Alphosyl or Polytar?

I was using Polytar for 40 years before it disappeared. I then used Alphosyl which also seemed good. Now Polytar is back and I’ve gone back to it but I really want to find out which has less carsinogenic tar. I’ve just unexpected kidney cancer and I’ve been thinking about how I got it. No family history, I don’t drink much etc. So wondered whether 40 yrs of coal tar might have been involved. Problem is both shampoos work well but I want to use the lower dose one. Alphosyl has Alcoholic extract of coal tar 5# w/w while Polytar has coal tar solution 4%. I don’t understand whether they’re comparing like with like etc. I think in the US coal tar preparations over 5% are banned as they are deemed unacceptably carsinogetic. Any advice from people who understand the chemistry of this better than I do (ie everyone!) would be great.