Warning: That old pottery site I was digging near Santa Fe tested positive for arsenic

I was reading through some soil reports from a dig up near the Pajarito Plateau last week. Turns out a lot of the ancient cooking vessels from that area have heavy residue of arsenic in the clay. I always thought it was just lead in the glaze that was dangerous, but this was in the raw material itself. The EPA threshold for soil is like 0.11 parts per million. These pots had 15 ppm. Has anyone else run into toxic elements in undisturbed sites like this?

2 comments

2 Comments

walker.robert6d ago

Read the same study those numbers came from. The 15 ppm is in the clay matrix itself, not bioavailable. Lab tests show it leaches at less than 1% even under acid conditions. Handling dry sherds is basically zero risk unless you're grinding and eating the dust. Totally different from lead glazes that actually transfer into food.

hill.barbara6d ago

Yeah but what about kids who pick up old pottery shards on hikes and then touch their faces or eat snacks without washing up first? Seems like a lot of trust in "less than 1%" leaching when we're talking about trace amounts building up over years.