Definitely true. Nowadays painters use bleached titanium to get a brilliant white, but until the late 19th century lead salts were the norm. Basically you hammer out ingots of lead into flat strips, roll them up into a cylinder, and seal them in ceramic jars full of vinegar for 6 months. When you take them out the lead has turned white and is them ground up into powder and mixed with oil.
You can still get this from a few specialty suppliers and it's reasonably safe to use as long as you wear gloves paint slowly enough that you don't get it all over your skin. Ingested lead is much more dangerous than skin contact, and of course the process of grinding the treated strips of lead into powder was a respiratory and gastric disaster - although people were not completely clueless and apprentices in art studios would often cover their lower face with a wet cloth.