James R. Jauchem

Chronic exposure of cancer-prone mice to low-level 2450 MHz radiofrequency radiation

The purpose of this study was to determine whether chronic, low-level exposure of mammary-tumor-prone mice to 2450 MHz radiofrequency radiation (RFR) promotes an earlier onset (decreased latency), a greater total incidence, or a faster growth rate of mammary tumors. One hundred C3H/ HeJ mice were exposed in circularly polarized waveguides (CWG) for 18 months (20 h/day, 7 days/wk) to continuous-wave, 2450 MHz RFR at a whole body average specific absorption rate (SAR) of 0.3 W/kg; 100 mice were sham exposed. Before exposure, SARs were determined calorimetrically; during experimentation, SARs were monitored by differential power measurement. All animals were visually inspected twice daily and were removed from the CWG cages for a weekly inspection, palpation, and weighing. From the time of detection, tumor size was measured weekly. Animals that died spontaneously, became moribund, or were killed after 18 months of exposure were completely necropsied; tissues were fixed and subjected to histopathological evaluations. Results showed no significant difference in weight profiles between sham-irradiated and irradiated mice. Concerning mammary carcinomas, there was no significant difference between groups with respect to palpated tumor incidence (sham = 52%; irradiated = 44%), latency to tumor onset (sham = 62.3 +/- 1.2 wk; irradiated = 64.0 +/- 1.6 wk), and rate of tumor growth. In general, histopathological examination revealed no significant differences in numbers of malignant, metastatic, or benign neoplasms between the two groups; a significantly greater incidence of alveolar-bronchiolar adenoma in the sham-irradiated mice was the only exception. In addition, survival analysis showed no significant difference in cumulative percent survival between sham and irradiated animals. Thus, results indicate that under the conditions of this study, long-term, low-level exposure of mammary-tumor-prone mice to 2450 MHz RFR did not affect mammary tumor incidence, latency to tumor onset, tumor growth rate, or animal longevity when compared with sham-irradiated controls.

The epidemiology of exposure to electromagnetic fields : an overview of the recent literature

Epidemiologic studies of exposure to electromagnetic fields (EMF) have been reviewed. Possible links to incidences of cancer and abnormal fetal development have been suggested by some investigators. In general, the results have been inconsistent. There are many deficiencies in the studies, and many questions have been raised about the validity of some of the conclusions proposed. There is currently no definitive evidence of an association between exposure to EMF and the alleged risks. Due to problems and limitations inherent in future studies (misconceptions about exposure levels, uncertainty about field variability, criticisms of surrogate measures), this question is unlikely to ever be answered with certainty. Unfortunately, many highly-publicized accounts of speculative and unsubstantiated claims have caused undue concern among the general public.

Heart rate and blood pressure changes during radiofrequency irradiation and environmental heating

1. Whole-body exposure of animals to radiofrequency radiation (RFR) can cause an increase in body temperature. 2. Responses to heating, whether due to RFR or to more conventional means, include changes in heart rate and blood pressure. 3. Although cardiovascular responses to various types of heating are similar, differences in the magnitude of changes may result from different thermal gradients within the body. 4. This review compares the effects of RFR and conventional environmental heating on heart rate and blood pressure.

Epidemiologic Studies of Electric and Magnetic Fields and Cancer: A Case Study of Distortions by the Media

Articles alleging hazards of electric or magnetic fields, based on epidemiologic studies, have appeared in the popular press. Some of these articles, which contain distortions of the scientific evidence, have been cited in the scientific and medical literature, thereby being given some degree of apparent legitimacy. In particular, articles appeared in 1989 in The New Yorker magazine, claiming a strong association between exposure to electric or magnetic fields and cancer. Assertions made in these articles (and a book dealing with essentially the same information) have been challenged by members of the scientific community. This paper will identify some additional misconceptions presented in two more recent articles from The New Yorker. Scientists and physicians should be aware of the deficiencies in these articles, and are encouraged to seek a more balanced view of the research performed in this area.

Blood biochemical factors in humans resistant and susceptible to formation of venous gas emboli during decompression

SummaryBlood biochemical parameters were measured in 12 male human subjects before and after exposure to a staged decompression protocol, with simulated extravehicular activity, during 3 days. Following the exposure, significant changes occurred in several parameters, including increases in blood urea nitrogen, inorganic phosphate, potassium, and osmolality, and decreases in uric acid and creatinine. Pre-exposure blood samples from subjects who were susceptible to formation of venous gas emboli (VGE) during decompression exhibited significantly greater levels of total cholesterol, high density lipoprotein cholesterol, potassium, inorganic phosphate, calcium, and magnesium. The results indicate that, following this decompression profile, small but significant (P<0.05) changes occur in several blood biochemical parameters, and that levels of certain blood factors may be related to susceptibility to VGE formation during decompression.

Environmental stressors during space flight: Potential effects on body temperature

1. Organisms may be affected by many environmental factors during space flight, e.g., acceleration, weightlessness, decreased pressure, changes in oxygen tension, radiofrequency radiation and vibration. 2. Previous studies of change in body temperature--one response to these environmental factors--are reviewed. 3. Conditions leading to heat stress and hypothermia are discussed.

Effects of exercise on the incidence of decompression sickness: a review of pertinent literature and current concepts.

SummaryThe effects of exercise on the incidence of decompression sickness (DCS) are not completely understood. This paper reviews studies that have addressed this question. Studies have involved exposures of animals and human subjects to high pressures, which would occur in SCUBA diving operations, and to low pressures, which exist during high-altitude aircraft flights and extravehicular activities during space flight. The temporal course of the exercise in relation to the decompression procedure and the nature of the exercise may influence effects on DCS incidence. Effects of exercise on the uptake and elimination of nitrogen, the production of bubbles due to limb movements, the potential role of carbon dioxide, and current plans for further research are discussed.

Tolazoline decreases survival time during microwave-induced lethal heat stress in anesthetized rats

Abstract Effects of α-adrenergic antagonists have been studied during environmental heating but not during microwave-induced heating. Tolazoline may exert some of its effects via α-adrenergic blockade. In the present study, ketamine-anesthetized Sprague-Dawley rats were exposed to 2450-MHz microwaves at an average power density of 60 mW/cm2 (whole-body specific absorption rate of approximately 14 W/kg) until lethal temperatures were attained. The effects of tolazoline (10 mg/kg body weight) on physiological responses (including changes in body temperature, heart rate, blood pressure, and respiratory rate) were examined. Survival time was significantly shorter in the tolazoline group than in saline-treated animals. In general, heart rate and blood pressure responses were similar to those that occur during environmental heat stress. Heart rate, however, was significantly elevated in animals that received tolazoline, both before and during terminal microwave exposure. It is possible that changes associated with the elevated heart rate (e.g., less cardiac filling) in tolazoline-treated animals resulted in greater susceptibility to microwave-induced heating and the lower survival time. [P.S.E.B.M. 1996, Vol 211]

Blood biochemical and cellular changes during decompression and simulated extravehicular activity

SummaryBlood biochemical and cellular parameters were measured in human subjects before and after exposure to a decompression schedule involving 6 h of oxygen prebreathing. The exposure was designed to simulate extravehicular activity for 6 h (subjects performed exercise while exposed to 29.6 kPa). There were no significant differences between blood samples from. subjects who were susceptible (n =11) versus those who were resistant (n = 27) to formation of venous gas emboli. Although several statistically significant (P < 0.05) changes in blood parameters were observed following the exposure (increases in white blood cell count, prothrombin time, and total bilirubin, and decreases in triglycerides, very-low-density lipoprotein cholesterol, and blood urea nitrogen), the changes were small in magnitude and blood factor levels remained within normal clinical ranges. Thus, the decompression schedule used in this study is not likely to result in blood changes that would pose a threat to astronauts during extravehicular activity.

Cardiovascular Responses to Radiofrequency Radiation

Cardiovascular changes during heating due to radiofrequency radiation (RFR) exposure have been reviewed previously.1 That review focused on physiological responses in animals, and compared studies of conventional environmental heating. Poison and Heynick2 also performed a recent review of bioeffects, including cardiovascular effects, due to RFR exposure. The main purpose of the present paper is to review studies of cardiovascular responses to RFR exposure in humans. In addition, cardiovascular responses to long-term, low-level RFR exposure in animals will be discussed. Cardiovascular changes during exposure to extremely low-frequency electric and magnetic fields are beyond the scope of this review.