-users (relative risk = 0.93; 95% confidence interval = 0.82-1.06) and lower among current users than among never-users (relative risk = 0.79; 95% confidence interval = 0.66-0.95). There was no evidence of a dose-response relation with increasing number of months that electric blankets had been used. This study provides evidence against a positive association between electric blanket or mattress cover use and breast cancer.

Lack of promotion of 7,12-dimethylbenz[a]anthracene-initiated mouse skin carcinogenesis by 1.5 GHz electromagnetic near fields

The effects of 1.5 GHz electromagnetic near fields of time division multiple access (TDMA) signal for the Personal Digital Cellular, Japanese cellular telephone standard (PDC) used for cellular phones, on mouse skin carcinogenesis initiated by 7,12-dimethylbenz[a]anthracene (DMBA) were examined. Ten-week-old ICR female mice were treated with a single application of DMBA on shaved dorsal skin by painting at a concentration of 100 microg/100 microl acetone per mouse. One week later, mice were divided into four groups, receiving electromagnetic near fields exposure (DMBA-EMF), sham-exposure (DMBA-Sham), 12-O-tetradecanoylphorbol-13-acetate (TPA, 4 microg /200 microl acetone/mouse), as a positive control (DMBA-TPA), and no-treatment (DMBA-Control). EMF near fields exposure conditions were as follows: skin local peak specific absorption rate (SAR) 2.0 W/kg, whole body average SAR 0.084 W/kg (ratio of peak to average SAR is 24), 90 min a day, 5 days a week, for 19 weeks. At week 20, animals were killed and skin tumors were analyzed histopathologically. The incidences of skin tumors in DMBA-EMF, DMBA-Sham, DMBA-TPA and DMBA-Control groups were 0/48 (0%), 0/48 (0%), 29/30 (96.6%) and 1/30 (3.3%), respectively. Histopathologically, papilloma and squamous cell carcinoma (SCC) were observed in the DMBA-TPA group and only papilloma observed in the DMBA-Control group. The incidences of squamous cell papillomas and squamous cell carcinomas in DMBA-TPA and DMBA-Control groups were 29/30 (96.6%) and 1/30 (3.3%), respectively, numbers of tumors per mouse (tumor multiplicity) being 18.8 +/- 13.4 and 0.1 +/- 0.5. These data clearly demonstrated that near fields exposure to 1.5 GHz EMF, used for cellular phones, does not exert any enhancing effect on skin tumorigenesis initiated by DMBA.

Rotating night shifts and risk of breast cancer in women participating in the nurses' health study

BACKGROUND

Melatonin shows potential oncostatic action, and light exposure during night suppresses melatonin production. There is little information, however, about the direct effect of night work on the risk of cancer. We investigated the effect of night work in breast cancer.

METHODS

We examined the relationship between breast cancer and working on rotating night shifts during 10 years of follow-up in 78 562 women from the Nurses' Health Study. Information was ascertained in 1988 about the total number of years during which the nurses had worked rotating night shifts with at least three nights per month. From June 1988 through May 1998, we documented 2441 incident breast cancer cases. Logistic regression models were used to calculate relative risks (RRs) and 95% confidence intervals (CIs), adjusted for confounding variables and breast cancer risk factors. All statistical tests were two-sided.

RESULTS

We observed a moderate increase in breast cancer risk among the women who worked 1-14 years or 15-29 years on rotating night shifts (multivariate adjusted RR = 1.08 [95% CI = 0.99 to 1.18] and RR = 1.08 [95% CI = 0.90 to 1.30], respectively). The risk was further increased among women who worked 30 or more years on the night shift (RR = 1.36; 95% CI = 1.04 to 1.78). The test for trend was statistically significant (P =.02).

CONCLUSIONS

Women who work on rotating night shifts with at least three nights per month, in addition to days and evenings in that month, appear to have a moderately increased risk of breast cancer after extended periods of working rotating night shifts.

Night shift work, light at night, and risk of breast cancer

BACKGROUND

Exposure to light at night may increase the risk of breast cancer by suppressing the normal nocturnal production of melatonin by the pineal gland, which, in turn, could increase the release of estrogen by the ovaries. This study investigated whether such exposure is associated with an increased risk of breast cancer in women.

METHODS

Case patients (n = 813), aged 20-74 years, were diagnosed from November 1992 through March 1995; control subjects (n = 793) were identified by random-digit dialing and were frequency matched according to 5-year age groups. An in-person interview was used to gather information on sleep habits and bedroom lighting environment in the 10 years before diagnosis and lifetime occupational history. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by use of conditional logistic regression, with adjustment for other potential risk factors.

RESULTS

Breast cancer risk was increased among subjects who frequently did not sleep during the period of the night when melatonin levels are typically at their highest (OR = 1.14 for each night per week; 95% CI = 1.01 to 1.28). Risk did not increase with interrupted sleep accompanied by turning on a light. There was an indication of increased risk among subjects with the brightest bedrooms. Graveyard shiftwork was associated with increased breast cancer risk (OR = 1.6; 95% CI = 1.0 to 2.5), with a trend of increased risk with increasing years and with more hours per week of graveyard shiftwork (P =.02, Wald chi-squared test).

CONCLUSION

The results of this study provide evidence that indicators of exposure to light at night may be associated with the risk of developing breast cancer.

Micronucleus induction in Syrian hamster embryo cells following exposure to 50 Hz magnetic fields, benzo(a)pyrene, and TPA in vitro

Electromagnetic fields (EMFs) have been associated with increased incidence of cancer suggested by epidemiological studies. To test the carcinogenic potency of EMF, the in vitro micronucleus assay with SHE cells has been used as a screening method for genotoxicity. A 50Hz magnetic field (MF) of 1mT field strength was applied either alone or with the tumour initiator benzo(a)pyrene (BP) or the tumour promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). All three treatments were applied in single, double or triple treatment regimes. MF or TPA (1nM) alone did not affect the number of micronuclei (MN) in initiated and non-initiated SHE cells. Changing the schedule of the typical initiation protocol, namely applying the initiator (BP) during exposure to MF, results in an 1.8-fold increased MN formation compared to BP treatment alone. Combined experiment with BP, TPA and MF did not cause further MN formation. Since initiation during MF exposure caused a significant increased MN formation, our findings suggest that MFs enhance the initiation process of BP. We think that this MF-enhanced co-carcinogenic effect is caused by an indirect "cell activation" process. The resulting genomic instability is proposed to be due to free radicals and/or to the unscheduled "switching-on" of signal transduction pathways.