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Ultraviolet
Radiation:
UV radiation is a type of radiation with wavelengths from 200 to 400
nanometers. A nanometer is one billionth of a meter. Ultraviolet radiation
is part of the invisible radiation that comes from the sun. About 6% of the energy that reaches the earth from the
sun is UV energy. Other sources of UV radiation include tanning beds, black
lights, welding arcs, and UV lasers.
Ultraviolet
is classified into:
UV-A (near) with a wavelength of 400 to 320 nm
UV-B (medium) with a wavelength of 320 to 280 nm
UV-C (far) with a wavelength of 280 to 100 nm.
All of the UV-C emitted by the sun is absorbed by
the ozone layer before it reaches the surface of the Earth. However, there are manmade
sources of UV-C that are used medically and commercially for its germicidal
properties.
The biological effect of UV-A
and UV-B on skin is to induce melanin production from melanocyte cells to
cause sun tanning of skin. Vitamin D is produced on the skin by a radical
reaction initiated by UV radiation.
US
Regulations:
The
Food and Drug Administration regulates UV radiation from sunlamps and
sunlamp products (tanning beds and booths) in 21CFR
Part 1040.20. Tanning facilities are additionally regulated
at the state level. In North Carolina, tanning facilities are
regulated by the Department of Health and Human Services, Radiation
Protection Section per 15A
NCAC Section .1400. Visit the North Carolina
Tanning Program
website for more information regarding the regulation of tanning facilities
in North Carolina.
There is no Occupational
Safety and Health Administration (OSHA) standard for exposure to
ultraviolet light, but the National Institute for Occupational Safety and
Health (NIOSH) recommends that the time of exposure to an intensity of 100
microwatts per square centimeter at wavelength 254 nanometers not exceed 1
minute. When averaged over an eight-hour work day, this value is 0.2
microwatts per square centimeter.
International Perspective:
See a summary of international policies in the IARC/WHO report
on Exposure to Artificial UV Radiation Appendix: European and
international positions regarding artifical
sources of UV radiation
Scientific/Medical:
Ultraviolet light can cause burns to skin, skin damage,
premature aging, melanoma, and other types of skin cancer. It can also
cause cataracts and other types of damage to the eyes. UV light can
be particularly hazardous because there are usually no immediate symptoms
of overexposure. The Center for Disease Control (CDC) warns of the effects
of exposure to ultraviolet radiation on their CDC
UV Information page.
UV-A and UV-B are technically non-ionizing, but all UV
wavelengths can cause photochemical reactions that to some extent mimic
ionization. For example, ultraviolet light, even in the non-ionizing range,
can produce free radicals that induce cellular damage and can cause skin
cancer. UV radiation is characterized by the International Agency of
Research on Cancer (IARC) as a known human carcinogen.
The World Health Organization and International Agency of
Research on Cancer published a report in 2006, WHO/IARC
Exposure to Artificial UV Radiation and Skin Cancer.
The WHO/IARC press release for this report states, "combined analysis of over 20 epidemiological studies
shows that the risk of cutaneous melanoma is increased by 75% when the use
of tanning devices starts before age 30. There is also sufficient evidence
of an increased risk of ocular melanoma associated with the use of tanning
devices. Studies in experimental animals support these conclusions and
demonstrate that ultraviolet radiation (UVA, UVB, and UVC) is carcinogenic
to humans. These findings reinforce current recommendations by the
World Health Organization to avoid sunlamps and tanning parlours
and to protect yourself from overexposure to the sun."
Additional Information on UV-A, UV-B, and the effects of artificial tanning
from the World Health Organization
NTP
2000 Report on
Carcinogens, Ultraviolet Section:
Minimize Your Risk:
Skin specialists recommend that people protect the skin from both kinds of
ultraviolet radiation (UV-A and UV-B). You can do this by:
*
Not using indoor tanning devices. FDA
Consumer Update
*
Not allowing your skin to burn.
*
Minimizing outdoor activities between 10 am and 2 pm.
*
Wearing a full brim hat with brim at least 7 cm.
*
Using sunscreen with SPF of 30.
*
Wearing tightly woven shirts/blouses (dark blue was best
in some studies) or, if using clothing with assigned UV protection factors
(UVP), by using 50+.
*
Getting Vitamin D from safe sources (food, supplements).
How much UV radiation you are exposed to outdoors depends on a number of factors including time of day, time of year,
latitude, altitude, and weather conditions. The Environmental
Protection Agency explains how these factors affect the UV Index Tool which can be used to determine
your risk for UV exposure at any give time and
location.
A number of different medications, supplements, cosmetics, and
foods can make you more sensitive to the effects of UV radiation.
Click here for a list of photosensitizing
agents.
Professional Resources:
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