Bastarache fills us in on the dangers of cadmium in the making
of ceramics. The toxicology of ceramic materials is often underestimated
and sometimes neglected in our ceramics institutions. Many thanks to Edouard
for this contribution to ceramic toxicolgy.
- cadmium oxide
- cadmium carbonate
- cadmium chloride
- cadmium sulfate
- cadmium sulfide
The metal is used in electroplating, in solder for aluminium, as a constituent
of easily fusible alloys, as a deoxidizer in nickel plating, in process
engraving, in cadmium-nickel batteries, and in reactor control rods. Cadmium
compounds are employed as TV phosphors, as pigments in glazes and enamels,
in dyeing and printing, and in semi-conductors and rectifiers.
The important thing is your level of exposure to cadmium, 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 the wet state, these compounds are certainly much less hazardous
than as dust ( route of entry being inhalation). Factories can afford the
monitoring of cadmium exposure but it is not the same for artists and craftpersons.
So good housekeeping 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 is mandatory.
- Cadmium oxide fume is a severe pulmonary irritant; cadmium dust is
a less potent irritant than cadmium fume because it has a larger particle
size. Chronic exposure is associated with nephrotoxicity. Several inorganic
cadmium compounds cause malignant tumors in animals.
- Inhalation exposure to high levels of cadmium fumes or dust is intensely
irritating to respiratory tissue. Particle size appears to be a more
important determinant of toxicity than chemical form. However, most
acute intoxications have been caused by inhalation of cadmium fume at
concentrations that did not provide sufficient warning symtoms of irritation.
Concentrations of fume responsible for fatalities have been 40 to 50
mg/m3 for 1 hour or 9 mg/m3 for 5 hours. There has been non-fatal cases
at lower concentrations. Pulmonary symptoms and clinical signs reflect
lesions ranging from nasopharyngeal and bronchial irritation to pulmonary
edema with also possibly headache, chills, muscle aches, nausea, vomiting,
and diarrhea. Among survivors, the subsequent course is unpredictable;
most cases resolve slowly, but respiratory symptoms may linger for several
weeks, and impairment of pulmonary function may persists for months.
- Long-term inhalation exposure at low levels leads to decreased lung
function and emphysema.
- Chronic exposure to cadmium results in renal damage which may continue
to progress even after exposure ceases.
- Other consequences of cadmium exposure are :
- yellow discoloration of the teeth
- occasional ulceration of the nasal septum
- damage to the olfactory nerve
- Chronic exposure to high levels of cadmium in food has caused bone
disorders, including osteoporosis and osteamalacia. Long term ingestion,
by a Japanese population, of water and food contaminated with cadmium,
was associated with a crippling condition, "itai-itai" (ouch-ouch)
disease. The affliction is characterized by pain in the back and joints,
osteomalacia (adult rickets), bone fractures, and occasional renal failure,
and most often affects women with multiple risk factors such as multiparity
and poor nutrition.
- Occupational exposure to cadmium has been implicated in a significant
increase of lung cancer. The IARC has determined that there is sufficient
evidence in humans for the carcinogenicity of cadmium and cadmium compounds.
It also appears that cadmium has the capability to alter genetic materials,
- The 1995 ACGIH threshod limit value-time-weighted average (TLV-TWA)
for elemental cadmium and compounds as Cd is 0.01 mg/m3 for total particulate
dust (while it is 10mg/m3 for titanium dioxide in Quebec); or 0.002
mg/m3 for the respirable fraction of dust,there is an A 2 suspected
human carcinogen designation for both forms.
- The urinary excretion of cadmium itself bears no known relationship
to the severity or duration of exposure and is only the confirmation
of absorption.Absorbed cadmium is retained in the body to a large extent,
and excretion is very slow.
Reference :Chemical Hazards of the Workplace, Proctor
& Hughes, 4th edition.
Edouard Bastarache M.D. (Occupational & Environmental Medicine)