California does keep adults safe from chemicals already - there's special Prop 65 labels you have to put on things in California if they contain chemicals.
If they contain known substances that cause cancer or birth defects*. There are plenty of substances that can harm you that aren't subject to requiring P65 warnings.
Don't worry, they still can poison the water you use:
https://www.cbsnews.com/news/supreme-court-epa-san-francisco...