Edouard Bastarache on tue 4 sep 01
Hello Snail,
Injuries Due to Radiation
1-Injuries Due to Ionizing Radiation :
X-rays, beta rays, and other radiation sources in adequate doses can =
cause ocular injury.
A) Lids :
The eyelid is particulary vulnerable to x-ray damage because of the =
thinness of its skin.
Loss of lashes and scarring can lead to inversion or eversion(entropion =
or ectropion)
of the lid margins and prevent adequate closure.
B)Conjonctiva :
Scarring of the conjonctiva can impair the production of mucus and the =
function of the=20
lacrymal gland ducts, thereby causing dryness of the eyes.
C)Lens :
X-ray radiation in a dose of 500-800 R. directed toward the lens =
surface can cause cataract, sometimes with a delay of several months to =
a year before the opacities appear
2-Injuries Due to Ultraviolet Radiation :
A)Cornea :
Ultraviolet radiation of wavelenghts shorter than 300 nm.(actinic rays) =
can damage the corneal
epithelium.This is most commonly the result of exposure to the sun at =
high altitude and in areas
where shorter wavelenghts are readily reflected from bright surfaces =
such as snow, water, and sand.
Exposure to radiation generated by a welding arc can cause welding flash =
burn , a form of keratitis.
B)Lens :
Wavelenghts of 300-400 nm.are transmitted through the cornea, and 80% =
are absorbed by the lens, where they can cause cataractous changes.
Epidemiologic studies suggest that exposure to solar radiation in these =
wavewlenghts near the equator is correlated with a higher incidence of =
cataracts.
They also indicate that workers exposed to bright sunlight in =
occupations such as farming,
truck driving and construction work appear to have a higher incidence of =
cataract than those who work primarely indoors.
Experimental studies have shown that these wavelenghts cause changes in =
the lens protein,
which lead to cataract formation in animals.
3-Injuries Due to Visible Radiation(Light):
Visible light has a spectrum of 400-750 nm. If the wavelenghts of this =
spectrum penetrate fully to the retina, they can cause thermal, =
mechanical, or photic injuries.
A)Thermal injuries:
They are produced by light intense enough to increase the temperature in =
the retina=20
by 10-20C.
Lasers used in therapy can cause this type of injury. The light is =
absorbed by the retinal pigment=20
epithelium, where its energy is converted to heat, and the heat causes =
photocoagulation of retinal tissue.
B)Mechanical injuries:
They can be produced by exposure to laser energy from a Q-switched or =
mode-locked laser,
which produces sonic shock waves that disrupt retinal tissue.
C)Photic injuries:
They are caused by prolonged exposure to intense light , which produces =
varying degrees of cellular damage in the retinal macula without a =
significant increase in the temperature of the tissue.
Sun gazing is the most common cause of this type of injury, but =
prolonged unprotected exposure to a welding arc can also damage the the =
retinal macula. There may be permanent decrease in visual acuity.
The intensity of light, lenght of exposure, and age are all important =
factors.The older ones are more sensitive, also those who have had =
cataract surgery because filtration of light by the lens is impaired.
4-Injuries Due to Infrared Radiation:
Wavelenghts greater than 750 nm. in the infrared spectrum can produce =
lens changes.
La "cataracte des verriers"( glassblower's cataract ) is an example of a =
heat injury that damages the anterior lens capsule. Denser cataractous =
changes can occur in unprotected workers who observe glowing masses of =
glass or iron for many hours a day. Also one factor that is very =
important is the distance between the worker and the source of =
radiation.
So i don't think any of these situations happen during firing pottery, =
the temperature being quite lower than in mild or stainless steel =
melting departments where melters have to wear tinted glasses.
Also if you add all the minutes you are exposed to infrared radiation =
the number is quite lower than in the case of glassblowers and/or =
melters when we speak of duration of exposure
being a major factor.
It is a good thing, at high temperature, to wear tinted glasses to =
better visualize cones.
You may go to a safety supplies store and buy lightly tinted industrial =
grade safety glasses for this purpose. Also, they are thicker and thus =
offer a better protection than typical sun-glasses in case of projection =
of dusts from a gas kiln when looking through the peephole in a soft =
brick door.
Even non-tinted industrial grade protective glasses will help to stop =
non-hazardous infra-red radiation.
Edouard Bastarache
Irreductible Quebecois
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
http://sorel-tracy.qc.ca/~edouardb/
http://www.absolutearts.com/portfolios/e/edouardb/
References :=20
Occupational & Environmental Medicine, Joseph Ladoue & al, last edition.
Fran=E7ois Demay M.D.,Ophtalmologist, Sorel-Tracy ,Quebec,=20
Canada (1998).
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