Is cast iron cookware from China safe?
I should have spent a bit more time searching. One of the searched results that looked like a fear video was actually the opposite. Here is some stuff from that video and comments.

First: Lead boils at about half the temperature that iron melts. So even if you start out with a mix of lead and iron, it won't last long. Second:


  A bit of arithmetic: - Cast Iron Assay can expect Lead content to be 0.001 to 0.15%. (By weight or volume is not significant, see below) My 26.5 cm Chinese skillet, as yet unused (which is why I am researching) weighs 2.1 kg. At 0.15% that is a total lead content of 3.15g. Realistically, how much of that can ever get into the food? Cast iron density is around 6800 - 7800 kg/m3. At the higher figure this works out to a volume for my skillet of 2.1/7800 m^3 = 2.7 x 10^-4 m^3= 270cc. Ignoring the handle and sides, let us consider only the flat cooking surface diameter 20cm, and assume a depth of say 1mm available to leach the lead. Volume of a cylinder = pi r^2 x h = 3.14 x 10cm^2 x 0.1 = 31.4cc. Thus 31.4/270 x 100 = roughly 11.6%. 11.6/100x3.15 = 0.37g = 370μg of lead available. Lead toxicity is at about 10 μg/dL of blood. Average human blood volume is 500dL. So, if ALL the available lead in the pan was taken out AT ONCE, and you managed to absorb it ALL, just into your blood, , you would have a blood level of 370/500 = 0.74μg/dL, about 1/14th the toxic level, before your system kicked it out at around half per 30 days. Go figure.


--flamencoprof

So no, I don't need to worry.

edit: Hmm. The video's figures were wrong. Iron melts at about 1811K and lead boils at about 1749. Close but not quite. Still, from this source it seems that a typical blast furnace should still boil lead.