Cast iron and lead.

There are so many cast irons and sources - it is hard to tell.
By general spec and use - no. But then a mixture of metal and what source the carbon is from - might make a difference.
Normally it would boil off - due to the low temp - but they make leaded steel by special methods.
Again, almost anything might be in a mix if it isn't a high quality requirement. Then it might be in the carbon used or in the Silicon used. Lead is a mineral found in veins like gold - in quartz. Quartz is a source of Silicon. (kinda like Thorium in soft coal.)
Junk iron like sash weights, lifting weights and counterbalance weights - they can contain everything from the kitchen sink to ball bearings.
If it makes a difference for some reason - and it present it would be nominal - have the metal tested. That is the only way to know.
Be sure you find out the price for and pick the correct test - Qualitative means a go-nogo and is cheapest. Quantitative means how much and cost a lot more.
Martin
Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member
Marco Filo wrote:

Lead is extremely deleterious in cast iron as it causes the graphite to grow tiny spikes on the surface of the flakes. This graphite form is termed "Type F" or "Widmanstatten Graphite".
The effect is to reduce tensile strength dramatically and to reduce what little impact strength there is even further. Its been shown to be detrimental at as low a level as 0.004%w/w.
Hope this helps, Simon