The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Lead test results on unglazed quarry tile and travertine tile

yankeedave's picture

Lead test results on unglazed quarry tile and travertine tile

I metioned this in a couple of threads and I know some people were interested in the results, so I'll put them here. I bought two tiles at a tile shop, an unglazed quarry tile and an "unfilled" travertine tile, and had them tested for lead. The results show 1.03 mg/kg lead for the quarry tile, and <0.662 mg/kg for the travertine.

Now I haven't yet determined the implications of those numbers as far as food safety is concerned, and the lab is not in the business of making those kinds of judgments or recommendations, so if anybody has any thoughts on those numbers, please weigh in.

blaisepascal's picture

I wouldn't eat the tile, at least.  According to a CDC site, allowable lead content varies.  In playground soils, lead content is limited to 400ppm, which would nearly 400 times the lead content of your quarry tile.  Another site had a case study of a group of ill children attributable to lead-contaminated Indian spices in the 1ppm range (about the same as your tile).  

How the experience of cooking with spices with 1ppm lead relates to cooking on the surface of a unglazed tile with a bulk level of 1ppm lead I'll let others weigh in.

yankeedave's picture

Yes, that works out to about 1 ppm. Lead in paint right now is limited to 600 ppm, and uncontaminated soil is <50 ppm. Assuming that leaching, if any, would result in far lower levels of lead being transferred to the dough, the risk seems almost nonexistent.

yankeedave's picture

I agree about Lowe's and Home Depot. The ones I've been to don't carry it and never have.

bonnibakes's picture

When I lived in New Bern, NC (1990-99) I bought unglazed quarry tiles that were thicker than the traditional thin ones (which they also carried) for under $1 each. They've been lining my ovens since then. I've closed by bakery/cafe and am thinking of taking the tiles out of the commercial convection oven before I sell it.

Caperchick's picture

Another concern I have regarding lead in tiles, is how lead reacts to high temperatures in the oven. Would there be a certain amount of lead released into the air when the tiles are heated?

Does anyone know if there is a way to test the lead content in older ceramic baking bowls? I've collected some over the years but am leary about using them for my doughs.

Mini Oven's picture
Mini Oven

:)   for info

yankeedave's picture

I don't think that heat alone releases lead "into the air." You need contact between the tiles or bowl and the bread or whatever you're baking, some moisture, and from what I've read, acidity to leach out the lead. But if you're baking in these bowls, some of those conditions may be met, so personally I wouldn't use them if I wasn't sure about their lead content. I don't think there's any way to test them without damaging them, though. With my tiles they had to grind up a little bit and test the powder.

Hank Gurdjieff's picture
Hank Gurdjieff

I'm thinking of picking up some quarry tiles for bread and pizza baking, saw this thread, and then found the following:

The Center for Environmental Health in Oakland, CA, offers free lead testing. You only have to mail in (or drop off, if you're nearby) a small chip of tile and they'll test it and send you the results. They're local, so once I get around to getting some tiles I'll have them tested and post results but it seems there are many colors/sources of tiles and content will surely vary. 

Hmm, lead - I wonder if lead paint is why I keep finding my dog licking the wall with a far-off, dumb look on his face...

dabrownman's picture

before sliding in the oven with a peel.  No leaching with parchment if you discount the silicone in the parchment :-0

yankeedave's picture

One of the experiments I keep meaning to do is to bake two bread loaves, on tile or a stone, side by side, one with parchment, the other without. When I use parchment, I usually slide it out halfway through the baking process, but even so, it seems to me that when I use parchment, the bottom doesn't get quite as charred. Maybe that's just a subjective perception. And it's not necessarily a bad thing, but if you're using a stone or tile, presumably you're looking for charring. And once the bottom is dry, I think leaching becomes much less of an issue, because it's the water that acts as a medium for the transfer of lead.