Section II. SAFETY AND COMFORT
4-18. VIDEO DISPLAY TERMINALS (VDT)
a. Safety. Safety may emerge as an issue of increasing importance in the years
to come. Currently, most private firms, agencies of government, and computer vendors
maintain that there are no health hazards associated with working at the video display
terminal. There is some evidence, however, to suggest that prolonged exposure to the
Video Display Terminal (VDT) can pose a health hazard, especially to pregnant women.
A cathode ray tube uses very high voltage to throw a beam of energy on a phosphor-
coated screen. The result is a discharge of low-level electromagnetic radiation (EMR)
that some scientists believe to be hazardous. (Most VDTs are of the cathode-ray tube
variety. Of the other two types of VDTs (Liquid Crystal Display (LCD) and plasma)),
LCDs have also been implicated. The prevailing opinion is that low-level magnetic
fields are harmless and that VDTs pose no threat to human health, no matter how many
a hours a user spends before a terminal. But a debate has sprung up, which will be
fully resolved only as more scientific data are gathered.
b. Growing Evidence. California's Kaiser Permanent Medical Group studied
1583 pregnant women, and found miscarriage rates twice the norm for women using
VTDs more than 20 hours per week. At Johns Hopkins University, researchers found
c. Growing Government Interest. The government's Office of Technology
Assessment asked researchers at the Carnegie-Mellon University's department of
engineering to develop a position paper on VDT safety. Congress' Office of Technology
Assessment plans to use the Carnegie-Mellon University paper to debate the issue and
eventually formulate a policy. The paper points out that "studies over the last 15 years
have demonstrated unequivocally that under certain circumstances the membranes of
cells can be sensitive to even fairly weak externally imposed low-frequency electro-
magnetic fields. Extremely small signal changes can trigger major biochemical
responses critical to the functioning of the cell." This conclusion is still being debated by
d. Prudent Avoidance and Low-Cost Preventive Measures Recommended.
Carnegie-Mellon advised a policy of "prudent avoidance," essentially, taking low-cost
countermeasures until science conclusively proves how serious the problem is. Public
health regulators, manufacturers, and corporate users have been slow to respond.
They are waiting for more solid evidence.
(1) Protective shield. Some companies claim to have come up with a low-
cost way of shielding users from radiation. Shields that cost to 0 are attached
to the front of the VDT screen by Velcro strips. They are designed to reduce EMR as
well as glare. Vendors report that entire municipalities in California are buying shields
as local governments, there, begin to pass legislation mandating VDT safety. Federal