What is the pupose of the Cancer warning signs posted almost everywhere.in California?

I was just in California – my first visit in well over 40 years. It seemed everywhere I went there were warning signs posted stating something like:“This hotel uses chemicals known to cause cancer.” or “This restaurant uses chemicals…”
The signs seemed ridiculous and a even little embarrassing. What is their purpose? Do Californians change their behavior when they see the signs? Does anyone actually go to a different restaurant, or hotel, or office, etc. if they do not see a sign?
The signs appear to be totally meaningless but maybe there is more to them than meets the eye.
Did some politician have a friend or relative who owned a sign company?