This is the material safety linked to by shapeway support and their response
"First of all when the material is exposed to great heat (soup or hot pizza) the material would warp and potentially melt."
It's not exactly nylon, it's polylaurinlactam which I don't know enough to say the difference.
In the material safety it says, it doesn't break down into anything known harmful and
"The product is a water-insoluble, solid polymer which, under environmental conditions,
is not expected to have a detrimental effect on plants, animals or