EMR from Computers

Unlike the TV set, whose somnolent spectators sit perhaps ten feet from the screen, a VDT operator's head is less than 30 inches from its cathode rays. The first indication that these devices were irradiating at a distance can perhaps be linked to complaints that home computers were affecting TV reception, not only in the user's own home, but even next door.

The VDT operates by firing electrons at a phosphor-coated screen, in some ways similar to the fluorescent lighting in offices, but much closer, and by means of magnets deflecting them en route to form the required image.

These emissions are at many frequencies including ELF, visible light, UV, and even soft x-rays. The screens are designed to filter out soft x-rays, a task they do not always accomplish over their entire life. Soft x-rays can also emerge from the back and side of a machine, and since such VDTs are often used in reception areas, waiting clients can find themselves gently irradiated while waiting for their appointment.

A National Institute for Occupational Safety and Health (NIOSH) report in 1985 states:
"X-radiation tests conducted by NIOSH since 1977 found maximum levels of between 0.25 and 0.3 millirems (mR) per hour emitted from VDTs. While this is below the 0.5 mR/hr standard, a continuous dose of 0.3 mR/hr over a working year would be equivalent to 450 mR which is nearly the same as the x-ray exposure standard maximum for therapeutic applications for the general public (currently 500 mR per year). This does not allow for any other irradiation from screens at home or outside the working environment".

As well as x-rays, VDTs emit radiation in the UV and non-ionising microwave frequencies. Skin cancers have been known for decades to result from UV radiation, but the effects of microwave irradiation of the head are only just being realised, as a result of research not on VDTs at all, but on mobile phones.

The background of hazards to health from chronic VDT exposure has been made infinitely easier by the publication of a book by Peggy Bentham, VDU Terminal Sickness. Her effort in bringing together between two covers most of the published research, as well as detailed references to scientific studies, makes the work the most definitive to date.

An early study by Weisburd (reported in Science News, vol 12) found that the DNA helix will resonate when irradiated by microwaves. More recent studies by Henry Lai at Washington University reported that exposure to microwaves at the frequencies used by mobile phones can cause single strand breaks in DNA.

Chiang, Wu and colleagues at the Microwave Institute, Zheijiang, China, exposed 89 Swiss Webster impregnated mice and divided them into four groups, one as a control, one for exposure to pulsed magnetic fields.

After 18 days the mother mice were euthanised and their fetuses were examined. The results left no doubt that exposure to the pulsed fields had a teratogenic effect on the unborn animals. This means that exposure of a fetus to VDT radiation could be hazardous, a suspicion left from an earlier study of 1583 pregnant VDT operators working more than 20 hours a week at the terminals. The Lai study further suggests that exposure of the kind used in mobile phones is in danger of fracturing DNA and possible mutation of the developing fetus.

Other early researchers like Webb and Booth (1969), Don Justesen (1980), and Dumansky & Shandala (1974) had already found sinister biological effects. One doctor, William Ham, was moved to advise that "both the retina and the lens should be protected throughout life from both blue light and near -UV radiation". His admonition followed the discovery that the retina is more sensitive to injury when exposed to light in the blue portion of the spectrum, - the blue light that we see in fluorescent lighting and VDT screens (Ham, 1983).

Webb & Booth (1969) found that DNA was affected by very specific frequencies, as if tuned to receive them. Don Justesen in 1980 reviewed eastern bloc studies uncovering an even worse concern. We have a barrier, known as the blood brain barrier (BBB), which keeps out contaminating agents from our cerebrospinal fluid. Microwaves appear to damage this barrier, making it permeable. Later the evidence was forthcoming to show by means of a dye that there is albumin leakage of the BBB with microwave exposure (Salford and Brun, 1993).

In Poland Yuri Dumansky and his research team was investigating the effect of microwave and related radiation in built-up areas in the early 1970s. They found that blood sugar levels rose and there were changes in carbohydrate metabolism as a result of exposure to densities as low as 100 to 1000 microWatts. In the US Deitrich Beischer also found blood changes, notably in what are known as triglycerides (a form of blood sugar) as a result of exposure to extra low frequency radiation for just one day. Meanwhile Dumansky had extended his work and found that changes in liver function were another corollary of microwave exposure.

Another early researcher into the effects of microwaves on our eyes, was Dr. Milton Zaret. He noticed that unusually large numbers of radar technicians were coming to him with post-lens cataracts, and eventually pinned it down to the microwave radiation to which they were occupationally exposed. The same sort of cataracts showed up in pilots, air traffic controllers, radar technicians, radio operators, and VDT operators (Zaret, 1984). "Except for the VDT operators", says Bob DeMatteo in his brilliant and exhaustive review of VDT hazards, "most of these other groups have been awarded compensation. In most of the cases the exposure levels were below the official Canadian limits of 1mW per square centimetre."

In 1987 Arthur "Bill" Guy was awarded the BEMS accolade of the D'Arsonval award, after a lifetime in bioelectromagnetic research. During his role as adviser to IBM he discovered that even exposure as low as less than half a milliWatt/cm2 could cause malignant tumours in rats. He was not alone in this finding: Stanislaw Szmigielsky from Warsaw, Susan Praunitz and Charles Susskind of Berkeley, California, and Bill Morton from Oregon all found correlations between extremely low (nanoWatt) levels of broadcast radiation and leukaemia, as did doctors John Lester and Dennis Moore from Kansas.

Changes in brain wave patterns are also induced by the kind of radiation coming from a VDT, even as low as power densities of 20 microWatts/cm2. The result is to induce behavioural symptoms such as sluggishness, depression and inability to concentrate. These may subsequently turn into myalgic encephalomyelitis and chronic disability.

How does the VDT produce this deadly cocktail? Microwaves are emitted by the two sweep oscillator circuits at the back of the CRT, and are therefore measured at their strongest at the flyback transformer at the rear, rather than the front of the screen, thus irradiating nearby workers.

These sweep oscillators are of two types, one vertical deflection coil, and one horizontal. The vertical coil moves the beam of electrons from top to bottom and up again sixty times a second, and thus produces a pulsed ELF field of the kind that Ross Adey found could damage cerebral tissue. The horizontal deflection coils move the electron beam left to right and back again 15 to 20 thousand times a second and thus pulses out a VLF field at 15 to 20 kHz.

There is a possibility that the higher frequencies from VDTs also have biological effects. One of these is RF hearing, where low intensity radiation affects the cochlear myosin filaments connecting the inner hair cells of the ear with the neural pathways to the brain and induces a sensation of noise. This may well persist in the head of the person exposed long after the "sound" has been switched off.

1. Ontario Hydro Research have found it causes hyperactivity in young children, and so it may cause the same effect in computer game crazy youngsters at VLF frequencies, which are more energetic.
2. Dr. Hari Sharma of Ontario's Waterloo University conducted a study among the VDT operators in the accounts department of the Surrey Memorial hospital at British Columbia. From a total of seven pregnancies there had been three miscarriages and three babies born with birth defects. Dr Sharma found that the VDTs in the accounting office had significantly higher pulsed VLF emissions than those in the medical records office, where pregnancy outcomes were normal .These results actually led to a change in the Ontario laws, excusing pregnant operators from VDT duties.
3. Arthur Guy, who was an adviser to IBM, showed that fields at these intensities still induced electrical currents in human tissue which were biologically significant, and in 1984 expressed concern about their long term effects on operators at the BEMS annual meeting in Atlanta Georgia.

His concern is that these levels of field strength are not uncommon in domestic houses when the return current is unbalanced, and if infants are chronically exposed to them it is my observation that cot death may occur within weeks. Guy also showed that the waveforms from the VDTs were not of the gentle sinusoidal type, but saw tooth, a shape known to be more biologically damaging.

Dr Marilyn Goldhaber of the Kaiser Permanente Medical Care program conducted a case-control study of 1,583 pregnant women from Northern California.

When they looked at the risk for women working more than 20 hours a week on the machines, they found the risk of miscarriage was nearly twice the normal expectation for that group.

Since the Goldhaber results were published substantial further studies have emerged to support their conclusions.