June Perry on sat 13 mar 99
Dear Monona:
Thanks for your input. I did finally download the pdf file from the epa on
barium toxicity. The bottom line after perusing 50 pages of info on rat and
human testing (admiteddly, rather quickly), was that it appears that they
don't seem to think it's important enough to warrant full testing. The couple
of human tests done were determined to be inconclusive because, as in one
instance, 35 test subjects was determined to not be a large enough group to
warrant them coming to conclusions on the test!
It does appear, after reading the file that the greatest danger appears to be
in inhaling it. There was some association with hypertension, some heart, lung
and kidney difficulty, but these were all based it seems on mega exposure, and
seemed to abate when exposure was removed.
I was amazed to find that some natural water supplies have very large amounts
of barium in them as do some foods like brazil nuts (150-300 mg/100g). Some
drinking water listed as high as 10,000vg/L (not sure what this figure
represents. I assume the L is for liter and don't know what the vg is.
They went on to say the the range was equivalent of 4-250mg Ba/kg a day,
assuming a 70 k adult body weight. The range of these 2 sources is .004 to
..026 mg Ba/kg a day. I wish someone could tell us based on some of the epa's
figures how much barium one could safely ingest on a daily basis. Also, how
long does it stay in the system? I've heard that the body releases it. How
long does it take to do that?
In one of the studies on 35 Japanese who had died of a heart problem
associated with barium, they found barium in their rib bones. Well if it
doesn't stay in the body, then what was it doing in the bones???? They also
didn't find the source of the barium contamination in the 35 subjects. I could
only wonder if it was from those wonderful barium oribe glazes! They did
determine that the tests was inconclusive because they didn't have enough
people in the study. Bottom line is that they haven't done a lot of human
testing on barium.
They list studies done with workers who would be inhaling the material, but
again, the study was inconclusive because the workers were dealing with other
materials as well as barium.
Unless I read that report wrong, and there's always the chance that I didn't
fully grasp the technical information, barium risks under normal usage and
common sense, will not pose any great risks to a potter or their customers if
proper precaution is taken in the studio and in glaze formulation.
Basically the risks listed were hypertension, some heart difficulties and some
kidney problems; but it seemed that most of these were less acute when, I
think they said, potassium or calcium was ample in the system. I forget which
at the moment.
If anyone wants to read the report, it is available on line at the epa site. I
just typed "barium toxicity" in the Metacrawler web search line and a list of
articles came up.
Warm regards,
June
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