search  current discussion  categories  glazes - cone 4-7 

copper in a c6 glaze

updated mon 7 dec 98


Monona Rossol on sun 6 dec 98

Tom Buck wrote:

> The recommended daily allowance for copper compounds in food is 2+
> (3 max) milligrams. So would 3 ppm be a problem? Would that be 3
> milligrams in a Litre? I always get confused with "ppm" quotes.<

Write this on your forehead:

ug/ml = mg/L = ppm.

The standard is 1.3 mg/L in drinking water, based partly on the lousy taste
at this level. Then if the RDA is 2 milligrams of total copper in the
diet, then drinking two liters of lousy tasting water would provide your RDA
and then some without any other source in your food and water.

Only very large doses of copper can kill. There are suicides on record with
copper sulfate in particular.

Copper is a problem for reproduction. It has been used as a spermicide, and
it causes birth defects and developmental problems in animal studies. The
dosages at which this might occur in humans, of course, are not known.
That's why I suggest people stick to the RDAs during pregnancy.

> I gather that excessive Cu ion would be a potential hazard for infants and
> young children (like lead is) but not necessarily for adults. <

I assume children may be more susceptible to copper than adults but I
didn't see anything clear on this. I do know that people with Wilson's
disease would have problems with copper even at the RDA.

> I'd really would like this copper question aired and made clear. <

I don't see what the question is. The RDAs are just in micrograms or
milligrams. The leach tests and water standards in milligrams/liter, so you
have to think about the volume ingested.

Hope this helps.


Arts, Crafts and Theater Safety
181 Thompson St., # 23
NYC NY 10012-2586 212/777-0062