WORLDS FINEST EYE-PROTECTION ANTI-GLARE SCREEN FILTERS
01. What is radiation
1. What is radiation? There
are various forms of electromagnetic radiation, such as radio waves,
infrared, visible light, ultraviolet, x-rays, and gamma rays. Whenever electric
charge undergoes acceleration an electromagnetic wave is formed which sends
energy through space; in somewhat the same way as waves spread out over water
when a stone is dropped into a pond. Radiation also includes the disintegration
of radioactive substances. The radioactive substances emit alpha, beta, and
gamma rays, which are streams of high-speed electrons. The radiation is produced
when atoms of natural radio-active material decay or split, generating streams
of photons vibrating at enormous speeds in wavelike form. Radiation has two
basic forms: ionizing and nonionizing. Ionizing radiation causes ionization
(splitting into charged atomic fragments) of the atoms and molecules that make
up the cells and tissue of living creatures.
2. What is natural "background" radiation?
We live in a smog of radiation due to cosmic rays from
outer space and intense radiation from solar activity. The air you breathe is
radioactive due to naturally occurring radioactive elements, such as uranium,
thorium, and radium in the rocks, soil, and masonry (like Grand Central's
granite walls). The house you live in is radio-active -- more so if it's brick
or stone than if it is wood. Much of the food you consume is radioactive from
naturally occurring radioactive forms of carbon, hydrogen, potassium, and
radium. Brazil nuts, milk, beer, and whiskey are naturally radioactive.
3. What are the units of radiation? Radiation
exposure is measured in roentgens and radiation absorption is radiation
absorbed dose (rad) or roentgen equivalents man (rem). The amount of radiation
delivered is referred to as dose and the measurement of these amounts is called
dosimeter. For x-rays, roentgen of exposure will usually produce about 1 rad of
absorbed dose in soft tissue. The rem is also a biological unit and represents
the amount of radiation that is equivalent to 1 rad of 250 kvp (kilovolt-peak)
4. What are the health hazards of infrared radiation? The sensory nerve endings in both the cornea and iris of the eye are quite sensitive to small temperature elevations. It is generally considered that the blink reflex provides protection against infrared radiation up to levels in excess of those that cause flash burns of the skin. The absorbed energy may be conducted to interior structures of the eye and raise the temperature of that tissue as well as the cornea itself. Heating of the iris by absorption is considered to play a major role in the development of opacities in the crystalline lens, at lest for short exposure time.
Quantitative data for the production of lenticular opacities following exposure to infrared radiation are very limited.
The biological effects of infrared radiation depends upon the conversion of this
radiation into heat as it falls on the surface. Prolonged exposure can cause the
retina to detach itself from the eyeball. Infrared exposure may also cause
opaqueness of the aqueous humor of the eye, resulting in partial or total
5. What are the health hazards of ultraviolet radiation? Certain people are allergic to ultraviolet radiation (called photoallergies, allergies produced by ultraviolet light and other radiations by which chemical changes are produced) that can effect skin pigmentation. Susceptibility can be determined by dermatologists using skin test equipment for the various types of photo dermatoses. One skin test uses a 6-watt fluorescent tube to determine allergies to ultraviolet light.
A sufficient exposure to actinic ultraviolet radiation results in erythema or
reddening of the skin (e.g., sunburn). Sufficient doses to the eye will cause
keratoconjunctivitis, that painful effect know to most as welder's flash. Some
individuals are hypersensitive to irradiation from specific optical spectral
bands and may develop skin reactions described as photosensitivity.
6. What are the health hazards of X-rays? X-rays, along with cosmic and gamma rays are ionizing radiation. The hazard is the shake up of the order of things in the body. The damaging action is either somatic or genetic. Somatic is the effect on the exposed individual; genetic is the effect on the progeny of the exposed person. Gamma and X-ray can pass through thick concrete without attenuation while other forms of ionizing radiation, such as alpha and beta particles, are readily stopped by a few inches of air, a sheet of paper, or foil.
Ionizing radiation can affect human cells by stripping one or more electrons
from an individual atom and forming an electrically charged particle, called an
ion. Depending in part on the rate and strength at which they are delivered,
these ions can disrupt the machinery of cells, kill them, or harm the genes that
pass human traits from one generation to the next.
7. Is all radiation bad?
No. There are benefits
of radiation for medical diagnosis and treatment, national defense and its
significant role in generating energy. The ideal is to limit radiation exposure
and avoid all unnecessary radiation. In 1981 the National Radiological
Protection Board in the United Kingdom revised and issued a popular booklet, Living
with Radiation. The booklet introduces the difficult subjects of collective
doses to the population, relative risks, and cost-benefit analysis. It also
includes the latest recommendations of the International Commission on
Radiological Protection that doses to individuals shall not exceed recommended
limits for the appropriate circumstances, no practice shall be adopted unless it
produces a positive net benefit, and all exposures shall be kept as low as
reasonably achievable, economic and social factors being taken into account.
8. What is "low-level radiation"?
Low-level X-radiation is generally applied to non-penetrating radiation when the
human body is exposed to radiation. The radiation is absorbed in the body
tissue. In comparison, "hard X-rays" used for radiology are absorbed
in bone, but pass through the body tissue.
9. Does low-level X-radiation pose a health hazard?
No one knows for sure. The radiation is absorbed by the first few layers of body
tissue and the amount is accumulated over your total lifetime. One way to
determine for sure would be to expose a certain number of persons to a daily
dose of low-level radiation over their entire life-time. Since this is not
practical, the risks are based on statistical data of large doses to large
populations. A certain percentage of the exposed population would develop
varying amounts of biological damage in themselves or cause genetic damage in
their offspring. The problem of knowing for sure is further complicated by the
fact that sensitivity to radiation varies by age and physiology, and different
rays have different potencies. There is no true threshold of medical damage by
X-rays. It depends on the individual and the dose. There is evidence to support
the premise that small doses of radiation carry a probability, however remote,
of some damage, particularly genetically.
10. What is a cathode ray tube? A CRT is
commonly called a picture tube in television sets. It is a vacuum tube in which
the electrons streaming from the cathode are directed to strike a fluorescent
screen and produce illuminated traces, visible from the exterior of the tube.
These tubes are also used as video displays in computer systems and
11. Can I avoid all radiation? No. You receive
an average of 100 millirems of unavoidable background radiation a year from
food, water, rocks, and cosmic rays. In France, people are exposed to as many as
350 millirems a year of background radiation compared with an average of 90
millirems in New York. The average background radiation is approximately 0.01 to
0.02 millirems per hour.
12. How does a CRT produce X-rays? X-rays can be
produced in any electron tube when a current is present and there is a potential
of at least 5,000 volts. It usually takes 10,000 volts or more to produce an
appreciable X-ray beam. The electrons are accelerated by the high voltage and
strike materials in the interior surface of the tube. X-rays are produced when
the high-speed electrons bombard the interior surface of the CRT. The problem is
more acute for color TV than black and white, because of the higher voltages
used for color TV. The voltage can be as much as 40,000 volts. Potential sources
of X-ray emissions are the picture tube, the high-voltage power supply, and the
shunt regulator tube.
13. When did the problem of X-radiation from TV's
start? In the late 1960's, a number of TV's with more than allowable
X-ray emissions found their way into American homes. Emission standards were
reevaluated after extensive measurements were made of TV's in American homes. In
a report published by the Institute of Electrical and Electronic Engineers
(IEEE), the basis for a common understanding of definitions and measurement
procedures in determining the extent of a potential hazard was outlined at a
conference held in Washington, DC The National Center for Radiological Health (NCRH)
requested a survey of TV's in the Pinelles County of Florida. The Health
Department found that 32% of the receivers emitted radiation in excess of the
standard set by the National Committee on Radiation Protection and Measurements
(NCRP). Almost concurrent with the Florida studies, a large scale survey of
X-radiation from color receivers in homes were started on December 16, 1967, by
the Technical Services Branch of the NCRH. Of the 1124 sets from 26 different
companies tested in the Washington, DC area, 66 receivers emitted more than the
standard. In 1971, the Bureau of Radiological Health was transferred to the Food
and Drug Administration (FDA). The agency enforces the Radiation Control for
Health and Safety Act of 1968 that provides radiation protection activities at
the Federal level. The Bureau educates consumers about the benefits and possible
risks of various radiation sources in their daily lives, from sunlamps to X-rays
as technology provides more and more radiation-emitting products. Beyond
assuring that these products are as safe as current techniques can make them, it
is FDA's job to help consumers understand benefits and risks, and make
intelligent decisions about their own radiation exposure.
14. What are the concerns of video display terminals
(VDT's)? About half a dozen studies have been done over the past two
years in Europe and the United States. The major concern has been complaints
from operators of VDT's who sit very close to the unit eight hours a day. A VDT
is no more than an ordinary cathode ray tube identical to the television screen
illuminating most American homes nightly. Personal computers and video games are
rapidly becoming a standard household item and are viewed at a distance much
closer than TV receivers.
15. What are some of the VDT hazards? Milton
Zaret, a New York consultant in clinical opthamology has made the strongest --
and most controversial -- claims that VDT's cause cataracts. He claims that
safety standards governing exposure to electromagnetic radiation are all
arbitrary. He also stated that dismissal of VDT's as a serious hazard was based
on "meaningless standards". Staring at a VDT for long periods of time
causes eyestrain. Reported "clusters" of miscarriages and birth
defects have baffled epidemiologists in the United States and Canada. New cases
of cataracts allegedly caused by video display terminals were reported at a
conference held at the Loughborough University in Britain. Static electricity
that builds up on the screen induces electric charges on the viewer's face. This
charge attracts dust which irritates the skin.
16. Why the concerns today? According to the
National Institute for Occupational Safety and Health (NIOSH), more than 7
million Americans now work at these VDT's. And that doesn't count those who
bought VDT's for home use. Some office workers have become concerned that the
VDT's could be causing a variety of health problems. VDT's can, in fact, produce
several types of radiation: X-rays, radio frequency, microwave, ultrasound,
ultraviolet, infrared, and visible light. Changing Times reported in its
February 1983 issue that anyone with a TV set manufactured before January 15,
1970, used as a display terminal for games or for home computers may be risking
eye damage. youngsters may be at risk for radiation exposure far in excess of
the National Council for Radiation Protection and measurement recommendations
for radiation exposure. Although both the Canadian and U.S. governments have
given VDT's what amounts to a clean bill of health, many unions, particularly in
Canada, have fought and won the right for pregnant women to refuse VDT work.
Canada's airline employees union want similar alternate-work provisions for its
pregnant employees and tests to monitor any nonionizing radiation emissions by
users of VDT's.
17. Are the reports on VDT's conclusive? Definitely no. As an example, the Food and Drug Administration reported in April 1981 that all but 8 out of 125 VDT's checked emitted no more than 0.4 milliRoentgens (mR) per hour. The worst reading was 2.0 mR (400% more than the standard for television sets). In another report published by the Human Factors Society in 1981, no detectable ionizing radiation was measured from 136 terminals that were tested. Researchers from the National Radiological Protection Board in Britain measured radiation from VDT's in almost every part of the electromagnetic spectrum. In another report, FDA gave computer video screens a clean bill of health. However, in the same report, Milton Zaret, an opthamologist, diagnosed radiant energy cataracts caused by exposure to microwave emissions from the VDT's used by two newspaper employees. In his view, the FDA, OSHA, and NIOSH have been "consistently wrong from the start". The federal research centers have issued bad reports, bringing discredit upon themselves.
18. What are the health problems with VDT's?
Various topics were discussed at a conference held in England in July 1981. The
conference was organized by the Human Sciences and Advanced Technology (HUSAT)
Research Group. Static electricity charge on a CRT reduces the level of negative
ions in the air breathed by the operator and can thereby aggravate the adverse
effects of negative ion depletion, including headaches, nausea, and dizziness.
Different light levels, eye movements from a manuscript and the CRT screen, and
reflections on the CRT screen are problems for most operators who use CRT's for
most of their workday. Eyestrain caused by staring at a CRT screen is a
long-term source of distress. The operator's ability to adapt to the relatively
low light levels emitted by the screen is further hampered by glare from
windows, unshielded luminaries, and shiny desk tops. Flicker, caused by a
phosphorescent image decaying before it is refreshed by the electron scan,
causes eyestrain. In another article, the "ideal" office work station,
which frees users from the time-consuming chores of walking to a filing cabinet
and mailing letters, might be ergonomically unacceptable. Remaining seated in
the same posture for hours can lead to permanent back injury, which, along with
the eyestrain caused by staring at the CRT screen, is a long-term source of
19. How much confidence is there in today's standards?
Disagreements about the somatic risks from low doses of ionizing radiation stem
from two difficulties fundamental to the logic of inference from observational
data. First, precise direct estimation of small risks requires impractically
large samples. Second, precise estimates of low-dose risks based largely on
high-dose data, for which the sample size requirements are more easily
satisfied, must depend heavily on assumptions about the shape of the
dose-response curve, even when only a few of the parameters of the theoretical
form of the curve are known. There seems to be no way to evade the problem of
curve fitting and extrapolation from high-dose estimates of excess risk.
Resources are not available for adequate epidemiologic studies of populations
exposed to low-levels of radiation, and if anyone should try to do them anyway,
they would run considerable risk of obtaining misleading results; results that
would derive at least some credibility from the vast effort of obtaining them.
Present experience indicates that the accuracy of evaluations is almost always
limited by biological uncertainties. Until these uncertainties are resolved, one
is obliged to use significant safety factors based upon knowledge of
extrapolating from animal to man, variation of susceptibility among individuals,
and the experience gained from accidental injuries. Recommendations in a
National Research Council report done for the National Cancer Institute advises
caution in undertaking any new studies of populations exposed to low levels of
ionizing radiation. The populations rarely will be large enough, nor their
exposures to radiation well enough documented, for a study to yield meaningful