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Chromium for
potters
Chromium can
have a valence of 2, 3, and 6. Chromium compounds vary greatly
in their toxic and carcinogenic effects.For this reason ACGIH
divides chromium and its inorganic compounds in a number of groupings.
Group #3 is
« Trivalent chromium compounds »
(Cr3+)(chromic compounds) :including chromic oxide (Cr2o3) which
is green chromic oxide, chromic sulfate, chromic chloride, chromic
potassium sulfate, and chromite ore.
Green chromic
oxide is the one i use and i think it is the same for all of
potters; the nastiest being hexavalent chromium in group #4,
i do not think governement officials would let us use the latter.
So what applies
is the toxicology of trivalent compounds.
Routes of Absorption
: Chromic salts are minimally absorbed following inhalation.Trivalent
chromium salts are generally poorly absorbed through intact skin,
once the dermal barrier is broken, however, absorption may occur.
Trivalent chromium salts are absorbed following ingestion, but
only 1-25% of the dose ingested is absorbed.
Toxicity :
There is little evidence of significant toxicity from chromic
salts, probably because of poor penetration of skin and mucous
membranes.Dermatitis from chromic salts has been reported.
The lungs of
some workers exposed to chromite dust have been shown to be the
seat of
pneumoconiotic changes consisting of slight thickening of interstitial
tissue and alveolar septa, with histological fibrosis and hyalinisation.
A refractory plant using chromite ore to make chromite brick
had no excess of lung cancer deaths over a 14-year period.
Inhalation of trivalent chromium salts can cause occupational
asthma.
The IARC(International
Agency for Research on Cancer, Lyon ,France) has determined that
there is inadequate evidence in humans and animals for the carcinogenicity
of metallic chromium and trivalent chromium compounds(III).
Trivalent compounds,
do not appear to cause other effects associated with the hexavalent
chromium compounds, such as chrome ulcers (hands and forearms),
irritative dermatitis, nasal septal perforation, lung cancer,
etc.
Edouard Bastarache
M.D.(Occupational & Environmental Medicine)
Author of « Substitutions for raw ceramic materials »
edouardb@sorel-tracy.qc.ca
http://www.sorel-tracy.qc.ca/~edouardb/
References
:
1-Chemical
Hazards of the Workplace, Proctor & Hughes.
2-Dangerous Properties of Industrial Materials, Sax & Lewis.
3-Hazardous Materials Toxicology, Sullivan & Krieger.
Below
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(edouardb@sorel-tracy.qc.ca) on Friday, September 10, 1999 at
21:47:19
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Manganese
& compounds
Manganese compounds used by potters
are inorganic , like manganese dioxide, oxide
and manganese carbonate; they do not penetrate the body via the
skin as compared to some organic compounds.
Metallic applications account for
most manganese consumption, with about 90% used in steelmaking.
Manganese is an essential mineral
for humans and animals. It is necessary for normal bone formation.
It has been estimated that a normal 70-kg man has a total of
12mg to 20 mg in his body.
Inhalation of dust or fume is the
major route of entry in occupational manganese poisonning. Also
inhaled large particles are ingested after mucociliary clearance
from the lungs. Gastrointestinal absorption is generally low
(10%). Very few poisonings have occured after ingestion. Tricarbonyls
(organic) of manganese can be absorbed by the skin. The primary
target organs of manganese toxicity are the brain and the lungs.
1-Neurological symptoms (chronic
manganese poisoning) are caused by inhalation of fumes or dusts
of manganese. Exposure to heavy concentrations of dusts or fumes
for as little as three months may produce the condition, but
usually cases develop after 1-3 years of exposure. The symptoms
may simulate progressive bulbar paralysis, postencephalitic Parkinsonism,
multiple sclerosis, amyotrophic lateral sclerosis and progressive
lenticular degeneration(Wilson's disease).
2-Toxicity (acute) to the lungs
(inhalation) is manifested as increased susceptibility to acute
bronchitis or, in more severe cases, manganic pneumonia.
According to Robert R. Lauwerys
( probably the best occupational toxicologist in the world) in
"Toxicologie Industrielle et Intoxications Professionnelles,
1999", the best way to diagnose, at an early stage, manganese
intoxication is neurological examination. A standardized questionnaire
of neurological symptoms is helpful.
Here are the symptoms to be looked
for in chronic manganese intoxication:
-nervousness
-irritability
-memory loss
-tiredness
-insomnia
-muscle weakness
-muscle pain
-trembling fingers
-stiffness of limbs
-difficulty with fine movements
-stuttering
-hoarse voice
-urinary problems
-impotence.
At physical examination your doctor
should look for signs of an extra-pyramidal syndrome at its beginning.
Workers exposed to manganese should
have a medical examination every 3 to 6 months (Shunk; Tanaka
et Lieben). Experts still differ about the precision of urinary
and/or blood
measurements of manganese as good indicators of exposure and
intoxication. Among workers kept away from their job on a temporary
basis, and from exposure to manganese dioxide, a good correlation
was observed between urinary and blood levels and the index of
cumulative exposure, on an individual basis(Lucchini and al.).
A correlation was also found between these tests and different
neurobehavioral tests.
But let us not forget that human
data are insufficient yet for proposing aa blood standard for
manganese. Tanaka & Lieben however observed a correlation
between the urinary excretion and the intensity of the exposure
and japanese authors suggested that manganese excretion higher
than 40-50 micrograms/liter corresponds to an exposure where
lesions can occur (Horiuchi & al.) .
Best thing to do is to treat a patient
not a lab test (an old saying in medicine).
I have heard of 2 cases of Parkinson
-like syndrome among unskilled workers making clays and glazes
for a local pottery supplies store (Montreal) that happened in
the 70's and 80's before Quebec passed its laws in Occupational
Health and Safety (I was personnally involved in this process).
The important thing is your exposure
to inorganic manganese, it may vary if you are a pottery factory
worker, a teacher, a full-time studio potter or a part-time.
It certainly depends also on the amount used over a given period
of time in clays and glazes.
In the wet state, as in moist clays and glazes, these compounds
are certainly much less hazardous than as dust.Factories can
afford the monitoring of manganese exposure but it is not the
same for artists and craftpersons.
So good house keeping of your studio
is important. Avoidance of processes generating unnecessary dust
is also important, and the wearing of an approved dust mask when
the exposure seems hazardous.
Edouard Bastarache
M.D. (Occupational & Environmental Medicine)
Author of « Substitutions for raw ceramic materials »
edouardb@sorel-tracy.qc.ca
http://www.sorel-tracy.qc.ca/~edouardb/
REFERENCES
1-Occupational Medicine, Carl Zenz, last edition.
2-Occupational & Environmental Medicine, Joseph LaDou, last
edition.
3-Chemical Hazards of the Workplace, Proctor & Hughes, last
edition.
4-Industrial Chemical Exposure, Lauwerys & Hoet, last edition.
Below
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(edouardb@sorel-tracy) on Friday, September 10, 1999 at 21:42:01
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COPPER &
COMPOUNDS
Copper is a
metal used as an alloy in brass and bronze, as a component in
some solders, in pigments such as emerald green, in ceramic glazes,
and as a salt in the lithographic process.
Copper is an
essential metal and the daily requirement has been estimated
at 30 micrograms/kg of body weight for an adult. The normal concentration
of copper in blood plasma is 1 mg/liter. The gastrointestinal
absorption of soluble copper is regulated by the need and is
usually around 50%; uptake may also take place after inhalation.
Elimination of copper is slow and takes place via bile.
The chronic
accumulation of copper in the body is rare and occurs in Wilson's
disease caused by an inborn error of the copper metabolism characterized
by a diminished capacity to eliminate copper via bile.This leads
to secondary lesions in the liver and the brain. The salts are
irritants to the skin, eyes,and mucous membranes. Ingestion of
copper salts may cause vomiting, diarrhea, hemorragic gastritis,
and excessive salivation.
Copper sulfate has clinically (medicine) been used as an emetic.
Vineyard sprayers using a solution containing aqeuous copper
sulfate developed granulomatous and fibrotic lung lesions.Liver
granulomatas containing copper have also been found in vineyard
sprayers.Clinical liver disease is usually not significant, but
liver granulomas occasionally result in hepatomegaly, necrosis
and fibrosis. Experimental studies in mice support that copper
is an etiologic(cause) for lung fibrosis.
Inhalation
of copper dust and fume results in irritation of the respiratory
tract, ulceration and perforation of nasal septum, metallic or
sweet taste, and in some instances, discoloration of the skin
and hair.The inhalation of metal fumes produced at high temperature,
such as welding, may cause "metal fume fever", an influenza-like(benign)
illness.
Copper sulfate
is also used in the whitewashing and leather industry.Toxicity
is primarily due to accidental and suicidal attempts, and results
in intravascular hemolysis, methemogloninemia, renal failure
and often death.
Remember clinical
liver disease due to copper is not usually significant.
High copper
content in drinking water and food may contribute to the development
of severe liver damage in infants.
Copper compounds
used by potters are not considered hazardous as well as for pottery
users.Copper in glazes fluxed by lead compounds will leach more
lead.
Good studio
housekeeping is always good practice. Avoidance of processes
generating unnecessary dust is also important and the wearing
of an approved dust mask when the exposure seems hazardous is
also good practice.
Edouard Bastarache
M.D. (Occupational & Environmental Medicine)
Author of « Substitutions for raw ceramic materials »
edouardb@sorel-tracy.qc.ca
http://www.sorel-tracy.qc.ca/~edouardb/
REFERENCES
1-Occupational Medicine,Carl Zenz, last edition.
2-Occupational & Environmental Medicine,Joseph Ladoue, last
edition.
3-Hazardous Materials Toxicology, Sullivan & Krieger; last
edition.
Hazardous Materials Used in Arts and Crafts,chapter 60,
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