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hensive across the entire surface of the body also adds anew _can claim its product to be free of relatively strong electromagnetic prel pro 'y dimension to the question of dose impact, the health implications of _fields. which still need to be explored further. : Although the electric blanket generates a greater field strength The Health Hazards of Electric Blankets and Heated than the heated waterbed, whose heating element is located on the | Waterbeds underside of the bed, the heated Because of the problem of having to waterbed produces a magnetic field : select a separate control population to = a five ~~ establish whether those who used electric gauss, the dose to which anyone lying blankets or heated waterbeds have a high- in the bed would be exposed. Since ‘tha: incide .. er incidence of cancer than those who do the hildren involved in Wertheimer’ They found that the incidence of siitiercscurchin the aren has been mere Te Poprercding wn miscarriage was 0 Lel« . eae : ae of these electrical appliances on foetal ares of a —s = milli- disproportionately higher during : development. This study is much sim- , gauss, the potential health risks asso- 1 as Be eS ler since it is possible to compare the ciated with —_— waterbeds cannot the months In which these Fifects of pnd oe fields on the same go unattended. In respect of the dose- earhe ; H : ulation. For example, by comparin; rate calculation, it is important to [waterbeds & electric blankets] en of samaniuan tude the end appreciate that while electric blankets Were used than when they Were versus the summer months for a single are ordinarily used only during the control population, it is possible to assess coldest months of the year, heated not. whether the use of electric blankets and waterbeds tend to be heated for heated waterbeds during the winter longer periods than electric blankets. increases the rate of miscarriage during , that period. Because the study deals with Why Electric Blankets Generate the coe group of people, it is possible to Magnetic Fields eliminate the confounding influence of other factors such as a cou- The parallel wires in the middle of the electric blanket form an'S' _ple’s dietary, smoking or drinking habits, thus isolating the role in pattern through which the electric current flows. Because of the miscarriage played by electromagnetic fields.” configuration of lines, the current flow through the 'S' pattem is bal- Once again, it was the pioneering work of Wertheimer and anced by the current flowing in the opposite direction, thus tending Leeper which has served to advance the frontiers of knowledge in to cancel out or prevent the generation of magnetic fields. The this area and encourage other researchers to continue their initial heating element within the waterbed is similarly designed to min- _ investigations. imise the generation of electric fields. The problem is that at the Utilising a rigorously controlled experiment, Wertheimer and outer edges of both the electric blanket and the heated waterbed, the Leeper compared the rate of miscarriages among users of electric current becomes unbalanced. When this happens, the relatively sig- _ blankets and heated waterbeds as they occurred during the summer nificant electromagnetic fields characteristic of each appliance are and winter months. They found that the incidence of miscarriage generated."* Whether electric blankets and heated waterbeds could —_—_ was disproportionately higher during the months in which these ever be constructed to avoid completely any current imbalance appliances were used than when they were not.” They discovered which might lead to the generation of a magnetic field strength of _also that the rate of miscarriage was higher between September and significance, is a moot engineering point. Suffice to say thattodate the end of January. The greatest risk of miscarriage was thus we know of no brand of electric blanket or heated waterbed which —_ observed to occur during the first months after conception and to coincide with the coldest period when the temperature setting of the appliances was likely to be set higher, thereby increasing the — —— strength of the magnetic field generated.” No such seasonal pattern of miscarriage was reported among non-users. The results of their (Ain study also demonstrated a trend towards slower foetal development, 3 P & - 55 and research is presently being done by Dr Michael Bracken of the SS C_ { Yale University School of Medicine to make more specific determi- —. — nations regarding the patterns of growth and development of chil- no BS dren exposed in utero to electromagnetic fields.” an wire ANL In their first study on this matter published in Bioelectromagnetics in 1986, Wertheimer and Leeper admitted that * the effects they had documented could also be interpreted as the effects of excessive heat exposure. In other words the increased £8 Core ae eens rate of miscarriage, slower foetal development, and perhaps even \o some forms of childhood disability, might be due to the heat radia- A tion generated by the appliances in question, rather than their elec- oS a vy ra tromagnetic fields. Excessive heat, for example, is known to have a Le SAN deleterious effect on both sperm and ova. In order to distinguish the different effects which each of these two factors might be playing in the increased risk of miscarriage, Wertheimer and Leeper undertook a new study in which the effect of electromagnetic radiation could be separated from the effects of : heat radiation.” To do this they now focused their investigations on ceiling cable heating units, popular in many homes built during the 1960s and 1970s in the Eugene, Oregon area. They conceived of the ceiling cable units as a kind of big electric blanket in the ceiling. As in the case of the electric blanket, the current flowing along the edges of the ceiling cable pattern was also unbalanced, thus gener- ating quite strong magnetic fields.” The difference was that while the human body would be exposed to the magnetic fields produced The Health Hazards of Electric Blankets and Heated Waterbeds Why Electric Blankets Generate Magnetic Fields The parallel wires in the middle of the electric blanket form an 'S' pattern through which the electric current flows. Because of the configuration of lines, the current flow through the 'S' pattem is bal- anced by the current flowing in the opposite direction, thus tending to cancel out or prevent the generation of magnetic fields. The heating element within the waterbed is similarly designed to min- imise the generation of electric fields. The problem is that at the outer edges of both the electric blanket and the heated waterbed, the current becomes unbalanced. When this happens, the relatively sig- nificant electromagnetic fields characteristic of each appliance are generated.'* Whether electric blankets and heated waterbeds could ever be constructed to avoid completely any current imbalance which might lead to the generation of a magnetic field strength of significance, is a moot engineering point. Suffice to say that to date we know of no brand of electric blanket or heated waterbed which —cucK. Vol 2, No 13 - 1993 44¢NEXUS au can claim its product to be free of relatively strong electromagnetic fields. Se