(CNN) -- For many families, having the children help decorate the Christmas tree is a treasured tradition, starting with the strands of lights. But a CNN analysis of four common brands of Christmas lights shows levels of lead experts say are high enough to be dangerous to children.

Manufacturers do not hide the fact that lead is part of the PVC insulation that insulates Christmas light wiring. Lead is used legally to stabilize polyvinyl chloride so it does not crack or crumble with age. The lead also acts as a fire retardant.

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Maybe they weren't hiding it, but it's the first I've heard. Lead is a PVC stabilizer? Criminy - I use PVC quite often. I handle PVC coated cables every day. Nobody told me before. Heck I used to extrude PVC - nasty stuff to breathe incidentally but I still don't remember using any lead in the products we made with it.

Course back in those days huffing hydrochloric acid and all kinds of other nasty stuff was part of the job description. We wore radiation badges - not to protect us from anything, but to tell us after the fact if we received a lethal dose and should quickly make peace with our creator.  Fishing in San Francisco Bay was not yet known to cause liver damage, though it had been doing so for a hundred years. I fished in San Francisco Bay.

So now they say you can get lead poisoning from handling electrical cables. Sigh...