![]() ![]() Evidence for cancer in adults from LF exposure is very weak. Therefore, the currently existing scientific evidence does not lead to the conclusion that prolonged exposure to LF is a cause of childhood leukemia. In addition, no biophysical mechanism has been identified and results from animal and cellular laboratory studies do not support the notion that exposure to 50-60 Hz magnetic fields is a cause of childhood leukemia. However, a combination of selection bias, some degree of confounding and chance could possibly explain these results. Long-term effects of low-level exposure stemming from the power distribution system including power lines and their relevance to health have been extensively studied over the last few decades.Įpidemiological studies have suggested that long-term low-level exposure to 50-60 Hz magnetic fields might be associated with an increased risk of childhood leukemia. At higher levels LF fields cause irreversible cardio-vascular effects or tissue burns. The effect is similar to that of a field generated by electric fields and currents.Ībove a certain level of exposure, referred to as threshold, the induced internal fields provoke reversible effects on excitable cells in the body such as a faint light flickering in the periphery of the visual field (phosphenes), electric charge effects at the skin level (similar to that experienced when you comb your hair, causing your hair to rise) or a stimulation of nerves and muscles experienced as a tingling sensation. If a charged object and an object connected to ground (where either of the two might be a person) come into contact, a discharge sometimes through a spark occurs. In addition these fields can charge objects that are not electrically connected to ground. ![]() At low levels these interactions go mostly unnoticed by the body and do not compromise health. The LF or static electric field interacts as a surface charge on the body. When people are exposed to LF fields, electric fields and currents are generated inside the body and they can interfere with the body’s own electric fields and current flows that are related to normal biological functioning. LF effects on the body and health implications However, the fields' strength diminishes quickly with distance from the line. The magnetic field, in contrast, passes unobstructed through most materials. The static electric field from overhead HVDC lines can expand further into the surroundings compared to AC lines (corona effects). In underground lines, the construction design is such that the electric field is completely shielded. ![]() Materials such as brick and clay are very efficient at shielding the electric field. The strength of the fields emitted by these lines depends mainly on the transmitted current and line voltage. HVDC lines emit static electric and magnetic fields. Power lines transmitting alternating current (AC) are surrounded by low frequency electric and magnetic fields. Over very long distances or underwater, transmission occurs sometimes with high voltage direct current (HVDC). Most commonly, and for efficiency reasons, the electricity is transported over long distances as alternating current at 50 or 60 Hz, carried overhead or underground using high voltage power lines or cables. Characteristics of the application and its useĭifferent types of power lines serve to transport electricity from the generation site to the end-users. ![]()
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