Don Jung on wed 8 apr 98
A while back I sent out a pretty old chart which I felt should be
updated.
Well I'm finally getting around to sending it out...here's an updated
version
compiled mostly from Michael McCann's 1991 edition of 'Artist Beware'.
Please feel free to correct this list as these things seem to change and
update
constantly.
regards,
Don Jung
in Vancouver BC... but soon to be in Italy :)
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Toxicity Ratings for Ceramic Materials
Toxicity ratings are determined by the effect of a substance on the
individual. The following chart lists ceramic materials and gives their
toxicity rating.
EXTREME TOXICITY: ET: Material causes major, possibly life threatening
damage.
HIGH TOXICITY: HT: Material causes major permanent or temporary damage
or disability.
MODERATE TOXICITY: MT: Material causes minor permanent or temporary
damage or disability.
SLIGHT TOXICITY: ST: Material causes illness which is reversible..
LOW TOXICITY: LT: Material is only toxic under abnormal conditions.
Materials are taken into the body:
-through the skin (based on normal contact with bare skin),
-through inhalation (repeated long term exposures to normal amounts;
like
years of breathing clay dust) and
-through ingestion (swallowing), based on probable oral lethal dosage
for
a 150lb adult (E< 1 teaspoon, H< 1 ounce, M< 1 pint or lb, S< 1 quart or
2.2 lbs, L> 1 quart or 2.2 lbs).
Extreme and abnormal exposure to any material such as contact through
burned or abraided skin or inhaling large amounts are not represented in
the chart and will likely result in serious harm. Ingestion in any
quantity of High or Extreme Toxicity materials or those noted with
asterisks (* ** ***) should be avoided.
Note: The ingestion toxicity levels are based on a probable lethal oral
dosage, not on repeated (chronic) ingestion of small amounts(such as
materials leached from a weak glaze). Leaching of any material is
undesireable but special attention should be paid to the (*) marked,
Extreme, High and even Moderate Toxicity materials. Many of these
materials are not easily eliminated by the body and end up accumulating
over time.
TOXICITY TABLE
CERAMIC MATERIAL SKIN INHALATION INGESTION
TOXICITY TOXICITY TOXICITY
ALBANY SLIP ST HT LT
ALUMINA HYDRATE LT MT LT
ANTIMONY * MT HT HT
ASBESTOS ** ST ET HT
BARIUM CARBONATE ST HT ET
BENTONITE ST HT LT
BONE ASH ST ST ST
BORON/BORAX ST MT MT
CADMIUM ** LT ET ET
CHROMATES * *** HT ET ET
CHROME OXIDE / GREEN CHROME * ST MT MT
CHROME YELLOW (LEAD CHROMATE) *** HT ET ET
CLAY ST HT LT
COBALT CARBONATE * ST HT HT
COBALT OXIDE * ST MT MT
COLEMANITE / GERSTLEY BORATE ST MT MT
COPPER CARBONATE ST MT HT
COPPER OXIDE ST MT MT
CRYOLITE MT HT ST
DOLOMITE LT LT LT
FELDSPARS ST HT LT
FIRE CLAYS ST HT LT
FLINT / SILICA LT HT LT
FLUORSPAR MT HT MT
IRON CHROMATE ** HT ET ET
IRON OXIDE (RED & BLACK) LT LT LT
KAOLIN LT MT LT
LEAD BISILICATE *** LT HT HT
LEAD CHROMATE *** HT ET HT
LEPIDOLITE MT HT MT
LITHIUM CARBONATE MT MT MT
MAGNESIUM LT LT MT
MANGANESE LT HT HT
NEPHELINE SYENITE ST HT LT
NICKEL OXIDE ** MT HT~ET HT
PETALITE ST HT LT
POTASH MT HT HT
PUMICE LT HT LT
RUTILE LT LT LT
SODA ASH MT HT MT
SODIUM SILICATE MT MT ST
STRONTIUM CARBONATE LT ST ST
TALC LT HT HT
TIN OXIDE ST ST LT
VANADIUM OXIDE MT HT ET
VERMICULITE (~high if contaminated w/ asbestos) LT ST~HT ST~HT
WHITE LEAD *** LT HT HT
WHITING (CALCIUM CARBONATE) LT LT LT
WOLLASTONITE ST ST ST
ZINC OXIDE LT ST ST
ZIRCONIUM ST MT ST
* Possible or probable carcinogen: may cause cancer in humans
** Carcinogen: known to cause cancer
*** Mutagen: causes mutation
For Further information , Read: "Artist Beware", Michael McCann.
This table has been updated from the 1991 edition.
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So what does all this mean to you?
Here are some guidelines for beginners / students to follow until
they've
learned enough to make their own assessment of the risks.
* Unless you are making glazes and handling the chemicals, you probably
won't come into direct contact with any of the Moderate, High or Extreme
toxicity materials. When working with chemicals, always wear an
appropriate dust mask and gloves and in an area with an extraction fan
or vent.
* You should avoid getting underglazes, glazes and other colorants on
your skin. If you do, wash them off with water. Plain old clay is not
a problem.
* Avoid inhaling or creating any and all dust. Work with clay that's
wet or leather hard. Do not scrape or trim dry clay. If you want to
work with it again, get it wet, use a water spray, put a wet cloth on it
and wrap it tightly for a little while.
* Always wet wipe or wash all clay and glaze splatters, splashes and
spills. Wet mop counters, floors and surfaces instead of dry sweeping
which creates dust.
* Don't taste any pottery materials and avoid food and drinks in the
studio. No smoking is permitted.
* Don't handle clay, glazes and materials with cuts or wounds that may
come into contact with the materials.
* If you are making functional pottery that comes into contact with food
or drinks, here are some things to keep in mind.
* A glossy clear or white 'liner' glaze is the best glaze to use for
food contact surfaces. Try to use no Extreme, high or even moderate
toxicity (ingestion) materials in the clear or white glazes.
* All glazes should be free of lead and cadmium .
* Dark glazes (black, dark blue, dark green, dark purple) have higher
amounts of oxides and colorants. Lighter colors are more suitable for
food contact surfaces with fewer oxides that can leach.
* The browns, rust and tans are OK unless marked 'Not Food Safe'. These
usually contain iron, albany and/or rutile which are of low toxicity
when ingested.
* Glazed surfaces should be free of crazing, cracks, crawling (bare
spots), pin holes and cover the entire food contact surface so it won't
trap bacteria or cause a cut.
* Glossy glazes are safer than matt for food contact and easier to clean
as well.
* Multiple or mixed glazes are not advisable for food contact surfaces,
especially with the dark glazes.
* Underglazes, slips and stains are generally OK if applied correctly
and completely covered with a sufficient coating of clear glaze.
* Onglaze and Majolica decoration should be done away from the surface
that contacts food/drink.
* Leaching is much more likely to happen with liquids such as orange or
apple juice, tomato sauce etc. Dry foodstuffs like nuts, cookies etc.
are not as likely.
* If at all in doubt, don't use it, ask questions, do some research
and/or take it to a lab for testing.
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