trioxide (MoO3) is used in ceramics as a colorant to produce
yellowish and yellow green colors.
is obtained from such ores as:
uses of molybdenum include:
such as its use in alloys;
a catalyst for the chemical industry;
commonly occurs during the liberation of dust from mining and
the processing of ore, from the grinding of metals or alloys,
from oxyacetylene cutting, and from dust from its various compounds.
A-Insoluble molybdenum compounds include:
B-Soluble compounds include:
molybdate dihydrate (Na2MoO4-2H2O).
II-Routes of Exposure:
to molybdenum and related compounds usually occurs via inhalation
of dust. If these compounds are water-soluble, absorption is
increased, and toxicity may be greater than that from non-water-soluble
absorption is approximately 50% of an ingested amount and depends
on the water solubility of the compound involved.
Metabolism, and Elimination:
is present in humans, with an average adult content of 9 mg.
whole blood levels average approximately 5 ng per ml.
is contained principally in:
than 50% of molybdenum is excreted primarely through the kidneys.
Approximately 6% is excreted through the bile when excess molybdenum
products may cause toxicity in humans, but adequate studies
reporting such effects are lacking.
high prevalence of articular effects in Armenian villages was
associated with a significant ingestion of molybdenum, which
caused a disorder of the metabolism of uric acid.
involved in producing molybdenum oxide have demonstrated a higher
skin and hair changes.
trioxide may cause irritation to mucous membranes (eyes, nose,
to molybdenum dust causes an increase in serum uric acid and
are extremely limited in regard to chronic toxicity from molybdenum
and its compounds. Molybdenum may cause a pneumoconiosis in
susceptible individuals, but definitive data are lacking.
V-Management of Toxicity
exposed to hazardous concentrations of molybdenum should be
removed from further exposure. Treatment is symptomatic, and
no specific therapy is available for removal of molybdenum from
tissues. Treatment of joint complaints is supportive.
1-Medical and Biological
measurements of serum and urinary molybdenum levels may be performed,
but levels do not correlate with signs and symptoms. Serum uric
acid and ceruloplasmin may be elevated.
of exposure is the mainstay in preventing toxicity, including
good process enclosures with general dilution ventilation and
local exhaust ventilation. NIOSH and OSHA recommend that workers
exposed to insoluble molybdenum compounds wear personal protective
equipment designed to limit dust, mist, or fume inhalation.
exposed to soluble compounds need impervious clothing, gloves,
face shields, and other appropriate clothing as necessary to
prevent skin contact.
no data are available regarding skin effects or clinical effects
from this route of absorption.
Quebec, the VEMP (Valeur d’Exposition Moyenne Pondérée)
compounds: 10 mg/m3 (as Mo)
compounds: 5 mg/m3 (as Mo).
Good house keeping of your studio is very important; to do so you may, among other things, use wet processes, or even a vacuum
system whose air is exhausted outside of the workshop.
Avoidance of processes generating unnecessary dust is also important.
to the severity of exposure, the preventive measures proposed
by NIOSH and OSHA should be applied.
Bastarache M.D. (Occupational & Environmental Medicine)
of « Substitutions for Raw Ceramic Materials »
Environmental Health and Toxic Exposures, Sullivan & Krieger;
Industrielle et Intoxications Professionnelles, Lauwerys R.