| Chromium for Potters
 hromium
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 (Cr203)
which is green chromium oxide, chromic sulfate, chromic chloride,
chromic potassium sulfate, and chromite ore. Green chromium 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 govt. 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:
- Chemical Hazards of the Workplace, Proctor & Hughes.
- Dangerous Properties of Industrial Materials, Sax & Lewis.
- Hazardous Materials Toxicology, Sullivan & Krieger.
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