Environment of Earth

April 19, 2012


Electromagnetic radiation consists of the waves of enery combining electical and magnetic fields. These include whole range of electromagnetic wave spectrum: from very long-wave radio waves at one end to X-rays and gamma rays at the other end of spectrum. Visible light falls in a very narrow wave band in the middle of the spectrum. Every iving and non-living object in nature is constantly being exposed to a natural background of electromagnetic radiation that comes from space as well is produced by radioactive elements in the Earth’s crust. A large proportion of the cosmic radiation coming from space is absorbed by the atmosphere and only a very small portion reaches the ground. However, there is no such filtering of radiation originating from the Earth itself. All living organisms are evolutionarily adapted to such natural radiations in their natural environments. In fact, animals and plants use electromagnetic radiation for a variety of their living activities e. g. communication, control and regulation of their various physiological, psychlogical and behavioural functions. Though essential for living organisms, exposure to excess such radiation beyond the naturally evolved tolerence limits causes various harmful effects in them. The effects of increased exposure to electromagnetic radiation on human, animal and plant bodies are now coming to light and are being increasingly studied.

In the present urban, domestic and working place environments, sources of electromagnetic radiations are increasing rapidly. Increasing radiations from sources like power lines, microwave, telecommunication, electrical appliances, radar, transmissions of radio and television etc. are causing the problem of increasing electromagnetic pollution of environment.

The electromagnetic radiation may be classified into two broad categories according to the frequency and their effects. First category includes relatively low-frequency radiation, from visible light wave band down through infra-red, microwave, radar, television and radio waves and constitutes non-ionizing radiation. Second category includes relatively high frequency gamma and X-rays and constitutes ionizing radiation. Exposure to excessive dose of both the types of radiations casuses various harmful effects on living organisms.

The effects of extremely low-frequency electromagnetic radiations are dependent on dose and duration of exposure and are cummulative. It may take years of exposure before symptoms will appear. Usually symptoms of such electromagnetic pollution manifest as constant headaches, lack of energy, loss of apetite, mental blocks, decreased ability to concentrated, insonia & sleep disturbances, palpitaions, dizziness, trembling and rashes. After prolonged exposure, the symptoms may proceed to blackouts, nervous & psychological disorders like depression, feeling of being trapped, anxiety attacks, increased suicidal impulses, epilepsy, lowered libido & fertility, increased risk of arthritis and even cancer. White blood cells (WBC) are particularly sensitive to electromagnetic radiation and the risk of leukaemia is increased in those areas where exposure to such radiations is high e.g. around around power lines. Exposure to alternating magnetic fields accompanies exposure to electromagnetic radiations around power lines and from a variety of electrical appliances. Such exposure causes build up of serum triglycerides i.e. The fats found in blood stream that are implicated in heart diseases. Constant or frequent overexposure to such radiations may contribute to onset of heart problems.

A fully loaded 400 kv power line creates an electromagnetic field for 350 metres on either side of the line. This can generate electrical currents in the body, which produce an effect comparable to those that gives relief from pain. This effect of electromagnetic radiation on body is possibly due induced production of endorphins (natural pain-killers in body). It has been observed that continuous exposure to such radiations results in development of addictive dependency in cows and they start to prefer standing under power pylons for grazing or resting. They show withdrawl symptoms when away from such stimulation. It has been found that excessive concentration of positive ions builds up under power pylons and laboratory animals have died after constant exposure of 3 months to such conditions. A 50 Hz electromagnetic field has been found to adversely affect E. coli bacteria and water of wells underneath power lines has been shown to be devoid of naturally occurring bacteria present in waters away from such exposure. Laboratory experiments on rats, mouse and animal cells have shown an increased activity of enzyme ornithine decarboxylase in electromagnetic field of strength comparable to that produced by power lines. This enzyme speeds up the growth of cancer cells. Similar frequencies of radiation have been found to affect loss of calcium from the brain. it has been suggested that the problems arising from exposure around power lines may partly be due the effects of such radiation on calcium metabolism of the body.

When an object, living or non-living, enters an electromagnetic field, the field folds over the object so that its strength may become several hundred times more than that of unperturbed field. In the animal body, head houses the most vital organ, the brain which is most sensitive to electromagnetic field. Therefore, the head is the most affected part by the field-strength enhancement effect of electromagnetic field folded over animal body. Researches on the effects of electric blankets had shown alarming results because the body of user is entirely exposed to electromagnetic field for quite a few hours regularly. Among user women, seasonal (September to June) increase in miscarriages has been reported. The menstrual cycle is also disturbed in user women, which may be a contributing factor in the incidence of hormone related cancers such as breast cancers. The effect of electromagnetic field on such cancers is thought to be due to the effect of the field on melatonin production in the body. Electrically heated beds and blankets have also been linked to slower foetal development and learning problems in children, especually if mothers also used these during pregnancy.

The strength of electrical field drops off quite quickly with distance from the source and its frequency is clearly that of the source. However, the magnetic field fluctuates more, has ‘contaminating frequencies’ and its strength does not decrease with distance as quickly as that of electrical field. Furthermore, with increased distance, there is more likelihood that distribution of magnetic field over the body is uniform. A 400 kv power line may be generating underneath it a magnetic field of 1 microtesla (when current is around 100 A) to 10 microtesla (at greater loads, usual maxima being 5000 A) depending upon many variables like load, capacity, ground and weather conditions. It has been observed that people living near incoming supply in high-rise flats or ground floors are exposed to average magnetic field of 0.2 to 0.4 microtesla. These people have been found to be more susceptible to risks of heart diseases, cancers, depression and thyroid problems than those living on top floors away from the supply lines where magnetic field may be only around 0.015 microtesla. in cities, there may be continuous exposure to magnetic field of less than 0.1 microtesla in normal households. Such exposure may cause depressive feelings in the inmates. Electrical workers may experience exposure to levels up to 5 microtesla and the risks of various bodily and psychological disturbances to them may well be more harmful than moving in and out of similar field. Probably unbalanced, non-uniform magnetic field causes greater risk of various diseases and disturbances in the exposed subject than a balanced and unform field.

Apart from human beings, a number of detrimental effects of electromagnetic radiations have also been observed on animals and plants. It has been observed that earthworms are distributed and move away from underground power cables. Hens living near power lines lay scrambled eggs in thin shells, bees seal up their hives and become aggressive, cows loose apetite znd birds such as homing pigeons become disoriented. Plants exposed to electromagnetic radiation show disturbed root growth, seed germination, growth of pollen tubes, ion & water uptake and photosynthesis.

Exposure to microwaves is also increasing particularly in households due to increasing use of microwave-producing gadgets. Such exposure is also posing health risks as microwave exposure is known to cause cataracts and have detrimental effects on nervous and cardio-vascular systems.