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.
- 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(Lou Gerhig's disease) and progressive
lenticular degeneration(Wilson's disease).
- Toxicity to the lungs is manifested as increased susceptibility
to 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. 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 for proposing
a a blood standard for manganese. 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 or 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.
- Occupational Medicine, Carl Zenz, last edition.
- Occupational & Environmental Medicine, Joseph LaDou, last edition.
- Chemical Hazards of the Workplace, Proctor & Hughes, last edition.
- Industrial Chemical Exposure, Lauwerys & Hoet, last edition.
Many thanks to Edouard
Bastarache for this further contribution to ceramic toxicolgy.
Ceramic Toxic Materials
Related Articles on Toxicity of Materials by Edouard Bastarache
- A compelling article about manganese poisoning by Elke Blodgett.
Anyone working with manganese should read this.