Edouard Bastarache Inc. on thu 21 oct 04
Hello Ron,
here is the score on this issue, green chromium oxide used by=20
potters is trivalent
a-Exzematous Dermatitis (Allergic Contact Dermatitis) :
=20
This clinical entity is characterized by erythematous, or =
vesico-papular,=20
wet, pruriginous lesions localised especially on the forearms (chromium =
bracelets).=20
It is very frequent among individuals in contact with cement.=20
In practice, only chromium hexavalent compounds are sensitizers.=20
Hexavalent chromium can penetrate the skin where it is reduced to=20
trivalent chromium which plays the role of an hapten; when fixed=20
on a protein, it becomes a complete antigen.
Chromate sensivity has proved fairly persistent once developed.=20
In one study, 92% of the study patients with dichromate sensivity=20
induced by exposure to Portland cement continued to display contact=20
dermatitis 10 years after initially developed symptoms.
Once induced, chromate sensivity may produce difficulty in multiple=20
settings.
Contact with textiles colored with chromate-based pigments can be=20
sufficient to exacerbate the dermatitis. The wearing of leather shoes=20
tanned with chromates can produce dermatitis of the feet if these=20
are allowed to remain sweaty. =AB Housewife exzema =BB may be=20
largely a chromate sensitivity phenomenon, as detergents and bleaches=20
in some areas contain more than trace amounts of chromate salts
In sensitized individuals, the absorption of chromium by pulmonary=20
and/or oral way could cause an exzematous reaction.=20
=20
Trivalent chromium only penetrates with much difficulty into the=20
skin and the risk of sensitizing is thus weak. Chromium metal is=20
not in theory an allergen=20
=20
The allergy to chromium is confirmed by skin patch testing.=20
Some authors claim that the measurement of urinary chromium=20
allows to confirm the occupational origin of dermatitis in tanners.
=20
b-Chrome ulcers :
=20
After cutaneous exposure to chromic acid, erosions of the skin may=20
occur. These =AB chrome holes =BB initially appear as papular lesions ,=20
either singly or grouped, with central ulceration. They occur chiefly=20
on the hands and forearms where there has been a break in the=20
epidermis; they are believed to be due to a direct necrotizing effect=20
of the chromate ion. These ulcers are from 5 to 10 mm in diameter,=20
painless, with sharp edges, sometimes itchy and have the possibility=20
of extending into joints; they heal slowly and produce a characteristic=20
depressed scar.
These ulcers are observed mainly among workers of the electrolytic=20
chromium plating industry.
References :
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1-Occupational Medicine,Carl Zenz, last edition.
2-Clinical Environmental Health and Toxic Exposures, Sullivan & Krieger; =
last edition.
3-Sax's Dangerous Properties of Industrial Materials, Lewis C., last =
edition.
4-Toxicologie Industrielle et Intoxications Professionnelles, Lauwerys =
R. last edition.
5-Chemical Hazards of the Workplace, Proctor & Hughes, 4th edition.
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Occupational skin disease in the construction=20
industry.
Bock M, Schmidt A, Bruckner T, Diepgen TL.
Department of Clinical Social Medicine, Centre of Occupational=20
and Environmental Dermatology, University of Heidelberg,=20
Thibautstrasse 3, D-69115 Heidelberg, Germany.(2003)
(...)
CONCLUSIONS: The results indicate that potassium dichromate=20
is still the most important allergen in the construction industry of=20
Northern Bavaria; there has been no significant decline during the=20
1990s. This contrasts with the Scandinavian countries, where the=20
prevalence of potassium dichromate sensitization declined following=20
the reduction of chromium VI levels resulting from the addition of=20
ferrous sulphate to cement. Within the construction industry,=20
tile setters and terrazzo workers have a strikingly high incidence=20
of OSD.
Potassium is a soluble hexavalent chromium compound, which confirms=20
my text above.
Later,
"Ils sont fous ces quebecois"
Edouard Bastarache
Irreductible Quebecois
Indomitable Quebeker
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
www.sorel-tracy.qc.ca/~edouardb/Welcome.html
http://perso.wanadoo.fr/smart2000/index.htm
http://www.digitalfire.com/education/toxicity/
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