| Eye Injuries in
Ceramic Practice
by Edouard Bastarache
ye injuries are not something we always consider when practicing
ceramics. They may especially occur over lengthy periods of time
from firing kilns. Unfortunately eye protection is something not
always emphasized enough in schools. I am grateful to Edouard Bastarache
for the use of the text below. * (Also available in French)
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 particularly 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) Conjunctiva :
Scarring of the conjunctiva can impair the production
of mucus and the function of the lachrymal 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 wavelengths 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 wavelengths 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 :
Wavelengths of 300-400 nm. are transmitted through
the cornea, and 80% are absorbed by the lens, where they can cause
cataractous changes. Epidemiological studies suggest that exposure
to solar radiation in these wavelengths 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 primarily indoors. Experimental
studies have shown that these wavelengths 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
wavelengths 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 by 10-20C. Lasers used in therapy
can cause this type of injury. The light is absorbed by the retinal
pigment 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 retinal macula. There may be permanent decrease in visual acuity.
The intensity of light, length 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:
Potters may be exposed to this type of radiation.
Wavelengths 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 among unprotected artists. Denser cataractous changes can
occur in unprotected workers who observe glowing masses of
glass or iron for many hours a day.
Another important factor is the distance
between the worker and the source of radiation. In the case of arc
welding, infrared radiation decreases rapidly as a function of distance,
so that farther than 3 feet away from where welding takes place,
it does not pose an ocular hazard anymore but, ultraviolet radiation
still does. That is why welders wear tinted glasses and surrounding
workers only have to wear clear ones.
Conclusion :
When we speak of type of exposure, potters look at
their cone packs for very short periods of time in a repeated way,
more often nearing the end of firing; and also according to the
use of other methods for measuring temperature, like the concomitant
use of a thermocouple and a reading device. So,
these " short-term " exposures are spaced by
quite longer " exposure-free " periods and the
sum of the former does not correlate with the concept of "many
hours a day".
We have searched the literature pertaining to Occupational
Health and Safety and have not found a single case of presumed " ceramist’s
or potter’s cataract ", even if the trade of potter is
quite older than the one of glassblower. Therefore,
I do not think that any of the above types of radiation present
a threat to potters.
It is a good thing, mainly at high temperature, to
wear lightly tinted industrial grade safety glasses to better visualize
cones (ocular ergonomics) and also to reassure those who are more
worried. These glasses also offer a better protection than typical
sunglasses in case of projection of hot dust particles from a gas
kiln when looking through the peephole in a soft brick door.
By the way with aging, most if not all of us, will
suffer from cataracts of the "senile" type. The progress
or change and the related reduction in vision is usually quite slow.
Nuclear sclerosis-an increasing density in the central mass of protein-causes
a myopic change than can be corrected by changing glasses for some
years-in many instances restoring vision to near normal.
Many thanks to Edouard
Bastarache M.D. (Occupational & Environmental Medicine)
Author of "Substitutions
for Raw Ceramic Materials" for the use of this text.
References :
- Occupational & Environmental Medicine, Joseph
Ladoue & al, last edition.
- Occupational Medicine, Zenz C., last edition.
- Precis de Medecine du Travail, Desoille H., Scherrer
J., Truhaut R., last edition.
- Oshline & Nioshtic database.
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