Plasticiser, is what that is.
We had a problem over here with the earlier PVC cables installed in the 60's and 70's.
My boss when I was an apprentice got some in his eye (why you'd rub your eye with that on your fingers, I have no idea, but there you go.)
It's like oil, because PVC itself is made from petroleum products.
I once had some pictures of this stuff (it was coloured green here, because it was corroding the bare earth wire in the cables) running out of the earth slot of a socket-outlet here and down the wall, it gets worse during the summer months when wall temperatures are higher.
Let's face it, these days if you're not young, you're old - Red Green