Case Number: 430

Case Mnemonic: VDT

Case Name: Visual Display Terminals

I. Identification

1. The Issue

One of the most essential pieces of home and office technology today is the computer monitor. While a monitor may allow a person to glimpse a city around the world, help them correspond with their mother across the country, help them write a paper for a college course or conduct cash-free financial transactions, it may also be harming their health. Radiation emitted by monitors has been a growing concern in recent years, as scientific studies are suggesting that the danger to humans may be life-threatening.

2. Description

Visual Display Terminals (VDTs), known to most as monitors, are the essential link between computers and people. VDTs translate complex computer languages into displayed text and pictures humans can comprehend and use. Without monitors, computers would still be the province of high-tech laboratories and university researchers, performing mathematical computations with complex printouts as their only output. Fortunately, VDTs have expanded the activities a computer can be made to perform and significantly contributed to the massive explosion in the day-to-day use of the machines, since color (and even black-and-white) displays add greatly to their usability.

However, VDTs may also be harming those they were designed to help. Several studies have suggested that the electromagnetic radiation given off by these machines may be harmful to those who use computers frequently. (Slesin 18) In order to understand the problem better, consider the following discussion on radiation:

"Electromagnetic radiation is always in the form of a wave composed of two parts: an electric field and a magnetic field. The energy of radiation is measured according to its frequency (the number of waves that pass a given point in a specific time period, usually one second), which is expressed in Hertz (cycles per second, abbreviated Hz). The higher the frequency, the more powerful the radiation. Frequency is inversely related to wavelength (the distance from point to point between waves); the higher the frequency, the shorter the wavelength. The various types of radiation are distributed across what is called the electromagnetic spectrum, which is itself usually divided into two basic categories, ionizing radiation and non-ionizing radiation." (Scalet 8)

When most people consider the connection between radiation and computers, ionizing radiation usually comes to mind. "Ionizing radiation is known to cause cellular changes. It affects matter by breaking chemical bonds and charging (ionizing) neutral molecules." (Scalet 9) This type of radiation is given off by televisions, monitors and nuclear detonations, and is known to cause cancer. However, the risk to humans from their TVS and computer monitors is minimal at best. The ionizing radiation they emit is stopped by a lead shield behind their display screens.

The current concern about VDTs centers around two other types of radiation they emit, namely VLF (Very Low Frequency) and ELF (Extremely Low Frequency) radiation, which are emitted from the back, top and sides of the machines. Televisions emit these types of radiation as well, but since people must sit much closer to their computers in order to use them properly, ELF and VLF radiation pose more of a risk when coming from a VDT. The following picture and description explain the process by which VLF and ELF emissions are created in monitors:

"The greatest amounts of radiation produced by VDTs, next to visible light, are VLF and ELF electromagnetic radiation. These are emitted from the line output transformer, also called the flyback transformer. The electron beam which 'paints' across the screen must return rapidly to its starting point at the upper left portion of the screen in order to begin the process again. This process occurs very rapidly (usually sixty times a second in VDTs made for use in the United States, and fifty times a second in VDTs made for use in Europe), and the energy emitted from the transformer by this process comes in short bursts, or pulses. As a result, the emissions of VLF and ELF are in the form of pulsed fields." (Scalet 14)

Studies involving ELF and VLF radiation have suggested that they can cause miscarriage, birth defects and contribute to the growth of cancerous tumors. (Cottrell) Concern over these possible effects has been heightened since these types of radiation have been proven to cause cellular change. Previously, they were thought to be too weak to do so.

"Some of the effects reported so far include changes in the flow of ionic compounds through cellular membranes. Also noted are changes in DNA synthesis, RNA transcription, and the response of cells to signaling molecules such as hormones and neurotransmitters. In addition, changes have been noted in the kinetics of some cellular biochemical reactions." (Iovine)

A particularly noteworthy study conducted by the Finnish Institute of Occupational Health found that "[...] pregnant women exposed to fields of over 3 milligaus were three times as likely to miscarry as others exposed to less than 1 mG." (Saffo 278) This study was based on a group of 585 women exposed to VLF and ELF emissions daily in their workplaces. (Sachs 12) A much larger study involving several thousand women is currently under way. In addition, while it has not been proven that these two types of radiation cause cancer, it has been shown that "ELF radiation can promote the disease after the cancer has been triggered by another agent."(Iovine)

Since the research conducted so far on this subject is still preliminary, experts have only suggested caution and a few guidelines for designing computer work spaces. These guidelines include: 1) designing work spaces at least 4 feet away from the back and sides of other computers -- radiation levels drop off significantly after this distance ("Visual Display Terminal Hazards"); 2) make sure this distance is maintained even in adjoining rooms -- ELF and VLF emissions can travel through walls (Greiner 16); 3) do not stand or lean against the back, top or sides of a monitor, as these are the areas of the greatest radiation concentration; 4) sit at least arms length away from the front of the computer screen; and 5) turn off monitors when not in use (Morgan 14).

One might wonder about the official government and industry positions on VLF and ELF emissions from computer monitors. The National Institute for Occupational Safety and Health's research indicates that "VDT users are working safely within acceptable established boundaries [for ELF and VLF emissions]." ("Healthy Choices for Computer Users: Radiation Emissions") In addition, the American Industrial Hygiene Association states the following in its "Expanded Position Statement on Extremely Low Frequency and Magnetic Fields":

"While additional information is developed, the AIHA finds it appropriate to fully characterize field exposure levels in industrial environments; to provide workers with education and training on the potential effects of exposure to ELF fields, current exposure guidelines, and measures designed to protect them; and to follow the exposure guidance developed by the ACGIH and the International Radiation Protection Association (IRPA)/International Commission on Non-Ionizing Radiation Protection (ICNIRP)." ("American Industrial Hygiene Association Expanded Position Statement on Extremely Low Frequency and Magnetic Fields")

As one can see, both organizations feel that ELF and VLF emissions are at safe levels. If the results of the large-scale studies currently underway support the findings of smaller scientific projects which suggest potential danger from these emissions, then these organizations will be forced to take more formal steps to address the issue. In the meantime, computer users should follow the suggestions given earlier.

Manufactures of computer monitors have already begun to take action in response to public concern, especially in Europe, where guidelines for radiation emissions developed in Sweden are the standard. Many manufacturers already produce monitors which meet these guidelines for sale in the United States. If the new studies provide conclusive evidence about the effects of radiation emitted by computer monitors, the U.S. government may be pressured to formally legislate these guidelines as well. The impact on the billion-dollar computer industry could be quite significant, as new monitors would need to be developed to meet the new guidelines, (if companies do not produce them already for the European market). As an alternative, monitors that do not rely on a cathode ray tube may be substituted. Flat screens and laptop computers already take advantage of this type of technology. It would just need to be adapted (i.e. become much cheaper) for the personal computer market.

3. Related Cases

3. Related Cases

(1): SPACEGAR: Space Garbage Case

(2): SPACEMIN: Space Mining Case

(3): SST: SST Ozone Case

(4): WEATHER: Weather Modification

(5): STATION: Int'l Space Station

(6): COMPUTER: Computer Recycling

Key Words

(1): Trade Product = Manufactures

(2): Geography = SPACE

(3): Environmental Problem = Pollution Air (POLA)

4. Draft Author: Caren Saxe (May, 1997)

II. Legal Cluster

5. Discourse and Status: DISAGREE and Allegation

Currently, there is much disagreement about the exact nature of the health threat posed by VDTs. In the United States, each individual State decides about how it wishes to regulate ELF and VLF emissions. In Europe, it has been done at the national level.

6. Forum and Scope: ISS and Global

While this case concentrated on the United States and European Union, this issue affects everyone who uses a computer and can therefore be considered to affect all countries.

7. Decision Breadth

Number of Parties Affected: 16, United States and European Union

8. Legal Standing

III. Geographic Cluster

9. Geography

A. Continental Domain: GLOBAL

B. Geographic Site: GLOBAL

C. Geographic Impact: GLOBAL

While this case concentrated on the United States and European Union, this issue affects everyone who uses a computer and can therefore be considered to affect all countries.

10. Sub-National Factors: No

11. Type of Habitat: Global

IV. Trade Cluster

12. Type of Measure:Import Standard

Monitors imported into Europe must meet the emission guidelines developed by the Swedes:

VLF range ELF range

(2 Khz to 400Khz) (5 Hz to 2 Khz)

Magnetic Fields .25 mG 2.5 mG

(25 nT) (250 nT)

Electric Fields 2.5 V/m 25 V/m


13. Direct vs. Indirect Impacts

Impact Direct [DIR] or Indirect [IND]: DIR

14. Relation of Measure to Impact

A. Directly Related to Product: YES

B. Indirectly Related to Product: NO

C. Not Related to Product: NO

D. Related to Process: NO

How computer monitors are made directly impacts there effect on their surrounding environment once they are turned on. The Swedish guidelines result in less radiation being released from VDTs and a smaller health threat to those who use them frequently.

15. Trade Product Identification:Computer Monitors

16. Economic Data

Industry Output ($): ~$60 BILLION (1994 figures--includes all computer equipment) (Miles)

Employment: Thousands

17. Degree of Competitive Impact: Low

Companies who produce the best quality monitors seem to do well no matter the trade measure. Price Effect: passed on to consumers.

18. Industry Sector

Industry Sector: EMACH

19. Exporter and Importer: Many and Many

The United States "controls more than 75 percent of the world computer market", and exported $34.6 billion worth of equipment in 1994.(Miles) The following table shows 1994 figures for other major computer equipment importers and exporters:
Value ($ Billion)
1989 1993 1994
World Exports 24.5 30.7 34.6
Imports 21.7 38.7 46.9
Canada Exports 2.8 4.9 5.6
Imports 1.5 2.3 3.2
Japan Exports 3.2 3.3 3.8
Imports 8.6 13.0 15.0
UK Exports 3.1 3.0 3.6
Imports 0.6 1.0 1.2
Germany Exports 2.5 2.7 2.6
Imports 0.4 0.6 0.7
Netherlands Exports 1.6 2.3 2.1
Imports 0.1 0.1 0.1
BEMs Exports 3.1 4.9 6.0
Imports 5.4 10.3 12.3
Rest of World Exports 8.2 9.6 10.9
Imports 5.1 11.4 14.4


V. Environment Cluster

20. Environmental Problem Type

Environmental Problem Type: POLA

21. Species Information

Name of Species: HUMAN

22. Impact and Effect: Low and Product

The harmful radiation emitted by monitors only effects their immediate environment (within 4 to 6 feet).

23. Urgency and Lifetime: Low and 75 years

Research is still being conducted to discover the exact effects of ELF and VLF radiation on people exposed to these forms of radiation on a daily basis.

24. Substitutes: Like Products

Technology currently exists that allows manufacturers to produce monitors which do not emit VLF and ELF radiation. LCD panels are one example. However, monitors which use this type of technology are currently too expensive for the average computer user to purchase.

Other Factors

25. Culture: No

26. Human Rights: No

27. Trans-Boundary Issues: NO

VDTs can be found wherever there are computers. Currently, that means the entire world. As previously stated, different countries have different regulations regarding electromagnetic radiation emissions.

28. Relevant Literature

"American Industrial Hygiene Association Expanded Position Statement on Extremely Low

Frequency and Magnetic Fields." ELF and Magnetic Fields Position Paper. 1995.

<> (24 Apr. 1997).

Cottrell, Janet. "Computer and Radiation: What are the Risks?" Computers and Radiation.

1991. <> (8 Nov. 1996).

Gilman, Joel B. "Facing VDT-Related Ills Sooner is Better." Computerworld. 30 Mar. 1992: 109.

Greiner, Ann Claire. "Terminal Hazards." Technology Review. Feb. 1991: 16-17.

"Healthy Choices for Computer Users: Radiation Emissions." UCSD/EH%S-Computer

Ergonomics/Radiation-HEALTHY CHOICES BOOKLET. 1996. <http://www> (24 Apr. 1997).

Iovine, John. "Electromagnetic Fields and Your Health." 1996.

<> (24 Apr. 1997). From Popular Electronics March


Miles, Tim. "Computer Equipment." 1995. <http://www.stat-> (30 Apr. 1997).

Morgan, Bill. "VDT Emissions Radiate Debate." Electronic Learning. Oct. 1990: 14.

Peterson, Baird and Richard Patten. The Ergonomic PC: Creating a Healthy

Computing Environment. New York: McGraw-Hill, 1995.

Sachs, Jessica. "Do V.D.T.s Cause Miscarriage?" New Woman. Dec. 1992: 124.

Saffo, Paul. "A Conspiracy of Silence." Byte. July 1993: 278.

Scalet, Elizabeth A. VDT Health and Safety: Issues and Solutions. Lawrence, Kansas:

Ergosyst Associates, 1987.

Slesin, Louis. "EMFs and Cancer." Columbia Journalism Review. 30.1 (1991): 17-18.

"Visual Display Terminal Hazards."

<> (24 Apr. 1997). May, 1997