Lead paint creates serious health risks, but this ad is from 1939, when lead in paint was normal. Many countries phased in bans starting in the 1970s or 80s, mandating lower and lower concentrations over time, or restricting permissible uses, or both. Some countries still allow unrestricted use of lead paint in 2026.
Lead exposure is very bad for anyone, especially children. Unlike certain other toxins, there's no known safe level of exposure, and it bioaccumulates. There are many other routes into the body besides paint, and some are associated with increased crime rates and intellectual deficits in children.
To me it sounds along the same lines of the curse "may you live in interesting times" or the more mundane "I hope you step on a lego"
Tho yours reminds me of the (I think) Yiddish curse "may all your teeth fall out except one, so you can have a toothache"
I feel there's a bit more nuance to this, like it's the same threat level, but there's an aire of my own suffering in this that I love. Like hoping the coworker that stole your lunch gets the runs from it. That the garbage you dumped on my lawn wafts into your house. Here I am, breaking my back to mine the lead and I can only hope you have to suffer similar damage for living around it.