Most of the heads you buy through tackle stores are lead, unless you specifically buy lead free heads you're getting real lead head jigs. I've been pouring 30+ years and I have no lead level when my blood is tested. Gloves, glasses, long sleeves, long pants, boots SAFETY!!!!!!!!!!!!!!!!!! pure and simple. Why lead cause it's still cheap and still legal. I'm hoping someone will come out with a material that melts, pours and weighs the same as lead but is lead free but I haven't seen it yet available in to home melters at the same cost as lead.
If you want to pour, pour but follow the safety rules and enjoy your home made products. If you don't want to, just buy the premade heads and paint them, plenty of folks pouring and selling.
Fatman