Safe Drinking Water and Toxic Enforcement Act of 1986 in Life After 60

All you Californians know about Proposition 65. The rest of us not so much, other than what we read on those warning labels. I mention them only because I see them on almost everything.
I just checked (again) and just bout everything I work with has the warning. And here is my concern, “This product is known to the State of California to cause cancer and/or reproductive harm, and birth defects or other reproductive harm.” Does this mean that only the State of California knows this or the chemicals only cause these problems in California.
Perhaps it is a combination of air pollution and additives in the drinking water that causes California to feel the need to issue this warning. I just find the wording strange. But then this is the state that gave us, Nancy Pelosi! Maybe there is some to this Proposition?