Q Since the concerns about the safety of computer VDUs [video display units] some 10 years ago, has there been more recent research that continues to voice health worries, or have new developments made VDUs less hazardous? Several friends have told me that they have stopped having headaches since they switched from CRT to LCD monitors. Is there any research to back this up? - BS, London W6
A The health hazards of VDUs are a good example of fashions in health scares. It was once the stuff of every other newspaper headline - and research grant, come to that - but today, you'd be hard-pressed to find any mention of it, even in the medical journals. The other health scare associated with computer use - RSI, or repetitive strain injury - also seems to have mysteriously disappeared from public view.
VDUs were once thought to cause headaches, tiredness, and skin and eye problems. A survey in 1982 among the clerical staff working at the Department of Employment concluded that VDUs were also likely to increase the risk of miscarriage. Furthermore, a Swedish study several years later suggested that pregnant women who regularly used a VDU while pregnant had an increased risk of a deformed baby or a stillbirth.
These problems were blamed on electromagnetic field (EMF) emissions from VDUs. The older-style VDUs radiated up to eight different types of radiation - from X-rays to ultraviolet, infrared, radio frequency, ELF, pulsed and static fields.
Critics argued that these emissions were far too low to have any damaging effects on health, and this view was supported by research carried out in the early 1990s. In one study, scientists compared two groups of women who had miscarried, and concluded that exposure to VDUs played no part in their early termination (Br J Ind Med, 1992; 49: 507-12).
What little research that has been done in recent years seems to support the sceptic. One Norwegian study was unable to replicate an earlier trial that concluded that skin problems were caused, or exacerbated, by VDU emissions. To test the original theory, the researchers monitored the health of 42 office workers who, for one week, worked on computers without a filter, then for three months with an inactive filter and, finally, for three months with an active filter. The participants did not know which filter was active. There was no difference in the symptoms of the participants at any time during the trial, suggesting that any health problems - including skin, eye or nervous system symptoms - were psychological (Scand J Work Environ Health, 1999; 25: 415-21).
Filters did, however, help to relieve eye strain, and improved the posture of computer operators, according to another trial. Of 60 study participants, 40 had a filter fitted to their VDU, while the remainder worked without one. Researchers found that those using filters complained of far fewer eye and musculoskeletal problems, or had problems that were shorter-lasting (Cent Eur J Public Health, 1998; 6: 249-53).
This last study captures the mood of the times. Ergonomic issues, such as screen glare, the positioning and angle of the VDU, and poor posture, seem to be the only concerns among health watchdog groups. The Health & Safety Executive highlights this thinking in its new booklet, Working With VDUs (HSE Books, 2003), which provides guidance for both employers and employees in the UK.
Incidentally, if the older VDUs were not a problem, why should people be feeling better with an LCD flat screen, such as used on portable computers? Although there is no research to support their anecdotal evidence, it is true that LCDs do not emit any electromagnetic radiation.
So, are the users' responses only in their heads, as some researchers have maintained, or could it be that the early VDUs did present more of a health risk than the studies would suggest?