When used and maintained properly, cast-iron pans themselves do not contain lead or cadmium. Cast iron is primarily made from iron and carbon, which are safe materials for cooking.
However, it's worth noting that some older or antique cast-iron pans may have been coated with enamel or other materials that could contain heavy metals like lead or cadmium. If you have inherited or acquired an old cast-iron pan with an unknown coating, it is advisable to avoid using it for cooking until you can determine its safety.
In terms of health concerns, using modern, uncoated cast-iron cookware does not pose a risk. Iron is an essential mineral for the body, and cooking with cast iron can actually contribute to your iron intake. Small amounts of iron can leach into food from the pan, which can be beneficial for individuals who are iron deficient. However, the actual amount of iron absorbed from cast iron cookware is generally quite low and unlikely to cause any health issues.
It's important to note that the seasoning (the layer of oil or fat that creates a natural non-stick surface) on cast iron pans does not contain heavy metals and is safe to use.
As with any cookware, it's always a good practice to purchase from reputable manufacturers and ensure that your cast-iron pan is in good condition, properly seasoned, and maintained to ensure its safety and longevity.